Fossil

  ){
    /* There's a versioned setting, and a non-versioned setting. Tell
    ** the user about the conflict */
    fossil_warning(
        "setting %s has both versioned and non-versioned values: using "
        "versioned value from file .fossil-settings/%s (to silence this "
        "warning, either create an empty file named "

        ".fossil-settings/%s.no-warn or delete the non-versioned setting "
        " with \"fossil unset %s\")", zName, zName, zName, zName
    );
  }
  /* Prefer the versioned setting */
  return ( zVersionedSetting!=0 ) ? zVersionedSetting : zNonVersionedSetting;
}


................................................................................
** %fossil unset PROPERTY ?OPTIONS?
**
** The "settings" command with no arguments lists all properties and their
** values.  With just a property name it shows the value of that property.
** With a value argument it changes the property for the current repository.
**
** Settings marked as versionable are overridden by the contents of the
** file named .fossil-settings/PROPERTY in the checked out files, if that
** file exists.
**
** The "unset" command clears a property setting.
**
**
**    access-log       If enabled, record successful and failed login attempts
**                     in the "accesslog" table.  Default: off

  ){
    /* There's a versioned setting, and a non-versioned setting. Tell
    ** the user about the conflict */
    fossil_warning(
        "setting %s has both versioned and non-versioned values: using "
        "versioned value from file .fossil-settings/%s (to silence this "
        "warning, either create an empty file named "
        ".fossil-settings/%s.no-warn in the check-out root, "
        "or delete the non-versioned setting "
        "with \"fossil unset %s\")", zName, zName, zName, zName
    );
  }
  /* Prefer the versioned setting */
  return ( zVersionedSetting!=0 ) ? zVersionedSetting : zNonVersionedSetting;
}


................................................................................
** %fossil unset PROPERTY ?OPTIONS?
**
** The "settings" command with no arguments lists all properties and their
** values.  With just a property name it shows the value of that property.
** With a value argument it changes the property for the current repository.
**
** Settings marked as versionable are overridden by the contents of the
** file named .fossil-settings/PROPERTY in the check-out root, if that
** file exists.
**
** The "unset" command clears a property setting.
**
**
**    access-log       If enabled, record successful and failed login attempts
**                     in the "accesslog" table.  Default: off

static void linenoiseAtExit(void);
int linenoiseHistoryAdd(const char *line);
static void refreshLine(struct linenoiseState *l);

/* Debugging macro. */
#if 0
FILE *lndebug_fp = NULL;
#define lndebug(...) \
    do { \
        if (lndebug_fp == NULL) { \
            lndebug_fp = fopen("/tmp/lndebug.txt","a"); \
            fprintf(lndebug_fp, \
            "[%d %d %d] p: %d, rows: %d, rpos: %d, max: %d, oldmax: %d\n", \
            (int)l->len,(int)l->pos,(int)l->oldpos,plen,rows,rpos, \
            (int)l->maxrows,old_rows); \
        } \
        fprintf(lndebug_fp, ", " __VA_ARGS__); \
        fflush(lndebug_fp); \
    } while (0)
#else
#define lndebug(fmt, ...)
#endif

/* ======================= Low level terminal handling ====================== */

/* Set if to use or not the multi line mode. */
void linenoiseSetMultiLine(int ml) {
    mlmode = ml;
................................................................................
        lndebug("go down %d", old_rows-rpos);
        snprintf(seq,64,"\x1b[%dB", old_rows-rpos);
        abAppend(&ab,seq,strlen(seq));
    }

    /* Now for every row clear it, go up. */
    for (j = 0; j < old_rows-1; j++) {
        lndebug("clear+up");
        snprintf(seq,64,"\r\x1b[0K\x1b[1A");
        abAppend(&ab,seq,strlen(seq));
    }

    /* Clean the top line. */
    lndebug("clear");
    snprintf(seq,64,"\r\x1b[0K");
    abAppend(&ab,seq,strlen(seq));

    /* Write the prompt and the current buffer content */
    abAppend(&ab,l->prompt,strlen(l->prompt));
    abAppend(&ab,l->buf,l->len);

    /* If we are at the very end of the screen with our prompt, we need to
     * emit a newline and move the prompt to the first column. */
    if (l->pos &&
        l->pos == l->len &&
        (l->pos+plen) % l->cols == 0)
    {
        lndebug("<newline>");
        abAppend(&ab,"\n",1);
        snprintf(seq,64,"\r");
        abAppend(&ab,seq,strlen(seq));
        rows++;
        if (rows > (int)l->maxrows) l->maxrows = rows;
    }

................................................................................
    lndebug("set col %d", 1+col);
    if (col)
        snprintf(seq,64,"\r\x1b[%dC", col);
    else
        snprintf(seq,64,"\r");
    abAppend(&ab,seq,strlen(seq));

    lndebug("\n");
    l->oldpos = l->pos;

    if (write(fd,ab.b,ab.len) == -1) {} /* Can't recover from write error. */
    abFree(&ab);
}

/* Calls the two low level functions refreshSingleLine() or

static void linenoiseAtExit(void);
int linenoiseHistoryAdd(const char *line);
static void refreshLine(struct linenoiseState *l);

/* Debugging macro. */
#if 0
FILE *lndebug_fp = NULL;
#define lndebug(fmt, arg1) \
    do { \
        if (lndebug_fp == NULL) { \
            lndebug_fp = fopen("/tmp/lndebug.txt","a"); \
            fprintf(lndebug_fp, \
            "[%d %d %d] p: %d, rows: %d, rpos: %d, max: %d, oldmax: %d\n", \
            (int)l->len,(int)l->pos,(int)l->oldpos,plen,rows,rpos, \
            (int)l->maxrows,old_rows); \
        } \
        fprintf(lndebug_fp, ", " fmt, arg1); \
        fflush(lndebug_fp); \
    } while (0)
#else
#define lndebug(fmt, arg1)
#endif

/* ======================= Low level terminal handling ====================== */

/* Set if to use or not the multi line mode. */
void linenoiseSetMultiLine(int ml) {
    mlmode = ml;
................................................................................
        lndebug("go down %d", old_rows-rpos);
        snprintf(seq,64,"\x1b[%dB", old_rows-rpos);
        abAppend(&ab,seq,strlen(seq));
    }

    /* Now for every row clear it, go up. */
    for (j = 0; j < old_rows-1; j++) {
        lndebug("clear+up", 0);
        snprintf(seq,64,"\r\x1b[0K\x1b[1A");
        abAppend(&ab,seq,strlen(seq));
    }

    /* Clean the top line. */
    lndebug("clear", 0);
    snprintf(seq,64,"\r\x1b[0K");
    abAppend(&ab,seq,strlen(seq));

    /* Write the prompt and the current buffer content */
    abAppend(&ab,l->prompt,strlen(l->prompt));
    abAppend(&ab,l->buf,l->len);

    /* If we are at the very end of the screen with our prompt, we need to
     * emit a newline and move the prompt to the first column. */
    if (l->pos &&
        l->pos == l->len &&
        (l->pos+plen) % l->cols == 0)
    {
        lndebug("<newline>", 0);
        abAppend(&ab,"\n",1);
        snprintf(seq,64,"\r");
        abAppend(&ab,seq,strlen(seq));
        rows++;
        if (rows > (int)l->maxrows) l->maxrows = rows;
    }

................................................................................
    lndebug("set col %d", 1+col);
    if (col)
        snprintf(seq,64,"\r\x1b[%dC", col);
    else
        snprintf(seq,64,"\r");
    abAppend(&ab,seq,strlen(seq));

    lndebug("\n", 0);
    l->oldpos = l->pos;

    if (write(fd,ab.b,ab.len) == -1) {} /* Can't recover from write error. */
    abFree(&ab);
}

/* Calls the two low level functions refreshSingleLine() or

                      (char*)pSet->def, hasVersionableValue);
      @<br />
    }
  }
  @ </td></tr></table>
  @ </div></form>
  @ <p>Settings marked with (v) are 'versionable' and will be overridden
  @ by the contents of files named <tt>.fossil-settings/PROPERTY</tt>.

  @ If such a file is present, the corresponding field above is not
  @ editable.</p><hr /><p>
  @ These settings work in the same way, as the <kbd>set</kbd>
  @ commandline:<br />
  @ </p><pre>%s(zHelp_setting_cmd)</pre>
  db_end_transaction(0);
  style_footer();

                      (char*)pSet->def, hasVersionableValue);
      @<br />
    }
  }
  @ </td></tr></table>
  @ </div></form>
  @ <p>Settings marked with (v) are 'versionable' and will be overridden
  @ by the contents of files named <tt>.fossil-settings/PROPERTY</tt>
  @ in the check-out root.
  @ If such a file is present, the corresponding field above is not
  @ editable.</p><hr /><p>
  @ These settings work in the same way, as the <kbd>set</kbd>
  @ commandline:<br />
  @ </p><pre>%s(zHelp_setting_cmd)</pre>
  db_end_transaction(0);
  style_footer();

**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.8.11"
#define SQLITE_VERSION_NUMBER 3008011
#define SQLITE_SOURCE_ID      "2015-07-08 16:22:42 5348ffc3fda5168c1e9e14aa88b0c6aedbda7c94"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version, sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
................................................................................
** circumstances in order to fix a problem with priority inversion.
** Applications should <em>not</em> use this file-control.
**
** <li>[[SQLITE_FCNTL_ZIPVFS]]
** The [SQLITE_FCNTL_ZIPVFS] opcode is implemented by zipvfs only. All other
** VFS should return SQLITE_NOTFOUND for this opcode.
**
** <li>[[SQLITE_FCNTL_OTA]]
** The [SQLITE_FCNTL_OTA] opcode is implemented by the special VFS used by
** the OTA extension only.  All other VFS should return SQLITE_NOTFOUND for
** this opcode.  
** </ul>
*/
#define SQLITE_FCNTL_LOCKSTATE               1
#define SQLITE_FCNTL_GET_LOCKPROXYFILE       2
#define SQLITE_FCNTL_SET_LOCKPROXYFILE       3
#define SQLITE_FCNTL_LAST_ERRNO              4
................................................................................
#define SQLITE_FCNTL_TRACE                  19
#define SQLITE_FCNTL_HAS_MOVED              20
#define SQLITE_FCNTL_SYNC                   21
#define SQLITE_FCNTL_COMMIT_PHASETWO        22
#define SQLITE_FCNTL_WIN32_SET_HANDLE       23
#define SQLITE_FCNTL_WAL_BLOCK              24
#define SQLITE_FCNTL_ZIPVFS                 25
#define SQLITE_FCNTL_OTA                    26

/* deprecated names */
#define SQLITE_GET_LOCKPROXYFILE      SQLITE_FCNTL_GET_LOCKPROXYFILE
#define SQLITE_SET_LOCKPROXYFILE      SQLITE_FCNTL_SET_LOCKPROXYFILE
#define SQLITE_LAST_ERRNO             SQLITE_FCNTL_LAST_ERRNO


................................................................................
#  define SQLITE_NOINLINE
#endif

/*
** Make sure that the compiler intrinsics we desire are enabled when
** compiling with an appropriate version of MSVC.
*/
#if defined(_MSC_VER) && _MSC_VER>=1300
#  include <intrin.h>
#  pragma intrinsic(_byteswap_ushort)
#  pragma intrinsic(_byteswap_ulong)
#endif

/*
** The SQLITE_THREADSAFE macro must be defined as 0, 1, or 2.
................................................................................
#   define SQLITE_MAX_MMAP_SIZE 0
# endif
#endif
#ifndef SQLITE_MAX_MMAP_SIZE
# if defined(__linux__) \
  || defined(_WIN32) \
  || (defined(__APPLE__) && defined(__MACH__)) \
  || defined(__sun)


#   define SQLITE_MAX_MMAP_SIZE 0x7fff0000  /* 2147418112 */
# else
#   define SQLITE_MAX_MMAP_SIZE 0
# endif
# define SQLITE_MAX_MMAP_SIZE_xc 1 /* exclude from ctime.c */
#endif

................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains definitions of global variables and constants.
*/


/* An array to map all upper-case characters into their corresponding
** lower-case character. 
**
** SQLite only considers US-ASCII (or EBCDIC) characters.  We do not
** handle case conversions for the UTF character set since the tables
** involved are nearly as big or bigger than SQLite itself.
................................................................................
** Changing the pending byte during operation will result in undefined
** and incorrect behavior.
*/
#ifndef SQLITE_OMIT_WSD
SQLITE_PRIVATE int sqlite3PendingByte = 0x40000000;
#endif


/*
** Properties of opcodes.  The OPFLG_INITIALIZER macro is
** created by mkopcodeh.awk during compilation.  Data is obtained
** from the comments following the "case OP_xxxx:" statements in
** the vdbe.c file.  
*/
SQLITE_PRIVATE const unsigned char sqlite3OpcodeProperty[] = OPFLG_INITIALIZER;
................................................................................
**
** This file implements routines used to report what compile-time options
** SQLite was built with.
*/

#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS



/*
** An array of names of all compile-time options.  This array should 
** be sorted A-Z.
**
** This array looks large, but in a typical installation actually uses
** only a handful of compile-time options, so most times this array is usually
................................................................................
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This module implements the sqlite3_status() interface and related
** functionality.
*/

/************** Include vdbeInt.h in the middle of status.c ******************/
/************** Begin file vdbeInt.h *****************************************/
/*
** 2003 September 6
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
................................................................................
**
**      Jean Meeus
**      Astronomical Algorithms, 2nd Edition, 1998
**      ISBM 0-943396-61-1
**      Willmann-Bell, Inc
**      Richmond, Virginia (USA)
*/

/* #include <stdlib.h> */
/* #include <assert.h> */
#include <time.h>

#ifndef SQLITE_OMIT_DATETIME_FUNCS


................................................................................
    p->D = 1;
  }else{
    Z = (int)((p->iJD + 43200000)/86400000);
    A = (int)((Z - 1867216.25)/36524.25);
    A = Z + 1 + A - (A/4);
    B = A + 1524;
    C = (int)((B - 122.1)/365.25);
    D = (36525*C)/100;
    E = (int)((B-D)/30.6001);
    X1 = (int)(30.6001*E);
    p->D = B - D - X1;
    p->M = E<14 ? E-1 : E-13;
    p->Y = p->M>2 ? C - 4716 : C - 4715;
  }
  p->validYMD = 1;
................................................................................
**
******************************************************************************
**
** This file contains OS interface code that is common to all
** architectures.
*/
#define _SQLITE_OS_C_ 1

#undef _SQLITE_OS_C_

/*
** The default SQLite sqlite3_vfs implementations do not allocate
** memory (actually, os_unix.c allocates a small amount of memory
** from within OsOpen()), but some third-party implementations may.
** So we test the effects of a malloc() failing and the sqlite3OsXXX()
................................................................................
** SQLITE_NOMEM) to the user. However, sometimes a fault is not necessarily
** fatal. For example, if a malloc fails while resizing a hash table, this 
** is completely recoverable simply by not carrying out the resize. The 
** hash table will continue to function normally.  So a malloc failure 
** during a hash table resize is a benign fault.
*/



#ifndef SQLITE_OMIT_BUILTIN_TEST

/*
** Global variables.
*/
typedef struct BenignMallocHooks BenignMallocHooks;
................................................................................
**
** This file contains a no-op memory allocation drivers for use when
** SQLITE_ZERO_MALLOC is defined.  The allocation drivers implemented
** here always fail.  SQLite will not operate with these drivers.  These
** are merely placeholders.  Real drivers must be substituted using
** sqlite3_config() before SQLite will operate.
*/


/*
** This version of the memory allocator is the default.  It is
** used when no other memory allocator is specified using compile-time
** macros.
*/
#ifdef SQLITE_ZERO_MALLOC
................................................................................
**                                building on older macs.
**
**    SQLITE_WITHOUT_MSIZE        Set this symbol to disable the use of
**                                _msize() on windows systems.  This might
**                                be necessary when compiling for Delphi,
**                                for example.
*/


/*
** This version of the memory allocator is the default.  It is
** used when no other memory allocator is specified using compile-time
** macros.
*/
#ifdef SQLITE_SYSTEM_MALLOC
................................................................................
** to obtain the memory it needs while adding lots of additional debugging
** information to each allocation in order to help detect and fix memory
** leaks and memory usage errors.
**
** This file contains implementations of the low-level memory allocation
** routines specified in the sqlite3_mem_methods object.
*/


/*
** This version of the memory allocator is used only if the
** SQLITE_MEMDEBUG macro is defined
*/
#ifdef SQLITE_MEMDEBUG

................................................................................
** implementations. Once sqlite3_initialize() has been called,
** the amount of memory available to SQLite is fixed and cannot
** be changed.
**
** This version of the memory allocation subsystem is included
** in the build only if SQLITE_ENABLE_MEMSYS3 is defined.
*/


/*
** This version of the memory allocator is only built into the library
** SQLITE_ENABLE_MEMSYS3 is defined. Defining this symbol does not
** mean that the library will use a memory-pool by default, just that
** it is available. The mempool allocator is activated by calling
** sqlite3_config().
................................................................................
** fragmentation as long as the following constraint holds:
**
**      N >=  M*(1 + log2(n)/2) - n + 1
**
** The sqlite3_status() logic tracks the maximum values of n and M so
** that an application can, at any time, verify this constraint.
*/


/*
** This version of the memory allocator is used only when 
** SQLITE_ENABLE_MEMSYS5 is defined.
*/
#ifdef SQLITE_ENABLE_MEMSYS5

................................................................................
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement mutexes.
**
** This file contains code that is common across all mutex implementations.
*/


#if defined(SQLITE_DEBUG) && !defined(SQLITE_MUTEX_OMIT)
/*
** For debugging purposes, record when the mutex subsystem is initialized
** and uninitialized so that we can assert() if there is an attempt to
** allocate a mutex while the system is uninitialized.
*/
................................................................................
**
** interface.
**
** If compiled with SQLITE_DEBUG, then additional logic is inserted
** that does error checking on mutexes to make sure they are being
** called correctly.
*/


#ifndef SQLITE_MUTEX_OMIT

#ifndef SQLITE_DEBUG
/*
** Stub routines for all mutex methods.
**
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement mutexes for pthreads
*/


/*
** The code in this file is only used if we are compiling threadsafe
** under unix with pthreads.
**
** Note that this implementation requires a version of pthreads that
** supports recursive mutexes.
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement mutexes for Win32.
*/


#if SQLITE_OS_WIN
/*
** Include code that is common to all os_*.c files
*/
/************** Include os_common.h in the middle of mutex_w32.c *************/
/************** Begin file os_common.h ***************************************/
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** Memory allocation functions used throughout sqlite.
*/

/* #include <stdarg.h> */

/*
** Attempt to release up to n bytes of non-essential memory currently
** held by SQLite. An example of non-essential memory is memory used to
** cache database pages that are not currently in use.
*/
................................................................................
**************************************************************************
**
** This file contains code for a set of "printf"-like routines.  These
** routines format strings much like the printf() from the standard C
** library, though the implementation here has enhancements to support
** SQLite.
*/


/*
** Conversion types fall into various categories as defined by the
** following enumeration.
*/
#define etRADIX       1 /* Integer types.  %d, %x, %o, and so forth */
#define etFLOAT       2 /* Floating point.  %f */
................................................................................
** This is the routine that actually formats the sqlite3_log() message.
** We house it in a separate routine from sqlite3_log() to avoid using
** stack space on small-stack systems when logging is disabled.
**
** sqlite3_log() must render into a static buffer.  It cannot dynamically
** allocate memory because it might be called while the memory allocator
** mutex is held.





*/
static void renderLogMsg(int iErrCode, const char *zFormat, va_list ap){
  StrAccum acc;                          /* String accumulator */
  char zMsg[SQLITE_PRINT_BUF_SIZE*3];    /* Complete log message */

  sqlite3StrAccumInit(&acc, 0, zMsg, sizeof(zMsg), 0);
  sqlite3VXPrintf(&acc, 0, zFormat, ap);
................................................................................
** This file contains C code to implement the TreeView debugging routines.
** These routines print a parse tree to standard output for debugging and
** analysis. 
**
** The interfaces in this file is only available when compiling
** with SQLITE_DEBUG.
*/

#ifdef SQLITE_DEBUG

/*
** Add a new subitem to the tree.  The moreToFollow flag indicates that this
** is not the last item in the tree.
*/
static TreeView *sqlite3TreeViewPush(TreeView *p, u8 moreToFollow){
................................................................................
*************************************************************************
** This file contains code to implement a pseudo-random number
** generator (PRNG) for SQLite.
**
** Random numbers are used by some of the database backends in order
** to generate random integer keys for tables or random filenames.
*/



/* All threads share a single random number generator.
** This structure is the current state of the generator.
*/
static SQLITE_WSD struct sqlite3PrngType {
  unsigned char isInit;          /* True if initialized */
................................................................................
** "thread" is done by the main thread at either the sqlite3ThreadCreate()
** or sqlite3ThreadJoin() call.  This is, in fact, what happens in
** single threaded systems.  Nothing in SQLite requires multiple threads.
** This interface exists so that applications that want to take advantage
** of multiple cores can do so, while also allowing applications to stay
** single-threaded if desired.
*/

#if SQLITE_OS_WIN

#endif

#if SQLITE_MAX_WORKER_THREADS>0

/********************************* Unix Pthreads ****************************/
#if SQLITE_OS_UNIX && defined(SQLITE_MUTEX_PTHREADS) && SQLITE_THREADSAFE>0

................................................................................
**
**
** BOM or Byte Order Mark:
**     0xff 0xfe   little-endian utf-16 follows
**     0xfe 0xff   big-endian utf-16 follows
**
*/

/* #include <assert.h> */


#ifndef SQLITE_AMALGAMATION
/*
** The following constant value is used by the SQLITE_BIGENDIAN and
** SQLITE_LITTLEENDIAN macros.
*/
SQLITE_PRIVATE const int sqlite3one = 1;
................................................................................
*************************************************************************
** Utility functions used throughout sqlite.
**
** This file contains functions for allocating memory, comparing
** strings, and stuff like that.
**
*/

/* #include <stdarg.h> */
#if HAVE_ISNAN || SQLITE_HAVE_ISNAN
# include <math.h>
#endif

/*
** Routine needed to support the testcase() macro.
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This is the implementation of generic hash-tables
** used in SQLite.
*/

/* #include <assert.h> */

/* Turn bulk memory into a hash table object by initializing the
** fields of the Hash structure.
**
** "pNew" is a pointer to the hash table that is to be initialized.
*/
................................................................................
**   *  Definitions of sqlite3_io_methods objects for all locking
**      methods plus "finder" functions for each locking method.
**   *  sqlite3_vfs method implementations.
**   *  Locking primitives for the proxy uber-locking-method. (MacOSX only)
**   *  Definitions of sqlite3_vfs objects for all locking methods
**      plus implementations of sqlite3_os_init() and sqlite3_os_end().
*/

#if SQLITE_OS_UNIX              /* This file is used on unix only */

/*
** There are various methods for file locking used for concurrency
** control:
**
**   1. POSIX locking (the default),
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains code that is specific to Windows.
*/

#if SQLITE_OS_WIN               /* This file is used for Windows only */

/*
** Include code that is common to all os_*.c files
*/
/************** Include os_common.h in the middle of os_win.c ****************/
/************** Begin file os_common.h ***************************************/
................................................................................

/************** End of os_common.h *******************************************/
/************** Continuing where we left off in os_win.c *********************/

/*
** Include the header file for the Windows VFS.
*/


/*
** Compiling and using WAL mode requires several APIs that are only
** available in Windows platforms based on the NT kernel.
*/
#if !SQLITE_OS_WINNT && !defined(SQLITE_OMIT_WAL)
#  error "WAL mode requires support from the Windows NT kernel, compile\
................................................................................
** Clear operations are exceedingly rare.  There are usually between
** 5 and 500 set operations per Bitvec object, though the number of sets can
** sometimes grow into tens of thousands or larger.  The size of the
** Bitvec object is the number of pages in the database file at the
** start of a transaction, and is thus usually less than a few thousand,
** but can be as large as 2 billion for a really big database.
*/


/* Size of the Bitvec structure in bytes. */
#define BITVEC_SZ        512

/* Round the union size down to the nearest pointer boundary, since that's how 
** it will be aligned within the Bitvec struct. */
#define BITVEC_USIZE     (((BITVEC_SZ-(3*sizeof(u32)))/sizeof(Bitvec*))*sizeof(Bitvec*))
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file implements that page cache.
*/


/*
** A complete page cache is an instance of this structure.
*/
struct PCache {
  PgHdr *pDirty, *pDirtyTail;         /* List of dirty pages in LRU order */
  PgHdr *pSynced;                     /* Last synced page in dirty page list */
................................................................................
** (3) is exhausted, subsequent allocations fail over to the general-purpose
** memory allocator (1).
**
** Earlier versions of SQLite used only methods (1) and (2).  But experiments
** show that method (3) with N==100 provides about a 5% performance boost for
** common workloads.
*/


typedef struct PCache1 PCache1;
typedef struct PgHdr1 PgHdr1;
typedef struct PgFreeslot PgFreeslot;
typedef struct PGroup PGroup;

/* Each page cache (or PCache) belongs to a PGroup.  A PGroup is a set 
................................................................................
  /* Variables related to SQLITE_CONFIG_PAGECACHE settings.  The
  ** szSlot, nSlot, pStart, pEnd, nReserve, and isInit values are all
  ** fixed at sqlite3_initialize() time and do not require mutex protection.
  ** The nFreeSlot and pFree values do require mutex protection.
  */
  int isInit;                    /* True if initialized */
  int separateCache;             /* Use a new PGroup for each PCache */

  int szSlot;                    /* Size of each free slot */
  int nSlot;                     /* The number of pcache slots */
  int nReserve;                  /* Try to keep nFreeSlot above this */
  void *pStart, *pEnd;           /* Bounds of global page cache memory */
  /* Above requires no mutex.  Use mutex below for variable that follow. */
  sqlite3_mutex *mutex;          /* Mutex for accessing the following: */
  PgFreeslot *pFree;             /* Free page blocks */
................................................................................
      p->pNext = pcache1.pFree;
      pcache1.pFree = p;
      pBuf = (void*)&((char*)pBuf)[sz];
    }
    pcache1.pEnd = pBuf;
  }
}






































/*
** Malloc function used within this file to allocate space from the buffer
** configured using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no 
** such buffer exists or there is no space left in it, this function falls 
** back to sqlite3Malloc().
**
................................................................................
** Allocate a new page object initially associated with cache pCache.
*/
static PgHdr1 *pcache1AllocPage(PCache1 *pCache){
  PgHdr1 *p = 0;
  void *pPg;

  assert( sqlite3_mutex_held(pCache->pGroup->mutex) );
  if( pCache->pFree ){
    p = pCache->pFree;
    pCache->pFree = p->pNext;
    p->pNext = 0;
  }else{
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
    /* The group mutex must be released before pcache1Alloc() is called. This
    ** is because it might call sqlite3_release_memory(), which assumes that 
................................................................................
  if( freeFlag ) pcache1FreePage(pPage);
}

/*
** If there are currently more than nMaxPage pages allocated, try
** to recycle pages to reduce the number allocated to nMaxPage.
*/
static void pcache1EnforceMaxPage(PGroup *pGroup){

  assert( sqlite3_mutex_held(pGroup->mutex) );
  while( pGroup->nCurrentPage>pGroup->nMaxPage && pGroup->pLruTail ){
    PgHdr1 *p = pGroup->pLruTail;
    assert( p->pCache->pGroup==pGroup );
    assert( p->isPinned==0 );
    pcache1PinPage(p);
    pcache1RemoveFromHash(p, 1);




  }
}

/*
** Discard all pages from cache pCache with a page number (key value) 
** greater than or equal to iLimit. Any pinned pages that meet this 
** criteria are unpinned before they are discarded.
................................................................................

#if SQLITE_THREADSAFE
  if( sqlite3GlobalConfig.bCoreMutex ){
    pcache1.grp.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU);
    pcache1.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_PMEM);
  }
#endif








  pcache1.grp.mxPinned = 10;
  pcache1.isInit = 1;
  return SQLITE_OK;
}

/*
** Implementation of the sqlite3_pcache.xShutdown method.
................................................................................
    pcache1ResizeHash(pCache);
    if( bPurgeable ){
      pCache->nMin = 10;
      pGroup->nMinPage += pCache->nMin;
      pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;
    }
    pcache1LeaveMutex(pGroup);
    /* Try to initialize the local bulk pagecache line allocation if using
    ** separate caches and if nPage!=0 */
    if( pcache1.separateCache
     && sqlite3GlobalConfig.nPage!=0
     && sqlite3GlobalConfig.pPage==0
    ){
      int szBulk;
      char *zBulk;
      sqlite3BeginBenignMalloc();
      if( sqlite3GlobalConfig.nPage>0 ){
        szBulk = pCache->szAlloc * sqlite3GlobalConfig.nPage;
      }else{
        szBulk = -1024*sqlite3GlobalConfig.nPage;
      }
      zBulk = pCache->pBulk = sqlite3Malloc( szBulk );
      sqlite3EndBenignMalloc();
      if( zBulk ){
        int nBulk = sqlite3MallocSize(zBulk)/pCache->szAlloc;
        int i;
        for(i=0; i<nBulk; i++){
          PgHdr1 *pX = (PgHdr1*)&zBulk[szPage];
          pX->page.pBuf = zBulk;
          pX->page.pExtra = &pX[1];
          pX->isBulkLocal = 1;
          pX->pNext = pCache->pFree;
          pCache->pFree = pX;
          zBulk += pCache->szAlloc;
        }
      }
    }
    if( pCache->nHash==0 ){
      pcache1Destroy((sqlite3_pcache*)pCache);
      pCache = 0;
    }
  }
  return (sqlite3_pcache *)pCache;
}
................................................................................
  if( pCache->bPurgeable ){
    PGroup *pGroup = pCache->pGroup;
    pcache1EnterMutex(pGroup);
    pGroup->nMaxPage += (nMax - pCache->nMax);
    pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;
    pCache->nMax = nMax;
    pCache->n90pct = pCache->nMax*9/10;
    pcache1EnforceMaxPage(pGroup);
    pcache1LeaveMutex(pGroup);
  }
}

/*
** Implementation of the sqlite3_pcache.xShrink method. 
**
................................................................................
  PCache1 *pCache = (PCache1*)p;
  if( pCache->bPurgeable ){
    PGroup *pGroup = pCache->pGroup;
    int savedMaxPage;
    pcache1EnterMutex(pGroup);
    savedMaxPage = pGroup->nMaxPage;
    pGroup->nMaxPage = 0;
    pcache1EnforceMaxPage(pGroup);
    pGroup->nMaxPage = savedMaxPage;
    pcache1LeaveMutex(pGroup);
  }
}

/*
** Implementation of the sqlite3_pcache.xPagecount method. 
................................................................................
  pcache1EnterMutex(pGroup);
  pcache1TruncateUnsafe(pCache, 0);
  assert( pGroup->nMaxPage >= pCache->nMax );
  pGroup->nMaxPage -= pCache->nMax;
  assert( pGroup->nMinPage >= pCache->nMin );
  pGroup->nMinPage -= pCache->nMin;
  pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;
  pcache1EnforceMaxPage(pGroup);
  pcache1LeaveMutex(pGroup);
  sqlite3_free(pCache->pBulk);
  sqlite3_free(pCache->apHash);
  sqlite3_free(pCache);
}

/*
................................................................................
** The cost of a TEST using the same batch number is O(logN).  The cost
** of the first SMALLEST is O(NlogN).  Second and subsequent SMALLEST
** primitives are constant time.  The cost of DESTROY is O(N).
**
** There is an added cost of O(N) when switching between TEST and
** SMALLEST primitives.
*/



/*
** Target size for allocation chunks.
*/
#define ROWSET_ALLOCATION_SIZE 1024

................................................................................
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
*/
#ifndef SQLITE_OMIT_DISKIO

/************** Include wal.h in the middle of pager.c ***********************/
/************** Begin file wal.h *********************************************/
/*
** 2010 February 1
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
................................................................................
** system. Refer to the comments below and the header comment attached to 
** the implementation of each function in log.c for further details.
*/

#ifndef _WAL_H_
#define _WAL_H_



/* Additional values that can be added to the sync_flags argument of
** sqlite3WalFrames():
*/
#define WAL_SYNC_TRANSACTIONS  0x20   /* Sync at the end of each transaction */
#define SQLITE_SYNC_MASK       0x13   /* Mask off the SQLITE_SYNC_* values */

................................................................................
**
** When a rollback occurs, the value of K is decreased. Hash table entries
** that correspond to frames greater than the new K value are removed
** from the hash table at this point.
*/
#ifndef SQLITE_OMIT_WAL



/*
** Trace output macros
*/
#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
SQLITE_PRIVATE int sqlite3WalTrace = 0;
# define WALTRACE(X)  if(sqlite3WalTrace) sqlite3DebugPrintf X
................................................................................
  volatile WalIndexHdr *aHdr = walIndexHdr(pWal);
  const int nCksum = offsetof(WalIndexHdr, aCksum);

  assert( pWal->writeLock );
  pWal->hdr.isInit = 1;
  pWal->hdr.iVersion = WALINDEX_MAX_VERSION;
  walChecksumBytes(1, (u8*)&pWal->hdr, nCksum, 0, pWal->hdr.aCksum);
  memcpy((void *)&aHdr[1], (void *)&pWal->hdr, sizeof(WalIndexHdr));
  walShmBarrier(pWal);
  memcpy((void *)&aHdr[0], (void *)&pWal->hdr, sizeof(WalIndexHdr));
}

/*
** This function encodes a single frame header and writes it to a buffer
** supplied by the caller. A frame-header is made up of a series of 
** 4-byte big-endian integers, as follows:
**
................................................................................
  memset((void *)&aPgno[iLimit+1], 0, nByte);

#ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT
  /* Verify that the every entry in the mapping region is still reachable
  ** via the hash table even after the cleanup.
  */
  if( iLimit ){
    int i;           /* Loop counter */
    int iKey;        /* Hash key */
    for(i=1; i<=iLimit; i++){
      for(iKey=walHash(aPgno[i]); aHash[iKey]; iKey=walNextHash(iKey)){
        if( aHash[iKey]==i ) break;
      }
      assert( aHash[iKey]==i );
    }
  }
#endif /* SQLITE_ENABLE_EXPENSIVE_ASSERT */
}


/*
................................................................................
    ht_slot *aList;               /* Pointer to sub-list content */
  };

  const int nList = *pnList;      /* Size of input list */
  int nMerge = 0;                 /* Number of elements in list aMerge */
  ht_slot *aMerge = 0;            /* List to be merged */
  int iList;                      /* Index into input list */
  int iSub = 0;                   /* Index into aSub array */
  struct Sublist aSub[13];        /* Array of sub-lists */

  memset(aSub, 0, sizeof(aSub));
  assert( nList<=HASHTABLE_NPAGE && nList>0 );
  assert( HASHTABLE_NPAGE==(1<<(ArraySize(aSub)-1)) );

  for(iList=0; iList<nList; iList++){
    nMerge = 1;
    aMerge = &aList[iList];
    for(iSub=0; iList & (1<<iSub); iSub++){
      struct Sublist *p = &aSub[iSub];


      assert( p->aList && p->nList<=(1<<iSub) );
      assert( p->aList==&aList[iList&~((2<<iSub)-1)] );
      walMerge(aContent, p->aList, p->nList, &aMerge, &nMerge, aBuffer);
    }
    aSub[iSub].aList = aMerge;
    aSub[iSub].nList = nMerge;
  }

  for(iSub++; iSub<ArraySize(aSub); iSub++){
    if( nList & (1<<iSub) ){
      struct Sublist *p = &aSub[iSub];


      assert( p->nList<=(1<<iSub) );
      assert( p->aList==&aList[nList&~((2<<iSub)-1)] );
      walMerge(aContent, p->aList, p->nList, &aMerge, &nMerge, aBuffer);
    }
  }
  assert( aMerge==aList );
  *pnList = nMerge;
................................................................................
** unspecified.  A trunk page looks like this:
**
**    SIZE    DESCRIPTION
**      4     Page number of next trunk page
**      4     Number of leaf pointers on this page
**      *     zero or more pages numbers of leaves
*/



/* The following value is the maximum cell size assuming a maximum page
** size give above.
*/
#define MX_CELL_SIZE(pBt)  ((int)(pBt->pageSize-8))

................................................................................
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file implements an external (disk-based) database using BTrees.
** See the header comment on "btreeInt.h" for additional information.
** Including a description of file format and an overview of operation.
*/


/*
** The header string that appears at the beginning of every
** SQLite database.
*/
static const char zMagicHeader[] = SQLITE_FILE_HEADER;

................................................................................
  u32 usableSize;          /* Usable size of the page */
  u32 contentOffset;       /* Offset to the start of the cell content area */
  u32 *heap = 0;           /* Min-heap used for checking cell coverage */
  u32 x, prev = 0;         /* Next and previous entry on the min-heap */
  const char *saved_zPfx = pCheck->zPfx;
  int saved_v1 = pCheck->v1;
  int saved_v2 = pCheck->v2;
  u8 savedIsInit;

  /* Check that the page exists
  */
  pBt = pCheck->pBt;
  usableSize = pBt->usableSize;
  if( iPage==0 ) return 0;
  if( checkRef(pCheck, iPage) ) return 0;
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the implementation of the sqlite3_backup_XXX() 
** API functions and the related features.
*/



/*
** Structure allocated for each backup operation.
*/
struct sqlite3_backup {
  sqlite3* pDestDb;        /* Destination database handle */
  Btree *pDest;            /* Destination b-tree file */
................................................................................
*************************************************************************
**
** This file contains code use to manipulate "Mem" structure.  A "Mem"
** stores a single value in the VDBE.  Mem is an opaque structure visible
** only within the VDBE.  Interface routines refer to a Mem using the
** name sqlite_value
*/



#ifdef SQLITE_DEBUG
/*
** Check invariants on a Mem object.
**
** This routine is intended for use inside of assert() statements, like
** this:    assert( sqlite3VdbeCheckMemInvariants(pMem) );
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used for creating, destroying, and populating
** a VDBE (or an "sqlite3_stmt" as it is known to the outside world.) 
*/



/*
** Create a new virtual database engine.
*/
SQLITE_PRIVATE Vdbe *sqlite3VdbeCreate(Parse *pParse){
  sqlite3 *db = pParse->db;
  Vdbe *p;
................................................................................
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains code use to implement APIs that are part of the
** VDBE.
*/



#ifndef SQLITE_OMIT_DEPRECATED
/*
** Return TRUE (non-zero) of the statement supplied as an argument needs
** to be recompiled.  A statement needs to be recompiled whenever the
** execution environment changes in a way that would alter the program
** that sqlite3_prepare() generates.  For example, if new functions or
................................................................................
    sqlite3_log(SQLITE_MISUSE, "API called with NULL prepared statement");
    return 1;
  }else{
    return vdbeSafety(p);
  }
}


























/*
** The following routine destroys a virtual machine that is created by
** the sqlite3_compile() routine. The integer returned is an SQLITE_
** success/failure code that describes the result of executing the virtual
** machine.
**
** This routine sets the error code and string returned by
................................................................................
    ** pointer is a harmless no-op. */
    rc = SQLITE_OK;
  }else{
    Vdbe *v = (Vdbe*)pStmt;
    sqlite3 *db = v->db;
    if( vdbeSafety(v) ) return SQLITE_MISUSE_BKPT;
    sqlite3_mutex_enter(db->mutex);

    rc = sqlite3VdbeFinalize(v);
    rc = sqlite3ApiExit(db, rc);
    sqlite3LeaveMutexAndCloseZombie(db);
  }
  return rc;
}

................................................................................
*/
SQLITE_API int SQLITE_STDCALL sqlite3_reset(sqlite3_stmt *pStmt){
  int rc;
  if( pStmt==0 ){
    rc = SQLITE_OK;
  }else{
    Vdbe *v = (Vdbe*)pStmt;

    sqlite3_mutex_enter(v->db->mutex);

    rc = sqlite3VdbeReset(v);
    sqlite3VdbeRewind(v);
    assert( (rc & (v->db->errMask))==rc );
    rc = sqlite3ApiExit(v->db, rc);
    sqlite3_mutex_leave(v->db->mutex);
  }
  return rc;
}

/*
** Set all the parameters in the compiled SQL statement to NULL.
*/
................................................................................
        rc = db->xWalCallback(db->pWalArg, db, db->aDb[i].zName, nEntry);
      }
    }
  }
#endif
  return rc;
}


/*
** Execute the statement pStmt, either until a row of data is ready, the
** statement is completely executed or an error occurs.
**
** This routine implements the bulk of the logic behind the sqlite_step()
** API.  The only thing omitted is the automatic recompile if a 
................................................................................
    }

    assert( db->nVdbeWrite>0 || db->autoCommit==0 
        || (db->nDeferredCons==0 && db->nDeferredImmCons==0)
    );

#ifndef SQLITE_OMIT_TRACE
    if( db->xProfile && !db->init.busy ){
      sqlite3OsCurrentTimeInt64(db->pVfs, &p->startTime);


    }
#endif

    db->nVdbeActive++;
    if( p->readOnly==0 ) db->nVdbeWrite++;
    if( p->bIsReader ) db->nVdbeRead++;
    p->pc = 0;
................................................................................
  {
    db->nVdbeExec++;
    rc = sqlite3VdbeExec(p);
    db->nVdbeExec--;
  }

#ifndef SQLITE_OMIT_TRACE
  /* Invoke the profile callback if there is one
  */
  if( rc!=SQLITE_ROW && db->xProfile && !db->init.busy && p->zSql ){
    sqlite3_int64 iNow;
    sqlite3OsCurrentTimeInt64(db->pVfs, &iNow);
    db->xProfile(db->pProfileArg, p->zSql, (iNow - p->startTime)*1000000);
  }

#endif

  if( rc==SQLITE_DONE ){
    assert( p->rc==SQLITE_OK );
    p->rc = doWalCallbacks(db);
    if( p->rc!=SQLITE_OK ){
      rc = SQLITE_ERROR;
................................................................................
*************************************************************************
**
** This file contains code used to insert the values of host parameters
** (aka "wildcards") into the SQL text output by sqlite3_trace().
**
** The Vdbe parse-tree explainer is also found here.
*/



#ifndef SQLITE_OMIT_TRACE

/*
** zSql is a zero-terminated string of UTF-8 SQL text.  Return the number of
** bytes in this text up to but excluding the first character in
** a host parameter.  If the text contains no host parameters, return
................................................................................
**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
*/



/*
** Invoke this macro on memory cells just prior to changing the
** value of the cell.  This macro verifies that shallow copies are
** not misused.  A shallow copy of a string or blob just copies a
** pointer to the string or blob, not the content.  If the original
** is changed while the copy is still in use, the string or blob might
................................................................................
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains code used to implement incremental BLOB I/O.
*/




#ifndef SQLITE_OMIT_INCRBLOB

/*
** Valid sqlite3_blob* handles point to Incrblob structures.
*/
typedef struct Incrblob Incrblob;
................................................................................
** If running in multi-threaded mode and there are more than
** SORTER_MAX_MERGE_COUNT PMAs on disk when Rewind() is called, then more
** than one background thread may be created. Specifically, there may be
** one background thread for each temporary file on disk, and one background
** thread to merge the output of each of the others to a single PMA for
** the main thread to read from.
*/



/* 
** If SQLITE_DEBUG_SORTER_THREADS is defined, this module outputs various
** messages to stderr that may be helpful in understanding the performance
** characteristics of the sorter in multi-threaded mode.
*/
#if 0
................................................................................
** on disk is not created or populated until either:
**
**   1) The in-memory representation grows too large for the allocated 
**      buffer, or
**   2) The sqlite3JournalCreate() function is called.
*/
#ifdef SQLITE_ENABLE_ATOMIC_WRITE



/*
** A JournalFile object is a subclass of sqlite3_file used by
** as an open file handle for journal files.
*/
struct JournalFile {
................................................................................
**
*************************************************************************
**
** This file contains code use to implement an in-memory rollback journal.
** The in-memory rollback journal is used to journal transactions for
** ":memory:" databases and when the journal_mode=MEMORY pragma is used.
*/


/* Forward references to internal structures */
typedef struct MemJournal MemJournal;
typedef struct FilePoint FilePoint;
typedef struct FileChunk FileChunk;

/* Space to hold the rollback journal is allocated in increments of
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains routines used for walking the parser tree for
** an SQL statement.
*/

/* #include <stdlib.h> */
/* #include <string.h> */


/*
** Walk an expression tree.  Invoke the callback once for each node
** of the expression, while descending.  (In other words, the callback
................................................................................
**
*************************************************************************
**
** This file contains routines used for walking the parser tree and
** resolve all identifiers by associating them with a particular
** table and column.
*/

/* #include <stdlib.h> */
/* #include <string.h> */

/*
** Walk the expression tree pExpr and increase the aggregate function
** depth (the Expr.op2 field) by N on every TK_AGG_FUNCTION node.
** This needs to occur when copying a TK_AGG_FUNCTION node from an
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
*/


/*
** Return the 'affinity' of the expression pExpr if any.
**
** If pExpr is a column, a reference to a column via an 'AS' alias,
** or a sub-select with a column as the return value, then the 
** affinity of that column is returned. Otherwise, 0x00 is returned,
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that used to generate VDBE code
** that implements the ALTER TABLE command.
*/


/*
** The code in this file only exists if we are not omitting the
** ALTER TABLE logic from the build.
*/
#ifndef SQLITE_OMIT_ALTERTABLE

................................................................................
** column contains the actual value of the left-most column instead
** of a blob encoding of the complete index key as is found in
** sqlite_stat4.sample.  The nEq, nLt, and nDLt entries of sqlite_stat3
** all contain just a single integer which is the same as the first
** integer in the equivalent columns in sqlite_stat4.
*/
#ifndef SQLITE_OMIT_ANALYZE


#if defined(SQLITE_ENABLE_STAT4)
# define IsStat4     1
# define IsStat3     0
#elif defined(SQLITE_ENABLE_STAT3)
# define IsStat4     0
# define IsStat3     1
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used to implement the ATTACH and DETACH commands.
*/


#ifndef SQLITE_OMIT_ATTACH
/*
** Resolve an expression that was part of an ATTACH or DETACH statement. This
** is slightly different from resolving a normal SQL expression, because simple
** identifiers are treated as strings, not possible column names or aliases.
**
................................................................................
**
*************************************************************************
** This file contains code used to implement the sqlite3_set_authorizer()
** API.  This facility is an optional feature of the library.  Embedded
** systems that do not need this facility may omit it by recompiling
** the library with -DSQLITE_OMIT_AUTHORIZATION=1
*/


/*
** All of the code in this file may be omitted by defining a single
** macro.
*/
#ifndef SQLITE_OMIT_AUTHORIZATION

................................................................................
**     CREATE INDEX
**     DROP INDEX
**     creating ID lists
**     BEGIN TRANSACTION
**     COMMIT
**     ROLLBACK
*/


/*
** This routine is called when a new SQL statement is beginning to
** be parsed.  Initialize the pParse structure as needed.
*/
SQLITE_PRIVATE void sqlite3BeginParse(Parse *pParse, int explainFlag){
  pParse->explain = (u8)explainFlag;
................................................................................
**
*************************************************************************
**
** This file contains functions used to access the internal hash tables
** of user defined functions and collation sequences.
*/



/*
** Invoke the 'collation needed' callback to request a collation sequence
** in the encoding enc of name zName, length nName.
*/
static void callCollNeeded(sqlite3 *db, int enc, const char *zName){
  assert( !db->xCollNeeded || !db->xCollNeeded16 );
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** in order to generate code for DELETE FROM statements.
*/


/*
** While a SrcList can in general represent multiple tables and subqueries
** (as in the FROM clause of a SELECT statement) in this case it contains
** the name of a single table, as one might find in an INSERT, DELETE,
** or UPDATE statement.  Look up that table in the symbol table and
** return a pointer.  Set an error message and return NULL if the table 
................................................................................
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C-language implementations for many of the SQL
** functions of SQLite.  (Some function, and in particular the date and
** time functions, are implemented separately.)
*/

/* #include <stdlib.h> */
/* #include <assert.h> */


/*
** Return the collating function associated with a function.
*/
static CollSeq *sqlite3GetFuncCollSeq(sqlite3_context *context){
  VdbeOp *pOp;
  assert( context->pVdbe!=0 );
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used by the compiler to add foreign key
** support to compiled SQL statements.
*/


#ifndef SQLITE_OMIT_FOREIGN_KEY
#ifndef SQLITE_OMIT_TRIGGER

/*
** Deferred and Immediate FKs
** --------------------------
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle INSERT statements in SQLite.
*/


/*
** Generate code that will 
**
**   (1) acquire a lock for table pTab then
**   (2) open pTab as cursor iCur.
**
................................................................................
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
*/



/*
** Execute SQL code.  Return one of the SQLITE_ success/failure
** codes.  Also write an error message into memory obtained from
** malloc() and make *pzErrMsg point to that message.
**
** If the SQL is a query, then for each row in the query result
................................................................................
** shared libraries that want to be imported as extensions into
** an SQLite instance.  Shared libraries that intend to be loaded
** as extensions by SQLite should #include this file instead of 
** sqlite3.h.
*/
#ifndef _SQLITE3EXT_H_
#define _SQLITE3EXT_H_


typedef struct sqlite3_api_routines sqlite3_api_routines;

/*
** The following structure holds pointers to all of the SQLite API
** routines.
**
................................................................................
# define SQLITE_EXTENSION_INIT3     /*no-op*/
#endif

#endif /* _SQLITE3EXT_H_ */

/************** End of sqlite3ext.h ******************************************/
/************** Continuing where we left off in loadext.c ********************/

/* #include <string.h> */

#ifndef SQLITE_OMIT_LOAD_EXTENSION

/*
** Some API routines are omitted when various features are
** excluded from a build of SQLite.  Substitute a NULL pointer
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used to implement the PRAGMA command.
*/


#if !defined(SQLITE_ENABLE_LOCKING_STYLE)
#  if defined(__APPLE__)
#    define SQLITE_ENABLE_LOCKING_STYLE 1
#  else
#    define SQLITE_ENABLE_LOCKING_STYLE 0
#  endif
................................................................................
  { /* zName:     */ "busy_timeout",
    /* ePragTyp:  */ PragTyp_BUSY_TIMEOUT,
    /* ePragFlag: */ 0,
    /* iArg:      */ 0 },
#if !defined(SQLITE_OMIT_PAGER_PRAGMAS)
  { /* zName:     */ "cache_size",
    /* ePragTyp:  */ PragTyp_CACHE_SIZE,
    /* ePragFlag: */ PragFlag_NeedSchema,
    /* iArg:      */ 0 },
#endif
#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
  { /* zName:     */ "cache_spill",
    /* ePragTyp:  */ PragTyp_FLAG,
    /* ePragFlag: */ 0,
    /* iArg:      */ SQLITE_CacheSpill },
................................................................................
  ** number of pages in the cache.  If N is negative, then the
  ** number of pages is adjusted so that the cache uses -N kibibytes
  ** of memory.
  */
  case PragTyp_CACHE_SIZE: {
    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
    if( !zRight ){

      returnSingleInt(pParse, "cache_size", pDb->pSchema->cache_size);
    }else{
      int size = sqlite3Atoi(zRight);
      pDb->pSchema->cache_size = size;
      sqlite3BtreeSetCacheSize(pDb->pBt, pDb->pSchema->cache_size);
    }
    break;
................................................................................
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the implementation of the sqlite3_prepare()
** interface, and routines that contribute to loading the database schema
** from disk.
*/


/*
** Fill the InitData structure with an error message that indicates
** that the database is corrupt.
*/
static void corruptSchema(
  InitData *pData,     /* Initialization context */
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
*/


/*
** Trace output macros
*/
#if SELECTTRACE_ENABLED
/***/ int sqlite3SelectTrace = 0;
# define SELECTTRACE(K,P,S,X)  \
................................................................................
      pInfo->aColl[i-iStart] = pColl;
      pInfo->aSortOrder[i-iStart] = pItem->sortOrder;
    }
  }
  return pInfo;
}

#ifndef SQLITE_OMIT_COMPOUND_SELECT
/*
** Name of the connection operator, used for error messages.
*/
static const char *selectOpName(int id){
  char *z;
  switch( id ){
    case TK_ALL:       z = "UNION ALL";   break;
    case TK_INTERSECT: z = "INTERSECT";   break;
    case TK_EXCEPT:    z = "EXCEPT";      break;
    default:           z = "UNION";       break;
  }
  return z;
}
#endif /* SQLITE_OMIT_COMPOUND_SELECT */

#ifndef SQLITE_OMIT_EXPLAIN
/*
** Unless an "EXPLAIN QUERY PLAN" command is being processed, this function
** is a no-op. Otherwise, it adds a single row of output to the EQP result,
** where the caption is of the form:
**
................................................................................
/* Forward references */
static int multiSelectOrderBy(
  Parse *pParse,        /* Parsing context */
  Select *p,            /* The right-most of SELECTs to be coded */
  SelectDest *pDest     /* What to do with query results */
);

/*
** Error message for when two or more terms of a compound select have different
** size result sets.
*/
SQLITE_PRIVATE void sqlite3SelectWrongNumTermsError(Parse *pParse, Select *p){
  if( p->selFlags & SF_Values ){
    sqlite3ErrorMsg(pParse, "all VALUES must have the same number of terms");
  }else{
    sqlite3ErrorMsg(pParse, "SELECTs to the left and right of %s"
      " do not have the same number of result columns", selectOpName(p->op));
  }
}

/*
** Handle the special case of a compound-select that originates from a
** VALUES clause.  By handling this as a special case, we avoid deep
** recursion, and thus do not need to enforce the SQLITE_LIMIT_COMPOUND_SELECT
** on a VALUES clause.
**
** Because the Select object originates from a VALUES clause:
................................................................................
multi_select_end:
  pDest->iSdst = dest.iSdst;
  pDest->nSdst = dest.nSdst;
  sqlite3SelectDelete(db, pDelete);
  return rc;
}
#endif /* SQLITE_OMIT_COMPOUND_SELECT */














/*
** Code an output subroutine for a coroutine implementation of a
** SELECT statment.
**
** The data to be output is contained in pIn->iSdst.  There are
** pIn->nSdst columns to be output.  pDest is where the output should
................................................................................
** This file contains the sqlite3_get_table() and sqlite3_free_table()
** interface routines.  These are just wrappers around the main
** interface routine of sqlite3_exec().
**
** These routines are in a separate files so that they will not be linked
** if they are not used.
*/

/* #include <stdlib.h> */
/* #include <string.h> */

#ifndef SQLITE_OMIT_GET_TABLE

/*
** This structure is used to pass data from sqlite3_get_table() through
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the implementation for TRIGGERs
*/


#ifndef SQLITE_OMIT_TRIGGER
/*
** Delete a linked list of TriggerStep structures.
*/
SQLITE_PRIVATE void sqlite3DeleteTriggerStep(sqlite3 *db, TriggerStep *pTriggerStep){
  while( pTriggerStep ){
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle UPDATE statements.
*/


#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Forward declaration */
static void updateVirtualTable(
  Parse *pParse,       /* The parsing context */
  SrcList *pSrc,       /* The virtual table to be modified */
  Table *pTab,         /* The virtual table */
................................................................................
**
*************************************************************************
** This file contains code used to implement the VACUUM command.
**
** Most of the code in this file may be omitted by defining the
** SQLITE_OMIT_VACUUM macro.
*/



#if !defined(SQLITE_OMIT_VACUUM) && !defined(SQLITE_OMIT_ATTACH)
/*
** Finalize a prepared statement.  If there was an error, store the
** text of the error message in *pzErrMsg.  Return the result code.
*/
static int vacuumFinalize(sqlite3 *db, sqlite3_stmt *pStmt, char **pzErrMsg){
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used to help implement virtual tables.
*/
#ifndef SQLITE_OMIT_VIRTUALTABLE


/*
** Before a virtual table xCreate() or xConnect() method is invoked, the
** sqlite3.pVtabCtx member variable is set to point to an instance of
** this struct allocated on the stack. It is used by the implementation of 
** the sqlite3_declare_vtab() and sqlite3_vtab_config() APIs, both of which
** are invoked only from within xCreate and xConnect methods.
................................................................................
** the WHERE clause of SQL statements.
**
** This file was split off from where.c on 2015-06-06 in order to reduce the
** size of where.c and make it easier to edit.  This file contains the routines
** that actually generate the bulk of the WHERE loop code.  The original where.c
** file retains the code that does query planning and analysis.
*/

/************** Include whereInt.h in the middle of wherecode.c **************/
/************** Begin file whereInt.h ****************************************/
/*
** 2013-11-12
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
................................................................................
              int nPk = pPk->nKeyCol;
              int iPk;

              /* Read the PK into an array of temp registers. */
              r = sqlite3GetTempRange(pParse, nPk);
              for(iPk=0; iPk<nPk; iPk++){
                int iCol = pPk->aiColumn[iPk];

                sqlite3ExprCodeGetColumn(pParse, pTab, iCol, iCur, r+iPk, 0);



              }

              /* Check if the temp table already contains this key. If so,
              ** the row has already been included in the result set and
              ** can be ignored (by jumping past the Gosub below). Otherwise,
              ** insert the key into the temp table and proceed with processing
              ** the row.
................................................................................
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.
**
** This file was originally part of where.c but was split out to improve
** readability and editabiliity.  This file contains utility routines for
** analyzing Expr objects in the WHERE clause.
*/



/* Forward declarations */
static void exprAnalyze(SrcList*, WhereClause*, int);

/*
** Deallocate all memory associated with a WhereOrInfo object.
*/
................................................................................
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.  This module is responsible for
** generating the code that loops through a table looking for applicable
** rows.  Indices are selected and used to speed the search when doing
** so is applicable.  Because this module is responsible for selecting
** indices, you might also think of this module as the "query optimizer".
*/



/* Forward declaration of methods */
static int whereLoopResize(sqlite3*, WhereLoop*, int);

/* Test variable that can be set to enable WHERE tracing */
#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
/***/ int sqlite3WhereTrace = 0;
................................................................................
** LALR(1) grammar but which are always false in the
** specific grammar used by SQLite.
*/
/* First off, code is included that follows the "include" declaration
** in the input grammar file. */
/* #include <stdio.h> */



/*
** Disable all error recovery processing in the parser push-down
** automaton.
*/
#define YYNOERRORRECOVERY 1

................................................................................
*************************************************************************
** An tokenizer for SQL
**
** This file contains C code that splits an SQL input string up into
** individual tokens and sends those tokens one-by-one over to the
** parser for analysis.
*/

/* #include <stdlib.h> */

/*
** The charMap() macro maps alphabetic characters into their
** lower-case ASCII equivalent.  On ASCII machines, this is just
** an upper-to-lower case map.  On EBCDIC machines we also need
** to adjust the encoding.  Only alphabetic characters and underscores
................................................................................
** An tokenizer for SQL
**
** This file contains C code that implements the sqlite3_complete() API.
** This code used to be part of the tokenizer.c source file.  But by
** separating it out, the code will be automatically omitted from
** static links that do not use it.
*/

#ifndef SQLITE_OMIT_COMPLETE

/*
** This is defined in tokenize.c.  We just have to import the definition.
*/
#ifndef SQLITE_AMALGAMATION
#ifdef SQLITE_ASCII
................................................................................
**
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
*/


#ifdef SQLITE_ENABLE_FTS3
/************** Include fts3.h in the middle of main.c ***********************/
/************** Begin file fts3.h ********************************************/
/*
** 2006 Oct 10
**
................................................................................
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This header file is used by programs that want to link against the
** FTS3 library.  All it does is declare the sqlite3Fts3Init() interface.
*/


#if 0
extern "C" {
#endif  /* __cplusplus */

SQLITE_PRIVATE int sqlite3Fts3Init(sqlite3 *db);

................................................................................
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This header file is used by programs that want to link against the
** RTREE library.  All it does is declare the sqlite3RtreeInit() interface.
*/


#if 0
extern "C" {
#endif  /* __cplusplus */

SQLITE_PRIVATE int sqlite3RtreeInit(sqlite3 *db);

................................................................................
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This header file is used by programs that want to link against the
** ICU extension.  All it does is declare the sqlite3IcuInit() interface.
*/


#if 0
extern "C" {
#endif  /* __cplusplus */

SQLITE_PRIVATE int sqlite3IcuInit(sqlite3 *db);

................................................................................
** The sz parameter is the number of bytes in each lookaside slot.
** The cnt parameter is the number of slots.  If pStart is NULL the
** space for the lookaside memory is obtained from sqlite3_malloc().
** If pStart is not NULL then it is sz*cnt bytes of memory to use for
** the lookaside memory.
*/
static int setupLookaside(sqlite3 *db, void *pBuf, int sz, int cnt){

  void *pStart;
  if( db->lookaside.nOut ){
    return SQLITE_BUSY;
  }
  /* Free any existing lookaside buffer for this handle before
  ** allocating a new one so we don't have to have space for 
  ** both at the same time.
................................................................................
    db->lookaside.bMalloced = pBuf==0 ?1:0;
  }else{
    db->lookaside.pStart = db;
    db->lookaside.pEnd = db;
    db->lookaside.bEnabled = 0;
    db->lookaside.bMalloced = 0;
  }

  return SQLITE_OK;
}

/*
** Return the mutex associated with a database connection.
*/
SQLITE_API sqlite3_mutex *SQLITE_STDCALL sqlite3_db_mutex(sqlite3 *db){
................................................................................
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains the implementation of the sqlite3_unlock_notify()
** API method and its associated functionality.
*/



/* Omit this entire file if SQLITE_ENABLE_UNLOCK_NOTIFY is not defined. */
#ifdef SQLITE_ENABLE_UNLOCK_NOTIFY

/*
** Public interfaces:
**
................................................................................
# define SQLITE_ENABLE_FTS3
#endif

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* If not building as part of the core, include sqlite3ext.h. */
#ifndef SQLITE_CORE

SQLITE_EXTENSION_INIT3
#endif


/************** Include fts3_tokenizer.h in the middle of fts3Int.h **********/
/************** Begin file fts3_tokenizer.h **********************************/
/*
** 2006 July 10
**
** The author disclaims copyright to this source code.
**
................................................................................
#ifndef _FTS3_TOKENIZER_H_
#define _FTS3_TOKENIZER_H_

/* TODO(shess) Only used for SQLITE_OK and SQLITE_DONE at this time.
** If tokenizers are to be allowed to call sqlite3_*() functions, then
** we will need a way to register the API consistently.
*/


/*
** Structures used by the tokenizer interface. When a new tokenizer
** implementation is registered, the caller provides a pointer to
** an sqlite3_tokenizer_module containing pointers to the callback
** functions that make up an implementation.
**
................................................................................
/* #include <assert.h> */
/* #include <stdlib.h> */
/* #include <stddef.h> */
/* #include <stdio.h> */
/* #include <string.h> */
/* #include <stdarg.h> */


#ifndef SQLITE_CORE 

  SQLITE_EXTENSION_INIT1
#endif

static int fts3EvalNext(Fts3Cursor *pCsr);
static int fts3EvalStart(Fts3Cursor *pCsr);
static int fts3TermSegReaderCursor(
    Fts3Cursor *, const char *, int, int, Fts3MultiSegReader **);
................................................................................
  assert( !p || (p>=aDoclist && p<=&aDoclist[nDoclist]) );

  if( p==0 ){
    p = aDoclist;
    p += sqlite3Fts3GetVarint(p, piDocid);
  }else{
    fts3PoslistCopy(0, &p);

    if( p>=&aDoclist[nDoclist] ){
      *pbEof = 1;
    }else{
      sqlite3_int64 iVar;
      p += sqlite3Fts3GetVarint(p, &iVar);
      *piDocid += ((bDescIdx ? -1 : 1) * iVar);
    }
................................................................................

  iDocid = pExpr->iDocid;
  pIter = pPhrase->doclist.pList;
  if( iDocid!=pCsr->iPrevId || pExpr->bEof ){
    int rc = SQLITE_OK;
    int bDescDoclist = pTab->bDescIdx;      /* For DOCID_CMP macro */
    int bOr = 0;
    u8 bEof = 0;
    u8 bTreeEof = 0;
    Fts3Expr *p;                  /* Used to iterate from pExpr to root */
    Fts3Expr *pNear;              /* Most senior NEAR ancestor (or pExpr) */


    /* Check if this phrase descends from an OR expression node. If not, 
    ** return NULL. Otherwise, the entry that corresponds to docid 
    ** pCsr->iPrevId may lie earlier in the doclist buffer. Or, if the
    ** tree that the node is part of has been marked as EOF, but the node
    ** itself is not EOF, then it may point to an earlier entry. */
    pNear = pExpr;
................................................................................
    if( bTreeEof ){
      while( rc==SQLITE_OK && !pNear->bEof ){
        fts3EvalNextRow(pCsr, pNear, &rc);
      }
    }
    if( rc!=SQLITE_OK ) return rc;











    pIter = pPhrase->pOrPoslist;
    iDocid = pPhrase->iOrDocid;
    if( pCsr->bDesc==bDescDoclist ){
      bEof = !pPhrase->doclist.nAll ||
                 (pIter >= (pPhrase->doclist.aAll + pPhrase->doclist.nAll));
      while( (pIter==0 || DOCID_CMP(iDocid, pCsr->iPrevId)<0 ) && bEof==0 ){
        sqlite3Fts3DoclistNext(
            bDescDoclist, pPhrase->doclist.aAll, pPhrase->doclist.nAll, 

            &pIter, &iDocid, &bEof
        );
      }
    }else{
      bEof = !pPhrase->doclist.nAll || (pIter && pIter<=pPhrase->doclist.aAll);
      while( (pIter==0 || DOCID_CMP(iDocid, pCsr->iPrevId)>0 ) && bEof==0 ){
        int dummy;
        sqlite3Fts3DoclistPrev(
            bDescDoclist, pPhrase->doclist.aAll, pPhrase->doclist.nAll, 

            &pIter, &iDocid, &dummy, &bEof
        );
      }
    }
    pPhrase->pOrPoslist = pIter;
    pPhrase->iOrDocid = iDocid;


    if( bEof || iDocid!=pCsr->iPrevId ) pIter = 0;






  }
  if( pIter==0 ) return SQLITE_OK;

  if( *pIter==0x01 ){
    pIter++;
    pIter += fts3GetVarint32(pIter, &iThis);
  }else{
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
*/

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* #include <string.h> */
/* #include <assert.h> */

typedef struct Fts3auxTable Fts3auxTable;
typedef struct Fts3auxCursor Fts3auxCursor;
................................................................................
******************************************************************************
**
** This module contains code that implements a parser for fts3 query strings
** (the right-hand argument to the MATCH operator). Because the supported 
** syntax is relatively simple, the whole tokenizer/parser system is
** hand-coded. 
*/

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/*
** By default, this module parses the legacy syntax that has been 
** traditionally used by fts3. Or, if SQLITE_ENABLE_FTS3_PARENTHESIS
** is defined, then it uses the new syntax. The differences between
** the new and the old syntaxes are:
................................................................................
**
**     * The FTS3 module is being built as an extension
**       (in which case SQLITE_CORE is not defined), or
**
**     * The FTS3 module is being built into the core of
**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
*/

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* #include <assert.h> */
/* #include <stdlib.h> */
/* #include <string.h> */



/*
** Malloc and Free functions
*/
static void *fts3HashMalloc(int n){
  void *p = sqlite3_malloc(n);
  if( p ){
................................................................................
**
**     * The FTS3 module is being built as an extension
**       (in which case SQLITE_CORE is not defined), or
**
**     * The FTS3 module is being built into the core of
**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
*/

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* #include <assert.h> */
/* #include <stdlib.h> */
/* #include <stdio.h> */
/* #include <string.h> */



/*
** Class derived from sqlite3_tokenizer
*/
typedef struct porter_tokenizer {
  sqlite3_tokenizer base;      /* Base class */
} porter_tokenizer;
................................................................................
**
**     * The FTS3 module is being built as an extension
**       (in which case SQLITE_CORE is not defined), or
**
**     * The FTS3 module is being built into the core of
**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
*/

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* #include <assert.h> */
/* #include <string.h> */

/*
** Implementation of the SQL scalar function for accessing the underlying 
................................................................................
**
**     * The FTS3 module is being built as an extension
**       (in which case SQLITE_CORE is not defined), or
**
**     * The FTS3 module is being built into the core of
**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
*/

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* #include <assert.h> */
/* #include <stdlib.h> */
/* #include <stdio.h> */
/* #include <string.h> */



typedef struct simple_tokenizer {
  sqlite3_tokenizer base;
  char delim[128];             /* flag ASCII delimiters */
} simple_tokenizer;

typedef struct simple_tokenizer_cursor {
................................................................................
**   token:   A token from the input.
**   start:   Byte offset of the token within the input <string>.
**   end:     Byte offset of the byte immediately following the end of the
**            token within the input string.
**   pos:     Token offset of token within input.
**
*/

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* #include <string.h> */
/* #include <assert.h> */

typedef struct Fts3tokTable Fts3tokTable;
typedef struct Fts3tokCursor Fts3tokCursor;
................................................................................
** This file is part of the SQLite FTS3 extension module. Specifically,
** this file contains code to insert, update and delete rows from FTS3
** tables. It also contains code to merge FTS3 b-tree segments. Some
** of the sub-routines used to merge segments are also used by the query 
** code in fts3.c.
*/


#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* #include <string.h> */
/* #include <assert.h> */
/* #include <stdlib.h> */


................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
*/


#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* #include <string.h> */
/* #include <assert.h> */

/*
** Characters that may appear in the second argument to matchinfo().
................................................................................
******************************************************************************
**
** Implementation of the "unicode" full-text-search tokenizer.
*/

#ifndef SQLITE_DISABLE_FTS3_UNICODE


#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* #include <assert.h> */
/* #include <stdlib.h> */
/* #include <stdio.h> */
/* #include <string.h> */



/*
** The following two macros - READ_UTF8 and WRITE_UTF8 - have been copied
** from the sqlite3 source file utf.c. If this file is compiled as part
** of the amalgamation, they are not required.
*/
#ifndef SQLITE_AMALGAMATION
................................................................................
**      of a record. For internal nodes it is the node number of a
**      child page.
*/

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_RTREE)

#ifndef SQLITE_CORE

  SQLITE_EXTENSION_INIT1
#else

#endif

/* #include <string.h> */
/* #include <assert.h> */
/* #include <stdio.h> */

#ifndef SQLITE_AMALGAMATION
................................................................................
#include <unicode/uregex.h>
#include <unicode/ustring.h>
#include <unicode/ucol.h>

/* #include <assert.h> */

#ifndef SQLITE_CORE

  SQLITE_EXTENSION_INIT1
#else

#endif

/*
** Maximum length (in bytes) of the pattern in a LIKE or GLOB
** operator.
*/
#ifndef SQLITE_MAX_LIKE_PATTERN_LENGTH
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file implements a tokenizer for fts3 based on the ICU library.
*/

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
#ifdef SQLITE_ENABLE_ICU

/* #include <assert.h> */
/* #include <string.h> */


#include <unicode/ubrk.h>
/* #include <unicode/ucol.h> */
/* #include <unicode/ustring.h> */
#include <unicode/utf16.h>

typedef struct IcuTokenizer IcuTokenizer;
................................................................................
  *ppModule = &icuTokenizerModule;
}

#endif /* defined(SQLITE_ENABLE_ICU) */
#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */

/************** End of fts3_icu.c ********************************************/
/************** Begin file sqlite3ota.c **************************************/
/*
** 2014 August 30
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
................................................................................
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
**
** OVERVIEW 
**
**  The OTA extension requires that the OTA update be packaged as an
**  SQLite database. The tables it expects to find are described in
**  sqlite3ota.h.  Essentially, for each table xyz in the target database
**  that the user wishes to write to, a corresponding data_xyz table is
**  created in the OTA database and populated with one row for each row to
**  update, insert or delete from the target table.
** 
**  The update proceeds in three stages:
** 
**  1) The database is updated. The modified database pages are written
**     to a *-oal file. A *-oal file is just like a *-wal file, except
**     that it is named "<database>-oal" instead of "<database>-wal".
**     Because regular SQLite clients do not look for file named
**     "<database>-oal", they go on using the original database in
**     rollback mode while the *-oal file is being generated.
** 
**     During this stage OTA does not update the database by writing
**     directly to the target tables. Instead it creates "imposter"
**     tables using the SQLITE_TESTCTRL_IMPOSTER interface that it uses
**     to update each b-tree individually. All updates required by each
**     b-tree are completed before moving on to the next, and all
**     updates are done in sorted key order.
** 
**  2) The "<database>-oal" file is moved to the equivalent "<database>-wal"
**     location using a call to rename(2). Before doing this the OTA
**     module takes an EXCLUSIVE lock on the database file, ensuring
**     that there are no other active readers.
** 
**     Once the EXCLUSIVE lock is released, any other database readers
**     detect the new *-wal file and read the database in wal mode. At
**     this point they see the new version of the database - including
**     the updates made as part of the OTA update.
** 
**  3) The new *-wal file is checkpointed. This proceeds in the same way 
**     as a regular database checkpoint, except that a single frame is
**     checkpointed each time sqlite3ota_step() is called. If the OTA
**     handle is closed before the entire *-wal file is checkpointed,
**     the checkpoint progress is saved in the OTA database and the
**     checkpoint can be resumed by another OTA client at some point in
**     the future.
**
** POTENTIAL PROBLEMS
** 
**  The rename() call might not be portable. And OTA is not currently
**  syncing the directory after renaming the file.
**
**  When state is saved, any commit to the *-oal file and the commit to
**  the OTA update database are not atomic. So if the power fails at the
**  wrong moment they might get out of sync. As the main database will be
**  committed before the OTA update database this will likely either just
**  pass unnoticed, or result in SQLITE_CONSTRAINT errors (due to UNIQUE
**  constraint violations).
**
**  If some client does modify the target database mid OTA update, or some
**  other error occurs, the OTA extension will keep throwing errors. It's
**  not really clear how to get out of this state. The system could just
**  by delete the OTA update database and *-oal file and have the device
**  download the update again and start over.
**
**  At present, for an UPDATE, both the new.* and old.* records are
**  collected in the ota_xyz table. And for both UPDATEs and DELETEs all
**  fields are collected.  This means we're probably writing a lot more
**  data to disk when saving the state of an ongoing update to the OTA
**  update database than is strictly necessary.
** 
*/

/* #include <assert.h> */
/* #include <string.h> */
/* #include <stdio.h> */
/* #include <unistd.h> */



#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_OTA)
/************** Include sqlite3ota.h in the middle of sqlite3ota.c ***********/
/************** Begin file sqlite3ota.h **************************************/
/*
** 2014 August 30
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains the public interface for the OTA extension. 
*/

/*
** SUMMARY
**
** Writing a transaction containing a large number of operations on 
** b-tree indexes that are collectively larger than the available cache
................................................................................
** guarantee that a single update process will run for long enough to apply 
** the entire update, for example because the update is being applied on a 
** mobile device that is frequently rebooted. Even after the writer process 
** has committed one or more sub-transactions, other database clients continue
** to read from the original database snapshot. In other words, partially 
** applied transactions are not visible to other clients. 
**
** "OTA" stands for "Over The Air" update. As in a large database update
** transmitted via a wireless network to a mobile device. A transaction
** applied using this extension is hence refered to as an "OTA update".
**
**
** LIMITATIONS
**
** An "OTA update" transaction is subject to the following limitations:
**
**   * The transaction must consist of INSERT, UPDATE and DELETE operations
**     only.
**
**   * INSERT statements may not use any default values.
**
**   * UPDATE and DELETE statements must identify their target rows by 
................................................................................
**   * CHECK constraints are not enforced.
**
**   * No constraint handling mode except for "OR ROLLBACK" is supported.
**
**
** PREPARATION
**
** An "OTA update" is stored as a separate SQLite database. A database
** containing an OTA update is an "OTA database". For each table in the 
** target database to be updated, the OTA database should contain a table
** named "data_<target name>" containing the same set of columns as the
** target table, and one more - "ota_control". The data_% table should 
** have no PRIMARY KEY or UNIQUE constraints, but each column should have
** the same type as the corresponding column in the target database.
** The "ota_control" column should have no type at all. For example, if
** the target database contains:
**
**   CREATE TABLE t1(a INTEGER PRIMARY KEY, b TEXT, c UNIQUE);
**
** Then the OTA database should contain:
**
**   CREATE TABLE data_t1(a INTEGER, b TEXT, c, ota_control);
**
** The order of the columns in the data_% table does not matter.
**
** If the target database table is a virtual table or a table that has no
** PRIMARY KEY declaration, the data_% table must also contain a column 
** named "ota_rowid". This column is mapped to the tables implicit primary 
** key column - "rowid". Virtual tables for which the "rowid" column does 
** not function like a primary key value cannot be updated using OTA. For 
** example, if the target db contains either of the following:
**
**   CREATE VIRTUAL TABLE x1 USING fts3(a, b);
**   CREATE TABLE x1(a, b)
**
** then the OTA database should contain:
**
**   CREATE TABLE data_x1(a, b, ota_rowid, ota_control);
**
** All non-hidden columns (i.e. all columns matched by "SELECT *") of the
** target table must be present in the input table. For virtual tables,
** hidden columns are optional - they are updated by OTA if present in
** the input table, or not otherwise. For example, to write to an fts4
** table with a hidden languageid column such as:
**
**   CREATE VIRTUAL TABLE ft1 USING fts4(a, b, languageid='langid');
**
** Either of the following input table schemas may be used:
**
**   CREATE TABLE data_ft1(a, b, langid, ota_rowid, ota_control);
**   CREATE TABLE data_ft1(a, b, ota_rowid, ota_control);
**
** For each row to INSERT into the target database as part of the OTA 
** update, the corresponding data_% table should contain a single record
** with the "ota_control" column set to contain integer value 0. The
** other columns should be set to the values that make up the new record 
** to insert. 
**
** If the target database table has an INTEGER PRIMARY KEY, it is not 
** possible to insert a NULL value into the IPK column. Attempting to 
** do so results in an SQLITE_MISMATCH error.
**
** For each row to DELETE from the target database as part of the OTA 
** update, the corresponding data_% table should contain a single record
** with the "ota_control" column set to contain integer value 1. The
** real primary key values of the row to delete should be stored in the
** corresponding columns of the data_% table. The values stored in the
** other columns are not used.
**
** For each row to UPDATE from the target database as part of the OTA 
** update, the corresponding data_% table should contain a single record
** with the "ota_control" column set to contain a value of type text.
** The real primary key values identifying the row to update should be 
** stored in the corresponding columns of the data_% table row, as should
** the new values of all columns being update. The text value in the 
** "ota_control" column must contain the same number of characters as
** there are columns in the target database table, and must consist entirely
** of 'x' and '.' characters (or in some special cases 'd' - see below). For 
** each column that is being updated, the corresponding character is set to
** 'x'. For those that remain as they are, the corresponding character of the
** ota_control value should be set to '.'. For example, given the tables 
** above, the update statement:
**
**   UPDATE t1 SET c = 'usa' WHERE a = 4;
**
** is represented by the data_t1 row created by:
**
**   INSERT INTO data_t1(a, b, c, ota_control) VALUES(4, NULL, 'usa', '..x');
**
** Instead of an 'x' character, characters of the ota_control value specified
** for UPDATEs may also be set to 'd'. In this case, instead of updating the
** target table with the value stored in the corresponding data_% column, the
** user-defined SQL function "ota_delta()" is invoked and the result stored in
** the target table column. ota_delta() is invoked with two arguments - the
** original value currently stored in the target table column and the 
** value specified in the data_xxx table.
**
** For example, this row:
**
**   INSERT INTO data_t1(a, b, c, ota_control) VALUES(4, NULL, 'usa', '..d');
**
** is similar to an UPDATE statement such as: 
**
**   UPDATE t1 SET c = ota_delta(c, 'usa') WHERE a = 4;
**
** If the target database table is a virtual table or a table with no PRIMARY
** KEY, the ota_control value should not include a character corresponding 
** to the ota_rowid value. For example, this:
**
**   INSERT INTO data_ft1(a, b, ota_rowid, ota_control) 
**       VALUES(NULL, 'usa', 12, '.x');
**
** causes a result similar to:
**
**   UPDATE ft1 SET b = 'usa' WHERE rowid = 12;
**
** The data_xxx tables themselves should have no PRIMARY KEY declarations.
** However, OTA is more efficient if reading the rows in from each data_xxx
** table in "rowid" order is roughly the same as reading them sorted by
** the PRIMARY KEY of the corresponding target database table. In other 
** words, rows should be sorted using the destination table PRIMARY KEY 
** fields before they are inserted into the data_xxx tables.
**
** USAGE
**
** The API declared below allows an application to apply an OTA update 
** stored on disk to an existing target database. Essentially, the 
** application:
**
**     1) Opens an OTA handle using the sqlite3ota_open() function.
**
**     2) Registers any required virtual table modules with the database
**        handle returned by sqlite3ota_db(). Also, if required, register
**        the ota_delta() implementation.
**
**     3) Calls the sqlite3ota_step() function one or more times on
**        the new handle. Each call to sqlite3ota_step() performs a single
**        b-tree operation, so thousands of calls may be required to apply 
**        a complete update.
**
**     4) Calls sqlite3ota_close() to close the OTA update handle. If
**        sqlite3ota_step() has been called enough times to completely
**        apply the update to the target database, then the OTA database
**        is marked as fully applied. Otherwise, the state of the OTA 
**        update application is saved in the OTA database for later 
**        resumption.
**
** See comments below for more detail on APIs.
**
** If an update is only partially applied to the target database by the
** time sqlite3ota_close() is called, various state information is saved 
** within the OTA database. This allows subsequent processes to automatically
** resume the OTA update from where it left off.
**
** To remove all OTA extension state information, returning an OTA database 
** to its original contents, it is sufficient to drop all tables that begin
** with the prefix "ota_"
**
** DATABASE LOCKING
**
** An OTA update may not be applied to a database in WAL mode. Attempting
** to do so is an error (SQLITE_ERROR).
**
** While an OTA handle is open, a SHARED lock may be held on the target
** database file. This means it is possible for other clients to read the
** database, but not to write it.
**
** If an OTA update is started and then suspended before it is completed,
** then an external client writes to the database, then attempting to resume
** the suspended OTA update is also an error (SQLITE_BUSY).
*/

#ifndef _SQLITE3OTA_H
#define _SQLITE3OTA_H



typedef struct sqlite3ota sqlite3ota;

/*
** Open an OTA handle.
**
** Argument zTarget is the path to the target database. Argument zOta is
** the path to the OTA database. Each call to this function must be matched
** by a call to sqlite3ota_close(). When opening the databases, OTA passes
** the SQLITE_CONFIG_URI flag to sqlite3_open_v2(). So if either zTarget
** or zOta begin with "file:", it will be interpreted as an SQLite 
** database URI, not a regular file name.
**
** If the zState argument is passed a NULL value, the OTA extension stores 
** the current state of the update (how many rows have been updated, which 
** indexes are yet to be updated etc.) within the OTA database itself. This
** can be convenient, as it means that the OTA application does not need to
** organize removing a separate state file after the update is concluded. 
** Or, if zState is non-NULL, it must be a path to a database file in which 
** the OTA extension can store the state of the update.
**
** When resuming an OTA update, the zState argument must be passed the same
** value as when the OTA update was started.
**
** Once the OTA update is finished, the OTA extension does not 
** automatically remove any zState database file, even if it created it.
**
** By default, OTA uses the default VFS to access the files on disk. To
** use a VFS other than the default, an SQLite "file:" URI containing a
** "vfs=..." option may be passed as the zTarget option.
**
** IMPORTANT NOTE FOR ZIPVFS USERS: The OTA extension works with all of
** SQLite's built-in VFSs, including the multiplexor VFS. However it does
** not work out of the box with zipvfs. Refer to the comment describing
** the zipvfs_create_vfs() API below for details on using OTA with zipvfs.
*/
SQLITE_API sqlite3ota *SQLITE_STDCALL sqlite3ota_open(
  const char *zTarget, 
  const char *zOta,
  const char *zState
);

/*
** Internally, each OTA connection uses a separate SQLite database 
** connection to access the target and ota update databases. This
** API allows the application direct access to these database handles.
**
** The first argument passed to this function must be a valid, open, OTA
** handle. The second argument should be passed zero to access the target
** database handle, or non-zero to access the ota update database handle.
** Accessing the underlying database handles may be useful in the
** following scenarios:
**
**   * If any target tables are virtual tables, it may be necessary to
**     call sqlite3_create_module() on the target database handle to 
**     register the required virtual table implementations.
**
**   * If the data_xxx tables in the OTA source database are virtual 
**     tables, the application may need to call sqlite3_create_module() on
**     the ota update db handle to any required virtual table
**     implementations.
**
**   * If the application uses the "ota_delta()" feature described above,
**     it must use sqlite3_create_function() or similar to register the
**     ota_delta() implementation with the target database handle.
**
** If an error has occurred, either while opening or stepping the OTA object,
** this function may return NULL. The error code and message may be collected
** when sqlite3ota_close() is called.
*/
SQLITE_API sqlite3 *SQLITE_STDCALL sqlite3ota_db(sqlite3ota*, int bOta);

/*
** Do some work towards applying the OTA update to the target db. 
**
** Return SQLITE_DONE if the update has been completely applied, or 
** SQLITE_OK if no error occurs but there remains work to do to apply
** the OTA update. If an error does occur, some other error code is 
** returned. 
**
** Once a call to sqlite3ota_step() has returned a value other than
** SQLITE_OK, all subsequent calls on the same OTA handle are no-ops
** that immediately return the same value.
*/
SQLITE_API int SQLITE_STDCALL sqlite3ota_step(sqlite3ota *pOta);

/*
** Close an OTA handle. 
**
** If the OTA update has been completely applied, mark the OTA database
** as fully applied. Otherwise, assuming no error has occurred, save the
** current state of the OTA update appliation to the OTA database.
**
** If an error has already occurred as part of an sqlite3ota_step()
** or sqlite3ota_open() call, or if one occurs within this function, an
** SQLite error code is returned. Additionally, *pzErrmsg may be set to
** point to a buffer containing a utf-8 formatted English language error
** message. It is the responsibility of the caller to eventually free any 
** such buffer using sqlite3_free().
**
** Otherwise, if no error occurs, this function returns SQLITE_OK if the
** update has been partially applied, or SQLITE_DONE if it has been 
** completely applied.
*/
SQLITE_API int SQLITE_STDCALL sqlite3ota_close(sqlite3ota *pOta, char **pzErrmsg);

/*
** Return the total number of key-value operations (inserts, deletes or 
** updates) that have been performed on the target database since the
** current OTA update was started.
*/
SQLITE_API sqlite3_int64 SQLITE_STDCALL sqlite3ota_progress(sqlite3ota *pOta);

/*
** Create an OTA VFS named zName that accesses the underlying file-system
** via existing VFS zParent. Or, if the zParent parameter is passed NULL, 
** then the new OTA VFS uses the default system VFS to access the file-system.
** The new object is registered as a non-default VFS with SQLite before 
** returning.
**
** Part of the OTA implementation uses a custom VFS object. Usually, this
** object is created and deleted automatically by OTA. 
**
** The exception is for applications that also use zipvfs. In this case,
** the custom VFS must be explicitly created by the user before the OTA
** handle is opened. The OTA VFS should be installed so that the zipvfs
** VFS uses the OTA VFS, which in turn uses any other VFS layers in use 
** (for example multiplexor) to access the file-system. For example,
** to assemble an OTA enabled VFS stack that uses both zipvfs and 
** multiplexor (error checking omitted):
**
**     // Create a VFS named "multiplex" (not the default).
**     sqlite3_multiplex_initialize(0, 0);
**
**     // Create an ota VFS named "ota" that uses multiplexor. If the
**     // second argument were replaced with NULL, the "ota" VFS would
**     // access the file-system via the system default VFS, bypassing the
**     // multiplexor.
**     sqlite3ota_create_vfs("ota", "multiplex");
**
**     // Create a zipvfs VFS named "zipvfs" that uses ota.
**     zipvfs_create_vfs_v3("zipvfs", "ota", 0, xCompressorAlgorithmDetector);
**
**     // Make zipvfs the default VFS.
**     sqlite3_vfs_register(sqlite3_vfs_find("zipvfs"), 1);
**
** Because the default VFS created above includes a OTA functionality, it
** may be used by OTA clients. Attempting to use OTA with a zipvfs VFS stack
** that does not include the OTA layer results in an error.
**
** The overhead of adding the "ota" VFS to the system is negligible for 
** non-OTA users. There is no harm in an application accessing the 
** file-system via "ota" all the time, even if it only uses OTA functionality 
** occasionally.
*/
SQLITE_API int SQLITE_STDCALL sqlite3ota_create_vfs(const char *zName, const char *zParent);

/*
** Deregister and destroy an OTA vfs created by an earlier call to
** sqlite3ota_create_vfs().
**
** VFS objects are not reference counted. If a VFS object is destroyed
** before all database handles that use it have been closed, the results
** are undefined.
*/
SQLITE_API void SQLITE_STDCALL sqlite3ota_destroy_vfs(const char *zName);

#endif /* _SQLITE3OTA_H */


/************** End of sqlite3ota.h ******************************************/
/************** Continuing where we left off in sqlite3ota.c *****************/

/* Maximum number of prepared UPDATE statements held by this module */
#define SQLITE_OTA_UPDATE_CACHESIZE 16

/*
** Swap two objects of type TYPE.
*/
#if !defined(SQLITE_AMALGAMATION)
# define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;}
#endif

/*
** The ota_state table is used to save the state of a partially applied
** update so that it can be resumed later. The table consists of integer
** keys mapped to values as follows:
**
** OTA_STATE_STAGE:
**   May be set to integer values 1, 2, 4 or 5. As follows:
**       1: the *-ota file is currently under construction.
**       2: the *-ota file has been constructed, but not yet moved 
**          to the *-wal path.
**       4: the checkpoint is underway.
**       5: the ota update has been checkpointed.
**
** OTA_STATE_TBL:
**   Only valid if STAGE==1. The target database name of the table 
**   currently being written.
**
** OTA_STATE_IDX:
**   Only valid if STAGE==1. The target database name of the index 
**   currently being written, or NULL if the main table is currently being
**   updated.
**
** OTA_STATE_ROW:
**   Only valid if STAGE==1. Number of rows already processed for the current
**   table/index.
**
** OTA_STATE_PROGRESS:
**   Total number of sqlite3ota_step() calls made so far as part of this
**   ota update.
**
** OTA_STATE_CKPT:
**   Valid if STAGE==4. The 64-bit checksum associated with the wal-index
**   header created by recovering the *-wal file. This is used to detect
**   cases when another client appends frames to the *-wal file in the
**   middle of an incremental checkpoint (an incremental checkpoint cannot
**   be continued if this happens).
**
** OTA_STATE_COOKIE:
**   Valid if STAGE==1. The current change-counter cookie value in the 
**   target db file.
**
** OTA_STATE_OALSZ:
**   Valid if STAGE==1. The size in bytes of the *-oal file.
*/
#define OTA_STATE_STAGE       1
#define OTA_STATE_TBL         2
#define OTA_STATE_IDX         3
#define OTA_STATE_ROW         4
#define OTA_STATE_PROGRESS    5
#define OTA_STATE_CKPT        6
#define OTA_STATE_COOKIE      7
#define OTA_STATE_OALSZ       8

#define OTA_STAGE_OAL         1
#define OTA_STAGE_MOVE        2
#define OTA_STAGE_CAPTURE     3
#define OTA_STAGE_CKPT        4
#define OTA_STAGE_DONE        5


#define OTA_CREATE_STATE \
  "CREATE TABLE IF NOT EXISTS %s.ota_state(k INTEGER PRIMARY KEY, v)"

typedef struct OtaFrame OtaFrame;
typedef struct OtaObjIter OtaObjIter;
typedef struct OtaState OtaState;
typedef struct ota_vfs ota_vfs;
typedef struct ota_file ota_file;
typedef struct OtaUpdateStmt OtaUpdateStmt;

#if !defined(SQLITE_AMALGAMATION)
typedef unsigned int u32;
typedef unsigned char u8;
typedef sqlite3_int64 i64;
#endif

................................................................................
** format.
*/
#define WAL_LOCK_WRITE  0
#define WAL_LOCK_CKPT   1
#define WAL_LOCK_READ0  3

/*
** A structure to store values read from the ota_state table in memory.
*/
struct OtaState {
  int eStage;
  char *zTbl;
  char *zIdx;
  i64 iWalCksum;
  int nRow;
  i64 nProgress;
  u32 iCookie;
  i64 iOalSz;
};

struct OtaUpdateStmt {
  char *zMask;                    /* Copy of update mask used with pUpdate */
  sqlite3_stmt *pUpdate;          /* Last update statement (or NULL) */
  OtaUpdateStmt *pNext;
};

/*
** An iterator of this type is used to iterate through all objects in
** the target database that require updating. For each such table, the
** iterator visits, in order:
**
................................................................................
** abIndexed:
**   If the table has no indexes on it, abIndexed is set to NULL. Otherwise,
**   it points to an array of flags nTblCol elements in size. The flag is
**   set for each column that is either a part of the PK or a part of an
**   index. Or clear otherwise.
**   
*/
struct OtaObjIter {
  sqlite3_stmt *pTblIter;         /* Iterate through tables */
  sqlite3_stmt *pIdxIter;         /* Index iterator */
  int nTblCol;                    /* Size of azTblCol[] array */
  char **azTblCol;                /* Array of unquoted target column names */
  char **azTblType;               /* Array of target column types */
  int *aiSrcOrder;                /* src table col -> target table col */
  u8 *abTblPk;                    /* Array of flags, set on target PK columns */
  u8 *abNotNull;                  /* Array of flags, set on NOT NULL columns */
  u8 *abIndexed;                  /* Array of flags, set on indexed & PK cols */
  int eType;                      /* Table type - an OTA_PK_XXX value */

  /* Output variables. zTbl==0 implies EOF. */
  int bCleanup;                   /* True in "cleanup" state */
  const char *zTbl;               /* Name of target db table */
  const char *zIdx;               /* Name of target db index (or null) */
  int iTnum;                      /* Root page of current object */
  int iPkTnum;                    /* If eType==EXTERNAL, root of PK index */
  int bUnique;                    /* Current index is unique */

  /* Statements created by otaObjIterPrepareAll() */
  int nCol;                       /* Number of columns in current object */
  sqlite3_stmt *pSelect;          /* Source data */
  sqlite3_stmt *pInsert;          /* Statement for INSERT operations */
  sqlite3_stmt *pDelete;          /* Statement for DELETE ops */
  sqlite3_stmt *pTmpInsert;       /* Insert into ota_tmp_$zTbl */

  /* Last UPDATE used (for PK b-tree updates only), or NULL. */
  OtaUpdateStmt *pOtaUpdate;
};

/*
** Values for OtaObjIter.eType
**
**     0: Table does not exist (error)
**     1: Table has an implicit rowid.
**     2: Table has an explicit IPK column.
**     3: Table has an external PK index.
**     4: Table is WITHOUT ROWID.
**     5: Table is a virtual table.
*/
#define OTA_PK_NOTABLE        0
#define OTA_PK_NONE           1
#define OTA_PK_IPK            2
#define OTA_PK_EXTERNAL       3
#define OTA_PK_WITHOUT_ROWID  4
#define OTA_PK_VTAB           5


/*
** Within the OTA_STAGE_OAL stage, each call to sqlite3ota_step() performs
** one of the following operations.
*/
#define OTA_INSERT     1          /* Insert on a main table b-tree */
#define OTA_DELETE     2          /* Delete a row from a main table b-tree */
#define OTA_IDX_DELETE 3          /* Delete a row from an aux. index b-tree */
#define OTA_IDX_INSERT 4          /* Insert on an aux. index b-tree */
#define OTA_UPDATE     5          /* Update a row in a main table b-tree */


/*
** A single step of an incremental checkpoint - frame iWalFrame of the wal
** file should be copied to page iDbPage of the database file.
*/
struct OtaFrame {
  u32 iDbPage;
  u32 iWalFrame;
};

/*
** OTA handle.
*/
struct sqlite3ota {
  int eStage;                     /* Value of OTA_STATE_STAGE field */
  sqlite3 *dbMain;                /* target database handle */
  sqlite3 *dbOta;                 /* ota database handle */
  char *zTarget;                  /* Path to target db */
  char *zOta;                     /* Path to ota db */
  char *zState;                   /* Path to state db (or NULL if zOta) */
  char zStateDb[5];               /* Db name for state ("stat" or "main") */
  int rc;                         /* Value returned by last ota_step() call */
  char *zErrmsg;                  /* Error message if rc!=SQLITE_OK */
  int nStep;                      /* Rows processed for current object */
  int nProgress;                  /* Rows processed for all objects */
  OtaObjIter objiter;             /* Iterator for skipping through tbl/idx */
  const char *zVfsName;           /* Name of automatically created ota vfs */
  ota_file *pTargetFd;            /* File handle open on target db */
  i64 iOalSz;

  /* The following state variables are used as part of the incremental
  ** checkpoint stage (eStage==OTA_STAGE_CKPT). See comments surrounding
  ** function otaSetupCheckpoint() for details.  */
  u32 iMaxFrame;                  /* Largest iWalFrame value in aFrame[] */
  u32 mLock;
  int nFrame;                     /* Entries in aFrame[] array */
  int nFrameAlloc;                /* Allocated size of aFrame[] array */
  OtaFrame *aFrame;
  int pgsz;
  u8 *aBuf;
  i64 iWalCksum;
};

/*
** An ota VFS is implemented using an instance of this structure.
*/
struct ota_vfs {
  sqlite3_vfs base;               /* ota VFS shim methods */
  sqlite3_vfs *pRealVfs;          /* Underlying VFS */
  sqlite3_mutex *mutex;           /* Mutex to protect pMain */
  ota_file *pMain;                /* Linked list of main db files */
};

/*
** Each file opened by an ota VFS is represented by an instance of
** the following structure.
*/
struct ota_file {
  sqlite3_file base;              /* sqlite3_file methods */
  sqlite3_file *pReal;            /* Underlying file handle */
  ota_vfs *pOtaVfs;               /* Pointer to the ota_vfs object */
  sqlite3ota *pOta;               /* Pointer to ota object (ota target only) */

  int openFlags;                  /* Flags this file was opened with */
  u32 iCookie;                    /* Cookie value for main db files */
  u8 iWriteVer;                   /* "write-version" value for main db files */

  int nShm;                       /* Number of entries in apShm[] array */
  char **apShm;                   /* Array of mmap'd *-shm regions */
  char *zDel;                     /* Delete this when closing file */

  const char *zWal;               /* Wal filename for this main db file */
  ota_file *pWalFd;               /* Wal file descriptor for this main db */
  ota_file *pMainNext;            /* Next MAIN_DB file */
};


/*
** Prepare the SQL statement in buffer zSql against database handle db.
** If successful, set *ppStmt to point to the new statement and return
** SQLITE_OK. 
................................................................................
    rc = prepareAndCollectError(db, ppStmt, pzErrmsg, zSql);
    sqlite3_free(zSql);
  }
  return rc;
}

/*
** Free the OtaObjIter.azTblCol[] and OtaObjIter.abTblPk[] arrays allocated
** by an earlier call to otaObjIterCacheTableInfo().
*/
static void otaObjIterFreeCols(OtaObjIter *pIter){
  int i;
  for(i=0; i<pIter->nTblCol; i++){
    sqlite3_free(pIter->azTblCol[i]);
    sqlite3_free(pIter->azTblType[i]);
  }
  sqlite3_free(pIter->azTblCol);
  pIter->azTblCol = 0;
................................................................................
  pIter->eType = 0;               /* Invalid value */
}

/*
** Finalize all statements and free all allocations that are specific to
** the current object (table/index pair).
*/
static void otaObjIterClearStatements(OtaObjIter *pIter){
  OtaUpdateStmt *pUp;

  sqlite3_finalize(pIter->pSelect);
  sqlite3_finalize(pIter->pInsert);
  sqlite3_finalize(pIter->pDelete);
  sqlite3_finalize(pIter->pTmpInsert);
  pUp = pIter->pOtaUpdate;
  while( pUp ){
    OtaUpdateStmt *pTmp = pUp->pNext;
    sqlite3_finalize(pUp->pUpdate);
    sqlite3_free(pUp);
    pUp = pTmp;
  }
  
  pIter->pSelect = 0;
  pIter->pInsert = 0;
  pIter->pDelete = 0;
  pIter->pOtaUpdate = 0;
  pIter->pTmpInsert = 0;
  pIter->nCol = 0;
}

/*
** Clean up any resources allocated as part of the iterator object passed
** as the only argument.
*/
static void otaObjIterFinalize(OtaObjIter *pIter){
  otaObjIterClearStatements(pIter);
  sqlite3_finalize(pIter->pTblIter);
  sqlite3_finalize(pIter->pIdxIter);
  otaObjIterFreeCols(pIter);
  memset(pIter, 0, sizeof(OtaObjIter));
}

/*
** Advance the iterator to the next position.
**
** If no error occurs, SQLITE_OK is returned and the iterator is left 
** pointing to the next entry. Otherwise, an error code and message is 
** left in the OTA handle passed as the first argument. A copy of the 
** error code is returned.
*/
static int otaObjIterNext(sqlite3ota *p, OtaObjIter *pIter){
  int rc = p->rc;
  if( rc==SQLITE_OK ){

    /* Free any SQLite statements used while processing the previous object */ 
    otaObjIterClearStatements(pIter);
    if( pIter->zIdx==0 ){
      rc = sqlite3_exec(p->dbMain,
          "DROP TRIGGER IF EXISTS temp.ota_insert_tr;"
          "DROP TRIGGER IF EXISTS temp.ota_update1_tr;"
          "DROP TRIGGER IF EXISTS temp.ota_update2_tr;"
          "DROP TRIGGER IF EXISTS temp.ota_delete_tr;"
          , 0, 0, &p->zErrmsg
      );
    }

    if( rc==SQLITE_OK ){
      if( pIter->bCleanup ){
        otaObjIterFreeCols(pIter);
        pIter->bCleanup = 0;
        rc = sqlite3_step(pIter->pTblIter);
        if( rc!=SQLITE_ROW ){
          rc = resetAndCollectError(pIter->pTblIter, &p->zErrmsg);
          pIter->zTbl = 0;
        }else{
          pIter->zTbl = (const char*)sqlite3_column_text(pIter->pTblIter, 0);
................................................................................
          }
        }
      }
    }
  }

  if( rc!=SQLITE_OK ){
    otaObjIterFinalize(pIter);
    p->rc = rc;
  }
  return rc;
}

/*
** Initialize the iterator structure passed as the second argument.
**
** If no error occurs, SQLITE_OK is returned and the iterator is left 
** pointing to the first entry. Otherwise, an error code and message is 
** left in the OTA handle passed as the first argument. A copy of the 
** error code is returned.
*/
static int otaObjIterFirst(sqlite3ota *p, OtaObjIter *pIter){
  int rc;
  memset(pIter, 0, sizeof(OtaObjIter));

  rc = prepareAndCollectError(p->dbOta, &pIter->pTblIter, &p->zErrmsg, 
      "SELECT substr(name, 6) FROM sqlite_master "
      "WHERE type='table' AND name LIKE 'data_%'"
  );

  if( rc==SQLITE_OK ){
    rc = prepareAndCollectError(p->dbMain, &pIter->pIdxIter, &p->zErrmsg,
        "SELECT name, rootpage, sql IS NULL OR substr(8, 6)=='UNIQUE' "
................................................................................
        "  FROM main.sqlite_master "
        "  WHERE type='index' AND tbl_name = ?"
    );
  }

  pIter->bCleanup = 1;
  p->rc = rc;
  return otaObjIterNext(p, pIter);
}

/*
** This is a wrapper around "sqlite3_mprintf(zFmt, ...)". If an OOM occurs,
** an error code is stored in the OTA handle passed as the first argument.
**
** If an error has already occurred (p->rc is already set to something other
** than SQLITE_OK), then this function returns NULL without modifying the
** stored error code. In this case it still calls sqlite3_free() on any 
** printf() parameters associated with %z conversions.
*/
static char *otaMPrintf(sqlite3ota *p, const char *zFmt, ...){
  char *zSql = 0;
  va_list ap;
  va_start(ap, zFmt);
  zSql = sqlite3_vmprintf(zFmt, ap);
  if( p->rc==SQLITE_OK ){
    if( zSql==0 ) p->rc = SQLITE_NOMEM;
  }else{
................................................................................
  return zSql;
}

/*
** Argument zFmt is a sqlite3_mprintf() style format string. The trailing
** arguments are the usual subsitution values. This function performs
** the printf() style substitutions and executes the result as an SQL
** statement on the OTA handles database.
**
** If an error occurs, an error code and error message is stored in the
** OTA handle. If an error has already occurred when this function is
** called, it is a no-op.
*/
static int otaMPrintfExec(sqlite3ota *p, sqlite3 *db, const char *zFmt, ...){
  va_list ap;
  va_start(ap, zFmt);
  char *zSql = sqlite3_vmprintf(zFmt, ap);
  if( p->rc==SQLITE_OK ){
    if( zSql==0 ){
      p->rc = SQLITE_NOMEM;
    }else{
................................................................................
}

/*
** Attempt to allocate and return a pointer to a zeroed block of nByte 
** bytes. 
**
** If an error (i.e. an OOM condition) occurs, return NULL and leave an 
** error code in the ota handle passed as the first argument. Or, if an 
** error has already occurred when this function is called, return NULL 
** immediately without attempting the allocation or modifying the stored
** error code.
*/
static void *otaMalloc(sqlite3ota *p, int nByte){
  void *pRet = 0;
  if( p->rc==SQLITE_OK ){
    assert( nByte>0 );
    pRet = sqlite3_malloc(nByte);
    if( pRet==0 ){
      p->rc = SQLITE_NOMEM;
    }else{
................................................................................
  return pRet;
}


/*
** Allocate and zero the pIter->azTblCol[] and abTblPk[] arrays so that
** there is room for at least nCol elements. If an OOM occurs, store an
** error code in the OTA handle passed as the first argument.
*/
static void otaAllocateIterArrays(sqlite3ota *p, OtaObjIter *pIter, int nCol){
  int nByte = (2*sizeof(char*) + sizeof(int) + 3*sizeof(u8)) * nCol;
  char **azNew;

  azNew = (char**)otaMalloc(p, nByte);
  if( azNew ){
    pIter->azTblCol = azNew;
    pIter->azTblType = &azNew[nCol];
    pIter->aiSrcOrder = (int*)&pIter->azTblType[nCol];
    pIter->abTblPk = (u8*)&pIter->aiSrcOrder[nCol];
    pIter->abNotNull = (u8*)&pIter->abTblPk[nCol];
    pIter->abIndexed = (u8*)&pIter->abNotNull[nCol];
................................................................................
** It is the responsibility of the caller to eventually free this memory
** using sqlite3_free().
**
** If an OOM condition is encountered when attempting to allocate memory,
** output variable (*pRc) is set to SQLITE_NOMEM before returning. Otherwise,
** if the allocation succeeds, (*pRc) is left unchanged.
*/
static char *otaStrndup(const char *zStr, int *pRc){
  char *zRet = 0;

  assert( *pRc==SQLITE_OK );
  if( zStr ){
    int nCopy = strlen(zStr) + 1;
    zRet = (char*)sqlite3_malloc(nCopy);
    if( zRet ){
................................................................................
  return zRet;
}

/*
** Finalize the statement passed as the second argument.
**
** If the sqlite3_finalize() call indicates that an error occurs, and the
** ota handle error code is not already set, set the error code and error
** message accordingly.
*/
static void otaFinalize(sqlite3ota *p, sqlite3_stmt *pStmt){
  sqlite3 *db = sqlite3_db_handle(pStmt);
  int rc = sqlite3_finalize(pStmt);
  if( p->rc==SQLITE_OK && rc!=SQLITE_OK ){
    p->rc = rc;
    p->zErrmsg = sqlite3_mprintf("%s", sqlite3_errmsg(db));
  }
}
................................................................................

/* Determine the type of a table.
**
**   peType is of type (int*), a pointer to an output parameter of type
**   (int). This call sets the output parameter as follows, depending
**   on the type of the table specified by parameters dbName and zTbl.
**
**     OTA_PK_NOTABLE:       No such table.
**     OTA_PK_NONE:          Table has an implicit rowid.
**     OTA_PK_IPK:           Table has an explicit IPK column.
**     OTA_PK_EXTERNAL:      Table has an external PK index.
**     OTA_PK_WITHOUT_ROWID: Table is WITHOUT ROWID.
**     OTA_PK_VTAB:          Table is a virtual table.
**
**   Argument *piPk is also of type (int*), and also points to an output
**   parameter. Unless the table has an external primary key index 
**   (i.e. unless *peType is set to 3), then *piPk is set to zero. Or,
**   if the table does have an external primary key index, then *piPk
**   is set to the root page number of the primary key index before
**   returning.
**
** ALGORITHM:
**
**   if( no entry exists in sqlite_master ){
**     return OTA_PK_NOTABLE
**   }else if( sql for the entry starts with "CREATE VIRTUAL" ){
**     return OTA_PK_VTAB
**   }else if( "PRAGMA index_list()" for the table contains a "pk" index ){
**     if( the index that is the pk exists in sqlite_master ){
**       *piPK = rootpage of that index.
**       return OTA_PK_EXTERNAL
**     }else{
**       return OTA_PK_WITHOUT_ROWID
**     }
**   }else if( "PRAGMA table_info()" lists one or more "pk" columns ){
**     return OTA_PK_IPK
**   }else{
**     return OTA_PK_NONE
**   }
*/
static void otaTableType(
  sqlite3ota *p,
  const char *zTab,
  int *peType,
  int *piTnum,
  int *piPk
){
  /*
  ** 0) SELECT count(*) FROM sqlite_master where name=%Q AND IsVirtual(%Q)
  ** 1) PRAGMA index_list = ?
  ** 2) SELECT count(*) FROM sqlite_master where name=%Q 
  ** 3) PRAGMA table_info = ?
  */
  sqlite3_stmt *aStmt[4] = {0, 0, 0, 0};

  *peType = OTA_PK_NOTABLE;
  *piPk = 0;

  assert( p->rc==SQLITE_OK );
  p->rc = prepareFreeAndCollectError(p->dbMain, &aStmt[0], &p->zErrmsg, 
    sqlite3_mprintf(
          "SELECT (sql LIKE 'create virtual%%'), rootpage"
          "  FROM sqlite_master"
          " WHERE name=%Q", zTab
  ));
  if( p->rc!=SQLITE_OK || sqlite3_step(aStmt[0])!=SQLITE_ROW ){
    /* Either an error, or no such table. */
    goto otaTableType_end;
  }
  if( sqlite3_column_int(aStmt[0], 0) ){
    *peType = OTA_PK_VTAB;                     /* virtual table */
    goto otaTableType_end;
  }
  *piTnum = sqlite3_column_int(aStmt[0], 1);

  p->rc = prepareFreeAndCollectError(p->dbMain, &aStmt[1], &p->zErrmsg, 
    sqlite3_mprintf("PRAGMA index_list=%Q",zTab)
  );
  if( p->rc ) goto otaTableType_end;
  while( sqlite3_step(aStmt[1])==SQLITE_ROW ){
    const u8 *zOrig = sqlite3_column_text(aStmt[1], 3);
    const u8 *zIdx = sqlite3_column_text(aStmt[1], 1);
    if( zOrig && zIdx && zOrig[0]=='p' ){
      p->rc = prepareFreeAndCollectError(p->dbMain, &aStmt[2], &p->zErrmsg, 
          sqlite3_mprintf(
            "SELECT rootpage FROM sqlite_master WHERE name = %Q", zIdx
      ));
      if( p->rc==SQLITE_OK ){
        if( sqlite3_step(aStmt[2])==SQLITE_ROW ){
          *piPk = sqlite3_column_int(aStmt[2], 0);
          *peType = OTA_PK_EXTERNAL;
        }else{
          *peType = OTA_PK_WITHOUT_ROWID;
        }
      }
      goto otaTableType_end;
    }
  }

  p->rc = prepareFreeAndCollectError(p->dbMain, &aStmt[3], &p->zErrmsg, 
    sqlite3_mprintf("PRAGMA table_info=%Q",zTab)
  );
  if( p->rc==SQLITE_OK ){
    while( sqlite3_step(aStmt[3])==SQLITE_ROW ){
      if( sqlite3_column_int(aStmt[3],5)>0 ){
        *peType = OTA_PK_IPK;                /* explicit IPK column */
        goto otaTableType_end;
      }
    }
    *peType = OTA_PK_NONE;
  }

otaTableType_end: {
    int i;
    for(i=0; i<sizeof(aStmt)/sizeof(aStmt[0]); i++){
      otaFinalize(p, aStmt[i]);
    }
  }
}

/*
** This is a helper function for otaObjIterCacheTableInfo(). It populates
** the pIter->abIndexed[] array.
*/
static void otaObjIterCacheIndexedCols(sqlite3ota *p, OtaObjIter *pIter){
  sqlite3_stmt *pList = 0;
  int bIndex = 0;

  if( p->rc==SQLITE_OK ){
    memcpy(pIter->abIndexed, pIter->abTblPk, sizeof(u8)*pIter->nTblCol);
    p->rc = prepareFreeAndCollectError(p->dbMain, &pList, &p->zErrmsg,
        sqlite3_mprintf("PRAGMA main.index_list = %Q", pIter->zTbl)
................................................................................
    p->rc = prepareFreeAndCollectError(p->dbMain, &pXInfo, &p->zErrmsg,
        sqlite3_mprintf("PRAGMA main.index_xinfo = %Q", zIdx)
    );
    while( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pXInfo) ){
      int iCid = sqlite3_column_int(pXInfo, 1);
      if( iCid>=0 ) pIter->abIndexed[iCid] = 1;
    }
    otaFinalize(p, pXInfo);
    bIndex = 1;
  }

  otaFinalize(p, pList);
  if( bIndex==0 ) pIter->abIndexed = 0;
}


/*
** If they are not already populated, populate the pIter->azTblCol[],
** pIter->abTblPk[], pIter->nTblCol and pIter->bRowid variables according to
** the table (not index) that the iterator currently points to.
**
** Return SQLITE_OK if successful, or an SQLite error code otherwise. If
** an error does occur, an error code and error message are also left in 
** the OTA handle.
*/
static int otaObjIterCacheTableInfo(sqlite3ota *p, OtaObjIter *pIter){
  if( pIter->azTblCol==0 ){
    sqlite3_stmt *pStmt = 0;
    int nCol = 0;
    int i;                        /* for() loop iterator variable */
    int bOtaRowid = 0;            /* If input table has column "ota_rowid" */
    int iOrder = 0;
    int iTnum = 0;

    /* Figure out the type of table this step will deal with. */
    assert( pIter->eType==0 );
    otaTableType(p, pIter->zTbl, &pIter->eType, &iTnum, &pIter->iPkTnum);
    if( p->rc==SQLITE_OK && pIter->eType==OTA_PK_NOTABLE ){
      p->rc = SQLITE_ERROR;
      p->zErrmsg = sqlite3_mprintf("no such table: %s", pIter->zTbl);
    }
    if( p->rc ) return p->rc;
    if( pIter->zIdx==0 ) pIter->iTnum = iTnum;

    assert( pIter->eType==OTA_PK_NONE || pIter->eType==OTA_PK_IPK 
         || pIter->eType==OTA_PK_EXTERNAL || pIter->eType==OTA_PK_WITHOUT_ROWID
         || pIter->eType==OTA_PK_VTAB
    );

    /* Populate the azTblCol[] and nTblCol variables based on the columns
    ** of the input table. Ignore any input table columns that begin with
    ** "ota_".  */
    p->rc = prepareFreeAndCollectError(p->dbOta, &pStmt, &p->zErrmsg, 
        sqlite3_mprintf("SELECT * FROM 'data_%q'", pIter->zTbl)
    );
    if( p->rc==SQLITE_OK ){
      nCol = sqlite3_column_count(pStmt);
      otaAllocateIterArrays(p, pIter, nCol);
    }
    for(i=0; p->rc==SQLITE_OK && i<nCol; i++){
      const char *zName = (const char*)sqlite3_column_name(pStmt, i);
      if( sqlite3_strnicmp("ota_", zName, 4) ){
        char *zCopy = otaStrndup(zName, &p->rc);
        pIter->aiSrcOrder[pIter->nTblCol] = pIter->nTblCol;
        pIter->azTblCol[pIter->nTblCol++] = zCopy;
      }
      else if( 0==sqlite3_stricmp("ota_rowid", zName) ){
        bOtaRowid = 1;
      }
    }
    sqlite3_finalize(pStmt);
    pStmt = 0;

    if( p->rc==SQLITE_OK
     && bOtaRowid!=(pIter->eType==OTA_PK_VTAB || pIter->eType==OTA_PK_NONE)
    ){
      p->rc = SQLITE_ERROR;
      p->zErrmsg = sqlite3_mprintf(
          "table data_%q %s ota_rowid column", pIter->zTbl,
          (bOtaRowid ? "may not have" : "requires")
      );
    }

    /* Check that all non-HIDDEN columns in the destination table are also
    ** present in the input table. Populate the abTblPk[], azTblType[] and
    ** aiTblOrder[] arrays at the same time.  */
    if( p->rc==SQLITE_OK ){
................................................................................
        const char *zType = (const char*)sqlite3_column_text(pStmt, 2);

        if( i!=iOrder ){
          SWAP(int, pIter->aiSrcOrder[i], pIter->aiSrcOrder[iOrder]);
          SWAP(char*, pIter->azTblCol[i], pIter->azTblCol[iOrder]);
        }

        pIter->azTblType[iOrder] = otaStrndup(zType, &p->rc);
        pIter->abTblPk[iOrder] = (iPk!=0);
        pIter->abNotNull[iOrder] = (u8)bNotNull || (iPk!=0);
        iOrder++;
      }
    }

    otaFinalize(p, pStmt);
    otaObjIterCacheIndexedCols(p, pIter);
    assert( pIter->eType!=OTA_PK_VTAB || pIter->abIndexed==0 );
  }

  return p->rc;
}

/*
** This function constructs and returns a pointer to a nul-terminated 
** string containing some SQL clause or list based on one or more of the 
** column names currently stored in the pIter->azTblCol[] array.
*/
static char *otaObjIterGetCollist(
  sqlite3ota *p,                  /* OTA object */
  OtaObjIter *pIter               /* Object iterator for column names */
){
  char *zList = 0;
  const char *zSep = "";
  int i;
  for(i=0; i<pIter->nTblCol; i++){
    const char *z = pIter->azTblCol[i];
    zList = otaMPrintf(p, "%z%s\"%w\"", zList, zSep, z);
    zSep = ", ";
  }
  return zList;
}

/*
** This function is used to create a SELECT list (the list of SQL 
** expressions that follows a SELECT keyword) for a SELECT statement 
** used to read from an data_xxx or ota_tmp_xxx table while updating the 
** index object currently indicated by the iterator object passed as the 
** second argument. A "PRAGMA index_xinfo = <idxname>" statement is used 
** to obtain the required information.
**
** If the index is of the following form:
**
**   CREATE INDEX i1 ON t1(c, b COLLATE nocase);
................................................................................
** As well as the returned string, three other malloc'd strings are 
** returned via output parameters. As follows:
**
**   pzImposterCols: ...
**   pzImposterPk: ...
**   pzWhere: ...
*/
static char *otaObjIterGetIndexCols(
  sqlite3ota *p,                  /* OTA object */
  OtaObjIter *pIter,              /* Object iterator for column names */
  char **pzImposterCols,          /* OUT: Columns for imposter table */
  char **pzImposterPk,            /* OUT: Imposter PK clause */
  char **pzWhere,                 /* OUT: WHERE clause */
  int *pnBind                     /* OUT: Total number of columns */
){
  int rc = p->rc;                 /* Error code */
  int rc2;                        /* sqlite3_finalize() return code */
  char *zRet = 0;                 /* String to return */
  char *zImpCols = 0;             /* String to return via *pzImposterCols */
  char *zImpPK = 0;               /* String to return via *pzImposterPK */
  char *zWhere = 0;               /* String to return via *pzWhere */
................................................................................
    int bDesc = sqlite3_column_int(pXInfo, 3);
    const char *zCollate = (const char*)sqlite3_column_text(pXInfo, 4);
    const char *zCol;
    const char *zType;

    if( iCid<0 ){
      /* An integer primary key. If the table has an explicit IPK, use
      ** its name. Otherwise, use "ota_rowid".  */
      if( pIter->eType==OTA_PK_IPK ){
        int i;
        for(i=0; pIter->abTblPk[i]==0; i++);
        assert( i<pIter->nTblCol );
        zCol = pIter->azTblCol[i];
      }else{
        zCol = "ota_rowid";
      }
      zType = "INTEGER";
    }else{
      zCol = pIter->azTblCol[iCid];
      zType = pIter->azTblType[iCid];
    }

    zRet = sqlite3_mprintf("%z%s\"%w\" COLLATE %Q", zRet, zCom, zCol, zCollate);
    if( pIter->bUnique==0 || sqlite3_column_int(pXInfo, 5) ){
      const char *zOrder = (bDesc ? " DESC" : "");
      zImpPK = sqlite3_mprintf("%z%s\"ota_imp_%d%w\"%s", 
          zImpPK, zCom, nBind, zCol, zOrder
      );
    }
    zImpCols = sqlite3_mprintf("%z%s\"ota_imp_%d%w\" %s COLLATE %Q", 
        zImpCols, zCom, nBind, zCol, zType, zCollate
    );
    zWhere = sqlite3_mprintf(
        "%z%s\"ota_imp_%d%w\" IS ?", zWhere, zAnd, nBind, zCol
    );
    if( zRet==0 || zImpPK==0 || zImpCols==0 || zWhere==0 ) rc = SQLITE_NOMEM;
    zCom = ", ";
    zAnd = " AND ";
    nBind++;
  }

................................................................................
** Assuming the current table columns are "a", "b" and "c", and the zObj
** paramter is passed "old", return a string of the form:
**
**     "old.a, old.b, old.b"
**
** With the column names escaped.
**
** For tables with implicit rowids - OTA_PK_EXTERNAL and OTA_PK_NONE, append
** the text ", old._rowid_" to the returned value.
*/
static char *otaObjIterGetOldlist(
  sqlite3ota *p, 
  OtaObjIter *pIter,
  const char *zObj
){
  char *zList = 0;
  if( p->rc==SQLITE_OK && pIter->abIndexed ){
    const char *zS = "";
    int i;
    for(i=0; i<pIter->nTblCol; i++){
................................................................................
      if( zList==0 ){
        p->rc = SQLITE_NOMEM;
        break;
      }
    }

    /* For a table with implicit rowids, append "old._rowid_" to the list. */
    if( pIter->eType==OTA_PK_EXTERNAL || pIter->eType==OTA_PK_NONE ){
      zList = otaMPrintf(p, "%z, %s._rowid_", zList, zObj);
    }
  }
  return zList;
}

/*
** Return an expression that can be used in a WHERE clause to match the
................................................................................
**
**   CREATE TABLE t1(a, b, c, PRIMARY KEY(b, c));
**
** Return the string:
**
**   "b = ?1 AND c = ?2"
*/
static char *otaObjIterGetWhere(
  sqlite3ota *p, 
  OtaObjIter *pIter
){
  char *zList = 0;
  if( pIter->eType==OTA_PK_VTAB || pIter->eType==OTA_PK_NONE ){
    zList = otaMPrintf(p, "_rowid_ = ?%d", pIter->nTblCol+1);
  }else if( pIter->eType==OTA_PK_EXTERNAL ){
    const char *zSep = "";
    int i;
    for(i=0; i<pIter->nTblCol; i++){
      if( pIter->abTblPk[i] ){
        zList = otaMPrintf(p, "%z%sc%d=?%d", zList, zSep, i, i+1);
        zSep = " AND ";
      }
    }
    zList = otaMPrintf(p, 
        "_rowid_ = (SELECT id FROM ota_imposter2 WHERE %z)", zList
    );

  }else{
    const char *zSep = "";
    int i;
    for(i=0; i<pIter->nTblCol; i++){
      if( pIter->abTblPk[i] ){
        const char *zCol = pIter->azTblCol[i];
        zList = otaMPrintf(p, "%z%s\"%w\"=?%d", zList, zSep, zCol, i+1);
        zSep = " AND ";
      }
    }
  }
  return zList;
}

/*
** The SELECT statement iterating through the keys for the current object
** (p->objiter.pSelect) currently points to a valid row. However, there
** is something wrong with the ota_control value in the ota_control value
** stored in the (p->nCol+1)'th column. Set the error code and error message
** of the OTA handle to something reflecting this.
*/
static void otaBadControlError(sqlite3ota *p){
  p->rc = SQLITE_ERROR;
  p->zErrmsg = sqlite3_mprintf("invalid ota_control value");
}


/*
** Return a nul-terminated string containing the comma separated list of
** assignments that should be included following the "SET" keyword of
** an UPDATE statement used to update the table object that the iterator
** passed as the second argument currently points to if the ota_control
** column of the data_xxx table entry is set to zMask.
**
** The memory for the returned string is obtained from sqlite3_malloc().
** It is the responsibility of the caller to eventually free it using
** sqlite3_free(). 
**
** If an OOM error is encountered when allocating space for the new
** string, an error code is left in the ota handle passed as the first
** argument and NULL is returned. Or, if an error has already occurred
** when this function is called, NULL is returned immediately, without
** attempting the allocation or modifying the stored error code.
*/
static char *otaObjIterGetSetlist(
  sqlite3ota *p,
  OtaObjIter *pIter,
  const char *zMask
){
  char *zList = 0;
  if( p->rc==SQLITE_OK ){
    int i;

    if( strlen(zMask)!=pIter->nTblCol ){
      otaBadControlError(p);
    }else{
      const char *zSep = "";
      for(i=0; i<pIter->nTblCol; i++){
        char c = zMask[pIter->aiSrcOrder[i]];
        if( c=='x' ){
          zList = otaMPrintf(p, "%z%s\"%w\"=?%d", 
              zList, zSep, pIter->azTblCol[i], i+1
          );
          zSep = ", ";
        }
        if( c=='d' ){
          zList = otaMPrintf(p, "%z%s\"%w\"=ota_delta(\"%w\", ?%d)", 
              zList, zSep, pIter->azTblCol[i], pIter->azTblCol[i], i+1
          );
          zSep = ", ";
        }
      }
    }
  }
................................................................................
** a buffer containing the string "?,?,?".
**
** The memory for the returned string is obtained from sqlite3_malloc().
** It is the responsibility of the caller to eventually free it using
** sqlite3_free(). 
**
** If an OOM error is encountered when allocating space for the new
** string, an error code is left in the ota handle passed as the first
** argument and NULL is returned. Or, if an error has already occurred
** when this function is called, NULL is returned immediately, without
** attempting the allocation or modifying the stored error code.
*/
static char *otaObjIterGetBindlist(sqlite3ota *p, int nBind){
  char *zRet = 0;
  int nByte = nBind*2 + 1;

  zRet = (char*)otaMalloc(p, nByte);
  if( zRet ){
    int i;
    for(i=0; i<nBind; i++){
      zRet[i*2] = '?';
      zRet[i*2+1] = (i+1==nBind) ? '\0' : ',';
    }
  }
  return zRet;
}

/*
** The iterator currently points to a table (not index) of type 
** OTA_PK_WITHOUT_ROWID. This function creates the PRIMARY KEY 
** declaration for the corresponding imposter table. For example,
** if the iterator points to a table created as:
**
**   CREATE TABLE t1(a, b, c, PRIMARY KEY(b, a DESC)) WITHOUT ROWID
**
** this function returns:
**
**   PRIMARY KEY("b", "a" DESC)
*/
static char *otaWithoutRowidPK(sqlite3ota *p, OtaObjIter *pIter){
  char *z = 0;
  assert( pIter->zIdx==0 );
  if( p->rc==SQLITE_OK ){
    const char *zSep = "PRIMARY KEY(";
    sqlite3_stmt *pXList = 0;     /* PRAGMA index_list = (pIter->zTbl) */
    sqlite3_stmt *pXInfo = 0;     /* PRAGMA index_xinfo = <pk-index> */
   
................................................................................
          p->rc = prepareFreeAndCollectError(p->dbMain, &pXInfo, &p->zErrmsg,
              sqlite3_mprintf("PRAGMA main.index_xinfo = %Q", zIdx)
          );
        }
        break;
      }
    }
    otaFinalize(p, pXList);

    while( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pXInfo) ){
      if( sqlite3_column_int(pXInfo, 5) ){
        /* int iCid = sqlite3_column_int(pXInfo, 0); */
        const char *zCol = (const char*)sqlite3_column_text(pXInfo, 2);
        const char *zDesc = sqlite3_column_int(pXInfo, 3) ? " DESC" : "";
        z = otaMPrintf(p, "%z%s\"%w\"%s", z, zSep, zCol, zDesc);
        zSep = ", ";
      }
    }
    z = otaMPrintf(p, "%z)", z);
    otaFinalize(p, pXInfo);
  }
  return z;
}

/*
** This function creates the second imposter table used when writing to
** a table b-tree where the table has an external primary key. If the
** iterator passed as the second argument does not currently point to
** a table (not index) with an external primary key, this function is a
** no-op. 
**
** Assuming the iterator does point to a table with an external PK, this
** function creates a WITHOUT ROWID imposter table named "ota_imposter2"
** used to access that PK index. For example, if the target table is
** declared as follows:
**
**   CREATE TABLE t1(a, b TEXT, c REAL, PRIMARY KEY(b, c));
**
** then the imposter table schema is:
**
**   CREATE TABLE ota_imposter2(c1 TEXT, c2 REAL, id INTEGER) WITHOUT ROWID;
**
*/
static void otaCreateImposterTable2(sqlite3ota *p, OtaObjIter *pIter){
  if( p->rc==SQLITE_OK && pIter->eType==OTA_PK_EXTERNAL ){
    int tnum = pIter->iPkTnum;    /* Root page of PK index */
    sqlite3_stmt *pQuery = 0;     /* SELECT name ... WHERE rootpage = $tnum */
    const char *zIdx = 0;         /* Name of PK index */
    sqlite3_stmt *pXInfo = 0;     /* PRAGMA main.index_xinfo = $zIdx */
    const char *zComma = "";
    char *zCols = 0;              /* Used to build up list of table cols */
    char *zPk = 0;                /* Used to build up table PK declaration */
................................................................................
      }
    }
    if( zIdx ){
      p->rc = prepareFreeAndCollectError(p->dbMain, &pXInfo, &p->zErrmsg,
          sqlite3_mprintf("PRAGMA main.index_xinfo = %Q", zIdx)
      );
    }
    otaFinalize(p, pQuery);

    while( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pXInfo) ){
      int bKey = sqlite3_column_int(pXInfo, 5);
      if( bKey ){
        int iCid = sqlite3_column_int(pXInfo, 1);
        int bDesc = sqlite3_column_int(pXInfo, 3);
        const char *zCollate = (const char*)sqlite3_column_text(pXInfo, 4);
        zCols = otaMPrintf(p, "%z%sc%d %s COLLATE %s", zCols, zComma, 
            iCid, pIter->azTblType[iCid], zCollate
        );
        zPk = otaMPrintf(p, "%z%sc%d%s", zPk, zComma, iCid, bDesc?" DESC":"");
        zComma = ", ";
      }
    }
    zCols = otaMPrintf(p, "%z, id INTEGER", zCols);
    otaFinalize(p, pXInfo);

    sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 1, tnum);
    otaMPrintfExec(p, p->dbMain,
        "CREATE TABLE ota_imposter2(%z, PRIMARY KEY(%z)) WITHOUT ROWID", 
        zCols, zPk
    );
    sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 0, 0);
  }
}

/*
** If an error has already occurred when this function is called, it 
** immediately returns zero (without doing any work). Or, if an error
** occurs during the execution of this function, it sets the error code
** in the sqlite3ota object indicated by the first argument and returns
** zero.
**
** The iterator passed as the second argument is guaranteed to point to
** a table (not an index) when this function is called. This function
** attempts to create any imposter table required to write to the main
** table b-tree of the table before returning. Non-zero is returned if
** an imposter table are created, or zero otherwise.
**
** An imposter table is required in all cases except OTA_PK_VTAB. Only
** virtual tables are written to directly. The imposter table has the 
** same schema as the actual target table (less any UNIQUE constraints). 
** More precisely, the "same schema" means the same columns, types, 
** collation sequences. For tables that do not have an external PRIMARY
** KEY, it also means the same PRIMARY KEY declaration.
*/
static void otaCreateImposterTable(sqlite3ota *p, OtaObjIter *pIter){
  if( p->rc==SQLITE_OK && pIter->eType!=OTA_PK_VTAB ){
    int tnum = pIter->iTnum;
    const char *zComma = "";
    char *zSql = 0;
    int iCol;
    sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 0, 1);

    for(iCol=0; p->rc==SQLITE_OK && iCol<pIter->nTblCol; iCol++){
................................................................................
      const char *zCol = pIter->azTblCol[iCol];
      const char *zColl = 0;

      p->rc = sqlite3_table_column_metadata(
          p->dbMain, "main", pIter->zTbl, zCol, 0, &zColl, 0, 0, 0
      );

      if( pIter->eType==OTA_PK_IPK && pIter->abTblPk[iCol] ){
        /* If the target table column is an "INTEGER PRIMARY KEY", add
        ** "PRIMARY KEY" to the imposter table column declaration. */
        zPk = "PRIMARY KEY ";
      }
      zSql = otaMPrintf(p, "%z%s\"%w\" %s %sCOLLATE %s%s", 
          zSql, zComma, zCol, pIter->azTblType[iCol], zPk, zColl,
          (pIter->abNotNull[iCol] ? " NOT NULL" : "")
      );
      zComma = ", ";
    }

    if( pIter->eType==OTA_PK_WITHOUT_ROWID ){
      char *zPk = otaWithoutRowidPK(p, pIter);
      if( zPk ){
        zSql = otaMPrintf(p, "%z, %z", zSql, zPk);
      }
    }

    sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 1, tnum);
    otaMPrintfExec(p, p->dbMain, "CREATE TABLE \"ota_imp_%w\"(%z)%s", 
        pIter->zTbl, zSql, 
        (pIter->eType==OTA_PK_WITHOUT_ROWID ? " WITHOUT ROWID" : "")
    );
    sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 0, 0);
  }
}

/*
** Prepare a statement used to insert rows into the "ota_tmp_xxx" table.
** Specifically a statement of the form:
**
**     INSERT INTO ota_tmp_xxx VALUES(?, ?, ? ...);
**
** The number of bound variables is equal to the number of columns in
** the target table, plus one (for the ota_control column), plus one more 
** (for the ota_rowid column) if the target table is an implicit IPK or 
** virtual table.
*/
static void otaObjIterPrepareTmpInsert(
  sqlite3ota *p, 
  OtaObjIter *pIter,
  const char *zCollist,
  const char *zOtaRowid
){
  int bOtaRowid = (pIter->eType==OTA_PK_EXTERNAL || pIter->eType==OTA_PK_NONE);
  char *zBind = otaObjIterGetBindlist(p, pIter->nTblCol + 1 + bOtaRowid);
  if( zBind ){
    assert( pIter->pTmpInsert==0 );
    p->rc = prepareFreeAndCollectError(
        p->dbOta, &pIter->pTmpInsert, &p->zErrmsg, sqlite3_mprintf(
          "INSERT INTO %s.'ota_tmp_%q'(ota_control,%s%s) VALUES(%z)", 
          p->zStateDb, pIter->zTbl, zCollist, zOtaRowid, zBind
    ));
  }
}

static void otaTmpInsertFunc(
  sqlite3_context *pCtx, 
  int nVal,
  sqlite3_value **apVal
){
  sqlite3ota *p = sqlite3_user_data(pCtx);
  int rc = SQLITE_OK;
  int i;

  for(i=0; rc==SQLITE_OK && i<nVal; i++){
    rc = sqlite3_bind_value(p->objiter.pTmpInsert, i+1, apVal[i]);
  }
  if( rc==SQLITE_OK ){
................................................................................
}

/*
** Ensure that the SQLite statement handles required to update the 
** target database object currently indicated by the iterator passed 
** as the second argument are available.
*/
static int otaObjIterPrepareAll(
  sqlite3ota *p, 
  OtaObjIter *pIter,
  int nOffset                     /* Add "LIMIT -1 OFFSET $nOffset" to SELECT */
){
  assert( pIter->bCleanup==0 );
  if( pIter->pSelect==0 && otaObjIterCacheTableInfo(p, pIter)==SQLITE_OK ){
    const int tnum = pIter->iTnum;
    char *zCollist = 0;           /* List of indexed columns */
    char **pz = &p->zErrmsg;
    const char *zIdx = pIter->zIdx;
    char *zLimit = 0;

    if( nOffset ){
................................................................................
      const char *zTbl = pIter->zTbl;
      char *zImposterCols = 0;    /* Columns for imposter table */
      char *zImposterPK = 0;      /* Primary key declaration for imposter */
      char *zWhere = 0;           /* WHERE clause on PK columns */
      char *zBind = 0;
      int nBind = 0;

      assert( pIter->eType!=OTA_PK_VTAB );
      zCollist = otaObjIterGetIndexCols(
          p, pIter, &zImposterCols, &zImposterPK, &zWhere, &nBind
      );
      zBind = otaObjIterGetBindlist(p, nBind);

      /* Create the imposter table used to write to this index. */
      sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 0, 1);
      sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 1,tnum);
      otaMPrintfExec(p, p->dbMain,
          "CREATE TABLE \"ota_imp_%w\"( %s, PRIMARY KEY( %s ) ) WITHOUT ROWID",
          zTbl, zImposterCols, zImposterPK
      );
      sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 0, 0);

      /* Create the statement to insert index entries */
      pIter->nCol = nBind;
      if( p->rc==SQLITE_OK ){
        p->rc = prepareFreeAndCollectError(
            p->dbMain, &pIter->pInsert, &p->zErrmsg,
          sqlite3_mprintf("INSERT INTO \"ota_imp_%w\" VALUES(%s)", zTbl, zBind)
        );
      }

      /* And to delete index entries */
      if( p->rc==SQLITE_OK ){
        p->rc = prepareFreeAndCollectError(
            p->dbMain, &pIter->pDelete, &p->zErrmsg,
          sqlite3_mprintf("DELETE FROM \"ota_imp_%w\" WHERE %s", zTbl, zWhere)
        );
      }

      /* Create the SELECT statement to read keys in sorted order */
      if( p->rc==SQLITE_OK ){
        char *zSql;
        if( pIter->eType==OTA_PK_EXTERNAL || pIter->eType==OTA_PK_NONE ){
          zSql = sqlite3_mprintf(
              "SELECT %s, ota_control FROM %s.'ota_tmp_%q' ORDER BY %s%s",
              zCollist, p->zStateDb, pIter->zTbl,
              zCollist, zLimit
          );
        }else{
          zSql = sqlite3_mprintf(
              "SELECT %s, ota_control FROM 'data_%q' "
              "WHERE typeof(ota_control)='integer' AND ota_control!=1 "
              "UNION ALL "
              "SELECT %s, ota_control FROM %s.'ota_tmp_%q' "
              "ORDER BY %s%s",
              zCollist, pIter->zTbl, 
              zCollist, p->zStateDb, pIter->zTbl, 
              zCollist, zLimit
          );
        }
        p->rc = prepareFreeAndCollectError(p->dbOta, &pIter->pSelect, pz, zSql);
      }

      sqlite3_free(zImposterCols);
      sqlite3_free(zImposterPK);
      sqlite3_free(zWhere);
      sqlite3_free(zBind);
    }else{
      int bOtaRowid = (pIter->eType==OTA_PK_VTAB || pIter->eType==OTA_PK_NONE);
      const char *zTbl = pIter->zTbl;       /* Table this step applies to */
      const char *zWrite;                   /* Imposter table name */

      char *zBindings = otaObjIterGetBindlist(p, pIter->nTblCol + bOtaRowid);
      char *zWhere = otaObjIterGetWhere(p, pIter);
      char *zOldlist = otaObjIterGetOldlist(p, pIter, "old");
      char *zNewlist = otaObjIterGetOldlist(p, pIter, "new");

      zCollist = otaObjIterGetCollist(p, pIter);
      pIter->nCol = pIter->nTblCol;

      /* Create the SELECT statement to read keys from data_xxx */
      if( p->rc==SQLITE_OK ){
        p->rc = prepareFreeAndCollectError(p->dbOta, &pIter->pSelect, pz,
            sqlite3_mprintf(
              "SELECT %s, ota_control%s FROM 'data_%q'%s", 
              zCollist, (bOtaRowid ? ", ota_rowid" : ""), zTbl, zLimit
            )
        );
      }

      /* Create the imposter table or tables (if required). */
      otaCreateImposterTable(p, pIter);
      otaCreateImposterTable2(p, pIter);
      zWrite = (pIter->eType==OTA_PK_VTAB ? "" : "ota_imp_");

      /* Create the INSERT statement to write to the target PK b-tree */
      if( p->rc==SQLITE_OK ){
        p->rc = prepareFreeAndCollectError(p->dbMain, &pIter->pInsert, pz,
            sqlite3_mprintf(
              "INSERT INTO \"%s%w\"(%s%s) VALUES(%s)", 
              zWrite, zTbl, zCollist, (bOtaRowid ? ", _rowid_" : ""), zBindings
            )
        );
      }

      /* Create the DELETE statement to write to the target PK b-tree */
      if( p->rc==SQLITE_OK ){
        p->rc = prepareFreeAndCollectError(p->dbMain, &pIter->pDelete, pz,
................................................................................
            sqlite3_mprintf(
              "DELETE FROM \"%s%w\" WHERE %s", zWrite, zTbl, zWhere
            )
        );
      }

      if( pIter->abIndexed ){
        const char *zOtaRowid = "";
        if( pIter->eType==OTA_PK_EXTERNAL || pIter->eType==OTA_PK_NONE ){
          zOtaRowid = ", ota_rowid";
        }

        /* Create the ota_tmp_xxx table and the triggers to populate it. */
        otaMPrintfExec(p, p->dbOta,
            "CREATE TABLE IF NOT EXISTS %s.'ota_tmp_%q' AS "
            "SELECT *%s FROM 'data_%q' WHERE 0;"
            , p->zStateDb
            , zTbl, (pIter->eType==OTA_PK_EXTERNAL ? ", 0 AS ota_rowid" : "")
            , zTbl
        );

        otaMPrintfExec(p, p->dbMain,
            "CREATE TEMP TRIGGER ota_delete_tr BEFORE DELETE ON \"%s%w\" "
            "BEGIN "
            "  SELECT ota_tmp_insert(2, %s);"
            "END;"

            "CREATE TEMP TRIGGER ota_update1_tr BEFORE UPDATE ON \"%s%w\" "
            "BEGIN "
            "  SELECT ota_tmp_insert(2, %s);"
            "END;"

            "CREATE TEMP TRIGGER ota_update2_tr AFTER UPDATE ON \"%s%w\" "
            "BEGIN "
            "  SELECT ota_tmp_insert(3, %s);"
            "END;",
            zWrite, zTbl, zOldlist,
            zWrite, zTbl, zOldlist,
            zWrite, zTbl, zNewlist
        );

        if( pIter->eType==OTA_PK_EXTERNAL || pIter->eType==OTA_PK_NONE ){
          otaMPrintfExec(p, p->dbMain,
              "CREATE TEMP TRIGGER ota_insert_tr AFTER INSERT ON \"%s%w\" "
              "BEGIN "
              "  SELECT ota_tmp_insert(0, %s);"
              "END;",
              zWrite, zTbl, zNewlist
          );
        }

        otaObjIterPrepareTmpInsert(p, pIter, zCollist, zOtaRowid);
      }

      sqlite3_free(zWhere);
      sqlite3_free(zOldlist);
      sqlite3_free(zNewlist);
      sqlite3_free(zBindings);
    }
................................................................................
  return p->rc;
}

/*
** Set output variable *ppStmt to point to an UPDATE statement that may
** be used to update the imposter table for the main table b-tree of the
** table object that pIter currently points to, assuming that the 
** ota_control column of the data_xyz table contains zMask.
** 
** If the zMask string does not specify any columns to update, then this
** is not an error. Output variable *ppStmt is set to NULL in this case.
*/
static int otaGetUpdateStmt(
  sqlite3ota *p,                  /* OTA handle */
  OtaObjIter *pIter,              /* Object iterator */
  const char *zMask,              /* ota_control value ('x.x.') */
  sqlite3_stmt **ppStmt           /* OUT: UPDATE statement handle */
){
  OtaUpdateStmt **pp;
  OtaUpdateStmt *pUp = 0;
  int nUp = 0;

  /* In case an error occurs */
  *ppStmt = 0;

  /* Search for an existing statement. If one is found, shift it to the front
  ** of the LRU queue and return immediately. Otherwise, leave nUp pointing
  ** to the number of statements currently in the cache and pUp to the
  ** last object in the list.  */
  for(pp=&pIter->pOtaUpdate; *pp; pp=&((*pp)->pNext)){
    pUp = *pp;
    if( strcmp(pUp->zMask, zMask)==0 ){
      *pp = pUp->pNext;
      pUp->pNext = pIter->pOtaUpdate;
      pIter->pOtaUpdate = pUp;
      *ppStmt = pUp->pUpdate; 
      return SQLITE_OK;
    }
    nUp++;
  }
  assert( pUp==0 || pUp->pNext==0 );

  if( nUp>=SQLITE_OTA_UPDATE_CACHESIZE ){
    for(pp=&pIter->pOtaUpdate; *pp!=pUp; pp=&((*pp)->pNext));
    *pp = 0;
    sqlite3_finalize(pUp->pUpdate);
    pUp->pUpdate = 0;
  }else{
    pUp = (OtaUpdateStmt*)otaMalloc(p, sizeof(OtaUpdateStmt)+pIter->nTblCol+1);
  }

  if( pUp ){
    char *zWhere = otaObjIterGetWhere(p, pIter);
    char *zSet = otaObjIterGetSetlist(p, pIter, zMask);
    char *zUpdate = 0;

    pUp->zMask = (char*)&pUp[1];
    memcpy(pUp->zMask, zMask, pIter->nTblCol);
    pUp->pNext = pIter->pOtaUpdate;
    pIter->pOtaUpdate = pUp;

    if( zSet ){
      const char *zPrefix = "";

      if( pIter->eType!=OTA_PK_VTAB ) zPrefix = "ota_imp_";
      zUpdate = sqlite3_mprintf("UPDATE \"%s%w\" SET %s WHERE %s", 
          zPrefix, pIter->zTbl, zSet, zWhere
      );
      p->rc = prepareFreeAndCollectError(
          p->dbMain, &pUp->pUpdate, &p->zErrmsg, zUpdate
      );
      *ppStmt = pUp->pUpdate;
................................................................................
    sqlite3_free(zWhere);
    sqlite3_free(zSet);
  }

  return p->rc;
}

static sqlite3 *otaOpenDbhandle(sqlite3ota *p, const char *zName){
  sqlite3 *db = 0;
  if( p->rc==SQLITE_OK ){
    const int flags = SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|SQLITE_OPEN_URI;
    p->rc = sqlite3_open_v2(zName, &db, flags, p->zVfsName);
    if( p->rc ){
      p->zErrmsg = sqlite3_mprintf("%s", sqlite3_errmsg(db));
      sqlite3_close(db);
................................................................................
      db = 0;
    }
  }
  return db;
}

/*
** Open the database handle and attach the OTA database as "ota". If an
** error occurs, leave an error code and message in the OTA handle.
*/
static void otaOpenDatabase(sqlite3ota *p){
  assert( p->rc==SQLITE_OK );
  assert( p->dbMain==0 && p->dbOta==0 );

  p->eStage = 0;
  p->dbMain = otaOpenDbhandle(p, p->zTarget);
  p->dbOta = otaOpenDbhandle(p, p->zOta);

  /* If using separate OTA and state databases, attach the state database to
  ** the OTA db handle now.  */
  if( p->zState ){
    otaMPrintfExec(p, p->dbOta, "ATTACH %Q AS stat", p->zState);
    memcpy(p->zStateDb, "stat", 4);
  }else{
    memcpy(p->zStateDb, "main", 4);
  }

  if( p->rc==SQLITE_OK ){
    p->rc = sqlite3_create_function(p->dbMain, 
        "ota_tmp_insert", -1, SQLITE_UTF8, (void*)p, otaTmpInsertFunc, 0, 0
    );
  }

  if( p->rc==SQLITE_OK ){
    p->rc = sqlite3_file_control(p->dbMain, "main", SQLITE_FCNTL_OTA, (void*)p);
  }
  otaMPrintfExec(p, p->dbMain, "SELECT * FROM sqlite_master");

  /* Mark the database file just opened as an OTA target database. If 
  ** this call returns SQLITE_NOTFOUND, then the OTA vfs is not in use.
  ** This is an error.  */
  if( p->rc==SQLITE_OK ){
    p->rc = sqlite3_file_control(p->dbMain, "main", SQLITE_FCNTL_OTA, (void*)p);
  }

  if( p->rc==SQLITE_NOTFOUND ){
    p->rc = SQLITE_ERROR;
    p->zErrmsg = sqlite3_mprintf("ota vfs not found");
  }
}

/*
** This routine is a copy of the sqlite3FileSuffix3() routine from the core.
** It is a no-op unless SQLITE_ENABLE_8_3_NAMES is defined.
**
................................................................................
** Examples:
**
**     test.db-journal    =>   test.nal
**     test.db-wal        =>   test.wal
**     test.db-shm        =>   test.shm
**     test.db-mj7f3319fa =>   test.9fa
*/
static void otaFileSuffix3(const char *zBase, char *z){
#ifdef SQLITE_ENABLE_8_3_NAMES
#if SQLITE_ENABLE_8_3_NAMES<2
  if( sqlite3_uri_boolean(zBase, "8_3_names", 0) )
#endif
  {
    int i, sz;
    sz = sqlite3Strlen30(z);
................................................................................
/*
** Return the current wal-index header checksum for the target database 
** as a 64-bit integer.
**
** The checksum is store in the first page of xShmMap memory as an 8-byte 
** blob starting at byte offset 40.
*/
static i64 otaShmChecksum(sqlite3ota *p){
  i64 iRet = 0;
  if( p->rc==SQLITE_OK ){
    sqlite3_file *pDb = p->pTargetFd->pReal;
    u32 volatile *ptr;
    p->rc = pDb->pMethods->xShmMap(pDb, 0, 32*1024, 0, (void volatile**)&ptr);
    if( p->rc==SQLITE_OK ){
      iRet = ((i64)ptr[10] << 32) + ptr[11];
................................................................................
  return iRet;
}

/*
** This function is called as part of initializing or reinitializing an
** incremental checkpoint. 
**
** It populates the sqlite3ota.aFrame[] array with the set of 
** (wal frame -> db page) copy operations required to checkpoint the 
** current wal file, and obtains the set of shm locks required to safely 
** perform the copy operations directly on the file-system.
**
** If argument pState is not NULL, then the incremental checkpoint is
** being resumed. In this case, if the checksum of the wal-index-header
** following recovery is not the same as the checksum saved in the OtaState
** object, then the ota handle is set to DONE state. This occurs if some
** other client appends a transaction to the wal file in the middle of
** an incremental checkpoint.
*/
static void otaSetupCheckpoint(sqlite3ota *p, OtaState *pState){

  /* If pState is NULL, then the wal file may not have been opened and
  ** recovered. Running a read-statement here to ensure that doing so
  ** does not interfere with the "capture" process below.  */
  if( pState==0 ){
    p->eStage = 0;
    if( p->rc==SQLITE_OK ){
      p->rc = sqlite3_exec(p->dbMain, "SELECT * FROM sqlite_master", 0, 0, 0);
    }
  }

  /* Assuming no error has occurred, run a "restart" checkpoint with the
  ** sqlite3ota.eStage variable set to CAPTURE. This turns on the following
  ** special behaviour in the ota VFS:
  **
  **   * If the exclusive shm WRITER or READ0 lock cannot be obtained,
  **     the checkpoint fails with SQLITE_BUSY (normally SQLite would
  **     proceed with running a passive checkpoint instead of failing).
  **
  **   * Attempts to read from the *-wal file or write to the database file
  **     do not perform any IO. Instead, the frame/page combinations that
  **     would be read/written are recorded in the sqlite3ota.aFrame[]
  **     array.
  **
  **   * Calls to xShmLock(UNLOCK) to release the exclusive shm WRITER, 
  **     READ0 and CHECKPOINT locks taken as part of the checkpoint are
  **     no-ops. These locks will not be released until the connection
  **     is closed.
  **
................................................................................
  ** array populated with a set of (frame -> page) mappings. Because the 
  ** WRITER, CHECKPOINT and READ0 locks are still held, it is safe to copy 
  ** data from the wal file into the database file according to the 
  ** contents of aFrame[].
  */
  if( p->rc==SQLITE_OK ){
    int rc2;
    p->eStage = OTA_STAGE_CAPTURE;
    rc2 = sqlite3_exec(p->dbMain, "PRAGMA main.wal_checkpoint=restart", 0, 0,0);
    if( rc2!=SQLITE_INTERNAL ) p->rc = rc2;
  }

  if( p->rc==SQLITE_OK ){
    p->eStage = OTA_STAGE_CKPT;
    p->nStep = (pState ? pState->nRow : 0);
    p->aBuf = otaMalloc(p, p->pgsz);
    p->iWalCksum = otaShmChecksum(p);
  }

  if( p->rc==SQLITE_OK && pState && pState->iWalCksum!=p->iWalCksum ){
    p->rc = SQLITE_DONE;
    p->eStage = OTA_STAGE_DONE;
  }
}

/*
** Called when iAmt bytes are read from offset iOff of the wal file while
** the ota object is in capture mode. Record the frame number of the frame
** being read in the aFrame[] array.
*/
static int otaCaptureWalRead(sqlite3ota *pOta, i64 iOff, int iAmt){
  const u32 mReq = (1<<WAL_LOCK_WRITE)|(1<<WAL_LOCK_CKPT)|(1<<WAL_LOCK_READ0);
  u32 iFrame;

  if( pOta->mLock!=mReq ){
    pOta->rc = SQLITE_BUSY;
    return SQLITE_INTERNAL;
  }

  pOta->pgsz = iAmt;
  if( pOta->nFrame==pOta->nFrameAlloc ){
    int nNew = (pOta->nFrameAlloc ? pOta->nFrameAlloc : 64) * 2;
    OtaFrame *aNew;
    aNew = (OtaFrame*)sqlite3_realloc(pOta->aFrame, nNew * sizeof(OtaFrame));
    if( aNew==0 ) return SQLITE_NOMEM;
    pOta->aFrame = aNew;
    pOta->nFrameAlloc = nNew;
  }

  iFrame = (u32)((iOff-32) / (i64)(iAmt+24)) + 1;
  if( pOta->iMaxFrame<iFrame ) pOta->iMaxFrame = iFrame;
  pOta->aFrame[pOta->nFrame].iWalFrame = iFrame;
  pOta->aFrame[pOta->nFrame].iDbPage = 0;
  pOta->nFrame++;
  return SQLITE_OK;
}

/*
** Called when a page of data is written to offset iOff of the database
** file while the ota handle is in capture mode. Record the page number 
** of the page being written in the aFrame[] array.
*/
static int otaCaptureDbWrite(sqlite3ota *pOta, i64 iOff){
  pOta->aFrame[pOta->nFrame-1].iDbPage = (u32)(iOff / pOta->pgsz) + 1;
  return SQLITE_OK;
}

/*
** This is called as part of an incremental checkpoint operation. Copy
** a single frame of data from the wal file into the database file, as
** indicated by the OtaFrame object.
*/
static void otaCheckpointFrame(sqlite3ota *p, OtaFrame *pFrame){
  sqlite3_file *pWal = p->pTargetFd->pWalFd->pReal;
  sqlite3_file *pDb = p->pTargetFd->pReal;
  i64 iOff;

  assert( p->rc==SQLITE_OK );
  iOff = (i64)(pFrame->iWalFrame-1) * (p->pgsz + 24) + 32 + 24;
  p->rc = pWal->pMethods->xRead(pWal, p->aBuf, p->pgsz, iOff);
................................................................................
  p->rc = pDb->pMethods->xWrite(pDb, p->aBuf, p->pgsz, iOff);
}


/*
** Take an EXCLUSIVE lock on the database file.
*/
static void otaLockDatabase(sqlite3ota *p){
  sqlite3_file *pReal = p->pTargetFd->pReal;
  assert( p->rc==SQLITE_OK );
  p->rc = pReal->pMethods->xLock(pReal, SQLITE_LOCK_SHARED);
  if( p->rc==SQLITE_OK ){
    p->rc = pReal->pMethods->xLock(pReal, SQLITE_LOCK_EXCLUSIVE);
  }
}

/*
** The OTA handle is currently in OTA_STAGE_OAL state, with a SHARED lock
** on the database file. This proc moves the *-oal file to the *-wal path,
** then reopens the database file (this time in vanilla, non-oal, WAL mode).
** If an error occurs, leave an error code and error message in the ota 
** handle.
*/
static void otaMoveOalFile(sqlite3ota *p){
  const char *zBase = sqlite3_db_filename(p->dbMain, "main");

  char *zWal = sqlite3_mprintf("%s-wal", zBase);
  char *zOal = sqlite3_mprintf("%s-oal", zBase);

  assert( p->eStage==OTA_STAGE_MOVE );
  assert( p->rc==SQLITE_OK && p->zErrmsg==0 );
  if( zWal==0 || zOal==0 ){
    p->rc = SQLITE_NOMEM;
  }else{
    /* Move the *-oal file to *-wal. At this point connection p->db is
    ** holding a SHARED lock on the target database file (because it is
    ** in WAL mode). So no other connection may be writing the db. 
    **
    ** In order to ensure that there are no database readers, an EXCLUSIVE
    ** lock is obtained here before the *-oal is moved to *-wal.
    */
    otaLockDatabase(p);
    if( p->rc==SQLITE_OK ){
      otaFileSuffix3(zBase, zWal);
      otaFileSuffix3(zBase, zOal);

      /* Re-open the databases. */
      otaObjIterFinalize(&p->objiter);
      sqlite3_close(p->dbMain);
      sqlite3_close(p->dbOta);
      p->rc = rename(zOal, zWal) ? SQLITE_IOERR : SQLITE_OK;
      if( p->rc==SQLITE_OK ){
        p->dbMain = 0;
        p->dbOta = 0;
        otaOpenDatabase(p);
        otaSetupCheckpoint(p, 0);
      }
    }
  }

  sqlite3_free(zWal);
  sqlite3_free(zOal);
}
................................................................................

/*
** The SELECT statement iterating through the keys for the current object
** (p->objiter.pSelect) currently points to a valid row. This function
** determines the type of operation requested by this row and returns
** one of the following values to indicate the result:
**
**     * OTA_INSERT
**     * OTA_DELETE
**     * OTA_IDX_DELETE
**     * OTA_UPDATE
**
** If OTA_UPDATE is returned, then output variable *pzMask is set to
** point to the text value indicating the columns to update.
**
** If the ota_control field contains an invalid value, an error code and
** message are left in the OTA handle and zero returned.
*/
static int otaStepType(sqlite3ota *p, const char **pzMask){
  int iCol = p->objiter.nCol;     /* Index of ota_control column */
  int res = 0;                    /* Return value */

  switch( sqlite3_column_type(p->objiter.pSelect, iCol) ){
    case SQLITE_INTEGER: {
      int iVal = sqlite3_column_int(p->objiter.pSelect, iCol);
      if( iVal==0 ){
        res = OTA_INSERT;
      }else if( iVal==1 ){
        res = OTA_DELETE;
      }else if( iVal==2 ){
        res = OTA_IDX_DELETE;
      }else if( iVal==3 ){
        res = OTA_IDX_INSERT;
      }
      break;
    }

    case SQLITE_TEXT: {
      const unsigned char *z = sqlite3_column_text(p->objiter.pSelect, iCol);
      if( z==0 ){
        p->rc = SQLITE_NOMEM;
      }else{
        *pzMask = (const char*)z;
      }
      res = OTA_UPDATE;

      break;
    }

    default:
      break;
  }

  if( res==0 ){
    otaBadControlError(p);
  }
  return res;
}

#ifdef SQLITE_DEBUG
/*
** Assert that column iCol of statement pStmt is named zName.
................................................................................
  assert( 0==sqlite3_stricmp(zName, zCol) );
}
#else
# define assertColumnName(x,y,z)
#endif

/*
** This function does the work for an sqlite3ota_step() call.
**
** The object-iterator (p->objiter) currently points to a valid object,
** and the input cursor (p->objiter.pSelect) currently points to a valid
** input row. Perform whatever processing is required and return.
**
** If no  error occurs, SQLITE_OK is returned. Otherwise, an error code
** and message is left in the OTA handle and a copy of the error code
** returned.
*/
static int otaStep(sqlite3ota *p){
  OtaObjIter *pIter = &p->objiter;
  const char *zMask = 0;
  int i;
  int eType = otaStepType(p, &zMask);

  if( eType ){
    assert( eType!=OTA_UPDATE || pIter->zIdx==0 );

    if( pIter->zIdx==0 && eType==OTA_IDX_DELETE ){
      otaBadControlError(p);
    }
    else if( 
        eType==OTA_INSERT 
     || eType==OTA_DELETE
     || eType==OTA_IDX_DELETE 
     || eType==OTA_IDX_INSERT
    ){
      sqlite3_value *pVal;
      sqlite3_stmt *pWriter;

      assert( eType!=OTA_UPDATE );
      assert( eType!=OTA_DELETE || pIter->zIdx==0 );

      if( eType==OTA_IDX_DELETE || eType==OTA_DELETE ){
        pWriter = pIter->pDelete;
      }else{
        pWriter = pIter->pInsert;
      }

      for(i=0; i<pIter->nCol; i++){
        /* If this is an INSERT into a table b-tree and the table has an
        ** explicit INTEGER PRIMARY KEY, check that this is not an attempt
        ** to write a NULL into the IPK column. That is not permitted.  */
        if( eType==OTA_INSERT 
         && pIter->zIdx==0 && pIter->eType==OTA_PK_IPK && pIter->abTblPk[i] 
         && sqlite3_column_type(pIter->pSelect, i)==SQLITE_NULL
        ){
          p->rc = SQLITE_MISMATCH;
          p->zErrmsg = sqlite3_mprintf("datatype mismatch");
          goto step_out;
        }

        if( eType==OTA_DELETE && pIter->abTblPk[i]==0 ){
          continue;
        }

        pVal = sqlite3_column_value(pIter->pSelect, i);
        p->rc = sqlite3_bind_value(pWriter, i+1, pVal);
        if( p->rc ) goto step_out;
      }
      if( pIter->zIdx==0
       && (pIter->eType==OTA_PK_VTAB || pIter->eType==OTA_PK_NONE) 
      ){
        /* For a virtual table, or a table with no primary key, the 
        ** SELECT statement is:
        **
        **   SELECT <cols>, ota_control, ota_rowid FROM ....
        **
        ** Hence column_value(pIter->nCol+1).
        */
        assertColumnName(pIter->pSelect, pIter->nCol+1, "ota_rowid");
        pVal = sqlite3_column_value(pIter->pSelect, pIter->nCol+1);
        p->rc = sqlite3_bind_value(pWriter, pIter->nCol+1, pVal);
      }
      if( p->rc==SQLITE_OK ){
        sqlite3_step(pWriter);
        p->rc = resetAndCollectError(pWriter, &p->zErrmsg);
      }
    }else{
      sqlite3_value *pVal;
      sqlite3_stmt *pUpdate = 0;
      assert( eType==OTA_UPDATE );
      otaGetUpdateStmt(p, pIter, zMask, &pUpdate);
      if( pUpdate ){
        for(i=0; p->rc==SQLITE_OK && i<pIter->nCol; i++){
          char c = zMask[pIter->aiSrcOrder[i]];
          pVal = sqlite3_column_value(pIter->pSelect, i);
          if( pIter->abTblPk[i] || c=='x' || c=='d' ){
            p->rc = sqlite3_bind_value(pUpdate, i+1, pVal);
          }
        }
        if( p->rc==SQLITE_OK 
         && (pIter->eType==OTA_PK_VTAB || pIter->eType==OTA_PK_NONE) 
        ){
          /* Bind the ota_rowid value to column _rowid_ */
          assertColumnName(pIter->pSelect, pIter->nCol+1, "ota_rowid");
          pVal = sqlite3_column_value(pIter->pSelect, pIter->nCol+1);
          p->rc = sqlite3_bind_value(pUpdate, pIter->nCol+1, pVal);
        }
        if( p->rc==SQLITE_OK ){
          sqlite3_step(pUpdate);
          p->rc = resetAndCollectError(pUpdate, &p->zErrmsg);
        }
................................................................................
 step_out:
  return p->rc;
}

/*
** Increment the schema cookie of the main database opened by p->dbMain.
*/
static void otaIncrSchemaCookie(sqlite3ota *p){
  if( p->rc==SQLITE_OK ){
    int iCookie = 1000000;
    sqlite3_stmt *pStmt;

    p->rc = prepareAndCollectError(p->dbMain, &pStmt, &p->zErrmsg, 
        "PRAGMA schema_version"
    );
................................................................................
      ** is already a transaction open, so the prepared statement cannot
      ** throw an SQLITE_SCHEMA exception. The only database page the
      ** statement reads is page 1, which is guaranteed to be in the cache.
      ** And no memory allocations are required.  */
      if( SQLITE_ROW==sqlite3_step(pStmt) ){
        iCookie = sqlite3_column_int(pStmt, 0);
      }
      otaFinalize(p, pStmt);
    }
    if( p->rc==SQLITE_OK ){
      otaMPrintfExec(p, p->dbMain, "PRAGMA schema_version = %d", iCookie+1);
    }
  }
}

/*
** Update the contents of the ota_state table within the ota database. The
** value stored in the OTA_STATE_STAGE column is eStage. All other values
** are determined by inspecting the ota handle passed as the first argument.
*/
static void otaSaveState(sqlite3ota *p, int eStage){
  if( p->rc==SQLITE_OK || p->rc==SQLITE_DONE ){
    sqlite3_stmt *pInsert = 0;
    int rc;

    assert( p->zErrmsg==0 );
    rc = prepareFreeAndCollectError(p->dbOta, &pInsert, &p->zErrmsg, 
        sqlite3_mprintf(
          "INSERT OR REPLACE INTO %s.ota_state(k, v) VALUES "
          "(%d, %d), "
          "(%d, %Q), "
          "(%d, %Q), "
          "(%d, %d), "
          "(%d, %d), "
          "(%d, %lld), "
          "(%d, %lld), "
          "(%d, %lld) ",
          p->zStateDb,
          OTA_STATE_STAGE, eStage,
          OTA_STATE_TBL, p->objiter.zTbl, 
          OTA_STATE_IDX, p->objiter.zIdx, 
          OTA_STATE_ROW, p->nStep, 
          OTA_STATE_PROGRESS, p->nProgress,
          OTA_STATE_CKPT, p->iWalCksum,
          OTA_STATE_COOKIE, (i64)p->pTargetFd->iCookie,
          OTA_STATE_OALSZ, p->iOalSz
      )
    );
    assert( pInsert==0 || rc==SQLITE_OK );

    if( rc==SQLITE_OK ){
      sqlite3_step(pInsert);
      rc = sqlite3_finalize(pInsert);
................................................................................
    }
    if( rc!=SQLITE_OK ) p->rc = rc;
  }
}


/*
** Step the OTA object.
*/
SQLITE_API int SQLITE_STDCALL sqlite3ota_step(sqlite3ota *p){
  if( p ){
    switch( p->eStage ){
      case OTA_STAGE_OAL: {
        OtaObjIter *pIter = &p->objiter;
        while( p->rc==SQLITE_OK && pIter->zTbl ){

          if( pIter->bCleanup ){
            /* Clean up the ota_tmp_xxx table for the previous table. It 
            ** cannot be dropped as there are currently active SQL statements.
            ** But the contents can be deleted.  */
            if( pIter->abIndexed ){
              otaMPrintfExec(p, p->dbOta, 
                  "DELETE FROM %s.'ota_tmp_%q'", p->zStateDb, pIter->zTbl
              );
            }
          }else{
            otaObjIterPrepareAll(p, pIter, 0);

            /* Advance to the next row to process. */
            if( p->rc==SQLITE_OK ){
              int rc = sqlite3_step(pIter->pSelect);
              if( rc==SQLITE_ROW ){
                p->nProgress++;
                p->nStep++;
                return otaStep(p);
              }
              p->rc = sqlite3_reset(pIter->pSelect);
              p->nStep = 0;
            }
          }

          otaObjIterNext(p, pIter);
        }

        if( p->rc==SQLITE_OK ){
          assert( pIter->zTbl==0 );
          otaSaveState(p, OTA_STAGE_MOVE);
          otaIncrSchemaCookie(p);
          if( p->rc==SQLITE_OK ){
            p->rc = sqlite3_exec(p->dbMain, "COMMIT", 0, 0, &p->zErrmsg);
          }
          if( p->rc==SQLITE_OK ){
            p->rc = sqlite3_exec(p->dbOta, "COMMIT", 0, 0, &p->zErrmsg);
          }
          p->eStage = OTA_STAGE_MOVE;
        }
        break;
      }

      case OTA_STAGE_MOVE: {
        if( p->rc==SQLITE_OK ){
          otaMoveOalFile(p);
          p->nProgress++;
        }
        break;
      }

      case OTA_STAGE_CKPT: {
        if( p->rc==SQLITE_OK ){
          if( p->nStep>=p->nFrame ){
            sqlite3_file *pDb = p->pTargetFd->pReal;
  
            /* Sync the db file */
            p->rc = pDb->pMethods->xSync(pDb, SQLITE_SYNC_NORMAL);
  
................................................................................
              p->rc = pDb->pMethods->xShmMap(pDb, 0, 32*1024, 0, &ptr);
              if( p->rc==SQLITE_OK ){
                ((u32 volatile*)ptr)[24] = p->iMaxFrame;
              }
            }
  
            if( p->rc==SQLITE_OK ){
              p->eStage = OTA_STAGE_DONE;
              p->rc = SQLITE_DONE;
            }
          }else{
            OtaFrame *pFrame = &p->aFrame[p->nStep];
            otaCheckpointFrame(p, pFrame);
            p->nStep++;
          }
          p->nProgress++;
        }
        break;
      }

................................................................................
    return p->rc;
  }else{
    return SQLITE_NOMEM;
  }
}

/*
** Free an OtaState object allocated by otaLoadState().
*/
static void otaFreeState(OtaState *p){
  if( p ){
    sqlite3_free(p->zTbl);
    sqlite3_free(p->zIdx);
    sqlite3_free(p);
  }
}

/*
** Allocate an OtaState object and load the contents of the ota_state 
** table into it. Return a pointer to the new object. It is the 
** responsibility of the caller to eventually free the object using
** sqlite3_free().
**
** If an error occurs, leave an error code and message in the ota handle
** and return NULL.
*/
static OtaState *otaLoadState(sqlite3ota *p){
  OtaState *pRet = 0;
  sqlite3_stmt *pStmt = 0;
  int rc;
  int rc2;

  pRet = (OtaState*)otaMalloc(p, sizeof(OtaState));
  if( pRet==0 ) return 0;

  rc = prepareFreeAndCollectError(p->dbOta, &pStmt, &p->zErrmsg, 
      sqlite3_mprintf("SELECT k, v FROM %s.ota_state", p->zStateDb)
  );
  while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
    switch( sqlite3_column_int(pStmt, 0) ){
      case OTA_STATE_STAGE:
        pRet->eStage = sqlite3_column_int(pStmt, 1);
        if( pRet->eStage!=OTA_STAGE_OAL
         && pRet->eStage!=OTA_STAGE_MOVE
         && pRet->eStage!=OTA_STAGE_CKPT
        ){
          p->rc = SQLITE_CORRUPT;
        }
        break;

      case OTA_STATE_TBL:
        pRet->zTbl = otaStrndup((char*)sqlite3_column_text(pStmt, 1), &rc);
        break;

      case OTA_STATE_IDX:
        pRet->zIdx = otaStrndup((char*)sqlite3_column_text(pStmt, 1), &rc);
        break;

      case OTA_STATE_ROW:
        pRet->nRow = sqlite3_column_int(pStmt, 1);
        break;

      case OTA_STATE_PROGRESS:
        pRet->nProgress = sqlite3_column_int64(pStmt, 1);
        break;

      case OTA_STATE_CKPT:
        pRet->iWalCksum = sqlite3_column_int64(pStmt, 1);
        break;

      case OTA_STATE_COOKIE:
        pRet->iCookie = (u32)sqlite3_column_int64(pStmt, 1);
        break;

      case OTA_STATE_OALSZ:
        pRet->iOalSz = (u32)sqlite3_column_int64(pStmt, 1);
        break;

      default:
        rc = SQLITE_CORRUPT;
        break;
    }
................................................................................
}

/*
** Compare strings z1 and z2, returning 0 if they are identical, or non-zero
** otherwise. Either or both argument may be NULL. Two NULL values are
** considered equal, and NULL is considered distinct from all other values.
*/
static int otaStrCompare(const char *z1, const char *z2){
  if( z1==0 && z2==0 ) return 0;
  if( z1==0 || z2==0 ) return 1;
  return (sqlite3_stricmp(z1, z2)!=0);
}

/*
** This function is called as part of sqlite3ota_open() when initializing
** an ota handle in OAL stage. If the ota update has not started (i.e.
** the ota_state table was empty) it is a no-op. Otherwise, it arranges
** things so that the next call to sqlite3ota_step() continues on from
** where the previous ota handle left off.
**
** If an error occurs, an error code and error message are left in the
** ota handle passed as the first argument.
*/
static void otaSetupOal(sqlite3ota *p, OtaState *pState){
  assert( p->rc==SQLITE_OK );
  if( pState->zTbl ){
    OtaObjIter *pIter = &p->objiter;
    int rc = SQLITE_OK;

    while( rc==SQLITE_OK && pIter->zTbl && (pIter->bCleanup 
       || otaStrCompare(pIter->zIdx, pState->zIdx)
       || otaStrCompare(pIter->zTbl, pState->zTbl) 
    )){
      rc = otaObjIterNext(p, pIter);
    }

    if( rc==SQLITE_OK && !pIter->zTbl ){
      rc = SQLITE_ERROR;
      p->zErrmsg = sqlite3_mprintf("ota_state mismatch error");
    }

    if( rc==SQLITE_OK ){
      p->nStep = pState->nRow;
      rc = otaObjIterPrepareAll(p, &p->objiter, p->nStep);
    }

    p->rc = rc;
  }
}

/*
** If there is a "*-oal" file in the file-system corresponding to the
** target database in the file-system, delete it. If an error occurs,
** leave an error code and error message in the ota handle.
*/
static void otaDeleteOalFile(sqlite3ota *p){
  char *zOal = sqlite3_mprintf("%s-oal", p->zTarget);
  assert( p->rc==SQLITE_OK && p->zErrmsg==0 );
  unlink(zOal);
  sqlite3_free(zOal);
}

/*
** Allocate a private ota VFS for the ota handle passed as the only
** argument. This VFS will be used unless the call to sqlite3ota_open()
** specified a URI with a vfs=? option in place of a target database
** file name.
*/
static void otaCreateVfs(sqlite3ota *p){
  int rnd;
  char zRnd[64];

  assert( p->rc==SQLITE_OK );
  sqlite3_randomness(sizeof(int), (void*)&rnd);
  sprintf(zRnd, "ota_vfs_%d", rnd);
  p->rc = sqlite3ota_create_vfs(zRnd, 0);
  if( p->rc==SQLITE_OK ){
    sqlite3_vfs *pVfs = sqlite3_vfs_find(zRnd);
    assert( pVfs );
    p->zVfsName = pVfs->zName;
  }
}

/*
** Destroy the private VFS created for the ota handle passed as the only
** argument by an earlier call to otaCreateVfs().
*/
static void otaDeleteVfs(sqlite3ota *p){
  if( p->zVfsName ){
    sqlite3ota_destroy_vfs(p->zVfsName);
    p->zVfsName = 0;
  }
}

/*
** Open and return a new OTA handle. 
*/
SQLITE_API sqlite3ota *SQLITE_STDCALL sqlite3ota_open(
  const char *zTarget, 
  const char *zOta,
  const char *zState
){
  sqlite3ota *p;
  int nTarget = strlen(zTarget);
  int nOta = strlen(zOta);
  int nState = zState ? strlen(zState) : 0;

  p = (sqlite3ota*)sqlite3_malloc(sizeof(sqlite3ota)+nTarget+1+nOta+1+nState+1);
  if( p ){
    OtaState *pState = 0;

    /* Create the custom VFS. */
    memset(p, 0, sizeof(sqlite3ota));
    otaCreateVfs(p);

    /* Open the target database */
    if( p->rc==SQLITE_OK ){
      p->zTarget = (char*)&p[1];
      memcpy(p->zTarget, zTarget, nTarget+1);
      p->zOta = &p->zTarget[nTarget+1];
      memcpy(p->zOta, zOta, nOta+1);
      if( zState ){
        p->zState = &p->zOta[nOta+1];
        memcpy(p->zState, zState, nState+1);
      }
      otaOpenDatabase(p);
    }

    /* If it has not already been created, create the ota_state table */
    otaMPrintfExec(p, p->dbOta, OTA_CREATE_STATE, p->zStateDb);

    if( p->rc==SQLITE_OK ){
      pState = otaLoadState(p);
      assert( pState || p->rc!=SQLITE_OK );
      if( p->rc==SQLITE_OK ){

        if( pState->eStage==0 ){ 
          otaDeleteOalFile(p);
          p->eStage = OTA_STAGE_OAL;
        }else{
          p->eStage = pState->eStage;
        }
        p->nProgress = pState->nProgress;
        p->iOalSz = pState->iOalSz;
      }
    }
    assert( p->rc!=SQLITE_OK || p->eStage!=0 );

    if( p->rc==SQLITE_OK && p->pTargetFd->pWalFd ){
      if( p->eStage==OTA_STAGE_OAL ){
        p->rc = SQLITE_ERROR;
        p->zErrmsg = sqlite3_mprintf("cannot update wal mode database");
      }else if( p->eStage==OTA_STAGE_MOVE ){
        p->eStage = OTA_STAGE_CKPT;
        p->nStep = 0;
      }
    }

    if( p->rc==SQLITE_OK
     && (p->eStage==OTA_STAGE_OAL || p->eStage==OTA_STAGE_MOVE)
     && pState->eStage!=0 && p->pTargetFd->iCookie!=pState->iCookie
    ){   
      /* At this point (pTargetFd->iCookie) contains the value of the
      ** change-counter cookie (the thing that gets incremented when a 
      ** transaction is committed in rollback mode) currently stored on 
      ** page 1 of the database file. */
      p->rc = SQLITE_BUSY;
      p->zErrmsg = sqlite3_mprintf("database modified during ota update");
    }

    if( p->rc==SQLITE_OK ){
      if( p->eStage==OTA_STAGE_OAL ){

        /* Open transactions both databases. The *-oal file is opened or
        ** created at this point. */
        p->rc = sqlite3_exec(p->dbMain, "BEGIN IMMEDIATE", 0, 0, &p->zErrmsg);
        if( p->rc==SQLITE_OK ){
          p->rc = sqlite3_exec(p->dbOta, "BEGIN IMMEDIATE", 0, 0, &p->zErrmsg);
        }
  
        /* Point the object iterator at the first object */
        if( p->rc==SQLITE_OK ){
          p->rc = otaObjIterFirst(p, &p->objiter);
        }

        /* If the OTA database contains no data_xxx tables, declare the OTA
        ** update finished.  */
        if( p->rc==SQLITE_OK && p->objiter.zTbl==0 ){
          p->rc = SQLITE_DONE;
        }

        if( p->rc==SQLITE_OK ){
          otaSetupOal(p, pState);
        }

      }else if( p->eStage==OTA_STAGE_MOVE ){
        /* no-op */
      }else if( p->eStage==OTA_STAGE_CKPT ){
        otaSetupCheckpoint(p, pState);
      }else if( p->eStage==OTA_STAGE_DONE ){
        p->rc = SQLITE_DONE;
      }else{
        p->rc = SQLITE_CORRUPT;
      }
    }

    otaFreeState(pState);
  }

  return p;
}


/*
** Return the database handle used by pOta.
*/
SQLITE_API sqlite3 *SQLITE_STDCALL sqlite3ota_db(sqlite3ota *pOta, int bOta){
  sqlite3 *db = 0;
  if( pOta ){
    db = (bOta ? pOta->dbOta : pOta->dbMain);
  }
  return db;
}


/*
** If the error code currently stored in the OTA handle is SQLITE_CONSTRAINT,
** then edit any error message string so as to remove all occurrences of
** the pattern "ota_imp_[0-9]*".
*/
static void otaEditErrmsg(sqlite3ota *p){
  if( p->rc==SQLITE_CONSTRAINT && p->zErrmsg ){
    int i;
    int nErrmsg = strlen(p->zErrmsg);
    for(i=0; i<(nErrmsg-8); i++){
      if( memcmp(&p->zErrmsg[i], "ota_imp_", 8)==0 ){
        int nDel = 8;
        while( p->zErrmsg[i+nDel]>='0' && p->zErrmsg[i+nDel]<='9' ) nDel++;
        memmove(&p->zErrmsg[i], &p->zErrmsg[i+nDel], nErrmsg + 1 - i - nDel);
        nErrmsg -= nDel;
      }
    }
  }
}

/*
** Close the OTA handle.
*/
SQLITE_API int SQLITE_STDCALL sqlite3ota_close(sqlite3ota *p, char **pzErrmsg){
  int rc;
  if( p ){

    /* Commit the transaction to the *-oal file. */
    if( p->rc==SQLITE_OK && p->eStage==OTA_STAGE_OAL ){
      p->rc = sqlite3_exec(p->dbMain, "COMMIT", 0, 0, &p->zErrmsg);
    }

    otaSaveState(p, p->eStage);

    if( p->rc==SQLITE_OK && p->eStage==OTA_STAGE_OAL ){
      p->rc = sqlite3_exec(p->dbOta, "COMMIT", 0, 0, &p->zErrmsg);
    }

    /* Close any open statement handles. */
    otaObjIterFinalize(&p->objiter);

    /* Close the open database handle and VFS object. */
    sqlite3_close(p->dbMain);
    sqlite3_close(p->dbOta);
    otaDeleteVfs(p);
    sqlite3_free(p->aBuf);
    sqlite3_free(p->aFrame);

    otaEditErrmsg(p);
    rc = p->rc;
    *pzErrmsg = p->zErrmsg;
    sqlite3_free(p);
  }else{
    rc = SQLITE_NOMEM;
    *pzErrmsg = 0;
  }
  return rc;
}

/*
** Return the total number of key-value operations (inserts, deletes or 
** updates) that have been performed on the target database since the
** current OTA update was started.
*/
SQLITE_API sqlite3_int64 SQLITE_STDCALL sqlite3ota_progress(sqlite3ota *pOta){
  return pOta->nProgress;
}

/**************************************************************************
** Beginning of OTA VFS shim methods. The VFS shim modifies the behaviour
** of a standard VFS in the following ways:
**
** 1. Whenever the first page of a main database file is read or 
**    written, the value of the change-counter cookie is stored in
**    ota_file.iCookie. Similarly, the value of the "write-version"
**    database header field is stored in ota_file.iWriteVer. This ensures
**    that the values are always trustworthy within an open transaction.
**
** 2. Whenever an SQLITE_OPEN_WAL file is opened, the (ota_file.pWalFd)
**    member variable of the associated database file descriptor is set
**    to point to the new file. A mutex protected linked list of all main 
**    db fds opened using a particular OTA VFS is maintained at 
**    ota_vfs.pMain to facilitate this.
**
** 3. Using a new file-control "SQLITE_FCNTL_OTA", a main db ota_file 
**    object can be marked as the target database of an OTA update. This
**    turns on the following extra special behaviour:
**
** 3a. If xAccess() is called to check if there exists a *-wal file 
**     associated with an OTA target database currently in OTA_STAGE_OAL
**     stage (preparing the *-oal file), the following special handling
**     applies:
**
**      * if the *-wal file does exist, return SQLITE_CANTOPEN. An OTA
**        target database may not be in wal mode already.
**
**      * if the *-wal file does not exist, set the output parameter to
**        non-zero (to tell SQLite that it does exist) anyway.
**
**     Then, when xOpen() is called to open the *-wal file associated with
**     the OTA target in OTA_STAGE_OAL stage, instead of opening the *-wal
**     file, the ota vfs opens the corresponding *-oal file instead. 
**
** 3b. The *-shm pages returned by xShmMap() for a target db file in
**     OTA_STAGE_OAL mode are actually stored in heap memory. This is to
**     avoid creating a *-shm file on disk. Additionally, xShmLock() calls
**     are no-ops on target database files in OTA_STAGE_OAL mode. This is
**     because assert() statements in some VFS implementations fail if 
**     xShmLock() is called before xShmMap().
**
** 3c. If an EXCLUSIVE lock is attempted on a target database file in any
**     mode except OTA_STAGE_DONE (all work completed and checkpointed), it 
**     fails with an SQLITE_BUSY error. This is to stop OTA connections
**     from automatically checkpointing a *-wal (or *-oal) file from within
**     sqlite3_close().
**
** 3d. In OTA_STAGE_CAPTURE mode, all xRead() calls on the wal file, and
**     all xWrite() calls on the target database file perform no IO. 
**     Instead the frame and page numbers that would be read and written
**     are recorded. Additionally, successful attempts to obtain exclusive
**     xShmLock() WRITER, CHECKPOINTER and READ0 locks on the target 
**     database file are recorded. xShmLock() calls to unlock the same
**     locks are no-ops (so that once obtained, these locks are never
**     relinquished). Finally, calls to xSync() on the target database
**     file fail with SQLITE_INTERNAL errors.
*/

static void otaUnlockShm(ota_file *p){
  if( p->pOta ){
    int (*xShmLock)(sqlite3_file*,int,int,int) = p->pReal->pMethods->xShmLock;
    int i;
    for(i=0; i<SQLITE_SHM_NLOCK;i++){
      if( (1<<i) & p->pOta->mLock ){
        xShmLock(p->pReal, i, 1, SQLITE_SHM_UNLOCK|SQLITE_SHM_EXCLUSIVE);
      }
    }
    p->pOta->mLock = 0;
  }
}

/*
** Close an ota file.
*/
static int otaVfsClose(sqlite3_file *pFile){
  ota_file *p = (ota_file*)pFile;
  int rc;
  int i;

  /* Free the contents of the apShm[] array. And the array itself. */
  for(i=0; i<p->nShm; i++){
    sqlite3_free(p->apShm[i]);
  }
  sqlite3_free(p->apShm);
  p->apShm = 0;
  sqlite3_free(p->zDel);

  if( p->openFlags & SQLITE_OPEN_MAIN_DB ){
    ota_file **pp;
    sqlite3_mutex_enter(p->pOtaVfs->mutex);
    for(pp=&p->pOtaVfs->pMain; *pp!=p; pp=&((*pp)->pMainNext));
    *pp = p->pMainNext;
    sqlite3_mutex_leave(p->pOtaVfs->mutex);
    otaUnlockShm(p);
    p->pReal->pMethods->xShmUnmap(p->pReal, 0);
  }

  /* Close the underlying file handle */
  rc = p->pReal->pMethods->xClose(p->pReal);
  return rc;
}


/*
** Read and return an unsigned 32-bit big-endian integer from the buffer 
** passed as the only argument.
*/
static u32 otaGetU32(u8 *aBuf){
  return ((u32)aBuf[0] << 24)
       + ((u32)aBuf[1] << 16)
       + ((u32)aBuf[2] <<  8)
       + ((u32)aBuf[3]);
}

/*
** Read data from an otaVfs-file.
*/
static int otaVfsRead(
  sqlite3_file *pFile, 
  void *zBuf, 
  int iAmt, 
  sqlite_int64 iOfst
){
  ota_file *p = (ota_file*)pFile;
  sqlite3ota *pOta = p->pOta;
  int rc;

  if( pOta && pOta->eStage==OTA_STAGE_CAPTURE ){
    assert( p->openFlags & SQLITE_OPEN_WAL );
    rc = otaCaptureWalRead(p->pOta, iOfst, iAmt);
  }else{
    if( pOta && pOta->eStage==OTA_STAGE_OAL 
     && (p->openFlags & SQLITE_OPEN_WAL) 
     && iOfst>=pOta->iOalSz 
    ){
      rc = SQLITE_OK;
      memset(zBuf, 0, iAmt);
    }else{
      rc = p->pReal->pMethods->xRead(p->pReal, zBuf, iAmt, iOfst);
    }
    if( rc==SQLITE_OK && iOfst==0 && (p->openFlags & SQLITE_OPEN_MAIN_DB) ){
      /* These look like magic numbers. But they are stable, as they are part
       ** of the definition of the SQLite file format, which may not change. */
      u8 *pBuf = (u8*)zBuf;
      p->iCookie = otaGetU32(&pBuf[24]);
      p->iWriteVer = pBuf[19];
    }
  }
  return rc;
}

/*
** Write data to an otaVfs-file.
*/
static int otaVfsWrite(
  sqlite3_file *pFile, 
  const void *zBuf, 
  int iAmt, 
  sqlite_int64 iOfst
){
  ota_file *p = (ota_file*)pFile;
  sqlite3ota *pOta = p->pOta;
  int rc;

  if( pOta && pOta->eStage==OTA_STAGE_CAPTURE ){
    assert( p->openFlags & SQLITE_OPEN_MAIN_DB );
    rc = otaCaptureDbWrite(p->pOta, iOfst);
  }else{
    if( pOta && pOta->eStage==OTA_STAGE_OAL 
     && (p->openFlags & SQLITE_OPEN_WAL) 
     && iOfst>=pOta->iOalSz
    ){
      pOta->iOalSz = iAmt + iOfst;
    }
    rc = p->pReal->pMethods->xWrite(p->pReal, zBuf, iAmt, iOfst);
    if( rc==SQLITE_OK && iOfst==0 && (p->openFlags & SQLITE_OPEN_MAIN_DB) ){
      /* These look like magic numbers. But they are stable, as they are part
      ** of the definition of the SQLite file format, which may not change. */
      u8 *pBuf = (u8*)zBuf;
      p->iCookie = otaGetU32(&pBuf[24]);
      p->iWriteVer = pBuf[19];
    }
  }
  return rc;
}

/*
** Truncate an otaVfs-file.
*/
static int otaVfsTruncate(sqlite3_file *pFile, sqlite_int64 size){
  ota_file *p = (ota_file*)pFile;
  return p->pReal->pMethods->xTruncate(p->pReal, size);
}

/*
** Sync an otaVfs-file.
*/
static int otaVfsSync(sqlite3_file *pFile, int flags){
  ota_file *p = (ota_file *)pFile;
  if( p->pOta && p->pOta->eStage==OTA_STAGE_CAPTURE ){
    if( p->openFlags & SQLITE_OPEN_MAIN_DB ){
      return SQLITE_INTERNAL;
    }
    return SQLITE_OK;
  }
  return p->pReal->pMethods->xSync(p->pReal, flags);
}

/*
** Return the current file-size of an otaVfs-file.
*/
static int otaVfsFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){
  ota_file *p = (ota_file *)pFile;
  return p->pReal->pMethods->xFileSize(p->pReal, pSize);
}

/*
** Lock an otaVfs-file.
*/
static int otaVfsLock(sqlite3_file *pFile, int eLock){
  ota_file *p = (ota_file*)pFile;
  sqlite3ota *pOta = p->pOta;
  int rc = SQLITE_OK;

  assert( p->openFlags & (SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_TEMP_DB) );
  if( pOta && eLock==SQLITE_LOCK_EXCLUSIVE && pOta->eStage!=OTA_STAGE_DONE ){
    /* Do not allow EXCLUSIVE locks. Preventing SQLite from taking this 
    ** prevents it from checkpointing the database from sqlite3_close(). */
    rc = SQLITE_BUSY;
  }else{
    rc = p->pReal->pMethods->xLock(p->pReal, eLock);
  }

  return rc;
}

/*
** Unlock an otaVfs-file.
*/
static int otaVfsUnlock(sqlite3_file *pFile, int eLock){
  ota_file *p = (ota_file *)pFile;
  return p->pReal->pMethods->xUnlock(p->pReal, eLock);
}

/*
** Check if another file-handle holds a RESERVED lock on an otaVfs-file.
*/
static int otaVfsCheckReservedLock(sqlite3_file *pFile, int *pResOut){
  ota_file *p = (ota_file *)pFile;
  return p->pReal->pMethods->xCheckReservedLock(p->pReal, pResOut);
}

/*
** File control method. For custom operations on an otaVfs-file.
*/
static int otaVfsFileControl(sqlite3_file *pFile, int op, void *pArg){
  ota_file *p = (ota_file *)pFile;
  int (*xControl)(sqlite3_file*,int,void*) = p->pReal->pMethods->xFileControl;
  int rc;

  assert( p->openFlags & (SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_TEMP_DB)
       || p->openFlags & (SQLITE_OPEN_TRANSIENT_DB|SQLITE_OPEN_TEMP_JOURNAL)
  );
  if( op==SQLITE_FCNTL_OTA ){
    sqlite3ota *pOta = (sqlite3ota*)pArg;

    /* First try to find another OTA vfs lower down in the vfs stack. If
    ** one is found, this vfs will operate in pass-through mode. The lower
    ** level vfs will do the special OTA handling.  */
    rc = xControl(p->pReal, op, pArg);

    if( rc==SQLITE_NOTFOUND ){
      /* Now search for a zipvfs instance lower down in the VFS stack. If
      ** one is found, this is an error.  */
      void *dummy = 0;
      rc = xControl(p->pReal, SQLITE_FCNTL_ZIPVFS, &dummy);
      if( rc==SQLITE_OK ){
        rc = SQLITE_ERROR;
        pOta->zErrmsg = sqlite3_mprintf("ota/zipvfs setup error");
      }else if( rc==SQLITE_NOTFOUND ){
        pOta->pTargetFd = p;
        p->pOta = pOta;
        if( p->pWalFd ) p->pWalFd->pOta = pOta;
        rc = SQLITE_OK;
      }
    }
    return rc;
  }

  rc = xControl(p->pReal, op, pArg);
  if( rc==SQLITE_OK && op==SQLITE_FCNTL_VFSNAME ){
    ota_vfs *pOtaVfs = p->pOtaVfs;
    char *zIn = *(char**)pArg;
    char *zOut = sqlite3_mprintf("ota(%s)/%z", pOtaVfs->base.zName, zIn);
    *(char**)pArg = zOut;
    if( zOut==0 ) rc = SQLITE_NOMEM;
  }

  return rc;
}

/*
** Return the sector-size in bytes for an otaVfs-file.
*/
static int otaVfsSectorSize(sqlite3_file *pFile){
  ota_file *p = (ota_file *)pFile;
  return p->pReal->pMethods->xSectorSize(p->pReal);
}

/*
** Return the device characteristic flags supported by an otaVfs-file.
*/
static int otaVfsDeviceCharacteristics(sqlite3_file *pFile){
  ota_file *p = (ota_file *)pFile;
  return p->pReal->pMethods->xDeviceCharacteristics(p->pReal);
}

/*
** Take or release a shared-memory lock.
*/
static int otaVfsShmLock(sqlite3_file *pFile, int ofst, int n, int flags){
  ota_file *p = (ota_file*)pFile;
  sqlite3ota *pOta = p->pOta;
  int rc = SQLITE_OK;

#ifdef SQLITE_AMALGAMATION
    assert( WAL_CKPT_LOCK==1 );
#endif

  assert( p->openFlags & (SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_TEMP_DB) );
  if( pOta && (pOta->eStage==OTA_STAGE_OAL || pOta->eStage==OTA_STAGE_MOVE) ){
    /* Magic number 1 is the WAL_CKPT_LOCK lock. Preventing SQLite from
    ** taking this lock also prevents any checkpoints from occurring. 
    ** todo: really, it's not clear why this might occur, as 
    ** wal_autocheckpoint ought to be turned off.  */
    if( ofst==WAL_LOCK_CKPT && n==1 ) rc = SQLITE_BUSY;
  }else{
    int bCapture = 0;
    if( n==1 && (flags & SQLITE_SHM_EXCLUSIVE)
     && pOta && pOta->eStage==OTA_STAGE_CAPTURE
     && (ofst==WAL_LOCK_WRITE || ofst==WAL_LOCK_CKPT || ofst==WAL_LOCK_READ0)
    ){
      bCapture = 1;
    }

    if( bCapture==0 || 0==(flags & SQLITE_SHM_UNLOCK) ){
      rc = p->pReal->pMethods->xShmLock(p->pReal, ofst, n, flags);
      if( bCapture && rc==SQLITE_OK ){
        pOta->mLock |= (1 << ofst);
      }
    }
  }

  return rc;
}

/*
** Obtain a pointer to a mapping of a single 32KiB page of the *-shm file.
*/
static int otaVfsShmMap(
  sqlite3_file *pFile, 
  int iRegion, 
  int szRegion, 
  int isWrite, 
  void volatile **pp
){
  ota_file *p = (ota_file*)pFile;
  int rc = SQLITE_OK;
  int eStage = (p->pOta ? p->pOta->eStage : 0);

  /* If not in OTA_STAGE_OAL, allow this call to pass through. Or, if this
  ** ota is in the OTA_STAGE_OAL state, use heap memory for *-shm space 
  ** instead of a file on disk.  */
  assert( p->openFlags & (SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_TEMP_DB) );
  if( eStage==OTA_STAGE_OAL || eStage==OTA_STAGE_MOVE ){
    if( iRegion<=p->nShm ){
      int nByte = (iRegion+1) * sizeof(char*);
      char **apNew = (char**)sqlite3_realloc(p->apShm, nByte);
      if( apNew==0 ){
        rc = SQLITE_NOMEM;
      }else{
        memset(&apNew[p->nShm], 0, sizeof(char*) * (1 + iRegion - p->nShm));
................................................................................

  return rc;
}

/*
** Memory barrier.
*/
static void otaVfsShmBarrier(sqlite3_file *pFile){
  ota_file *p = (ota_file *)pFile;
  p->pReal->pMethods->xShmBarrier(p->pReal);
}

/*
** The xShmUnmap method.
*/
static int otaVfsShmUnmap(sqlite3_file *pFile, int delFlag){
  ota_file *p = (ota_file*)pFile;
  int rc = SQLITE_OK;
  int eStage = (p->pOta ? p->pOta->eStage : 0);

  assert( p->openFlags & (SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_TEMP_DB) );
  if( eStage==OTA_STAGE_OAL || eStage==OTA_STAGE_MOVE ){
    /* no-op */
  }else{
    /* Release the checkpointer and writer locks */
    otaUnlockShm(p);
    rc = p->pReal->pMethods->xShmUnmap(p->pReal, delFlag);
  }
  return rc;
}

/*
** Given that zWal points to a buffer containing a wal file name passed to 
** either the xOpen() or xAccess() VFS method, return a pointer to the
** file-handle opened by the same database connection on the corresponding
** database file.
*/
static ota_file *otaFindMaindb(ota_vfs *pOtaVfs, const char *zWal){
  ota_file *pDb;
  sqlite3_mutex_enter(pOtaVfs->mutex);
  for(pDb=pOtaVfs->pMain; pDb && pDb->zWal!=zWal; pDb=pDb->pMainNext);
  sqlite3_mutex_leave(pOtaVfs->mutex);
  return pDb;
}

/*
** Open an ota file handle.
*/
static int otaVfsOpen(
  sqlite3_vfs *pVfs,
  const char *zName,
  sqlite3_file *pFile,
  int flags,
  int *pOutFlags
){
  static sqlite3_io_methods otavfs_io_methods = {
    2,                            /* iVersion */
    otaVfsClose,                  /* xClose */
    otaVfsRead,                   /* xRead */
    otaVfsWrite,                  /* xWrite */
    otaVfsTruncate,               /* xTruncate */
    otaVfsSync,                   /* xSync */
    otaVfsFileSize,               /* xFileSize */
    otaVfsLock,                   /* xLock */
    otaVfsUnlock,                 /* xUnlock */
    otaVfsCheckReservedLock,      /* xCheckReservedLock */
    otaVfsFileControl,            /* xFileControl */
    otaVfsSectorSize,             /* xSectorSize */
    otaVfsDeviceCharacteristics,  /* xDeviceCharacteristics */
    otaVfsShmMap,                 /* xShmMap */
    otaVfsShmLock,                /* xShmLock */
    otaVfsShmBarrier,             /* xShmBarrier */
    otaVfsShmUnmap                /* xShmUnmap */
  };
  ota_vfs *pOtaVfs = (ota_vfs*)pVfs;
  sqlite3_vfs *pRealVfs = pOtaVfs->pRealVfs;
  ota_file *pFd = (ota_file *)pFile;
  int rc = SQLITE_OK;
  const char *zOpen = zName;

  memset(pFd, 0, sizeof(ota_file));
  pFd->pReal = (sqlite3_file*)&pFd[1];
  pFd->pOtaVfs = pOtaVfs;
  pFd->openFlags = flags;
  if( zName ){
    if( flags & SQLITE_OPEN_MAIN_DB ){
      /* A main database has just been opened. The following block sets
      ** (pFd->zWal) to point to a buffer owned by SQLite that contains
      ** the name of the *-wal file this db connection will use. SQLite
      ** happens to pass a pointer to this buffer when using xAccess()
................................................................................
      }else{
        while( *z==0 ) z++;
      }
      z += (n + 8 + 1);
      pFd->zWal = z;
    }
    else if( flags & SQLITE_OPEN_WAL ){
      ota_file *pDb = otaFindMaindb(pOtaVfs, zName);
      if( pDb ){
        if( pDb->pOta && pDb->pOta->eStage==OTA_STAGE_OAL ){
          /* This call is to open a *-wal file. Intead, open the *-oal. This
          ** code ensures that the string passed to xOpen() is terminated by a
          ** pair of '\0' bytes in case the VFS attempts to extract a URI 
          ** parameter from it.  */
          int nCopy = strlen(zName);
          char *zCopy = sqlite3_malloc(nCopy+2);
          if( zCopy ){
................................................................................
            zCopy[nCopy-3] = 'o';
            zCopy[nCopy] = '\0';
            zCopy[nCopy+1] = '\0';
            zOpen = (const char*)(pFd->zDel = zCopy);
          }else{
            rc = SQLITE_NOMEM;
          }
          pFd->pOta = pDb->pOta;
        }
        pDb->pWalFd = pFd;
      }
    }
  }

  if( rc==SQLITE_OK ){
    rc = pRealVfs->xOpen(pRealVfs, zOpen, pFd->pReal, flags, pOutFlags);
  }
  if( pFd->pReal->pMethods ){
    /* The xOpen() operation has succeeded. Set the sqlite3_file.pMethods
    ** pointer and, if the file is a main database file, link it into the
    ** mutex protected linked list of all such files.  */
    pFile->pMethods = &otavfs_io_methods;
    if( flags & SQLITE_OPEN_MAIN_DB ){
      sqlite3_mutex_enter(pOtaVfs->mutex);
      pFd->pMainNext = pOtaVfs->pMain;
      pOtaVfs->pMain = pFd;
      sqlite3_mutex_leave(pOtaVfs->mutex);
    }
  }else{
    sqlite3_free(pFd->zDel);
  }

  return rc;
}

/*
** Delete the file located at zPath.
*/
static int otaVfsDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
  sqlite3_vfs *pRealVfs = ((ota_vfs*)pVfs)->pRealVfs;
  return pRealVfs->xDelete(pRealVfs, zPath, dirSync);
}

/*
** Test for access permissions. Return true if the requested permission
** is available, or false otherwise.
*/
static int otaVfsAccess(
  sqlite3_vfs *pVfs, 
  const char *zPath, 
  int flags, 
  int *pResOut
){
  ota_vfs *pOtaVfs = (ota_vfs*)pVfs;
  sqlite3_vfs *pRealVfs = pOtaVfs->pRealVfs;
  int rc;

  rc = pRealVfs->xAccess(pRealVfs, zPath, flags, pResOut);

  /* If this call is to check if a *-wal file associated with an OTA target
  ** database connection exists, and the OTA update is in OTA_STAGE_OAL,
  ** the following special handling is activated:
  **
  **   a) if the *-wal file does exist, return SQLITE_CANTOPEN. This
  **      ensures that the OTA extension never tries to update a database
  **      in wal mode, even if the first page of the database file has
  **      been damaged. 
  **
  **   b) if the *-wal file does not exist, claim that it does anyway,
  **      causing SQLite to call xOpen() to open it. This call will also
  **      be intercepted (see the otaVfsOpen() function) and the *-oal
  **      file opened instead.
  */
  if( rc==SQLITE_OK && flags==SQLITE_ACCESS_EXISTS ){
    ota_file *pDb = otaFindMaindb(pOtaVfs, zPath);
    if( pDb && pDb->pOta && pDb->pOta->eStage==OTA_STAGE_OAL ){
      if( *pResOut ){
        rc = SQLITE_CANTOPEN;
      }else{
        *pResOut = 1;
      }
    }
  }
................................................................................
}

/*
** Populate buffer zOut with the full canonical pathname corresponding
** to the pathname in zPath. zOut is guaranteed to point to a buffer
** of at least (DEVSYM_MAX_PATHNAME+1) bytes.
*/
static int otaVfsFullPathname(
  sqlite3_vfs *pVfs, 
  const char *zPath, 
  int nOut, 
  char *zOut
){
  sqlite3_vfs *pRealVfs = ((ota_vfs*)pVfs)->pRealVfs;
  return pRealVfs->xFullPathname(pRealVfs, zPath, nOut, zOut);
}

#ifndef SQLITE_OMIT_LOAD_EXTENSION
/*
** Open the dynamic library located at zPath and return a handle.
*/
static void *otaVfsDlOpen(sqlite3_vfs *pVfs, const char *zPath){
  sqlite3_vfs *pRealVfs = ((ota_vfs*)pVfs)->pRealVfs;
  return pRealVfs->xDlOpen(pRealVfs, zPath);
}

/*
** Populate the buffer zErrMsg (size nByte bytes) with a human readable
** utf-8 string describing the most recent error encountered associated 
** with dynamic libraries.
*/
static void otaVfsDlError(sqlite3_vfs *pVfs, int nByte, char *zErrMsg){
  sqlite3_vfs *pRealVfs = ((ota_vfs*)pVfs)->pRealVfs;
  pRealVfs->xDlError(pRealVfs, nByte, zErrMsg);
}

/*
** Return a pointer to the symbol zSymbol in the dynamic library pHandle.
*/
static void (*otaVfsDlSym(
  sqlite3_vfs *pVfs, 
  void *pArg, 
  const char *zSym
))(void){
  sqlite3_vfs *pRealVfs = ((ota_vfs*)pVfs)->pRealVfs;
  return pRealVfs->xDlSym(pRealVfs, pArg, zSym);
}

/*
** Close the dynamic library handle pHandle.
*/
static void otaVfsDlClose(sqlite3_vfs *pVfs, void *pHandle){
  sqlite3_vfs *pRealVfs = ((ota_vfs*)pVfs)->pRealVfs;
  return pRealVfs->xDlClose(pRealVfs, pHandle);
}
#endif /* SQLITE_OMIT_LOAD_EXTENSION */

/*
** Populate the buffer pointed to by zBufOut with nByte bytes of 
** random data.
*/
static int otaVfsRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
  sqlite3_vfs *pRealVfs = ((ota_vfs*)pVfs)->pRealVfs;
  return pRealVfs->xRandomness(pRealVfs, nByte, zBufOut);
}

/*
** Sleep for nMicro microseconds. Return the number of microseconds 
** actually slept.
*/
static int otaVfsSleep(sqlite3_vfs *pVfs, int nMicro){
  sqlite3_vfs *pRealVfs = ((ota_vfs*)pVfs)->pRealVfs;
  return pRealVfs->xSleep(pRealVfs, nMicro);
}

/*
** Return the current time as a Julian Day number in *pTimeOut.
*/
static int otaVfsCurrentTime(sqlite3_vfs *pVfs, double *pTimeOut){
  sqlite3_vfs *pRealVfs = ((ota_vfs*)pVfs)->pRealVfs;
  return pRealVfs->xCurrentTime(pRealVfs, pTimeOut);
}

/*
** No-op.
*/
static int otaVfsGetLastError(sqlite3_vfs *pVfs, int a, char *b){
  return 0;
}

/*
** Deregister and destroy an OTA vfs created by an earlier call to
** sqlite3ota_create_vfs().
*/
SQLITE_API void SQLITE_STDCALL sqlite3ota_destroy_vfs(const char *zName){
  sqlite3_vfs *pVfs = sqlite3_vfs_find(zName);
  if( pVfs && pVfs->xOpen==otaVfsOpen ){
    sqlite3_mutex_free(((ota_vfs*)pVfs)->mutex);
    sqlite3_vfs_unregister(pVfs);
    sqlite3_free(pVfs);
  }
}

/*
** Create an OTA VFS named zName that accesses the underlying file-system
** via existing VFS zParent. The new object is registered as a non-default
** VFS with SQLite before returning.
*/
SQLITE_API int SQLITE_STDCALL sqlite3ota_create_vfs(const char *zName, const char *zParent){

  /* Template for VFS */
  static sqlite3_vfs vfs_template = {
    1,                            /* iVersion */
    0,                            /* szOsFile */
    0,                            /* mxPathname */
    0,                            /* pNext */
    0,                            /* zName */
    0,                            /* pAppData */
    otaVfsOpen,                   /* xOpen */
    otaVfsDelete,                 /* xDelete */
    otaVfsAccess,                 /* xAccess */
    otaVfsFullPathname,           /* xFullPathname */

#ifndef SQLITE_OMIT_LOAD_EXTENSION
    otaVfsDlOpen,                 /* xDlOpen */
    otaVfsDlError,                /* xDlError */
    otaVfsDlSym,                  /* xDlSym */
    otaVfsDlClose,                /* xDlClose */
#else
    0, 0, 0, 0,
#endif

    otaVfsRandomness,             /* xRandomness */
    otaVfsSleep,                  /* xSleep */
    otaVfsCurrentTime,            /* xCurrentTime */
    otaVfsGetLastError,           /* xGetLastError */
    0,                            /* xCurrentTimeInt64 (version 2) */
    0, 0, 0                       /* Unimplemented version 3 methods */
  };

  ota_vfs *pNew = 0;              /* Newly allocated VFS */
  int nName;
  int rc = SQLITE_OK;

  int nByte;
  nName = strlen(zName);
  nByte = sizeof(ota_vfs) + nName + 1;
  pNew = (ota_vfs*)sqlite3_malloc(nByte);
  if( pNew==0 ){
    rc = SQLITE_NOMEM;
  }else{
    sqlite3_vfs *pParent;           /* Parent VFS */
    memset(pNew, 0, nByte);
    pParent = sqlite3_vfs_find(zParent);
    if( pParent==0 ){
      rc = SQLITE_NOTFOUND;
    }else{
      char *zSpace;
      memcpy(&pNew->base, &vfs_template, sizeof(sqlite3_vfs));
      pNew->base.mxPathname = pParent->mxPathname;
      pNew->base.szOsFile = sizeof(ota_file) + pParent->szOsFile;
      pNew->pRealVfs = pParent;
      pNew->base.zName = (const char*)(zSpace = (char*)&pNew[1]);
      memcpy(zSpace, zName, nName);

      /* Allocate the mutex and register the new VFS (not as the default) */
      pNew->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_RECURSIVE);
      if( pNew->mutex==0 ){
................................................................................

  return rc;
}


/**************************************************************************/

#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_OTA) */

/************** End of sqlite3ota.c ******************************************/
/************** Begin file dbstat.c ******************************************/
/*
** 2010 July 12
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
................................................................................
**
** The dbstat virtual table is used to extract low-level formatting
** information from an SQLite database in order to implement the
** "sqlite3_analyzer" utility.  See the ../tool/spaceanal.tcl script
** for an example implementation.
*/


#if (defined(SQLITE_ENABLE_DBSTAT_VTAB) || defined(SQLITE_TEST)) \
    && !defined(SQLITE_OMIT_VIRTUALTABLE)

/*
** Page paths:
** 
**   The value of the 'path' column describes the path taken from the 

**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.8.11"
#define SQLITE_VERSION_NUMBER 3008011
#define SQLITE_SOURCE_ID      "2015-07-23 20:44:49 017c5019e1ce042025d4f327e50ec50af49f9fa4"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version, sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
................................................................................
** circumstances in order to fix a problem with priority inversion.
** Applications should <em>not</em> use this file-control.
**
** <li>[[SQLITE_FCNTL_ZIPVFS]]
** The [SQLITE_FCNTL_ZIPVFS] opcode is implemented by zipvfs only. All other
** VFS should return SQLITE_NOTFOUND for this opcode.
**
** <li>[[SQLITE_FCNTL_RBU]]
** The [SQLITE_FCNTL_RBU] opcode is implemented by the special VFS used by
** the RBU extension only.  All other VFS should return SQLITE_NOTFOUND for
** this opcode.  
** </ul>
*/
#define SQLITE_FCNTL_LOCKSTATE               1
#define SQLITE_FCNTL_GET_LOCKPROXYFILE       2
#define SQLITE_FCNTL_SET_LOCKPROXYFILE       3
#define SQLITE_FCNTL_LAST_ERRNO              4
................................................................................
#define SQLITE_FCNTL_TRACE                  19
#define SQLITE_FCNTL_HAS_MOVED              20
#define SQLITE_FCNTL_SYNC                   21
#define SQLITE_FCNTL_COMMIT_PHASETWO        22
#define SQLITE_FCNTL_WIN32_SET_HANDLE       23
#define SQLITE_FCNTL_WAL_BLOCK              24
#define SQLITE_FCNTL_ZIPVFS                 25
#define SQLITE_FCNTL_RBU                    26

/* deprecated names */
#define SQLITE_GET_LOCKPROXYFILE      SQLITE_FCNTL_GET_LOCKPROXYFILE
#define SQLITE_SET_LOCKPROXYFILE      SQLITE_FCNTL_SET_LOCKPROXYFILE
#define SQLITE_LAST_ERRNO             SQLITE_FCNTL_LAST_ERRNO


................................................................................
#  define SQLITE_NOINLINE
#endif

/*
** Make sure that the compiler intrinsics we desire are enabled when
** compiling with an appropriate version of MSVC.
*/
#if defined(_MSC_VER) && _MSC_VER>=1300 && !defined(_WIN32_WCE)
#  include <intrin.h>
#  pragma intrinsic(_byteswap_ushort)
#  pragma intrinsic(_byteswap_ulong)
#endif

/*
** The SQLITE_THREADSAFE macro must be defined as 0, 1, or 2.
................................................................................
#   define SQLITE_MAX_MMAP_SIZE 0
# endif
#endif
#ifndef SQLITE_MAX_MMAP_SIZE
# if defined(__linux__) \
  || defined(_WIN32) \
  || (defined(__APPLE__) && defined(__MACH__)) \
  || defined(__sun) \
  || defined(__FreeBSD__) \
  || defined(__DragonFly__)
#   define SQLITE_MAX_MMAP_SIZE 0x7fff0000  /* 2147418112 */
# else
#   define SQLITE_MAX_MMAP_SIZE 0
# endif
# define SQLITE_MAX_MMAP_SIZE_xc 1 /* exclude from ctime.c */
#endif

................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains definitions of global variables and constants.
*/
/* #include "sqliteInt.h" */

/* An array to map all upper-case characters into their corresponding
** lower-case character. 
**
** SQLite only considers US-ASCII (or EBCDIC) characters.  We do not
** handle case conversions for the UTF character set since the tables
** involved are nearly as big or bigger than SQLite itself.
................................................................................
** Changing the pending byte during operation will result in undefined
** and incorrect behavior.
*/
#ifndef SQLITE_OMIT_WSD
SQLITE_PRIVATE int sqlite3PendingByte = 0x40000000;
#endif

/* #include "opcodes.h" */
/*
** Properties of opcodes.  The OPFLG_INITIALIZER macro is
** created by mkopcodeh.awk during compilation.  Data is obtained
** from the comments following the "case OP_xxxx:" statements in
** the vdbe.c file.  
*/
SQLITE_PRIVATE const unsigned char sqlite3OpcodeProperty[] = OPFLG_INITIALIZER;
................................................................................
**
** This file implements routines used to report what compile-time options
** SQLite was built with.
*/

#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS

/* #include "sqliteInt.h" */

/*
** An array of names of all compile-time options.  This array should 
** be sorted A-Z.
**
** This array looks large, but in a typical installation actually uses
** only a handful of compile-time options, so most times this array is usually
................................................................................
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This module implements the sqlite3_status() interface and related
** functionality.
*/
/* #include "sqliteInt.h" */
/************** Include vdbeInt.h in the middle of status.c ******************/
/************** Begin file vdbeInt.h *****************************************/
/*
** 2003 September 6
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
................................................................................
**
**      Jean Meeus
**      Astronomical Algorithms, 2nd Edition, 1998
**      ISBM 0-943396-61-1
**      Willmann-Bell, Inc
**      Richmond, Virginia (USA)
*/
/* #include "sqliteInt.h" */
/* #include <stdlib.h> */
/* #include <assert.h> */
#include <time.h>

#ifndef SQLITE_OMIT_DATETIME_FUNCS


................................................................................
    p->D = 1;
  }else{
    Z = (int)((p->iJD + 43200000)/86400000);
    A = (int)((Z - 1867216.25)/36524.25);
    A = Z + 1 + A - (A/4);
    B = A + 1524;
    C = (int)((B - 122.1)/365.25);
    D = (36525*(C&32767))/100;
    E = (int)((B-D)/30.6001);
    X1 = (int)(30.6001*E);
    p->D = B - D - X1;
    p->M = E<14 ? E-1 : E-13;
    p->Y = p->M>2 ? C - 4716 : C - 4715;
  }
  p->validYMD = 1;
................................................................................
**
******************************************************************************
**
** This file contains OS interface code that is common to all
** architectures.
*/
#define _SQLITE_OS_C_ 1
/* #include "sqliteInt.h" */
#undef _SQLITE_OS_C_

/*
** The default SQLite sqlite3_vfs implementations do not allocate
** memory (actually, os_unix.c allocates a small amount of memory
** from within OsOpen()), but some third-party implementations may.
** So we test the effects of a malloc() failing and the sqlite3OsXXX()
................................................................................
** SQLITE_NOMEM) to the user. However, sometimes a fault is not necessarily
** fatal. For example, if a malloc fails while resizing a hash table, this 
** is completely recoverable simply by not carrying out the resize. The 
** hash table will continue to function normally.  So a malloc failure 
** during a hash table resize is a benign fault.
*/

/* #include "sqliteInt.h" */

#ifndef SQLITE_OMIT_BUILTIN_TEST

/*
** Global variables.
*/
typedef struct BenignMallocHooks BenignMallocHooks;
................................................................................
**
** This file contains a no-op memory allocation drivers for use when
** SQLITE_ZERO_MALLOC is defined.  The allocation drivers implemented
** here always fail.  SQLite will not operate with these drivers.  These
** are merely placeholders.  Real drivers must be substituted using
** sqlite3_config() before SQLite will operate.
*/
/* #include "sqliteInt.h" */

/*
** This version of the memory allocator is the default.  It is
** used when no other memory allocator is specified using compile-time
** macros.
*/
#ifdef SQLITE_ZERO_MALLOC
................................................................................
**                                building on older macs.
**
**    SQLITE_WITHOUT_MSIZE        Set this symbol to disable the use of
**                                _msize() on windows systems.  This might
**                                be necessary when compiling for Delphi,
**                                for example.
*/
/* #include "sqliteInt.h" */

/*
** This version of the memory allocator is the default.  It is
** used when no other memory allocator is specified using compile-time
** macros.
*/
#ifdef SQLITE_SYSTEM_MALLOC
................................................................................
** to obtain the memory it needs while adding lots of additional debugging
** information to each allocation in order to help detect and fix memory
** leaks and memory usage errors.
**
** This file contains implementations of the low-level memory allocation
** routines specified in the sqlite3_mem_methods object.
*/
/* #include "sqliteInt.h" */

/*
** This version of the memory allocator is used only if the
** SQLITE_MEMDEBUG macro is defined
*/
#ifdef SQLITE_MEMDEBUG

................................................................................
** implementations. Once sqlite3_initialize() has been called,
** the amount of memory available to SQLite is fixed and cannot
** be changed.
**
** This version of the memory allocation subsystem is included
** in the build only if SQLITE_ENABLE_MEMSYS3 is defined.
*/
/* #include "sqliteInt.h" */

/*
** This version of the memory allocator is only built into the library
** SQLITE_ENABLE_MEMSYS3 is defined. Defining this symbol does not
** mean that the library will use a memory-pool by default, just that
** it is available. The mempool allocator is activated by calling
** sqlite3_config().
................................................................................
** fragmentation as long as the following constraint holds:
**
**      N >=  M*(1 + log2(n)/2) - n + 1
**
** The sqlite3_status() logic tracks the maximum values of n and M so
** that an application can, at any time, verify this constraint.
*/
/* #include "sqliteInt.h" */

/*
** This version of the memory allocator is used only when 
** SQLITE_ENABLE_MEMSYS5 is defined.
*/
#ifdef SQLITE_ENABLE_MEMSYS5

................................................................................
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement mutexes.
**
** This file contains code that is common across all mutex implementations.
*/
/* #include "sqliteInt.h" */

#if defined(SQLITE_DEBUG) && !defined(SQLITE_MUTEX_OMIT)
/*
** For debugging purposes, record when the mutex subsystem is initialized
** and uninitialized so that we can assert() if there is an attempt to
** allocate a mutex while the system is uninitialized.
*/
................................................................................
**
** interface.
**
** If compiled with SQLITE_DEBUG, then additional logic is inserted
** that does error checking on mutexes to make sure they are being
** called correctly.
*/
/* #include "sqliteInt.h" */

#ifndef SQLITE_MUTEX_OMIT

#ifndef SQLITE_DEBUG
/*
** Stub routines for all mutex methods.
**
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement mutexes for pthreads
*/
/* #include "sqliteInt.h" */

/*
** The code in this file is only used if we are compiling threadsafe
** under unix with pthreads.
**
** Note that this implementation requires a version of pthreads that
** supports recursive mutexes.
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement mutexes for Win32.
*/
/* #include "sqliteInt.h" */

#if SQLITE_OS_WIN
/*
** Include code that is common to all os_*.c files
*/
/************** Include os_common.h in the middle of mutex_w32.c *************/
/************** Begin file os_common.h ***************************************/
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** Memory allocation functions used throughout sqlite.
*/
/* #include "sqliteInt.h" */
/* #include <stdarg.h> */

/*
** Attempt to release up to n bytes of non-essential memory currently
** held by SQLite. An example of non-essential memory is memory used to
** cache database pages that are not currently in use.
*/
................................................................................
**************************************************************************
**
** This file contains code for a set of "printf"-like routines.  These
** routines format strings much like the printf() from the standard C
** library, though the implementation here has enhancements to support
** SQLite.
*/
/* #include "sqliteInt.h" */

/*
** Conversion types fall into various categories as defined by the
** following enumeration.
*/
#define etRADIX       1 /* Integer types.  %d, %x, %o, and so forth */
#define etFLOAT       2 /* Floating point.  %f */
................................................................................
** This is the routine that actually formats the sqlite3_log() message.
** We house it in a separate routine from sqlite3_log() to avoid using
** stack space on small-stack systems when logging is disabled.
**
** sqlite3_log() must render into a static buffer.  It cannot dynamically
** allocate memory because it might be called while the memory allocator
** mutex is held.
**
** sqlite3VXPrintf() might ask for *temporary* memory allocations for
** certain format characters (%q) or for very large precisions or widths.
** Care must be taken that any sqlite3_log() calls that occur while the
** memory mutex is held do not use these mechanisms.
*/
static void renderLogMsg(int iErrCode, const char *zFormat, va_list ap){
  StrAccum acc;                          /* String accumulator */
  char zMsg[SQLITE_PRINT_BUF_SIZE*3];    /* Complete log message */

  sqlite3StrAccumInit(&acc, 0, zMsg, sizeof(zMsg), 0);
  sqlite3VXPrintf(&acc, 0, zFormat, ap);
................................................................................
** This file contains C code to implement the TreeView debugging routines.
** These routines print a parse tree to standard output for debugging and
** analysis. 
**
** The interfaces in this file is only available when compiling
** with SQLITE_DEBUG.
*/
/* #include "sqliteInt.h" */
#ifdef SQLITE_DEBUG

/*
** Add a new subitem to the tree.  The moreToFollow flag indicates that this
** is not the last item in the tree.
*/
static TreeView *sqlite3TreeViewPush(TreeView *p, u8 moreToFollow){
................................................................................
*************************************************************************
** This file contains code to implement a pseudo-random number
** generator (PRNG) for SQLite.
**
** Random numbers are used by some of the database backends in order
** to generate random integer keys for tables or random filenames.
*/
/* #include "sqliteInt.h" */


/* All threads share a single random number generator.
** This structure is the current state of the generator.
*/
static SQLITE_WSD struct sqlite3PrngType {
  unsigned char isInit;          /* True if initialized */
................................................................................
** "thread" is done by the main thread at either the sqlite3ThreadCreate()
** or sqlite3ThreadJoin() call.  This is, in fact, what happens in
** single threaded systems.  Nothing in SQLite requires multiple threads.
** This interface exists so that applications that want to take advantage
** of multiple cores can do so, while also allowing applications to stay
** single-threaded if desired.
*/
/* #include "sqliteInt.h" */
#if SQLITE_OS_WIN
/* #  include "os_win.h" */
#endif

#if SQLITE_MAX_WORKER_THREADS>0

/********************************* Unix Pthreads ****************************/
#if SQLITE_OS_UNIX && defined(SQLITE_MUTEX_PTHREADS) && SQLITE_THREADSAFE>0

................................................................................
**
**
** BOM or Byte Order Mark:
**     0xff 0xfe   little-endian utf-16 follows
**     0xfe 0xff   big-endian utf-16 follows
**
*/
/* #include "sqliteInt.h" */
/* #include <assert.h> */
/* #include "vdbeInt.h" */

#ifndef SQLITE_AMALGAMATION
/*
** The following constant value is used by the SQLITE_BIGENDIAN and
** SQLITE_LITTLEENDIAN macros.
*/
SQLITE_PRIVATE const int sqlite3one = 1;
................................................................................
*************************************************************************
** Utility functions used throughout sqlite.
**
** This file contains functions for allocating memory, comparing
** strings, and stuff like that.
**
*/
/* #include "sqliteInt.h" */
/* #include <stdarg.h> */
#if HAVE_ISNAN || SQLITE_HAVE_ISNAN
# include <math.h>
#endif

/*
** Routine needed to support the testcase() macro.
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This is the implementation of generic hash-tables
** used in SQLite.
*/
/* #include "sqliteInt.h" */
/* #include <assert.h> */

/* Turn bulk memory into a hash table object by initializing the
** fields of the Hash structure.
**
** "pNew" is a pointer to the hash table that is to be initialized.
*/
................................................................................
**   *  Definitions of sqlite3_io_methods objects for all locking
**      methods plus "finder" functions for each locking method.
**   *  sqlite3_vfs method implementations.
**   *  Locking primitives for the proxy uber-locking-method. (MacOSX only)
**   *  Definitions of sqlite3_vfs objects for all locking methods
**      plus implementations of sqlite3_os_init() and sqlite3_os_end().
*/
/* #include "sqliteInt.h" */
#if SQLITE_OS_UNIX              /* This file is used on unix only */

/*
** There are various methods for file locking used for concurrency
** control:
**
**   1. POSIX locking (the default),
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains code that is specific to Windows.
*/
/* #include "sqliteInt.h" */
#if SQLITE_OS_WIN               /* This file is used for Windows only */

/*
** Include code that is common to all os_*.c files
*/
/************** Include os_common.h in the middle of os_win.c ****************/
/************** Begin file os_common.h ***************************************/
................................................................................

/************** End of os_common.h *******************************************/
/************** Continuing where we left off in os_win.c *********************/

/*
** Include the header file for the Windows VFS.
*/
/* #include "os_win.h" */

/*
** Compiling and using WAL mode requires several APIs that are only
** available in Windows platforms based on the NT kernel.
*/
#if !SQLITE_OS_WINNT && !defined(SQLITE_OMIT_WAL)
#  error "WAL mode requires support from the Windows NT kernel, compile\
................................................................................
** Clear operations are exceedingly rare.  There are usually between
** 5 and 500 set operations per Bitvec object, though the number of sets can
** sometimes grow into tens of thousands or larger.  The size of the
** Bitvec object is the number of pages in the database file at the
** start of a transaction, and is thus usually less than a few thousand,
** but can be as large as 2 billion for a really big database.
*/
/* #include "sqliteInt.h" */

/* Size of the Bitvec structure in bytes. */
#define BITVEC_SZ        512

/* Round the union size down to the nearest pointer boundary, since that's how 
** it will be aligned within the Bitvec struct. */
#define BITVEC_USIZE     (((BITVEC_SZ-(3*sizeof(u32)))/sizeof(Bitvec*))*sizeof(Bitvec*))
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file implements that page cache.
*/
/* #include "sqliteInt.h" */

/*
** A complete page cache is an instance of this structure.
*/
struct PCache {
  PgHdr *pDirty, *pDirtyTail;         /* List of dirty pages in LRU order */
  PgHdr *pSynced;                     /* Last synced page in dirty page list */
................................................................................
** (3) is exhausted, subsequent allocations fail over to the general-purpose
** memory allocator (1).
**
** Earlier versions of SQLite used only methods (1) and (2).  But experiments
** show that method (3) with N==100 provides about a 5% performance boost for
** common workloads.
*/
/* #include "sqliteInt.h" */

typedef struct PCache1 PCache1;
typedef struct PgHdr1 PgHdr1;
typedef struct PgFreeslot PgFreeslot;
typedef struct PGroup PGroup;

/* Each page cache (or PCache) belongs to a PGroup.  A PGroup is a set 
................................................................................
  /* Variables related to SQLITE_CONFIG_PAGECACHE settings.  The
  ** szSlot, nSlot, pStart, pEnd, nReserve, and isInit values are all
  ** fixed at sqlite3_initialize() time and do not require mutex protection.
  ** The nFreeSlot and pFree values do require mutex protection.
  */
  int isInit;                    /* True if initialized */
  int separateCache;             /* Use a new PGroup for each PCache */
  int nInitPage;                 /* Initial bulk allocation size */   
  int szSlot;                    /* Size of each free slot */
  int nSlot;                     /* The number of pcache slots */
  int nReserve;                  /* Try to keep nFreeSlot above this */
  void *pStart, *pEnd;           /* Bounds of global page cache memory */
  /* Above requires no mutex.  Use mutex below for variable that follow. */
  sqlite3_mutex *mutex;          /* Mutex for accessing the following: */
  PgFreeslot *pFree;             /* Free page blocks */
................................................................................
      p->pNext = pcache1.pFree;
      pcache1.pFree = p;
      pBuf = (void*)&((char*)pBuf)[sz];
    }
    pcache1.pEnd = pBuf;
  }
}

/*
** Try to initialize the pCache->pFree and pCache->pBulk fields.  Return
** true if pCache->pFree ends up containing one or more free pages.
*/
static int pcache1InitBulk(PCache1 *pCache){
  i64 szBulk;
  char *zBulk;
  if( pcache1.nInitPage==0 ) return 0;
  /* Do not bother with a bulk allocation if the cache size very small */
  if( pCache->nMax<3 ) return 0;
  sqlite3BeginBenignMalloc();
  if( pcache1.nInitPage>0 ){
    szBulk = pCache->szAlloc * (i64)pcache1.nInitPage;
  }else{
    szBulk = -1024 * (i64)pcache1.nInitPage;
  }
  if( szBulk > pCache->szAlloc*(i64)pCache->nMax ){
    szBulk = pCache->szAlloc*pCache->nMax;
  }
  zBulk = pCache->pBulk = sqlite3Malloc( szBulk );
  sqlite3EndBenignMalloc();
  if( zBulk ){
    int nBulk = sqlite3MallocSize(zBulk)/pCache->szAlloc;
    int i;
    for(i=0; i<nBulk; i++){
      PgHdr1 *pX = (PgHdr1*)&zBulk[pCache->szPage];
      pX->page.pBuf = zBulk;
      pX->page.pExtra = &pX[1];
      pX->isBulkLocal = 1;
      pX->pNext = pCache->pFree;
      pCache->pFree = pX;
      zBulk += pCache->szAlloc;
    }
  }
  return pCache->pFree!=0;
}

/*
** Malloc function used within this file to allocate space from the buffer
** configured using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no 
** such buffer exists or there is no space left in it, this function falls 
** back to sqlite3Malloc().
**
................................................................................
** Allocate a new page object initially associated with cache pCache.
*/
static PgHdr1 *pcache1AllocPage(PCache1 *pCache){
  PgHdr1 *p = 0;
  void *pPg;

  assert( sqlite3_mutex_held(pCache->pGroup->mutex) );
  if( pCache->pFree || (pCache->nPage==0 && pcache1InitBulk(pCache)) ){
    p = pCache->pFree;
    pCache->pFree = p->pNext;
    p->pNext = 0;
  }else{
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
    /* The group mutex must be released before pcache1Alloc() is called. This
    ** is because it might call sqlite3_release_memory(), which assumes that 
................................................................................
  if( freeFlag ) pcache1FreePage(pPage);
}

/*
** If there are currently more than nMaxPage pages allocated, try
** to recycle pages to reduce the number allocated to nMaxPage.
*/
static void pcache1EnforceMaxPage(PCache1 *pCache){
  PGroup *pGroup = pCache->pGroup;
  assert( sqlite3_mutex_held(pGroup->mutex) );
  while( pGroup->nCurrentPage>pGroup->nMaxPage && pGroup->pLruTail ){
    PgHdr1 *p = pGroup->pLruTail;
    assert( p->pCache->pGroup==pGroup );
    assert( p->isPinned==0 );
    pcache1PinPage(p);
    pcache1RemoveFromHash(p, 1);
  }
  if( pCache->nPage==0 && pCache->pBulk ){
    sqlite3_free(pCache->pBulk);
    pCache->pBulk = pCache->pFree = 0;
  }
}

/*
** Discard all pages from cache pCache with a page number (key value) 
** greater than or equal to iLimit. Any pinned pages that meet this 
** criteria are unpinned before they are discarded.
................................................................................

#if SQLITE_THREADSAFE
  if( sqlite3GlobalConfig.bCoreMutex ){
    pcache1.grp.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU);
    pcache1.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_PMEM);
  }
#endif
  if( pcache1.separateCache
   && sqlite3GlobalConfig.nPage!=0
   && sqlite3GlobalConfig.pPage==0
  ){
    pcache1.nInitPage = sqlite3GlobalConfig.nPage;
  }else{
    pcache1.nInitPage = 0;
  }
  pcache1.grp.mxPinned = 10;
  pcache1.isInit = 1;
  return SQLITE_OK;
}

/*
** Implementation of the sqlite3_pcache.xShutdown method.
................................................................................
    pcache1ResizeHash(pCache);
    if( bPurgeable ){
      pCache->nMin = 10;
      pGroup->nMinPage += pCache->nMin;
      pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;
    }
    pcache1LeaveMutex(pGroup);






























    if( pCache->nHash==0 ){
      pcache1Destroy((sqlite3_pcache*)pCache);
      pCache = 0;
    }
  }
  return (sqlite3_pcache *)pCache;
}
................................................................................
  if( pCache->bPurgeable ){
    PGroup *pGroup = pCache->pGroup;
    pcache1EnterMutex(pGroup);
    pGroup->nMaxPage += (nMax - pCache->nMax);
    pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;
    pCache->nMax = nMax;
    pCache->n90pct = pCache->nMax*9/10;
    pcache1EnforceMaxPage(pCache);
    pcache1LeaveMutex(pGroup);
  }
}

/*
** Implementation of the sqlite3_pcache.xShrink method. 
**
................................................................................
  PCache1 *pCache = (PCache1*)p;
  if( pCache->bPurgeable ){
    PGroup *pGroup = pCache->pGroup;
    int savedMaxPage;
    pcache1EnterMutex(pGroup);
    savedMaxPage = pGroup->nMaxPage;
    pGroup->nMaxPage = 0;
    pcache1EnforceMaxPage(pCache);
    pGroup->nMaxPage = savedMaxPage;
    pcache1LeaveMutex(pGroup);
  }
}

/*
** Implementation of the sqlite3_pcache.xPagecount method. 
................................................................................
  pcache1EnterMutex(pGroup);
  pcache1TruncateUnsafe(pCache, 0);
  assert( pGroup->nMaxPage >= pCache->nMax );
  pGroup->nMaxPage -= pCache->nMax;
  assert( pGroup->nMinPage >= pCache->nMin );
  pGroup->nMinPage -= pCache->nMin;
  pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;
  pcache1EnforceMaxPage(pCache);
  pcache1LeaveMutex(pGroup);
  sqlite3_free(pCache->pBulk);
  sqlite3_free(pCache->apHash);
  sqlite3_free(pCache);
}

/*
................................................................................
** The cost of a TEST using the same batch number is O(logN).  The cost
** of the first SMALLEST is O(NlogN).  Second and subsequent SMALLEST
** primitives are constant time.  The cost of DESTROY is O(N).
**
** There is an added cost of O(N) when switching between TEST and
** SMALLEST primitives.
*/
/* #include "sqliteInt.h" */


/*
** Target size for allocation chunks.
*/
#define ROWSET_ALLOCATION_SIZE 1024

................................................................................
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
*/
#ifndef SQLITE_OMIT_DISKIO
/* #include "sqliteInt.h" */
/************** Include wal.h in the middle of pager.c ***********************/
/************** Begin file wal.h *********************************************/
/*
** 2010 February 1
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
................................................................................
** system. Refer to the comments below and the header comment attached to 
** the implementation of each function in log.c for further details.
*/

#ifndef _WAL_H_
#define _WAL_H_

/* #include "sqliteInt.h" */

/* Additional values that can be added to the sync_flags argument of
** sqlite3WalFrames():
*/
#define WAL_SYNC_TRANSACTIONS  0x20   /* Sync at the end of each transaction */
#define SQLITE_SYNC_MASK       0x13   /* Mask off the SQLITE_SYNC_* values */

................................................................................
**
** When a rollback occurs, the value of K is decreased. Hash table entries
** that correspond to frames greater than the new K value are removed
** from the hash table at this point.
*/
#ifndef SQLITE_OMIT_WAL

/* #include "wal.h" */

/*
** Trace output macros
*/
#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
SQLITE_PRIVATE int sqlite3WalTrace = 0;
# define WALTRACE(X)  if(sqlite3WalTrace) sqlite3DebugPrintf X
................................................................................
  volatile WalIndexHdr *aHdr = walIndexHdr(pWal);
  const int nCksum = offsetof(WalIndexHdr, aCksum);

  assert( pWal->writeLock );
  pWal->hdr.isInit = 1;
  pWal->hdr.iVersion = WALINDEX_MAX_VERSION;
  walChecksumBytes(1, (u8*)&pWal->hdr, nCksum, 0, pWal->hdr.aCksum);
  memcpy((void*)&aHdr[1], (const void*)&pWal->hdr, sizeof(WalIndexHdr));
  walShmBarrier(pWal);
  memcpy((void*)&aHdr[0], (const void*)&pWal->hdr, sizeof(WalIndexHdr));
}

/*
** This function encodes a single frame header and writes it to a buffer
** supplied by the caller. A frame-header is made up of a series of 
** 4-byte big-endian integers, as follows:
**
................................................................................
  memset((void *)&aPgno[iLimit+1], 0, nByte);

#ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT
  /* Verify that the every entry in the mapping region is still reachable
  ** via the hash table even after the cleanup.
  */
  if( iLimit ){
    int j;           /* Loop counter */
    int iKey;        /* Hash key */
    for(j=1; j<=iLimit; j++){
      for(iKey=walHash(aPgno[j]); aHash[iKey]; iKey=walNextHash(iKey)){
        if( aHash[iKey]==j ) break;
      }
      assert( aHash[iKey]==j );
    }
  }
#endif /* SQLITE_ENABLE_EXPENSIVE_ASSERT */
}


/*
................................................................................
    ht_slot *aList;               /* Pointer to sub-list content */
  };

  const int nList = *pnList;      /* Size of input list */
  int nMerge = 0;                 /* Number of elements in list aMerge */
  ht_slot *aMerge = 0;            /* List to be merged */
  int iList;                      /* Index into input list */
  u32 iSub = 0;                   /* Index into aSub array */
  struct Sublist aSub[13];        /* Array of sub-lists */

  memset(aSub, 0, sizeof(aSub));
  assert( nList<=HASHTABLE_NPAGE && nList>0 );
  assert( HASHTABLE_NPAGE==(1<<(ArraySize(aSub)-1)) );

  for(iList=0; iList<nList; iList++){
    nMerge = 1;
    aMerge = &aList[iList];
    for(iSub=0; iList & (1<<iSub); iSub++){
      struct Sublist *p;
      assert( iSub<ArraySize(aSub) );
      p = &aSub[iSub];
      assert( p->aList && p->nList<=(1<<iSub) );
      assert( p->aList==&aList[iList&~((2<<iSub)-1)] );
      walMerge(aContent, p->aList, p->nList, &aMerge, &nMerge, aBuffer);
    }
    aSub[iSub].aList = aMerge;
    aSub[iSub].nList = nMerge;
  }

  for(iSub++; iSub<ArraySize(aSub); iSub++){
    if( nList & (1<<iSub) ){
      struct Sublist *p;
      assert( iSub<ArraySize(aSub) );
      p = &aSub[iSub];
      assert( p->nList<=(1<<iSub) );
      assert( p->aList==&aList[nList&~((2<<iSub)-1)] );
      walMerge(aContent, p->aList, p->nList, &aMerge, &nMerge, aBuffer);
    }
  }
  assert( aMerge==aList );
  *pnList = nMerge;
................................................................................
** unspecified.  A trunk page looks like this:
**
**    SIZE    DESCRIPTION
**      4     Page number of next trunk page
**      4     Number of leaf pointers on this page
**      *     zero or more pages numbers of leaves
*/
/* #include "sqliteInt.h" */


/* The following value is the maximum cell size assuming a maximum page
** size give above.
*/
#define MX_CELL_SIZE(pBt)  ((int)(pBt->pageSize-8))

................................................................................
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file implements an external (disk-based) database using BTrees.
** See the header comment on "btreeInt.h" for additional information.
** Including a description of file format and an overview of operation.
*/
/* #include "btreeInt.h" */

/*
** The header string that appears at the beginning of every
** SQLite database.
*/
static const char zMagicHeader[] = SQLITE_FILE_HEADER;

................................................................................
  u32 usableSize;          /* Usable size of the page */
  u32 contentOffset;       /* Offset to the start of the cell content area */
  u32 *heap = 0;           /* Min-heap used for checking cell coverage */
  u32 x, prev = 0;         /* Next and previous entry on the min-heap */
  const char *saved_zPfx = pCheck->zPfx;
  int saved_v1 = pCheck->v1;
  int saved_v2 = pCheck->v2;
  u8 savedIsInit = 0;

  /* Check that the page exists
  */
  pBt = pCheck->pBt;
  usableSize = pBt->usableSize;
  if( iPage==0 ) return 0;
  if( checkRef(pCheck, iPage) ) return 0;
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the implementation of the sqlite3_backup_XXX() 
** API functions and the related features.
*/
/* #include "sqliteInt.h" */
/* #include "btreeInt.h" */

/*
** Structure allocated for each backup operation.
*/
struct sqlite3_backup {
  sqlite3* pDestDb;        /* Destination database handle */
  Btree *pDest;            /* Destination b-tree file */
................................................................................
*************************************************************************
**
** This file contains code use to manipulate "Mem" structure.  A "Mem"
** stores a single value in the VDBE.  Mem is an opaque structure visible
** only within the VDBE.  Interface routines refer to a Mem using the
** name sqlite_value
*/
/* #include "sqliteInt.h" */
/* #include "vdbeInt.h" */

#ifdef SQLITE_DEBUG
/*
** Check invariants on a Mem object.
**
** This routine is intended for use inside of assert() statements, like
** this:    assert( sqlite3VdbeCheckMemInvariants(pMem) );
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used for creating, destroying, and populating
** a VDBE (or an "sqlite3_stmt" as it is known to the outside world.) 
*/
/* #include "sqliteInt.h" */
/* #include "vdbeInt.h" */

/*
** Create a new virtual database engine.
*/
SQLITE_PRIVATE Vdbe *sqlite3VdbeCreate(Parse *pParse){
  sqlite3 *db = pParse->db;
  Vdbe *p;
................................................................................
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains code use to implement APIs that are part of the
** VDBE.
*/
/* #include "sqliteInt.h" */
/* #include "vdbeInt.h" */

#ifndef SQLITE_OMIT_DEPRECATED
/*
** Return TRUE (non-zero) of the statement supplied as an argument needs
** to be recompiled.  A statement needs to be recompiled whenever the
** execution environment changes in a way that would alter the program
** that sqlite3_prepare() generates.  For example, if new functions or
................................................................................
    sqlite3_log(SQLITE_MISUSE, "API called with NULL prepared statement");
    return 1;
  }else{
    return vdbeSafety(p);
  }
}

#ifndef SQLITE_OMIT_TRACE
/*
** Invoke the profile callback.  This routine is only called if we already
** know that the profile callback is defined and needs to be invoked.
*/
static SQLITE_NOINLINE void invokeProfileCallback(sqlite3 *db, Vdbe *p){
  sqlite3_int64 iNow;
  assert( p->startTime>0 );
  assert( db->xProfile!=0 );
  assert( db->init.busy==0 );
  assert( p->zSql!=0 );
  sqlite3OsCurrentTimeInt64(db->pVfs, &iNow);
  db->xProfile(db->pProfileArg, p->zSql, (iNow - p->startTime)*1000000);
  p->startTime = 0;
}
/*
** The checkProfileCallback(DB,P) macro checks to see if a profile callback
** is needed, and it invokes the callback if it is needed.
*/
# define checkProfileCallback(DB,P) \
   if( ((P)->startTime)>0 ){ invokeProfileCallback(DB,P); }
#else
# define checkProfileCallback(DB,P)  /*no-op*/
#endif

/*
** The following routine destroys a virtual machine that is created by
** the sqlite3_compile() routine. The integer returned is an SQLITE_
** success/failure code that describes the result of executing the virtual
** machine.
**
** This routine sets the error code and string returned by
................................................................................
    ** pointer is a harmless no-op. */
    rc = SQLITE_OK;
  }else{
    Vdbe *v = (Vdbe*)pStmt;
    sqlite3 *db = v->db;
    if( vdbeSafety(v) ) return SQLITE_MISUSE_BKPT;
    sqlite3_mutex_enter(db->mutex);
    checkProfileCallback(db, v);
    rc = sqlite3VdbeFinalize(v);
    rc = sqlite3ApiExit(db, rc);
    sqlite3LeaveMutexAndCloseZombie(db);
  }
  return rc;
}

................................................................................
*/
SQLITE_API int SQLITE_STDCALL sqlite3_reset(sqlite3_stmt *pStmt){
  int rc;
  if( pStmt==0 ){
    rc = SQLITE_OK;
  }else{
    Vdbe *v = (Vdbe*)pStmt;
    sqlite3 *db = v->db;
    sqlite3_mutex_enter(db->mutex);
    checkProfileCallback(db, v);
    rc = sqlite3VdbeReset(v);
    sqlite3VdbeRewind(v);
    assert( (rc & (db->errMask))==rc );
    rc = sqlite3ApiExit(db, rc);
    sqlite3_mutex_leave(db->mutex);
  }
  return rc;
}

/*
** Set all the parameters in the compiled SQL statement to NULL.
*/
................................................................................
        rc = db->xWalCallback(db->pWalArg, db, db->aDb[i].zName, nEntry);
      }
    }
  }
#endif
  return rc;
}


/*
** Execute the statement pStmt, either until a row of data is ready, the
** statement is completely executed or an error occurs.
**
** This routine implements the bulk of the logic behind the sqlite_step()
** API.  The only thing omitted is the automatic recompile if a 
................................................................................
    }

    assert( db->nVdbeWrite>0 || db->autoCommit==0 
        || (db->nDeferredCons==0 && db->nDeferredImmCons==0)
    );

#ifndef SQLITE_OMIT_TRACE
    if( db->xProfile && !db->init.busy && p->zSql ){
      sqlite3OsCurrentTimeInt64(db->pVfs, &p->startTime);
    }else{
      assert( p->startTime==0 );
    }
#endif

    db->nVdbeActive++;
    if( p->readOnly==0 ) db->nVdbeWrite++;
    if( p->bIsReader ) db->nVdbeRead++;
    p->pc = 0;
................................................................................
  {
    db->nVdbeExec++;
    rc = sqlite3VdbeExec(p);
    db->nVdbeExec--;
  }

#ifndef SQLITE_OMIT_TRACE
  /* If the statement completed successfully, invoke the profile callback */






  if( rc!=SQLITE_ROW ) checkProfileCallback(db, p);
#endif

  if( rc==SQLITE_DONE ){
    assert( p->rc==SQLITE_OK );
    p->rc = doWalCallbacks(db);
    if( p->rc!=SQLITE_OK ){
      rc = SQLITE_ERROR;
................................................................................
*************************************************************************
**
** This file contains code used to insert the values of host parameters
** (aka "wildcards") into the SQL text output by sqlite3_trace().
**
** The Vdbe parse-tree explainer is also found here.
*/
/* #include "sqliteInt.h" */
/* #include "vdbeInt.h" */

#ifndef SQLITE_OMIT_TRACE

/*
** zSql is a zero-terminated string of UTF-8 SQL text.  Return the number of
** bytes in this text up to but excluding the first character in
** a host parameter.  If the text contains no host parameters, return
................................................................................
**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
*/
/* #include "sqliteInt.h" */
/* #include "vdbeInt.h" */

/*
** Invoke this macro on memory cells just prior to changing the
** value of the cell.  This macro verifies that shallow copies are
** not misused.  A shallow copy of a string or blob just copies a
** pointer to the string or blob, not the content.  If the original
** is changed while the copy is still in use, the string or blob might
................................................................................
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains code used to implement incremental BLOB I/O.
*/

/* #include "sqliteInt.h" */
/* #include "vdbeInt.h" */

#ifndef SQLITE_OMIT_INCRBLOB

/*
** Valid sqlite3_blob* handles point to Incrblob structures.
*/
typedef struct Incrblob Incrblob;
................................................................................
** If running in multi-threaded mode and there are more than
** SORTER_MAX_MERGE_COUNT PMAs on disk when Rewind() is called, then more
** than one background thread may be created. Specifically, there may be
** one background thread for each temporary file on disk, and one background
** thread to merge the output of each of the others to a single PMA for
** the main thread to read from.
*/
/* #include "sqliteInt.h" */
/* #include "vdbeInt.h" */

/* 
** If SQLITE_DEBUG_SORTER_THREADS is defined, this module outputs various
** messages to stderr that may be helpful in understanding the performance
** characteristics of the sorter in multi-threaded mode.
*/
#if 0
................................................................................
** on disk is not created or populated until either:
**
**   1) The in-memory representation grows too large for the allocated 
**      buffer, or
**   2) The sqlite3JournalCreate() function is called.
*/
#ifdef SQLITE_ENABLE_ATOMIC_WRITE
/* #include "sqliteInt.h" */


/*
** A JournalFile object is a subclass of sqlite3_file used by
** as an open file handle for journal files.
*/
struct JournalFile {
................................................................................
**
*************************************************************************
**
** This file contains code use to implement an in-memory rollback journal.
** The in-memory rollback journal is used to journal transactions for
** ":memory:" databases and when the journal_mode=MEMORY pragma is used.
*/
/* #include "sqliteInt.h" */

/* Forward references to internal structures */
typedef struct MemJournal MemJournal;
typedef struct FilePoint FilePoint;
typedef struct FileChunk FileChunk;

/* Space to hold the rollback journal is allocated in increments of
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains routines used for walking the parser tree for
** an SQL statement.
*/
/* #include "sqliteInt.h" */
/* #include <stdlib.h> */
/* #include <string.h> */


/*
** Walk an expression tree.  Invoke the callback once for each node
** of the expression, while descending.  (In other words, the callback
................................................................................
**
*************************************************************************
**
** This file contains routines used for walking the parser tree and
** resolve all identifiers by associating them with a particular
** table and column.
*/
/* #include "sqliteInt.h" */
/* #include <stdlib.h> */
/* #include <string.h> */

/*
** Walk the expression tree pExpr and increase the aggregate function
** depth (the Expr.op2 field) by N on every TK_AGG_FUNCTION node.
** This needs to occur when copying a TK_AGG_FUNCTION node from an
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
*/
/* #include "sqliteInt.h" */

/*
** Return the 'affinity' of the expression pExpr if any.
**
** If pExpr is a column, a reference to a column via an 'AS' alias,
** or a sub-select with a column as the return value, then the 
** affinity of that column is returned. Otherwise, 0x00 is returned,
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that used to generate VDBE code
** that implements the ALTER TABLE command.
*/
/* #include "sqliteInt.h" */

/*
** The code in this file only exists if we are not omitting the
** ALTER TABLE logic from the build.
*/
#ifndef SQLITE_OMIT_ALTERTABLE

................................................................................
** column contains the actual value of the left-most column instead
** of a blob encoding of the complete index key as is found in
** sqlite_stat4.sample.  The nEq, nLt, and nDLt entries of sqlite_stat3
** all contain just a single integer which is the same as the first
** integer in the equivalent columns in sqlite_stat4.
*/
#ifndef SQLITE_OMIT_ANALYZE
/* #include "sqliteInt.h" */

#if defined(SQLITE_ENABLE_STAT4)
# define IsStat4     1
# define IsStat3     0
#elif defined(SQLITE_ENABLE_STAT3)
# define IsStat4     0
# define IsStat3     1
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used to implement the ATTACH and DETACH commands.
*/
/* #include "sqliteInt.h" */

#ifndef SQLITE_OMIT_ATTACH
/*
** Resolve an expression that was part of an ATTACH or DETACH statement. This
** is slightly different from resolving a normal SQL expression, because simple
** identifiers are treated as strings, not possible column names or aliases.
**
................................................................................
**
*************************************************************************
** This file contains code used to implement the sqlite3_set_authorizer()
** API.  This facility is an optional feature of the library.  Embedded
** systems that do not need this facility may omit it by recompiling
** the library with -DSQLITE_OMIT_AUTHORIZATION=1
*/
/* #include "sqliteInt.h" */

/*
** All of the code in this file may be omitted by defining a single
** macro.
*/
#ifndef SQLITE_OMIT_AUTHORIZATION

................................................................................
**     CREATE INDEX
**     DROP INDEX
**     creating ID lists
**     BEGIN TRANSACTION
**     COMMIT
**     ROLLBACK
*/
/* #include "sqliteInt.h" */

/*
** This routine is called when a new SQL statement is beginning to
** be parsed.  Initialize the pParse structure as needed.
*/
SQLITE_PRIVATE void sqlite3BeginParse(Parse *pParse, int explainFlag){
  pParse->explain = (u8)explainFlag;
................................................................................
**
*************************************************************************
**
** This file contains functions used to access the internal hash tables
** of user defined functions and collation sequences.
*/

/* #include "sqliteInt.h" */

/*
** Invoke the 'collation needed' callback to request a collation sequence
** in the encoding enc of name zName, length nName.
*/
static void callCollNeeded(sqlite3 *db, int enc, const char *zName){
  assert( !db->xCollNeeded || !db->xCollNeeded16 );
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** in order to generate code for DELETE FROM statements.
*/
/* #include "sqliteInt.h" */

/*
** While a SrcList can in general represent multiple tables and subqueries
** (as in the FROM clause of a SELECT statement) in this case it contains
** the name of a single table, as one might find in an INSERT, DELETE,
** or UPDATE statement.  Look up that table in the symbol table and
** return a pointer.  Set an error message and return NULL if the table 
................................................................................
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C-language implementations for many of the SQL
** functions of SQLite.  (Some function, and in particular the date and
** time functions, are implemented separately.)
*/
/* #include "sqliteInt.h" */
/* #include <stdlib.h> */
/* #include <assert.h> */
/* #include "vdbeInt.h" */

/*
** Return the collating function associated with a function.
*/
static CollSeq *sqlite3GetFuncCollSeq(sqlite3_context *context){
  VdbeOp *pOp;
  assert( context->pVdbe!=0 );
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used by the compiler to add foreign key
** support to compiled SQL statements.
*/
/* #include "sqliteInt.h" */

#ifndef SQLITE_OMIT_FOREIGN_KEY
#ifndef SQLITE_OMIT_TRIGGER

/*
** Deferred and Immediate FKs
** --------------------------
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle INSERT statements in SQLite.
*/
/* #include "sqliteInt.h" */

/*
** Generate code that will 
**
**   (1) acquire a lock for table pTab then
**   (2) open pTab as cursor iCur.
**
................................................................................
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
*/

/* #include "sqliteInt.h" */

/*
** Execute SQL code.  Return one of the SQLITE_ success/failure
** codes.  Also write an error message into memory obtained from
** malloc() and make *pzErrMsg point to that message.
**
** If the SQL is a query, then for each row in the query result
................................................................................
** shared libraries that want to be imported as extensions into
** an SQLite instance.  Shared libraries that intend to be loaded
** as extensions by SQLite should #include this file instead of 
** sqlite3.h.
*/
#ifndef _SQLITE3EXT_H_
#define _SQLITE3EXT_H_
/* #include "sqlite3.h" */

typedef struct sqlite3_api_routines sqlite3_api_routines;

/*
** The following structure holds pointers to all of the SQLite API
** routines.
**
................................................................................
# define SQLITE_EXTENSION_INIT3     /*no-op*/
#endif

#endif /* _SQLITE3EXT_H_ */

/************** End of sqlite3ext.h ******************************************/
/************** Continuing where we left off in loadext.c ********************/
/* #include "sqliteInt.h" */
/* #include <string.h> */

#ifndef SQLITE_OMIT_LOAD_EXTENSION

/*
** Some API routines are omitted when various features are
** excluded from a build of SQLite.  Substitute a NULL pointer
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used to implement the PRAGMA command.
*/
/* #include "sqliteInt.h" */

#if !defined(SQLITE_ENABLE_LOCKING_STYLE)
#  if defined(__APPLE__)
#    define SQLITE_ENABLE_LOCKING_STYLE 1
#  else
#    define SQLITE_ENABLE_LOCKING_STYLE 0
#  endif
................................................................................
  { /* zName:     */ "busy_timeout",
    /* ePragTyp:  */ PragTyp_BUSY_TIMEOUT,
    /* ePragFlag: */ 0,
    /* iArg:      */ 0 },
#if !defined(SQLITE_OMIT_PAGER_PRAGMAS)
  { /* zName:     */ "cache_size",
    /* ePragTyp:  */ PragTyp_CACHE_SIZE,
    /* ePragFlag: */ 0,
    /* iArg:      */ 0 },
#endif
#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
  { /* zName:     */ "cache_spill",
    /* ePragTyp:  */ PragTyp_FLAG,
    /* ePragFlag: */ 0,
    /* iArg:      */ SQLITE_CacheSpill },
................................................................................
  ** number of pages in the cache.  If N is negative, then the
  ** number of pages is adjusted so that the cache uses -N kibibytes
  ** of memory.
  */
  case PragTyp_CACHE_SIZE: {
    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
    if( !zRight ){
      if( sqlite3ReadSchema(pParse) ) goto pragma_out;
      returnSingleInt(pParse, "cache_size", pDb->pSchema->cache_size);
    }else{
      int size = sqlite3Atoi(zRight);
      pDb->pSchema->cache_size = size;
      sqlite3BtreeSetCacheSize(pDb->pBt, pDb->pSchema->cache_size);
    }
    break;
................................................................................
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the implementation of the sqlite3_prepare()
** interface, and routines that contribute to loading the database schema
** from disk.
*/
/* #include "sqliteInt.h" */

/*
** Fill the InitData structure with an error message that indicates
** that the database is corrupt.
*/
static void corruptSchema(
  InitData *pData,     /* Initialization context */
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
*/
/* #include "sqliteInt.h" */

/*
** Trace output macros
*/
#if SELECTTRACE_ENABLED
/***/ int sqlite3SelectTrace = 0;
# define SELECTTRACE(K,P,S,X)  \
................................................................................
      pInfo->aColl[i-iStart] = pColl;
      pInfo->aSortOrder[i-iStart] = pItem->sortOrder;
    }
  }
  return pInfo;
}


/*
** Name of the connection operator, used for error messages.
*/
static const char *selectOpName(int id){
  char *z;
  switch( id ){
    case TK_ALL:       z = "UNION ALL";   break;
    case TK_INTERSECT: z = "INTERSECT";   break;
    case TK_EXCEPT:    z = "EXCEPT";      break;
    default:           z = "UNION";       break;
  }
  return z;
}


#ifndef SQLITE_OMIT_EXPLAIN
/*
** Unless an "EXPLAIN QUERY PLAN" command is being processed, this function
** is a no-op. Otherwise, it adds a single row of output to the EQP result,
** where the caption is of the form:
**
................................................................................
/* Forward references */
static int multiSelectOrderBy(
  Parse *pParse,        /* Parsing context */
  Select *p,            /* The right-most of SELECTs to be coded */
  SelectDest *pDest     /* What to do with query results */
);














/*
** Handle the special case of a compound-select that originates from a
** VALUES clause.  By handling this as a special case, we avoid deep
** recursion, and thus do not need to enforce the SQLITE_LIMIT_COMPOUND_SELECT
** on a VALUES clause.
**
** Because the Select object originates from a VALUES clause:
................................................................................
multi_select_end:
  pDest->iSdst = dest.iSdst;
  pDest->nSdst = dest.nSdst;
  sqlite3SelectDelete(db, pDelete);
  return rc;
}
#endif /* SQLITE_OMIT_COMPOUND_SELECT */

/*
** Error message for when two or more terms of a compound select have different
** size result sets.
*/
SQLITE_PRIVATE void sqlite3SelectWrongNumTermsError(Parse *pParse, Select *p){
  if( p->selFlags & SF_Values ){
    sqlite3ErrorMsg(pParse, "all VALUES must have the same number of terms");
  }else{
    sqlite3ErrorMsg(pParse, "SELECTs to the left and right of %s"
      " do not have the same number of result columns", selectOpName(p->op));
  }
}

/*
** Code an output subroutine for a coroutine implementation of a
** SELECT statment.
**
** The data to be output is contained in pIn->iSdst.  There are
** pIn->nSdst columns to be output.  pDest is where the output should
................................................................................
** This file contains the sqlite3_get_table() and sqlite3_free_table()
** interface routines.  These are just wrappers around the main
** interface routine of sqlite3_exec().
**
** These routines are in a separate files so that they will not be linked
** if they are not used.
*/
/* #include "sqliteInt.h" */
/* #include <stdlib.h> */
/* #include <string.h> */

#ifndef SQLITE_OMIT_GET_TABLE

/*
** This structure is used to pass data from sqlite3_get_table() through
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the implementation for TRIGGERs
*/
/* #include "sqliteInt.h" */

#ifndef SQLITE_OMIT_TRIGGER
/*
** Delete a linked list of TriggerStep structures.
*/
SQLITE_PRIVATE void sqlite3DeleteTriggerStep(sqlite3 *db, TriggerStep *pTriggerStep){
  while( pTriggerStep ){
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle UPDATE statements.
*/
/* #include "sqliteInt.h" */

#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Forward declaration */
static void updateVirtualTable(
  Parse *pParse,       /* The parsing context */
  SrcList *pSrc,       /* The virtual table to be modified */
  Table *pTab,         /* The virtual table */
................................................................................
**
*************************************************************************
** This file contains code used to implement the VACUUM command.
**
** Most of the code in this file may be omitted by defining the
** SQLITE_OMIT_VACUUM macro.
*/
/* #include "sqliteInt.h" */
/* #include "vdbeInt.h" */

#if !defined(SQLITE_OMIT_VACUUM) && !defined(SQLITE_OMIT_ATTACH)
/*
** Finalize a prepared statement.  If there was an error, store the
** text of the error message in *pzErrMsg.  Return the result code.
*/
static int vacuumFinalize(sqlite3 *db, sqlite3_stmt *pStmt, char **pzErrMsg){
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used to help implement virtual tables.
*/
#ifndef SQLITE_OMIT_VIRTUALTABLE
/* #include "sqliteInt.h" */

/*
** Before a virtual table xCreate() or xConnect() method is invoked, the
** sqlite3.pVtabCtx member variable is set to point to an instance of
** this struct allocated on the stack. It is used by the implementation of 
** the sqlite3_declare_vtab() and sqlite3_vtab_config() APIs, both of which
** are invoked only from within xCreate and xConnect methods.
................................................................................
** the WHERE clause of SQL statements.
**
** This file was split off from where.c on 2015-06-06 in order to reduce the
** size of where.c and make it easier to edit.  This file contains the routines
** that actually generate the bulk of the WHERE loop code.  The original where.c
** file retains the code that does query planning and analysis.
*/
/* #include "sqliteInt.h" */
/************** Include whereInt.h in the middle of wherecode.c **************/
/************** Begin file whereInt.h ****************************************/
/*
** 2013-11-12
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
................................................................................
              int nPk = pPk->nKeyCol;
              int iPk;

              /* Read the PK into an array of temp registers. */
              r = sqlite3GetTempRange(pParse, nPk);
              for(iPk=0; iPk<nPk; iPk++){
                int iCol = pPk->aiColumn[iPk];
                int rx;
                rx = sqlite3ExprCodeGetColumn(pParse, pTab, iCol, iCur,r+iPk,0);
                if( rx!=r+iPk ){
                  sqlite3VdbeAddOp2(v, OP_SCopy, rx, r+iPk);
                }
              }

              /* Check if the temp table already contains this key. If so,
              ** the row has already been included in the result set and
              ** can be ignored (by jumping past the Gosub below). Otherwise,
              ** insert the key into the temp table and proceed with processing
              ** the row.
................................................................................
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.
**
** This file was originally part of where.c but was split out to improve
** readability and editabiliity.  This file contains utility routines for
** analyzing Expr objects in the WHERE clause.
*/
/* #include "sqliteInt.h" */
/* #include "whereInt.h" */

/* Forward declarations */
static void exprAnalyze(SrcList*, WhereClause*, int);

/*
** Deallocate all memory associated with a WhereOrInfo object.
*/
................................................................................
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.  This module is responsible for
** generating the code that loops through a table looking for applicable
** rows.  Indices are selected and used to speed the search when doing
** so is applicable.  Because this module is responsible for selecting
** indices, you might also think of this module as the "query optimizer".
*/
/* #include "sqliteInt.h" */
/* #include "whereInt.h" */

/* Forward declaration of methods */
static int whereLoopResize(sqlite3*, WhereLoop*, int);

/* Test variable that can be set to enable WHERE tracing */
#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
/***/ int sqlite3WhereTrace = 0;
................................................................................
** LALR(1) grammar but which are always false in the
** specific grammar used by SQLite.
*/
/* First off, code is included that follows the "include" declaration
** in the input grammar file. */
/* #include <stdio.h> */

/* #include "sqliteInt.h" */

/*
** Disable all error recovery processing in the parser push-down
** automaton.
*/
#define YYNOERRORRECOVERY 1

................................................................................
*************************************************************************
** An tokenizer for SQL
**
** This file contains C code that splits an SQL input string up into
** individual tokens and sends those tokens one-by-one over to the
** parser for analysis.
*/
/* #include "sqliteInt.h" */
/* #include <stdlib.h> */

/*
** The charMap() macro maps alphabetic characters into their
** lower-case ASCII equivalent.  On ASCII machines, this is just
** an upper-to-lower case map.  On EBCDIC machines we also need
** to adjust the encoding.  Only alphabetic characters and underscores
................................................................................
** An tokenizer for SQL
**
** This file contains C code that implements the sqlite3_complete() API.
** This code used to be part of the tokenizer.c source file.  But by
** separating it out, the code will be automatically omitted from
** static links that do not use it.
*/
/* #include "sqliteInt.h" */
#ifndef SQLITE_OMIT_COMPLETE

/*
** This is defined in tokenize.c.  We just have to import the definition.
*/
#ifndef SQLITE_AMALGAMATION
#ifdef SQLITE_ASCII
................................................................................
**
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
*/
/* #include "sqliteInt.h" */

#ifdef SQLITE_ENABLE_FTS3
/************** Include fts3.h in the middle of main.c ***********************/
/************** Begin file fts3.h ********************************************/
/*
** 2006 Oct 10
**
................................................................................
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This header file is used by programs that want to link against the
** FTS3 library.  All it does is declare the sqlite3Fts3Init() interface.
*/
/* #include "sqlite3.h" */

#if 0
extern "C" {
#endif  /* __cplusplus */

SQLITE_PRIVATE int sqlite3Fts3Init(sqlite3 *db);

................................................................................
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This header file is used by programs that want to link against the
** RTREE library.  All it does is declare the sqlite3RtreeInit() interface.
*/
/* #include "sqlite3.h" */

#if 0
extern "C" {
#endif  /* __cplusplus */

SQLITE_PRIVATE int sqlite3RtreeInit(sqlite3 *db);

................................................................................
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This header file is used by programs that want to link against the
** ICU extension.  All it does is declare the sqlite3IcuInit() interface.
*/
/* #include "sqlite3.h" */

#if 0
extern "C" {
#endif  /* __cplusplus */

SQLITE_PRIVATE int sqlite3IcuInit(sqlite3 *db);

................................................................................
** The sz parameter is the number of bytes in each lookaside slot.
** The cnt parameter is the number of slots.  If pStart is NULL the
** space for the lookaside memory is obtained from sqlite3_malloc().
** If pStart is not NULL then it is sz*cnt bytes of memory to use for
** the lookaside memory.
*/
static int setupLookaside(sqlite3 *db, void *pBuf, int sz, int cnt){
#ifndef SQLITE_OMIT_LOOKASIDE
  void *pStart;
  if( db->lookaside.nOut ){
    return SQLITE_BUSY;
  }
  /* Free any existing lookaside buffer for this handle before
  ** allocating a new one so we don't have to have space for 
  ** both at the same time.
................................................................................
    db->lookaside.bMalloced = pBuf==0 ?1:0;
  }else{
    db->lookaside.pStart = db;
    db->lookaside.pEnd = db;
    db->lookaside.bEnabled = 0;
    db->lookaside.bMalloced = 0;
  }
#endif /* SQLITE_OMIT_LOOKASIDE */
  return SQLITE_OK;
}

/*
** Return the mutex associated with a database connection.
*/
SQLITE_API sqlite3_mutex *SQLITE_STDCALL sqlite3_db_mutex(sqlite3 *db){
................................................................................
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains the implementation of the sqlite3_unlock_notify()
** API method and its associated functionality.
*/
/* #include "sqliteInt.h" */
/* #include "btreeInt.h" */

/* Omit this entire file if SQLITE_ENABLE_UNLOCK_NOTIFY is not defined. */
#ifdef SQLITE_ENABLE_UNLOCK_NOTIFY

/*
** Public interfaces:
**
................................................................................
# define SQLITE_ENABLE_FTS3
#endif

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* If not building as part of the core, include sqlite3ext.h. */
#ifndef SQLITE_CORE
/* # include "sqlite3ext.h"  */
SQLITE_EXTENSION_INIT3
#endif

/* #include "sqlite3.h" */
/************** Include fts3_tokenizer.h in the middle of fts3Int.h **********/
/************** Begin file fts3_tokenizer.h **********************************/
/*
** 2006 July 10
**
** The author disclaims copyright to this source code.
**
................................................................................
#ifndef _FTS3_TOKENIZER_H_
#define _FTS3_TOKENIZER_H_

/* TODO(shess) Only used for SQLITE_OK and SQLITE_DONE at this time.
** If tokenizers are to be allowed to call sqlite3_*() functions, then
** we will need a way to register the API consistently.
*/
/* #include "sqlite3.h" */

/*
** Structures used by the tokenizer interface. When a new tokenizer
** implementation is registered, the caller provides a pointer to
** an sqlite3_tokenizer_module containing pointers to the callback
** functions that make up an implementation.
**
................................................................................
/* #include <assert.h> */
/* #include <stdlib.h> */
/* #include <stddef.h> */
/* #include <stdio.h> */
/* #include <string.h> */
/* #include <stdarg.h> */

/* #include "fts3.h" */
#ifndef SQLITE_CORE 
/* # include "sqlite3ext.h" */
  SQLITE_EXTENSION_INIT1
#endif

static int fts3EvalNext(Fts3Cursor *pCsr);
static int fts3EvalStart(Fts3Cursor *pCsr);
static int fts3TermSegReaderCursor(
    Fts3Cursor *, const char *, int, int, Fts3MultiSegReader **);
................................................................................
  assert( !p || (p>=aDoclist && p<=&aDoclist[nDoclist]) );

  if( p==0 ){
    p = aDoclist;
    p += sqlite3Fts3GetVarint(p, piDocid);
  }else{
    fts3PoslistCopy(0, &p);
    while( p<&aDoclist[nDoclist] && *p==0 ) p++; 
    if( p>=&aDoclist[nDoclist] ){
      *pbEof = 1;
    }else{
      sqlite3_int64 iVar;
      p += sqlite3Fts3GetVarint(p, &iVar);
      *piDocid += ((bDescIdx ? -1 : 1) * iVar);
    }
................................................................................

  iDocid = pExpr->iDocid;
  pIter = pPhrase->doclist.pList;
  if( iDocid!=pCsr->iPrevId || pExpr->bEof ){
    int rc = SQLITE_OK;
    int bDescDoclist = pTab->bDescIdx;      /* For DOCID_CMP macro */
    int bOr = 0;

    u8 bTreeEof = 0;
    Fts3Expr *p;                  /* Used to iterate from pExpr to root */
    Fts3Expr *pNear;              /* Most senior NEAR ancestor (or pExpr) */
    int bMatch;

    /* Check if this phrase descends from an OR expression node. If not, 
    ** return NULL. Otherwise, the entry that corresponds to docid 
    ** pCsr->iPrevId may lie earlier in the doclist buffer. Or, if the
    ** tree that the node is part of has been marked as EOF, but the node
    ** itself is not EOF, then it may point to an earlier entry. */
    pNear = pExpr;
................................................................................
    if( bTreeEof ){
      while( rc==SQLITE_OK && !pNear->bEof ){
        fts3EvalNextRow(pCsr, pNear, &rc);
      }
    }
    if( rc!=SQLITE_OK ) return rc;

    bMatch = 1;
    for(p=pNear; p; p=p->pLeft){
      u8 bEof = 0;
      Fts3Expr *pTest = p;
      Fts3Phrase *pPh;
      assert( pTest->eType==FTSQUERY_NEAR || pTest->eType==FTSQUERY_PHRASE );
      if( pTest->eType==FTSQUERY_NEAR ) pTest = pTest->pRight;
      assert( pTest->eType==FTSQUERY_PHRASE );
      pPh = pTest->pPhrase;

      pIter = pPh->pOrPoslist;
      iDocid = pPh->iOrDocid;
      if( pCsr->bDesc==bDescDoclist ){
        bEof = !pPh->doclist.nAll ||
          (pIter >= (pPh->doclist.aAll + pPh->doclist.nAll));
        while( (pIter==0 || DOCID_CMP(iDocid, pCsr->iPrevId)<0 ) && bEof==0 ){
          sqlite3Fts3DoclistNext(

              bDescDoclist, pPh->doclist.aAll, pPh->doclist.nAll, 
              &pIter, &iDocid, &bEof
          );
        }
      }else{
        bEof = !pPh->doclist.nAll || (pIter && pIter<=pPh->doclist.aAll);
        while( (pIter==0 || DOCID_CMP(iDocid, pCsr->iPrevId)>0 ) && bEof==0 ){
          int dummy;
          sqlite3Fts3DoclistPrev(

              bDescDoclist, pPh->doclist.aAll, pPh->doclist.nAll, 
              &pIter, &iDocid, &dummy, &bEof
              );
        }
      }
      pPh->pOrPoslist = pIter;
      pPh->iOrDocid = iDocid;
      if( bEof || iDocid!=pCsr->iPrevId ) bMatch = 0;
    }


    if( bMatch ){
      pIter = pPhrase->pOrPoslist;
    }else{
      pIter = 0;
    }
  }
  if( pIter==0 ) return SQLITE_OK;

  if( *pIter==0x01 ){
    pIter++;
    pIter += fts3GetVarint32(pIter, &iThis);
  }else{
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
*/
/* #include "fts3Int.h" */
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* #include <string.h> */
/* #include <assert.h> */

typedef struct Fts3auxTable Fts3auxTable;
typedef struct Fts3auxCursor Fts3auxCursor;
................................................................................
******************************************************************************
**
** This module contains code that implements a parser for fts3 query strings
** (the right-hand argument to the MATCH operator). Because the supported 
** syntax is relatively simple, the whole tokenizer/parser system is
** hand-coded. 
*/
/* #include "fts3Int.h" */
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/*
** By default, this module parses the legacy syntax that has been 
** traditionally used by fts3. Or, if SQLITE_ENABLE_FTS3_PARENTHESIS
** is defined, then it uses the new syntax. The differences between
** the new and the old syntaxes are:
................................................................................
**
**     * The FTS3 module is being built as an extension
**       (in which case SQLITE_CORE is not defined), or
**
**     * The FTS3 module is being built into the core of
**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
*/
/* #include "fts3Int.h" */
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* #include <assert.h> */
/* #include <stdlib.h> */
/* #include <string.h> */

/* #include "fts3_hash.h" */

/*
** Malloc and Free functions
*/
static void *fts3HashMalloc(int n){
  void *p = sqlite3_malloc(n);
  if( p ){
................................................................................
**
**     * The FTS3 module is being built as an extension
**       (in which case SQLITE_CORE is not defined), or
**
**     * The FTS3 module is being built into the core of
**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
*/
/* #include "fts3Int.h" */
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* #include <assert.h> */
/* #include <stdlib.h> */
/* #include <stdio.h> */
/* #include <string.h> */

/* #include "fts3_tokenizer.h" */

/*
** Class derived from sqlite3_tokenizer
*/
typedef struct porter_tokenizer {
  sqlite3_tokenizer base;      /* Base class */
} porter_tokenizer;
................................................................................
**
**     * The FTS3 module is being built as an extension
**       (in which case SQLITE_CORE is not defined), or
**
**     * The FTS3 module is being built into the core of
**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
*/
/* #include "fts3Int.h" */
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* #include <assert.h> */
/* #include <string.h> */

/*
** Implementation of the SQL scalar function for accessing the underlying 
................................................................................
**
**     * The FTS3 module is being built as an extension
**       (in which case SQLITE_CORE is not defined), or
**
**     * The FTS3 module is being built into the core of
**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
*/
/* #include "fts3Int.h" */
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* #include <assert.h> */
/* #include <stdlib.h> */
/* #include <stdio.h> */
/* #include <string.h> */

/* #include "fts3_tokenizer.h" */

typedef struct simple_tokenizer {
  sqlite3_tokenizer base;
  char delim[128];             /* flag ASCII delimiters */
} simple_tokenizer;

typedef struct simple_tokenizer_cursor {
................................................................................
**   token:   A token from the input.
**   start:   Byte offset of the token within the input <string>.
**   end:     Byte offset of the byte immediately following the end of the
**            token within the input string.
**   pos:     Token offset of token within input.
**
*/
/* #include "fts3Int.h" */
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* #include <string.h> */
/* #include <assert.h> */

typedef struct Fts3tokTable Fts3tokTable;
typedef struct Fts3tokCursor Fts3tokCursor;
................................................................................
** This file is part of the SQLite FTS3 extension module. Specifically,
** this file contains code to insert, update and delete rows from FTS3
** tables. It also contains code to merge FTS3 b-tree segments. Some
** of the sub-routines used to merge segments are also used by the query 
** code in fts3.c.
*/

/* #include "fts3Int.h" */
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* #include <string.h> */
/* #include <assert.h> */
/* #include <stdlib.h> */


................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
*/

/* #include "fts3Int.h" */
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* #include <string.h> */
/* #include <assert.h> */

/*
** Characters that may appear in the second argument to matchinfo().
................................................................................
******************************************************************************
**
** Implementation of the "unicode" full-text-search tokenizer.
*/

#ifndef SQLITE_DISABLE_FTS3_UNICODE

/* #include "fts3Int.h" */
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

/* #include <assert.h> */
/* #include <stdlib.h> */
/* #include <stdio.h> */
/* #include <string.h> */

/* #include "fts3_tokenizer.h" */

/*
** The following two macros - READ_UTF8 and WRITE_UTF8 - have been copied
** from the sqlite3 source file utf.c. If this file is compiled as part
** of the amalgamation, they are not required.
*/
#ifndef SQLITE_AMALGAMATION
................................................................................
**      of a record. For internal nodes it is the node number of a
**      child page.
*/

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_RTREE)

#ifndef SQLITE_CORE
/*   #include "sqlite3ext.h" */
  SQLITE_EXTENSION_INIT1
#else
/*   #include "sqlite3.h" */
#endif

/* #include <string.h> */
/* #include <assert.h> */
/* #include <stdio.h> */

#ifndef SQLITE_AMALGAMATION
................................................................................
#include <unicode/uregex.h>
#include <unicode/ustring.h>
#include <unicode/ucol.h>

/* #include <assert.h> */

#ifndef SQLITE_CORE
/*   #include "sqlite3ext.h" */
  SQLITE_EXTENSION_INIT1
#else
/*   #include "sqlite3.h" */
#endif

/*
** Maximum length (in bytes) of the pattern in a LIKE or GLOB
** operator.
*/
#ifndef SQLITE_MAX_LIKE_PATTERN_LENGTH
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file implements a tokenizer for fts3 based on the ICU library.
*/
/* #include "fts3Int.h" */
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
#ifdef SQLITE_ENABLE_ICU

/* #include <assert.h> */
/* #include <string.h> */
/* #include "fts3_tokenizer.h" */

#include <unicode/ubrk.h>
/* #include <unicode/ucol.h> */
/* #include <unicode/ustring.h> */
#include <unicode/utf16.h>

typedef struct IcuTokenizer IcuTokenizer;
................................................................................
  *ppModule = &icuTokenizerModule;
}

#endif /* defined(SQLITE_ENABLE_ICU) */
#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */

/************** End of fts3_icu.c ********************************************/
/************** Begin file sqlite3rbu.c **************************************/
/*
** 2014 August 30
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
................................................................................
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
**
** OVERVIEW 
**
**  The RBU extension requires that the RBU update be packaged as an
**  SQLite database. The tables it expects to find are described in
**  sqlite3rbu.h.  Essentially, for each table xyz in the target database
**  that the user wishes to write to, a corresponding data_xyz table is
**  created in the RBU database and populated with one row for each row to
**  update, insert or delete from the target table.
** 
**  The update proceeds in three stages:
** 
**  1) The database is updated. The modified database pages are written
**     to a *-oal file. A *-oal file is just like a *-wal file, except
**     that it is named "<database>-oal" instead of "<database>-wal".
**     Because regular SQLite clients do not look for file named
**     "<database>-oal", they go on using the original database in
**     rollback mode while the *-oal file is being generated.
** 
**     During this stage RBU does not update the database by writing
**     directly to the target tables. Instead it creates "imposter"
**     tables using the SQLITE_TESTCTRL_IMPOSTER interface that it uses
**     to update each b-tree individually. All updates required by each
**     b-tree are completed before moving on to the next, and all
**     updates are done in sorted key order.
** 
**  2) The "<database>-oal" file is moved to the equivalent "<database>-wal"
**     location using a call to rename(2). Before doing this the RBU
**     module takes an EXCLUSIVE lock on the database file, ensuring
**     that there are no other active readers.
** 
**     Once the EXCLUSIVE lock is released, any other database readers
**     detect the new *-wal file and read the database in wal mode. At
**     this point they see the new version of the database - including
**     the updates made as part of the RBU update.
** 
**  3) The new *-wal file is checkpointed. This proceeds in the same way 
**     as a regular database checkpoint, except that a single frame is
**     checkpointed each time sqlite3rbu_step() is called. If the RBU
**     handle is closed before the entire *-wal file is checkpointed,
**     the checkpoint progress is saved in the RBU database and the
**     checkpoint can be resumed by another RBU client at some point in
**     the future.
**
** POTENTIAL PROBLEMS
** 
**  The rename() call might not be portable. And RBU is not currently
**  syncing the directory after renaming the file.
**
**  When state is saved, any commit to the *-oal file and the commit to
**  the RBU update database are not atomic. So if the power fails at the
**  wrong moment they might get out of sync. As the main database will be
**  committed before the RBU update database this will likely either just
**  pass unnoticed, or result in SQLITE_CONSTRAINT errors (due to UNIQUE
**  constraint violations).
**
**  If some client does modify the target database mid RBU update, or some
**  other error occurs, the RBU extension will keep throwing errors. It's
**  not really clear how to get out of this state. The system could just
**  by delete the RBU update database and *-oal file and have the device
**  download the update again and start over.
**
**  At present, for an UPDATE, both the new.* and old.* records are
**  collected in the rbu_xyz table. And for both UPDATEs and DELETEs all
**  fields are collected.  This means we're probably writing a lot more
**  data to disk when saving the state of an ongoing update to the RBU
**  update database than is strictly necessary.
** 
*/

/* #include <assert.h> */
/* #include <string.h> */
/* #include <stdio.h> */
/* #include <unistd.h> */

/* #include "sqlite3.h" */

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_RBU)
/************** Include sqlite3rbu.h in the middle of sqlite3rbu.c ***********/
/************** Begin file sqlite3rbu.h **************************************/
/*
** 2014 August 30
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains the public interface for the RBU extension. 
*/

/*
** SUMMARY
**
** Writing a transaction containing a large number of operations on 
** b-tree indexes that are collectively larger than the available cache
................................................................................
** guarantee that a single update process will run for long enough to apply 
** the entire update, for example because the update is being applied on a 
** mobile device that is frequently rebooted. Even after the writer process 
** has committed one or more sub-transactions, other database clients continue
** to read from the original database snapshot. In other words, partially 
** applied transactions are not visible to other clients. 
**
** "RBU" stands for "Over The Air" update. As in a large database update
** transmitted via a wireless network to a mobile device. A transaction
** applied using this extension is hence refered to as an "RBU update".
**
**
** LIMITATIONS
**
** An "RBU update" transaction is subject to the following limitations:
**
**   * The transaction must consist of INSERT, UPDATE and DELETE operations
**     only.
**
**   * INSERT statements may not use any default values.
**
**   * UPDATE and DELETE statements must identify their target rows by 
................................................................................
**   * CHECK constraints are not enforced.
**
**   * No constraint handling mode except for "OR ROLLBACK" is supported.
**
**
** PREPARATION
**
** An "RBU update" is stored as a separate SQLite database. A database
** containing an RBU update is an "RBU database". For each table in the 
** target database to be updated, the RBU database should contain a table
** named "data_<target name>" containing the same set of columns as the
** target table, and one more - "rbu_control". The data_% table should 
** have no PRIMARY KEY or UNIQUE constraints, but each column should have
** the same type as the corresponding column in the target database.
** The "rbu_control" column should have no type at all. For example, if
** the target database contains:
**
**   CREATE TABLE t1(a INTEGER PRIMARY KEY, b TEXT, c UNIQUE);
**
** Then the RBU database should contain:
**
**   CREATE TABLE data_t1(a INTEGER, b TEXT, c, rbu_control);
**
** The order of the columns in the data_% table does not matter.
**
** If the target database table is a virtual table or a table that has no
** PRIMARY KEY declaration, the data_% table must also contain a column 
** named "rbu_rowid". This column is mapped to the tables implicit primary 
** key column - "rowid". Virtual tables for which the "rowid" column does 
** not function like a primary key value cannot be updated using RBU. For 
** example, if the target db contains either of the following:
**
**   CREATE VIRTUAL TABLE x1 USING fts3(a, b);
**   CREATE TABLE x1(a, b)
**
** then the RBU database should contain:
**
**   CREATE TABLE data_x1(a, b, rbu_rowid, rbu_control);
**
** All non-hidden columns (i.e. all columns matched by "SELECT *") of the
** target table must be present in the input table. For virtual tables,
** hidden columns are optional - they are updated by RBU if present in
** the input table, or not otherwise. For example, to write to an fts4
** table with a hidden languageid column such as:
**
**   CREATE VIRTUAL TABLE ft1 USING fts4(a, b, languageid='langid');
**
** Either of the following input table schemas may be used:
**
**   CREATE TABLE data_ft1(a, b, langid, rbu_rowid, rbu_control);
**   CREATE TABLE data_ft1(a, b, rbu_rowid, rbu_control);
**
** For each row to INSERT into the target database as part of the RBU 
** update, the corresponding data_% table should contain a single record
** with the "rbu_control" column set to contain integer value 0. The
** other columns should be set to the values that make up the new record 
** to insert. 
**
** If the target database table has an INTEGER PRIMARY KEY, it is not 
** possible to insert a NULL value into the IPK column. Attempting to 
** do so results in an SQLITE_MISMATCH error.
**
** For each row to DELETE from the target database as part of the RBU 
** update, the corresponding data_% table should contain a single record
** with the "rbu_control" column set to contain integer value 1. The
** real primary key values of the row to delete should be stored in the
** corresponding columns of the data_% table. The values stored in the
** other columns are not used.
**
** For each row to UPDATE from the target database as part of the RBU 
** update, the corresponding data_% table should contain a single record
** with the "rbu_control" column set to contain a value of type text.
** The real primary key values identifying the row to update should be 
** stored in the corresponding columns of the data_% table row, as should
** the new values of all columns being update. The text value in the 
** "rbu_control" column must contain the same number of characters as
** there are columns in the target database table, and must consist entirely
** of 'x' and '.' characters (or in some special cases 'd' - see below). For 
** each column that is being updated, the corresponding character is set to
** 'x'. For those that remain as they are, the corresponding character of the
** rbu_control value should be set to '.'. For example, given the tables 
** above, the update statement:
**
**   UPDATE t1 SET c = 'usa' WHERE a = 4;
**
** is represented by the data_t1 row created by:
**
**   INSERT INTO data_t1(a, b, c, rbu_control) VALUES(4, NULL, 'usa', '..x');
**
** Instead of an 'x' character, characters of the rbu_control value specified
** for UPDATEs may also be set to 'd'. In this case, instead of updating the
** target table with the value stored in the corresponding data_% column, the
** user-defined SQL function "rbu_delta()" is invoked and the result stored in
** the target table column. rbu_delta() is invoked with two arguments - the
** original value currently stored in the target table column and the 
** value specified in the data_xxx table.
**
** For example, this row:
**
**   INSERT INTO data_t1(a, b, c, rbu_control) VALUES(4, NULL, 'usa', '..d');
**
** is similar to an UPDATE statement such as: 
**
**   UPDATE t1 SET c = rbu_delta(c, 'usa') WHERE a = 4;
**
** If the target database table is a virtual table or a table with no PRIMARY
** KEY, the rbu_control value should not include a character corresponding 
** to the rbu_rowid value. For example, this:
**
**   INSERT INTO data_ft1(a, b, rbu_rowid, rbu_control) 
**       VALUES(NULL, 'usa', 12, '.x');
**
** causes a result similar to:
**
**   UPDATE ft1 SET b = 'usa' WHERE rowid = 12;
**
** The data_xxx tables themselves should have no PRIMARY KEY declarations.
** However, RBU is more efficient if reading the rows in from each data_xxx
** table in "rowid" order is roughly the same as reading them sorted by
** the PRIMARY KEY of the corresponding target database table. In other 
** words, rows should be sorted using the destination table PRIMARY KEY 
** fields before they are inserted into the data_xxx tables.
**
** USAGE
**
** The API declared below allows an application to apply an RBU update 
** stored on disk to an existing target database. Essentially, the 
** application:
**
**     1) Opens an RBU handle using the sqlite3rbu_open() function.
**
**     2) Registers any required virtual table modules with the database
**        handle returned by sqlite3rbu_db(). Also, if required, register
**        the rbu_delta() implementation.
**
**     3) Calls the sqlite3rbu_step() function one or more times on
**        the new handle. Each call to sqlite3rbu_step() performs a single
**        b-tree operation, so thousands of calls may be required to apply 
**        a complete update.
**
**     4) Calls sqlite3rbu_close() to close the RBU update handle. If
**        sqlite3rbu_step() has been called enough times to completely
**        apply the update to the target database, then the RBU database
**        is marked as fully applied. Otherwise, the state of the RBU 
**        update application is saved in the RBU database for later 
**        resumption.
**
** See comments below for more detail on APIs.
**
** If an update is only partially applied to the target database by the
** time sqlite3rbu_close() is called, various state information is saved 
** within the RBU database. This allows subsequent processes to automatically
** resume the RBU update from where it left off.
**
** To remove all RBU extension state information, returning an RBU database 
** to its original contents, it is sufficient to drop all tables that begin
** with the prefix "rbu_"
**
** DATABASE LOCKING
**
** An RBU update may not be applied to a database in WAL mode. Attempting
** to do so is an error (SQLITE_ERROR).
**
** While an RBU handle is open, a SHARED lock may be held on the target
** database file. This means it is possible for other clients to read the
** database, but not to write it.
**
** If an RBU update is started and then suspended before it is completed,
** then an external client writes to the database, then attempting to resume
** the suspended RBU update is also an error (SQLITE_BUSY).
*/

#ifndef _SQLITE3RBU_H
#define _SQLITE3RBU_H

/* #include "sqlite3.h"              ** Required for error code definitions ** */

typedef struct sqlite3rbu sqlite3rbu;

/*
** Open an RBU handle.
**
** Argument zTarget is the path to the target database. Argument zRbu is
** the path to the RBU database. Each call to this function must be matched
** by a call to sqlite3rbu_close(). When opening the databases, RBU passes
** the SQLITE_CONFIG_URI flag to sqlite3_open_v2(). So if either zTarget
** or zRbu begin with "file:", it will be interpreted as an SQLite 
** database URI, not a regular file name.
**
** If the zState argument is passed a NULL value, the RBU extension stores 
** the current state of the update (how many rows have been updated, which 
** indexes are yet to be updated etc.) within the RBU database itself. This
** can be convenient, as it means that the RBU application does not need to
** organize removing a separate state file after the update is concluded. 
** Or, if zState is non-NULL, it must be a path to a database file in which 
** the RBU extension can store the state of the update.
**
** When resuming an RBU update, the zState argument must be passed the same
** value as when the RBU update was started.
**
** Once the RBU update is finished, the RBU extension does not 
** automatically remove any zState database file, even if it created it.
**
** By default, RBU uses the default VFS to access the files on disk. To
** use a VFS other than the default, an SQLite "file:" URI containing a
** "vfs=..." option may be passed as the zTarget option.
**
** IMPORTANT NOTE FOR ZIPVFS USERS: The RBU extension works with all of
** SQLite's built-in VFSs, including the multiplexor VFS. However it does
** not work out of the box with zipvfs. Refer to the comment describing
** the zipvfs_create_vfs() API below for details on using RBU with zipvfs.
*/
SQLITE_API sqlite3rbu *SQLITE_STDCALL sqlite3rbu_open(
  const char *zTarget, 
  const char *zRbu,
  const char *zState
);

/*
** Internally, each RBU connection uses a separate SQLite database 
** connection to access the target and rbu update databases. This
** API allows the application direct access to these database handles.
**
** The first argument passed to this function must be a valid, open, RBU
** handle. The second argument should be passed zero to access the target
** database handle, or non-zero to access the rbu update database handle.
** Accessing the underlying database handles may be useful in the
** following scenarios:
**
**   * If any target tables are virtual tables, it may be necessary to
**     call sqlite3_create_module() on the target database handle to 
**     register the required virtual table implementations.
**
**   * If the data_xxx tables in the RBU source database are virtual 
**     tables, the application may need to call sqlite3_create_module() on
**     the rbu update db handle to any required virtual table
**     implementations.
**
**   * If the application uses the "rbu_delta()" feature described above,
**     it must use sqlite3_create_function() or similar to register the
**     rbu_delta() implementation with the target database handle.
**
** If an error has occurred, either while opening or stepping the RBU object,
** this function may return NULL. The error code and message may be collected
** when sqlite3rbu_close() is called.
*/
SQLITE_API sqlite3 *SQLITE_STDCALL sqlite3rbu_db(sqlite3rbu*, int bRbu);

/*
** Do some work towards applying the RBU update to the target db. 
**
** Return SQLITE_DONE if the update has been completely applied, or 
** SQLITE_OK if no error occurs but there remains work to do to apply
** the RBU update. If an error does occur, some other error code is 
** returned. 
**
** Once a call to sqlite3rbu_step() has returned a value other than
** SQLITE_OK, all subsequent calls on the same RBU handle are no-ops
** that immediately return the same value.
*/
SQLITE_API int SQLITE_STDCALL sqlite3rbu_step(sqlite3rbu *pRbu);

/*
** Close an RBU handle. 
**
** If the RBU update has been completely applied, mark the RBU database
** as fully applied. Otherwise, assuming no error has occurred, save the
** current state of the RBU update appliation to the RBU database.
**
** If an error has already occurred as part of an sqlite3rbu_step()
** or sqlite3rbu_open() call, or if one occurs within this function, an
** SQLite error code is returned. Additionally, *pzErrmsg may be set to
** point to a buffer containing a utf-8 formatted English language error
** message. It is the responsibility of the caller to eventually free any 
** such buffer using sqlite3_free().
**
** Otherwise, if no error occurs, this function returns SQLITE_OK if the
** update has been partially applied, or SQLITE_DONE if it has been 
** completely applied.
*/
SQLITE_API int SQLITE_STDCALL sqlite3rbu_close(sqlite3rbu *pRbu, char **pzErrmsg);

/*
** Return the total number of key-value operations (inserts, deletes or 
** updates) that have been performed on the target database since the
** current RBU update was started.
*/
SQLITE_API sqlite3_int64 SQLITE_STDCALL sqlite3rbu_progress(sqlite3rbu *pRbu);

/*
** Create an RBU VFS named zName that accesses the underlying file-system
** via existing VFS zParent. Or, if the zParent parameter is passed NULL, 
** then the new RBU VFS uses the default system VFS to access the file-system.
** The new object is registered as a non-default VFS with SQLite before 
** returning.
**
** Part of the RBU implementation uses a custom VFS object. Usually, this
** object is created and deleted automatically by RBU. 
**
** The exception is for applications that also use zipvfs. In this case,
** the custom VFS must be explicitly created by the user before the RBU
** handle is opened. The RBU VFS should be installed so that the zipvfs
** VFS uses the RBU VFS, which in turn uses any other VFS layers in use 
** (for example multiplexor) to access the file-system. For example,
** to assemble an RBU enabled VFS stack that uses both zipvfs and 
** multiplexor (error checking omitted):
**
**     // Create a VFS named "multiplex" (not the default).
**     sqlite3_multiplex_initialize(0, 0);
**
**     // Create an rbu VFS named "rbu" that uses multiplexor. If the
**     // second argument were replaced with NULL, the "rbu" VFS would
**     // access the file-system via the system default VFS, bypassing the
**     // multiplexor.
**     sqlite3rbu_create_vfs("rbu", "multiplex");
**
**     // Create a zipvfs VFS named "zipvfs" that uses rbu.
**     zipvfs_create_vfs_v3("zipvfs", "rbu", 0, xCompressorAlgorithmDetector);
**
**     // Make zipvfs the default VFS.
**     sqlite3_vfs_register(sqlite3_vfs_find("zipvfs"), 1);
**
** Because the default VFS created above includes a RBU functionality, it
** may be used by RBU clients. Attempting to use RBU with a zipvfs VFS stack
** that does not include the RBU layer results in an error.
**
** The overhead of adding the "rbu" VFS to the system is negligible for 
** non-RBU users. There is no harm in an application accessing the 
** file-system via "rbu" all the time, even if it only uses RBU functionality 
** occasionally.
*/
SQLITE_API int SQLITE_STDCALL sqlite3rbu_create_vfs(const char *zName, const char *zParent);

/*
** Deregister and destroy an RBU vfs created by an earlier call to
** sqlite3rbu_create_vfs().
**
** VFS objects are not reference counted. If a VFS object is destroyed
** before all database handles that use it have been closed, the results
** are undefined.
*/
SQLITE_API void SQLITE_STDCALL sqlite3rbu_destroy_vfs(const char *zName);

#endif /* _SQLITE3RBU_H */


/************** End of sqlite3rbu.h ******************************************/
/************** Continuing where we left off in sqlite3rbu.c *****************/

/* Maximum number of prepared UPDATE statements held by this module */
#define SQLITE_RBU_UPDATE_CACHESIZE 16

/*
** Swap two objects of type TYPE.
*/
#if !defined(SQLITE_AMALGAMATION)
# define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;}
#endif

/*
** The rbu_state table is used to save the state of a partially applied
** update so that it can be resumed later. The table consists of integer
** keys mapped to values as follows:
**
** RBU_STATE_STAGE:
**   May be set to integer values 1, 2, 4 or 5. As follows:
**       1: the *-rbu file is currently under construction.
**       2: the *-rbu file has been constructed, but not yet moved 
**          to the *-wal path.
**       4: the checkpoint is underway.
**       5: the rbu update has been checkpointed.
**
** RBU_STATE_TBL:
**   Only valid if STAGE==1. The target database name of the table 
**   currently being written.
**
** RBU_STATE_IDX:
**   Only valid if STAGE==1. The target database name of the index 
**   currently being written, or NULL if the main table is currently being
**   updated.
**
** RBU_STATE_ROW:
**   Only valid if STAGE==1. Number of rows already processed for the current
**   table/index.
**
** RBU_STATE_PROGRESS:
**   Trbul number of sqlite3rbu_step() calls made so far as part of this
**   rbu update.
**
** RBU_STATE_CKPT:
**   Valid if STAGE==4. The 64-bit checksum associated with the wal-index
**   header created by recovering the *-wal file. This is used to detect
**   cases when another client appends frames to the *-wal file in the
**   middle of an incremental checkpoint (an incremental checkpoint cannot
**   be continued if this happens).
**
** RBU_STATE_COOKIE:
**   Valid if STAGE==1. The current change-counter cookie value in the 
**   target db file.
**
** RBU_STATE_OALSZ:
**   Valid if STAGE==1. The size in bytes of the *-oal file.
*/
#define RBU_STATE_STAGE       1
#define RBU_STATE_TBL         2
#define RBU_STATE_IDX         3
#define RBU_STATE_ROW         4
#define RBU_STATE_PROGRESS    5
#define RBU_STATE_CKPT        6
#define RBU_STATE_COOKIE      7
#define RBU_STATE_OALSZ       8

#define RBU_STAGE_OAL         1
#define RBU_STAGE_MOVE        2
#define RBU_STAGE_CAPTURE     3
#define RBU_STAGE_CKPT        4
#define RBU_STAGE_DONE        5


#define RBU_CREATE_STATE \
  "CREATE TABLE IF NOT EXISTS %s.rbu_state(k INTEGER PRIMARY KEY, v)"

typedef struct RbuFrame RbuFrame;
typedef struct RbuObjIter RbuObjIter;
typedef struct RbuState RbuState;
typedef struct rbu_vfs rbu_vfs;
typedef struct rbu_file rbu_file;
typedef struct RbuUpdateStmt RbuUpdateStmt;

#if !defined(SQLITE_AMALGAMATION)
typedef unsigned int u32;
typedef unsigned char u8;
typedef sqlite3_int64 i64;
#endif

................................................................................
** format.
*/
#define WAL_LOCK_WRITE  0
#define WAL_LOCK_CKPT   1
#define WAL_LOCK_READ0  3

/*
** A structure to store values read from the rbu_state table in memory.
*/
struct RbuState {
  int eStage;
  char *zTbl;
  char *zIdx;
  i64 iWalCksum;
  int nRow;
  i64 nProgress;
  u32 iCookie;
  i64 iOalSz;
};

struct RbuUpdateStmt {
  char *zMask;                    /* Copy of update mask used with pUpdate */
  sqlite3_stmt *pUpdate;          /* Last update statement (or NULL) */
  RbuUpdateStmt *pNext;
};

/*
** An iterator of this type is used to iterate through all objects in
** the target database that require updating. For each such table, the
** iterator visits, in order:
**
................................................................................
** abIndexed:
**   If the table has no indexes on it, abIndexed is set to NULL. Otherwise,
**   it points to an array of flags nTblCol elements in size. The flag is
**   set for each column that is either a part of the PK or a part of an
**   index. Or clear otherwise.
**   
*/
struct RbuObjIter {
  sqlite3_stmt *pTblIter;         /* Iterate through tables */
  sqlite3_stmt *pIdxIter;         /* Index iterator */
  int nTblCol;                    /* Size of azTblCol[] array */
  char **azTblCol;                /* Array of unquoted target column names */
  char **azTblType;               /* Array of target column types */
  int *aiSrcOrder;                /* src table col -> target table col */
  u8 *abTblPk;                    /* Array of flags, set on target PK columns */
  u8 *abNotNull;                  /* Array of flags, set on NOT NULL columns */
  u8 *abIndexed;                  /* Array of flags, set on indexed & PK cols */
  int eType;                      /* Table type - an RBU_PK_XXX value */

  /* Output variables. zTbl==0 implies EOF. */
  int bCleanup;                   /* True in "cleanup" state */
  const char *zTbl;               /* Name of target db table */
  const char *zIdx;               /* Name of target db index (or null) */
  int iTnum;                      /* Root page of current object */
  int iPkTnum;                    /* If eType==EXTERNAL, root of PK index */
  int bUnique;                    /* Current index is unique */

  /* Statements created by rbuObjIterPrepareAll() */
  int nCol;                       /* Number of columns in current object */
  sqlite3_stmt *pSelect;          /* Source data */
  sqlite3_stmt *pInsert;          /* Statement for INSERT operations */
  sqlite3_stmt *pDelete;          /* Statement for DELETE ops */
  sqlite3_stmt *pTmpInsert;       /* Insert into rbu_tmp_$zTbl */

  /* Last UPDATE used (for PK b-tree updates only), or NULL. */
  RbuUpdateStmt *pRbuUpdate;
};

/*
** Values for RbuObjIter.eType
**
**     0: Table does not exist (error)
**     1: Table has an implicit rowid.
**     2: Table has an explicit IPK column.
**     3: Table has an external PK index.
**     4: Table is WITHOUT ROWID.
**     5: Table is a virtual table.
*/
#define RBU_PK_NOTABLE        0
#define RBU_PK_NONE           1
#define RBU_PK_IPK            2
#define RBU_PK_EXTERNAL       3
#define RBU_PK_WITHOUT_ROWID  4
#define RBU_PK_VTAB           5


/*
** Within the RBU_STAGE_OAL stage, each call to sqlite3rbu_step() performs
** one of the following operations.
*/
#define RBU_INSERT     1          /* Insert on a main table b-tree */
#define RBU_DELETE     2          /* Delete a row from a main table b-tree */
#define RBU_IDX_DELETE 3          /* Delete a row from an aux. index b-tree */
#define RBU_IDX_INSERT 4          /* Insert on an aux. index b-tree */
#define RBU_UPDATE     5          /* Update a row in a main table b-tree */


/*
** A single step of an incremental checkpoint - frame iWalFrame of the wal
** file should be copied to page iDbPage of the database file.
*/
struct RbuFrame {
  u32 iDbPage;
  u32 iWalFrame;
};

/*
** RBU handle.
*/
struct sqlite3rbu {
  int eStage;                     /* Value of RBU_STATE_STAGE field */
  sqlite3 *dbMain;                /* target database handle */
  sqlite3 *dbRbu;                 /* rbu database handle */
  char *zTarget;                  /* Path to target db */
  char *zRbu;                     /* Path to rbu db */
  char *zState;                   /* Path to state db (or NULL if zRbu) */
  char zStateDb[5];               /* Db name for state ("stat" or "main") */
  int rc;                         /* Value returned by last rbu_step() call */
  char *zErrmsg;                  /* Error message if rc!=SQLITE_OK */
  int nStep;                      /* Rows processed for current object */
  int nProgress;                  /* Rows processed for all objects */
  RbuObjIter objiter;             /* Iterator for skipping through tbl/idx */
  const char *zVfsName;           /* Name of automatically created rbu vfs */
  rbu_file *pTargetFd;            /* File handle open on target db */
  i64 iOalSz;

  /* The following state variables are used as part of the incremental
  ** checkpoint stage (eStage==RBU_STAGE_CKPT). See comments surrounding
  ** function rbuSetupCheckpoint() for details.  */
  u32 iMaxFrame;                  /* Largest iWalFrame value in aFrame[] */
  u32 mLock;
  int nFrame;                     /* Entries in aFrame[] array */
  int nFrameAlloc;                /* Allocated size of aFrame[] array */
  RbuFrame *aFrame;
  int pgsz;
  u8 *aBuf;
  i64 iWalCksum;
};

/*
** An rbu VFS is implemented using an instance of this structure.
*/
struct rbu_vfs {
  sqlite3_vfs base;               /* rbu VFS shim methods */
  sqlite3_vfs *pRealVfs;          /* Underlying VFS */
  sqlite3_mutex *mutex;           /* Mutex to protect pMain */
  rbu_file *pMain;                /* Linked list of main db files */
};

/*
** Each file opened by an rbu VFS is represented by an instance of
** the following structure.
*/
struct rbu_file {
  sqlite3_file base;              /* sqlite3_file methods */
  sqlite3_file *pReal;            /* Underlying file handle */
  rbu_vfs *pRbuVfs;               /* Pointer to the rbu_vfs object */
  sqlite3rbu *pRbu;               /* Pointer to rbu object (rbu target only) */

  int openFlags;                  /* Flags this file was opened with */
  u32 iCookie;                    /* Cookie value for main db files */
  u8 iWriteVer;                   /* "write-version" value for main db files */

  int nShm;                       /* Number of entries in apShm[] array */
  char **apShm;                   /* Array of mmap'd *-shm regions */
  char *zDel;                     /* Delete this when closing file */

  const char *zWal;               /* Wal filename for this main db file */
  rbu_file *pWalFd;               /* Wal file descriptor for this main db */
  rbu_file *pMainNext;            /* Next MAIN_DB file */
};


/*
** Prepare the SQL statement in buffer zSql against database handle db.
** If successful, set *ppStmt to point to the new statement and return
** SQLITE_OK. 
................................................................................
    rc = prepareAndCollectError(db, ppStmt, pzErrmsg, zSql);
    sqlite3_free(zSql);
  }
  return rc;
}

/*
** Free the RbuObjIter.azTblCol[] and RbuObjIter.abTblPk[] arrays allocated
** by an earlier call to rbuObjIterCacheTableInfo().
*/
static void rbuObjIterFreeCols(RbuObjIter *pIter){
  int i;
  for(i=0; i<pIter->nTblCol; i++){
    sqlite3_free(pIter->azTblCol[i]);
    sqlite3_free(pIter->azTblType[i]);
  }
  sqlite3_free(pIter->azTblCol);
  pIter->azTblCol = 0;
................................................................................
  pIter->eType = 0;               /* Invalid value */
}

/*
** Finalize all statements and free all allocations that are specific to
** the current object (table/index pair).
*/
static void rbuObjIterClearStatements(RbuObjIter *pIter){
  RbuUpdateStmt *pUp;

  sqlite3_finalize(pIter->pSelect);
  sqlite3_finalize(pIter->pInsert);
  sqlite3_finalize(pIter->pDelete);
  sqlite3_finalize(pIter->pTmpInsert);
  pUp = pIter->pRbuUpdate;
  while( pUp ){
    RbuUpdateStmt *pTmp = pUp->pNext;
    sqlite3_finalize(pUp->pUpdate);
    sqlite3_free(pUp);
    pUp = pTmp;
  }
  
  pIter->pSelect = 0;
  pIter->pInsert = 0;
  pIter->pDelete = 0;
  pIter->pRbuUpdate = 0;
  pIter->pTmpInsert = 0;
  pIter->nCol = 0;
}

/*
** Clean up any resources allocated as part of the iterator object passed
** as the only argument.
*/
static void rbuObjIterFinalize(RbuObjIter *pIter){
  rbuObjIterClearStatements(pIter);
  sqlite3_finalize(pIter->pTblIter);
  sqlite3_finalize(pIter->pIdxIter);
  rbuObjIterFreeCols(pIter);
  memset(pIter, 0, sizeof(RbuObjIter));
}

/*
** Advance the iterator to the next position.
**
** If no error occurs, SQLITE_OK is returned and the iterator is left 
** pointing to the next entry. Otherwise, an error code and message is 
** left in the RBU handle passed as the first argument. A copy of the 
** error code is returned.
*/
static int rbuObjIterNext(sqlite3rbu *p, RbuObjIter *pIter){
  int rc = p->rc;
  if( rc==SQLITE_OK ){

    /* Free any SQLite statements used while processing the previous object */ 
    rbuObjIterClearStatements(pIter);
    if( pIter->zIdx==0 ){
      rc = sqlite3_exec(p->dbMain,
          "DROP TRIGGER IF EXISTS temp.rbu_insert_tr;"
          "DROP TRIGGER IF EXISTS temp.rbu_update1_tr;"
          "DROP TRIGGER IF EXISTS temp.rbu_update2_tr;"
          "DROP TRIGGER IF EXISTS temp.rbu_delete_tr;"
          , 0, 0, &p->zErrmsg
      );
    }

    if( rc==SQLITE_OK ){
      if( pIter->bCleanup ){
        rbuObjIterFreeCols(pIter);
        pIter->bCleanup = 0;
        rc = sqlite3_step(pIter->pTblIter);
        if( rc!=SQLITE_ROW ){
          rc = resetAndCollectError(pIter->pTblIter, &p->zErrmsg);
          pIter->zTbl = 0;
        }else{
          pIter->zTbl = (const char*)sqlite3_column_text(pIter->pTblIter, 0);
................................................................................
          }
        }
      }
    }
  }

  if( rc!=SQLITE_OK ){
    rbuObjIterFinalize(pIter);
    p->rc = rc;
  }
  return rc;
}

/*
** Initialize the iterator structure passed as the second argument.
**
** If no error occurs, SQLITE_OK is returned and the iterator is left 
** pointing to the first entry. Otherwise, an error code and message is 
** left in the RBU handle passed as the first argument. A copy of the 
** error code is returned.
*/
static int rbuObjIterFirst(sqlite3rbu *p, RbuObjIter *pIter){
  int rc;
  memset(pIter, 0, sizeof(RbuObjIter));

  rc = prepareAndCollectError(p->dbRbu, &pIter->pTblIter, &p->zErrmsg, 
      "SELECT substr(name, 6) FROM sqlite_master "
      "WHERE type='table' AND name LIKE 'data_%'"
  );

  if( rc==SQLITE_OK ){
    rc = prepareAndCollectError(p->dbMain, &pIter->pIdxIter, &p->zErrmsg,
        "SELECT name, rootpage, sql IS NULL OR substr(8, 6)=='UNIQUE' "
................................................................................
        "  FROM main.sqlite_master "
        "  WHERE type='index' AND tbl_name = ?"
    );
  }

  pIter->bCleanup = 1;
  p->rc = rc;
  return rbuObjIterNext(p, pIter);
}

/*
** This is a wrapper around "sqlite3_mprintf(zFmt, ...)". If an OOM occurs,
** an error code is stored in the RBU handle passed as the first argument.
**
** If an error has already occurred (p->rc is already set to something other
** than SQLITE_OK), then this function returns NULL without modifying the
** stored error code. In this case it still calls sqlite3_free() on any 
** printf() parameters associated with %z conversions.
*/
static char *rbuMPrintf(sqlite3rbu *p, const char *zFmt, ...){
  char *zSql = 0;
  va_list ap;
  va_start(ap, zFmt);
  zSql = sqlite3_vmprintf(zFmt, ap);
  if( p->rc==SQLITE_OK ){
    if( zSql==0 ) p->rc = SQLITE_NOMEM;
  }else{
................................................................................
  return zSql;
}

/*
** Argument zFmt is a sqlite3_mprintf() style format string. The trailing
** arguments are the usual subsitution values. This function performs
** the printf() style substitutions and executes the result as an SQL
** statement on the RBU handles database.
**
** If an error occurs, an error code and error message is stored in the
** RBU handle. If an error has already occurred when this function is
** called, it is a no-op.
*/
static int rbuMPrintfExec(sqlite3rbu *p, sqlite3 *db, const char *zFmt, ...){
  va_list ap;
  va_start(ap, zFmt);
  char *zSql = sqlite3_vmprintf(zFmt, ap);
  if( p->rc==SQLITE_OK ){
    if( zSql==0 ){
      p->rc = SQLITE_NOMEM;
    }else{
................................................................................
}

/*
** Attempt to allocate and return a pointer to a zeroed block of nByte 
** bytes. 
**
** If an error (i.e. an OOM condition) occurs, return NULL and leave an 
** error code in the rbu handle passed as the first argument. Or, if an 
** error has already occurred when this function is called, return NULL 
** immediately without attempting the allocation or modifying the stored
** error code.
*/
static void *rbuMalloc(sqlite3rbu *p, int nByte){
  void *pRet = 0;
  if( p->rc==SQLITE_OK ){
    assert( nByte>0 );
    pRet = sqlite3_malloc(nByte);
    if( pRet==0 ){
      p->rc = SQLITE_NOMEM;
    }else{
................................................................................
  return pRet;
}


/*
** Allocate and zero the pIter->azTblCol[] and abTblPk[] arrays so that
** there is room for at least nCol elements. If an OOM occurs, store an
** error code in the RBU handle passed as the first argument.
*/
static void rbuAllocateIterArrays(sqlite3rbu *p, RbuObjIter *pIter, int nCol){
  int nByte = (2*sizeof(char*) + sizeof(int) + 3*sizeof(u8)) * nCol;
  char **azNew;

  azNew = (char**)rbuMalloc(p, nByte);
  if( azNew ){
    pIter->azTblCol = azNew;
    pIter->azTblType = &azNew[nCol];
    pIter->aiSrcOrder = (int*)&pIter->azTblType[nCol];
    pIter->abTblPk = (u8*)&pIter->aiSrcOrder[nCol];
    pIter->abNotNull = (u8*)&pIter->abTblPk[nCol];
    pIter->abIndexed = (u8*)&pIter->abNotNull[nCol];
................................................................................
** It is the responsibility of the caller to eventually free this memory
** using sqlite3_free().
**
** If an OOM condition is encountered when attempting to allocate memory,
** output variable (*pRc) is set to SQLITE_NOMEM before returning. Otherwise,
** if the allocation succeeds, (*pRc) is left unchanged.
*/
static char *rbuStrndup(const char *zStr, int *pRc){
  char *zRet = 0;

  assert( *pRc==SQLITE_OK );
  if( zStr ){
    int nCopy = strlen(zStr) + 1;
    zRet = (char*)sqlite3_malloc(nCopy);
    if( zRet ){
................................................................................
  return zRet;
}

/*
** Finalize the statement passed as the second argument.
**
** If the sqlite3_finalize() call indicates that an error occurs, and the
** rbu handle error code is not already set, set the error code and error
** message accordingly.
*/
static void rbuFinalize(sqlite3rbu *p, sqlite3_stmt *pStmt){
  sqlite3 *db = sqlite3_db_handle(pStmt);
  int rc = sqlite3_finalize(pStmt);
  if( p->rc==SQLITE_OK && rc!=SQLITE_OK ){
    p->rc = rc;
    p->zErrmsg = sqlite3_mprintf("%s", sqlite3_errmsg(db));
  }
}
................................................................................

/* Determine the type of a table.
**
**   peType is of type (int*), a pointer to an output parameter of type
**   (int). This call sets the output parameter as follows, depending
**   on the type of the table specified by parameters dbName and zTbl.
**
**     RBU_PK_NOTABLE:       No such table.
**     RBU_PK_NONE:          Table has an implicit rowid.
**     RBU_PK_IPK:           Table has an explicit IPK column.
**     RBU_PK_EXTERNAL:      Table has an external PK index.
**     RBU_PK_WITHOUT_ROWID: Table is WITHOUT ROWID.
**     RBU_PK_VTAB:          Table is a virtual table.
**
**   Argument *piPk is also of type (int*), and also points to an output
**   parameter. Unless the table has an external primary key index 
**   (i.e. unless *peType is set to 3), then *piPk is set to zero. Or,
**   if the table does have an external primary key index, then *piPk
**   is set to the root page number of the primary key index before
**   returning.
**
** ALGORITHM:
**
**   if( no entry exists in sqlite_master ){
**     return RBU_PK_NOTABLE
**   }else if( sql for the entry starts with "CREATE VIRTUAL" ){
**     return RBU_PK_VTAB
**   }else if( "PRAGMA index_list()" for the table contains a "pk" index ){
**     if( the index that is the pk exists in sqlite_master ){
**       *piPK = rootpage of that index.
**       return RBU_PK_EXTERNAL
**     }else{
**       return RBU_PK_WITHOUT_ROWID
**     }
**   }else if( "PRAGMA table_info()" lists one or more "pk" columns ){
**     return RBU_PK_IPK
**   }else{
**     return RBU_PK_NONE
**   }
*/
static void rbuTableType(
  sqlite3rbu *p,
  const char *zTab,
  int *peType,
  int *piTnum,
  int *piPk
){
  /*
  ** 0) SELECT count(*) FROM sqlite_master where name=%Q AND IsVirtual(%Q)
  ** 1) PRAGMA index_list = ?
  ** 2) SELECT count(*) FROM sqlite_master where name=%Q 
  ** 3) PRAGMA table_info = ?
  */
  sqlite3_stmt *aStmt[4] = {0, 0, 0, 0};

  *peType = RBU_PK_NOTABLE;
  *piPk = 0;

  assert( p->rc==SQLITE_OK );
  p->rc = prepareFreeAndCollectError(p->dbMain, &aStmt[0], &p->zErrmsg, 
    sqlite3_mprintf(
          "SELECT (sql LIKE 'create virtual%%'), rootpage"
          "  FROM sqlite_master"
          " WHERE name=%Q", zTab
  ));
  if( p->rc!=SQLITE_OK || sqlite3_step(aStmt[0])!=SQLITE_ROW ){
    /* Either an error, or no such table. */
    goto rbuTableType_end;
  }
  if( sqlite3_column_int(aStmt[0], 0) ){
    *peType = RBU_PK_VTAB;                     /* virtual table */
    goto rbuTableType_end;
  }
  *piTnum = sqlite3_column_int(aStmt[0], 1);

  p->rc = prepareFreeAndCollectError(p->dbMain, &aStmt[1], &p->zErrmsg, 
    sqlite3_mprintf("PRAGMA index_list=%Q",zTab)
  );
  if( p->rc ) goto rbuTableType_end;
  while( sqlite3_step(aStmt[1])==SQLITE_ROW ){
    const u8 *zOrig = sqlite3_column_text(aStmt[1], 3);
    const u8 *zIdx = sqlite3_column_text(aStmt[1], 1);
    if( zOrig && zIdx && zOrig[0]=='p' ){
      p->rc = prepareFreeAndCollectError(p->dbMain, &aStmt[2], &p->zErrmsg, 
          sqlite3_mprintf(
            "SELECT rootpage FROM sqlite_master WHERE name = %Q", zIdx
      ));
      if( p->rc==SQLITE_OK ){
        if( sqlite3_step(aStmt[2])==SQLITE_ROW ){
          *piPk = sqlite3_column_int(aStmt[2], 0);
          *peType = RBU_PK_EXTERNAL;
        }else{
          *peType = RBU_PK_WITHOUT_ROWID;
        }
      }
      goto rbuTableType_end;
    }
  }

  p->rc = prepareFreeAndCollectError(p->dbMain, &aStmt[3], &p->zErrmsg, 
    sqlite3_mprintf("PRAGMA table_info=%Q",zTab)
  );
  if( p->rc==SQLITE_OK ){
    while( sqlite3_step(aStmt[3])==SQLITE_ROW ){
      if( sqlite3_column_int(aStmt[3],5)>0 ){
        *peType = RBU_PK_IPK;                /* explicit IPK column */
        goto rbuTableType_end;
      }
    }
    *peType = RBU_PK_NONE;
  }

rbuTableType_end: {
    int i;
    for(i=0; i<sizeof(aStmt)/sizeof(aStmt[0]); i++){
      rbuFinalize(p, aStmt[i]);
    }
  }
}

/*
** This is a helper function for rbuObjIterCacheTableInfo(). It populates
** the pIter->abIndexed[] array.
*/
static void rbuObjIterCacheIndexedCols(sqlite3rbu *p, RbuObjIter *pIter){
  sqlite3_stmt *pList = 0;
  int bIndex = 0;

  if( p->rc==SQLITE_OK ){
    memcpy(pIter->abIndexed, pIter->abTblPk, sizeof(u8)*pIter->nTblCol);
    p->rc = prepareFreeAndCollectError(p->dbMain, &pList, &p->zErrmsg,
        sqlite3_mprintf("PRAGMA main.index_list = %Q", pIter->zTbl)
................................................................................
    p->rc = prepareFreeAndCollectError(p->dbMain, &pXInfo, &p->zErrmsg,
        sqlite3_mprintf("PRAGMA main.index_xinfo = %Q", zIdx)
    );
    while( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pXInfo) ){
      int iCid = sqlite3_column_int(pXInfo, 1);
      if( iCid>=0 ) pIter->abIndexed[iCid] = 1;
    }
    rbuFinalize(p, pXInfo);
    bIndex = 1;
  }

  rbuFinalize(p, pList);
  if( bIndex==0 ) pIter->abIndexed = 0;
}


/*
** If they are not already populated, populate the pIter->azTblCol[],
** pIter->abTblPk[], pIter->nTblCol and pIter->bRowid variables according to
** the table (not index) that the iterator currently points to.
**
** Return SQLITE_OK if successful, or an SQLite error code otherwise. If
** an error does occur, an error code and error message are also left in 
** the RBU handle.
*/
static int rbuObjIterCacheTableInfo(sqlite3rbu *p, RbuObjIter *pIter){
  if( pIter->azTblCol==0 ){
    sqlite3_stmt *pStmt = 0;
    int nCol = 0;
    int i;                        /* for() loop iterator variable */
    int bRbuRowid = 0;            /* If input table has column "rbu_rowid" */
    int iOrder = 0;
    int iTnum = 0;

    /* Figure out the type of table this step will deal with. */
    assert( pIter->eType==0 );
    rbuTableType(p, pIter->zTbl, &pIter->eType, &iTnum, &pIter->iPkTnum);
    if( p->rc==SQLITE_OK && pIter->eType==RBU_PK_NOTABLE ){
      p->rc = SQLITE_ERROR;
      p->zErrmsg = sqlite3_mprintf("no such table: %s", pIter->zTbl);
    }
    if( p->rc ) return p->rc;
    if( pIter->zIdx==0 ) pIter->iTnum = iTnum;

    assert( pIter->eType==RBU_PK_NONE || pIter->eType==RBU_PK_IPK 
         || pIter->eType==RBU_PK_EXTERNAL || pIter->eType==RBU_PK_WITHOUT_ROWID
         || pIter->eType==RBU_PK_VTAB
    );

    /* Populate the azTblCol[] and nTblCol variables based on the columns
    ** of the input table. Ignore any input table columns that begin with
    ** "rbu_".  */
    p->rc = prepareFreeAndCollectError(p->dbRbu, &pStmt, &p->zErrmsg, 
        sqlite3_mprintf("SELECT * FROM 'data_%q'", pIter->zTbl)
    );
    if( p->rc==SQLITE_OK ){
      nCol = sqlite3_column_count(pStmt);
      rbuAllocateIterArrays(p, pIter, nCol);
    }
    for(i=0; p->rc==SQLITE_OK && i<nCol; i++){
      const char *zName = (const char*)sqlite3_column_name(pStmt, i);
      if( sqlite3_strnicmp("rbu_", zName, 4) ){
        char *zCopy = rbuStrndup(zName, &p->rc);
        pIter->aiSrcOrder[pIter->nTblCol] = pIter->nTblCol;
        pIter->azTblCol[pIter->nTblCol++] = zCopy;
      }
      else if( 0==sqlite3_stricmp("rbu_rowid", zName) ){
        bRbuRowid = 1;
      }
    }
    sqlite3_finalize(pStmt);
    pStmt = 0;

    if( p->rc==SQLITE_OK
     && bRbuRowid!=(pIter->eType==RBU_PK_VTAB || pIter->eType==RBU_PK_NONE)
    ){
      p->rc = SQLITE_ERROR;
      p->zErrmsg = sqlite3_mprintf(
          "table data_%q %s rbu_rowid column", pIter->zTbl,
          (bRbuRowid ? "may not have" : "requires")
      );
    }

    /* Check that all non-HIDDEN columns in the destination table are also
    ** present in the input table. Populate the abTblPk[], azTblType[] and
    ** aiTblOrder[] arrays at the same time.  */
    if( p->rc==SQLITE_OK ){
................................................................................
        const char *zType = (const char*)sqlite3_column_text(pStmt, 2);

        if( i!=iOrder ){
          SWAP(int, pIter->aiSrcOrder[i], pIter->aiSrcOrder[iOrder]);
          SWAP(char*, pIter->azTblCol[i], pIter->azTblCol[iOrder]);
        }

        pIter->azTblType[iOrder] = rbuStrndup(zType, &p->rc);
        pIter->abTblPk[iOrder] = (iPk!=0);
        pIter->abNotNull[iOrder] = (u8)bNotNull || (iPk!=0);
        iOrder++;
      }
    }

    rbuFinalize(p, pStmt);
    rbuObjIterCacheIndexedCols(p, pIter);
    assert( pIter->eType!=RBU_PK_VTAB || pIter->abIndexed==0 );
  }

  return p->rc;
}

/*
** This function constructs and returns a pointer to a nul-terminated 
** string containing some SQL clause or list based on one or more of the 
** column names currently stored in the pIter->azTblCol[] array.
*/
static char *rbuObjIterGetCollist(
  sqlite3rbu *p,                  /* RBU object */
  RbuObjIter *pIter               /* Object iterator for column names */
){
  char *zList = 0;
  const char *zSep = "";
  int i;
  for(i=0; i<pIter->nTblCol; i++){
    const char *z = pIter->azTblCol[i];
    zList = rbuMPrintf(p, "%z%s\"%w\"", zList, zSep, z);
    zSep = ", ";
  }
  return zList;
}

/*
** This function is used to create a SELECT list (the list of SQL 
** expressions that follows a SELECT keyword) for a SELECT statement 
** used to read from an data_xxx or rbu_tmp_xxx table while updating the 
** index object currently indicated by the iterator object passed as the 
** second argument. A "PRAGMA index_xinfo = <idxname>" statement is used 
** to obtain the required information.
**
** If the index is of the following form:
**
**   CREATE INDEX i1 ON t1(c, b COLLATE nocase);
................................................................................
** As well as the returned string, three other malloc'd strings are 
** returned via output parameters. As follows:
**
**   pzImposterCols: ...
**   pzImposterPk: ...
**   pzWhere: ...
*/
static char *rbuObjIterGetIndexCols(
  sqlite3rbu *p,                  /* RBU object */
  RbuObjIter *pIter,              /* Object iterator for column names */
  char **pzImposterCols,          /* OUT: Columns for imposter table */
  char **pzImposterPk,            /* OUT: Imposter PK clause */
  char **pzWhere,                 /* OUT: WHERE clause */
  int *pnBind                     /* OUT: Trbul number of columns */
){
  int rc = p->rc;                 /* Error code */
  int rc2;                        /* sqlite3_finalize() return code */
  char *zRet = 0;                 /* String to return */
  char *zImpCols = 0;             /* String to return via *pzImposterCols */
  char *zImpPK = 0;               /* String to return via *pzImposterPK */
  char *zWhere = 0;               /* String to return via *pzWhere */
................................................................................
    int bDesc = sqlite3_column_int(pXInfo, 3);
    const char *zCollate = (const char*)sqlite3_column_text(pXInfo, 4);
    const char *zCol;
    const char *zType;

    if( iCid<0 ){
      /* An integer primary key. If the table has an explicit IPK, use
      ** its name. Otherwise, use "rbu_rowid".  */
      if( pIter->eType==RBU_PK_IPK ){
        int i;
        for(i=0; pIter->abTblPk[i]==0; i++);
        assert( i<pIter->nTblCol );
        zCol = pIter->azTblCol[i];
      }else{
        zCol = "rbu_rowid";
      }
      zType = "INTEGER";
    }else{
      zCol = pIter->azTblCol[iCid];
      zType = pIter->azTblType[iCid];
    }

    zRet = sqlite3_mprintf("%z%s\"%w\" COLLATE %Q", zRet, zCom, zCol, zCollate);
    if( pIter->bUnique==0 || sqlite3_column_int(pXInfo, 5) ){
      const char *zOrder = (bDesc ? " DESC" : "");
      zImpPK = sqlite3_mprintf("%z%s\"rbu_imp_%d%w\"%s", 
          zImpPK, zCom, nBind, zCol, zOrder
      );
    }
    zImpCols = sqlite3_mprintf("%z%s\"rbu_imp_%d%w\" %s COLLATE %Q", 
        zImpCols, zCom, nBind, zCol, zType, zCollate
    );
    zWhere = sqlite3_mprintf(
        "%z%s\"rbu_imp_%d%w\" IS ?", zWhere, zAnd, nBind, zCol
    );
    if( zRet==0 || zImpPK==0 || zImpCols==0 || zWhere==0 ) rc = SQLITE_NOMEM;
    zCom = ", ";
    zAnd = " AND ";
    nBind++;
  }

................................................................................
** Assuming the current table columns are "a", "b" and "c", and the zObj
** paramter is passed "old", return a string of the form:
**
**     "old.a, old.b, old.b"
**
** With the column names escaped.
**
** For tables with implicit rowids - RBU_PK_EXTERNAL and RBU_PK_NONE, append
** the text ", old._rowid_" to the returned value.
*/
static char *rbuObjIterGetOldlist(
  sqlite3rbu *p, 
  RbuObjIter *pIter,
  const char *zObj
){
  char *zList = 0;
  if( p->rc==SQLITE_OK && pIter->abIndexed ){
    const char *zS = "";
    int i;
    for(i=0; i<pIter->nTblCol; i++){
................................................................................
      if( zList==0 ){
        p->rc = SQLITE_NOMEM;
        break;
      }
    }

    /* For a table with implicit rowids, append "old._rowid_" to the list. */
    if( pIter->eType==RBU_PK_EXTERNAL || pIter->eType==RBU_PK_NONE ){
      zList = rbuMPrintf(p, "%z, %s._rowid_", zList, zObj);
    }
  }
  return zList;
}

/*
** Return an expression that can be used in a WHERE clause to match the
................................................................................
**
**   CREATE TABLE t1(a, b, c, PRIMARY KEY(b, c));
**
** Return the string:
**
**   "b = ?1 AND c = ?2"
*/
static char *rbuObjIterGetWhere(
  sqlite3rbu *p, 
  RbuObjIter *pIter
){
  char *zList = 0;
  if( pIter->eType==RBU_PK_VTAB || pIter->eType==RBU_PK_NONE ){
    zList = rbuMPrintf(p, "_rowid_ = ?%d", pIter->nTblCol+1);
  }else if( pIter->eType==RBU_PK_EXTERNAL ){
    const char *zSep = "";
    int i;
    for(i=0; i<pIter->nTblCol; i++){
      if( pIter->abTblPk[i] ){
        zList = rbuMPrintf(p, "%z%sc%d=?%d", zList, zSep, i, i+1);
        zSep = " AND ";
      }
    }
    zList = rbuMPrintf(p, 
        "_rowid_ = (SELECT id FROM rbu_imposter2 WHERE %z)", zList
    );

  }else{
    const char *zSep = "";
    int i;
    for(i=0; i<pIter->nTblCol; i++){
      if( pIter->abTblPk[i] ){
        const char *zCol = pIter->azTblCol[i];
        zList = rbuMPrintf(p, "%z%s\"%w\"=?%d", zList, zSep, zCol, i+1);
        zSep = " AND ";
      }
    }
  }
  return zList;
}

/*
** The SELECT statement iterating through the keys for the current object
** (p->objiter.pSelect) currently points to a valid row. However, there
** is something wrong with the rbu_control value in the rbu_control value
** stored in the (p->nCol+1)'th column. Set the error code and error message
** of the RBU handle to something reflecting this.
*/
static void rbuBadControlError(sqlite3rbu *p){
  p->rc = SQLITE_ERROR;
  p->zErrmsg = sqlite3_mprintf("invalid rbu_control value");
}


/*
** Return a nul-terminated string containing the comma separated list of
** assignments that should be included following the "SET" keyword of
** an UPDATE statement used to update the table object that the iterator
** passed as the second argument currently points to if the rbu_control
** column of the data_xxx table entry is set to zMask.
**
** The memory for the returned string is obtained from sqlite3_malloc().
** It is the responsibility of the caller to eventually free it using
** sqlite3_free(). 
**
** If an OOM error is encountered when allocating space for the new
** string, an error code is left in the rbu handle passed as the first
** argument and NULL is returned. Or, if an error has already occurred
** when this function is called, NULL is returned immediately, without
** attempting the allocation or modifying the stored error code.
*/
static char *rbuObjIterGetSetlist(
  sqlite3rbu *p,
  RbuObjIter *pIter,
  const char *zMask
){
  char *zList = 0;
  if( p->rc==SQLITE_OK ){
    int i;

    if( strlen(zMask)!=pIter->nTblCol ){
      rbuBadControlError(p);
    }else{
      const char *zSep = "";
      for(i=0; i<pIter->nTblCol; i++){
        char c = zMask[pIter->aiSrcOrder[i]];
        if( c=='x' ){
          zList = rbuMPrintf(p, "%z%s\"%w\"=?%d", 
              zList, zSep, pIter->azTblCol[i], i+1
          );
          zSep = ", ";
        }
        if( c=='d' ){
          zList = rbuMPrintf(p, "%z%s\"%w\"=rbu_delta(\"%w\", ?%d)", 
              zList, zSep, pIter->azTblCol[i], pIter->azTblCol[i], i+1
          );
          zSep = ", ";
        }
      }
    }
  }
................................................................................
** a buffer containing the string "?,?,?".
**
** The memory for the returned string is obtained from sqlite3_malloc().
** It is the responsibility of the caller to eventually free it using
** sqlite3_free(). 
**
** If an OOM error is encountered when allocating space for the new
** string, an error code is left in the rbu handle passed as the first
** argument and NULL is returned. Or, if an error has already occurred
** when this function is called, NULL is returned immediately, without
** attempting the allocation or modifying the stored error code.
*/
static char *rbuObjIterGetBindlist(sqlite3rbu *p, int nBind){
  char *zRet = 0;
  int nByte = nBind*2 + 1;

  zRet = (char*)rbuMalloc(p, nByte);
  if( zRet ){
    int i;
    for(i=0; i<nBind; i++){
      zRet[i*2] = '?';
      zRet[i*2+1] = (i+1==nBind) ? '\0' : ',';
    }
  }
  return zRet;
}

/*
** The iterator currently points to a table (not index) of type 
** RBU_PK_WITHOUT_ROWID. This function creates the PRIMARY KEY 
** declaration for the corresponding imposter table. For example,
** if the iterator points to a table created as:
**
**   CREATE TABLE t1(a, b, c, PRIMARY KEY(b, a DESC)) WITHOUT ROWID
**
** this function returns:
**
**   PRIMARY KEY("b", "a" DESC)
*/
static char *rbuWithoutRowidPK(sqlite3rbu *p, RbuObjIter *pIter){
  char *z = 0;
  assert( pIter->zIdx==0 );
  if( p->rc==SQLITE_OK ){
    const char *zSep = "PRIMARY KEY(";
    sqlite3_stmt *pXList = 0;     /* PRAGMA index_list = (pIter->zTbl) */
    sqlite3_stmt *pXInfo = 0;     /* PRAGMA index_xinfo = <pk-index> */
   
................................................................................
          p->rc = prepareFreeAndCollectError(p->dbMain, &pXInfo, &p->zErrmsg,
              sqlite3_mprintf("PRAGMA main.index_xinfo = %Q", zIdx)
          );
        }
        break;
      }
    }
    rbuFinalize(p, pXList);

    while( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pXInfo) ){
      if( sqlite3_column_int(pXInfo, 5) ){
        /* int iCid = sqlite3_column_int(pXInfo, 0); */
        const char *zCol = (const char*)sqlite3_column_text(pXInfo, 2);
        const char *zDesc = sqlite3_column_int(pXInfo, 3) ? " DESC" : "";
        z = rbuMPrintf(p, "%z%s\"%w\"%s", z, zSep, zCol, zDesc);
        zSep = ", ";
      }
    }
    z = rbuMPrintf(p, "%z)", z);
    rbuFinalize(p, pXInfo);
  }
  return z;
}

/*
** This function creates the second imposter table used when writing to
** a table b-tree where the table has an external primary key. If the
** iterator passed as the second argument does not currently point to
** a table (not index) with an external primary key, this function is a
** no-op. 
**
** Assuming the iterator does point to a table with an external PK, this
** function creates a WITHOUT ROWID imposter table named "rbu_imposter2"
** used to access that PK index. For example, if the target table is
** declared as follows:
**
**   CREATE TABLE t1(a, b TEXT, c REAL, PRIMARY KEY(b, c));
**
** then the imposter table schema is:
**
**   CREATE TABLE rbu_imposter2(c1 TEXT, c2 REAL, id INTEGER) WITHOUT ROWID;
**
*/
static void rbuCreateImposterTable2(sqlite3rbu *p, RbuObjIter *pIter){
  if( p->rc==SQLITE_OK && pIter->eType==RBU_PK_EXTERNAL ){
    int tnum = pIter->iPkTnum;    /* Root page of PK index */
    sqlite3_stmt *pQuery = 0;     /* SELECT name ... WHERE rootpage = $tnum */
    const char *zIdx = 0;         /* Name of PK index */
    sqlite3_stmt *pXInfo = 0;     /* PRAGMA main.index_xinfo = $zIdx */
    const char *zComma = "";
    char *zCols = 0;              /* Used to build up list of table cols */
    char *zPk = 0;                /* Used to build up table PK declaration */
................................................................................
      }
    }
    if( zIdx ){
      p->rc = prepareFreeAndCollectError(p->dbMain, &pXInfo, &p->zErrmsg,
          sqlite3_mprintf("PRAGMA main.index_xinfo = %Q", zIdx)
      );
    }
    rbuFinalize(p, pQuery);

    while( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pXInfo) ){
      int bKey = sqlite3_column_int(pXInfo, 5);
      if( bKey ){
        int iCid = sqlite3_column_int(pXInfo, 1);
        int bDesc = sqlite3_column_int(pXInfo, 3);
        const char *zCollate = (const char*)sqlite3_column_text(pXInfo, 4);
        zCols = rbuMPrintf(p, "%z%sc%d %s COLLATE %s", zCols, zComma, 
            iCid, pIter->azTblType[iCid], zCollate
        );
        zPk = rbuMPrintf(p, "%z%sc%d%s", zPk, zComma, iCid, bDesc?" DESC":"");
        zComma = ", ";
      }
    }
    zCols = rbuMPrintf(p, "%z, id INTEGER", zCols);
    rbuFinalize(p, pXInfo);

    sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 1, tnum);
    rbuMPrintfExec(p, p->dbMain,
        "CREATE TABLE rbu_imposter2(%z, PRIMARY KEY(%z)) WITHOUT ROWID", 
        zCols, zPk
    );
    sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 0, 0);
  }
}

/*
** If an error has already occurred when this function is called, it 
** immediately returns zero (without doing any work). Or, if an error
** occurs during the execution of this function, it sets the error code
** in the sqlite3rbu object indicated by the first argument and returns
** zero.
**
** The iterator passed as the second argument is guaranteed to point to
** a table (not an index) when this function is called. This function
** attempts to create any imposter table required to write to the main
** table b-tree of the table before returning. Non-zero is returned if
** an imposter table are created, or zero otherwise.
**
** An imposter table is required in all cases except RBU_PK_VTAB. Only
** virtual tables are written to directly. The imposter table has the 
** same schema as the actual target table (less any UNIQUE constraints). 
** More precisely, the "same schema" means the same columns, types, 
** collation sequences. For tables that do not have an external PRIMARY
** KEY, it also means the same PRIMARY KEY declaration.
*/
static void rbuCreateImposterTable(sqlite3rbu *p, RbuObjIter *pIter){
  if( p->rc==SQLITE_OK && pIter->eType!=RBU_PK_VTAB ){
    int tnum = pIter->iTnum;
    const char *zComma = "";
    char *zSql = 0;
    int iCol;
    sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 0, 1);

    for(iCol=0; p->rc==SQLITE_OK && iCol<pIter->nTblCol; iCol++){
................................................................................
      const char *zCol = pIter->azTblCol[iCol];
      const char *zColl = 0;

      p->rc = sqlite3_table_column_metadata(
          p->dbMain, "main", pIter->zTbl, zCol, 0, &zColl, 0, 0, 0
      );

      if( pIter->eType==RBU_PK_IPK && pIter->abTblPk[iCol] ){
        /* If the target table column is an "INTEGER PRIMARY KEY", add
        ** "PRIMARY KEY" to the imposter table column declaration. */
        zPk = "PRIMARY KEY ";
      }
      zSql = rbuMPrintf(p, "%z%s\"%w\" %s %sCOLLATE %s%s", 
          zSql, zComma, zCol, pIter->azTblType[iCol], zPk, zColl,
          (pIter->abNotNull[iCol] ? " NOT NULL" : "")
      );
      zComma = ", ";
    }

    if( pIter->eType==RBU_PK_WITHOUT_ROWID ){
      char *zPk = rbuWithoutRowidPK(p, pIter);
      if( zPk ){
        zSql = rbuMPrintf(p, "%z, %z", zSql, zPk);
      }
    }

    sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 1, tnum);
    rbuMPrintfExec(p, p->dbMain, "CREATE TABLE \"rbu_imp_%w\"(%z)%s", 
        pIter->zTbl, zSql, 
        (pIter->eType==RBU_PK_WITHOUT_ROWID ? " WITHOUT ROWID" : "")
    );
    sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 0, 0);
  }
}

/*
** Prepare a statement used to insert rows into the "rbu_tmp_xxx" table.
** Specifically a statement of the form:
**
**     INSERT INTO rbu_tmp_xxx VALUES(?, ?, ? ...);
**
** The number of bound variables is equal to the number of columns in
** the target table, plus one (for the rbu_control column), plus one more 
** (for the rbu_rowid column) if the target table is an implicit IPK or 
** virtual table.
*/
static void rbuObjIterPrepareTmpInsert(
  sqlite3rbu *p, 
  RbuObjIter *pIter,
  const char *zCollist,
  const char *zRbuRowid
){
  int bRbuRowid = (pIter->eType==RBU_PK_EXTERNAL || pIter->eType==RBU_PK_NONE);
  char *zBind = rbuObjIterGetBindlist(p, pIter->nTblCol + 1 + bRbuRowid);
  if( zBind ){
    assert( pIter->pTmpInsert==0 );
    p->rc = prepareFreeAndCollectError(
        p->dbRbu, &pIter->pTmpInsert, &p->zErrmsg, sqlite3_mprintf(
          "INSERT INTO %s.'rbu_tmp_%q'(rbu_control,%s%s) VALUES(%z)", 
          p->zStateDb, pIter->zTbl, zCollist, zRbuRowid, zBind
    ));
  }
}

static void rbuTmpInsertFunc(
  sqlite3_context *pCtx, 
  int nVal,
  sqlite3_value **apVal
){
  sqlite3rbu *p = sqlite3_user_data(pCtx);
  int rc = SQLITE_OK;
  int i;

  for(i=0; rc==SQLITE_OK && i<nVal; i++){
    rc = sqlite3_bind_value(p->objiter.pTmpInsert, i+1, apVal[i]);
  }
  if( rc==SQLITE_OK ){
................................................................................
}

/*
** Ensure that the SQLite statement handles required to update the 
** target database object currently indicated by the iterator passed 
** as the second argument are available.
*/
static int rbuObjIterPrepareAll(
  sqlite3rbu *p, 
  RbuObjIter *pIter,
  int nOffset                     /* Add "LIMIT -1 OFFSET $nOffset" to SELECT */
){
  assert( pIter->bCleanup==0 );
  if( pIter->pSelect==0 && rbuObjIterCacheTableInfo(p, pIter)==SQLITE_OK ){
    const int tnum = pIter->iTnum;
    char *zCollist = 0;           /* List of indexed columns */
    char **pz = &p->zErrmsg;
    const char *zIdx = pIter->zIdx;
    char *zLimit = 0;

    if( nOffset ){
................................................................................
      const char *zTbl = pIter->zTbl;
      char *zImposterCols = 0;    /* Columns for imposter table */
      char *zImposterPK = 0;      /* Primary key declaration for imposter */
      char *zWhere = 0;           /* WHERE clause on PK columns */
      char *zBind = 0;
      int nBind = 0;

      assert( pIter->eType!=RBU_PK_VTAB );
      zCollist = rbuObjIterGetIndexCols(
          p, pIter, &zImposterCols, &zImposterPK, &zWhere, &nBind
      );
      zBind = rbuObjIterGetBindlist(p, nBind);

      /* Create the imposter table used to write to this index. */
      sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 0, 1);
      sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 1,tnum);
      rbuMPrintfExec(p, p->dbMain,
          "CREATE TABLE \"rbu_imp_%w\"( %s, PRIMARY KEY( %s ) ) WITHOUT ROWID",
          zTbl, zImposterCols, zImposterPK
      );
      sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->dbMain, "main", 0, 0);

      /* Create the statement to insert index entries */
      pIter->nCol = nBind;
      if( p->rc==SQLITE_OK ){
        p->rc = prepareFreeAndCollectError(
            p->dbMain, &pIter->pInsert, &p->zErrmsg,
          sqlite3_mprintf("INSERT INTO \"rbu_imp_%w\" VALUES(%s)", zTbl, zBind)
        );
      }

      /* And to delete index entries */
      if( p->rc==SQLITE_OK ){
        p->rc = prepareFreeAndCollectError(
            p->dbMain, &pIter->pDelete, &p->zErrmsg,
          sqlite3_mprintf("DELETE FROM \"rbu_imp_%w\" WHERE %s", zTbl, zWhere)
        );
      }

      /* Create the SELECT statement to read keys in sorted order */
      if( p->rc==SQLITE_OK ){
        char *zSql;
        if( pIter->eType==RBU_PK_EXTERNAL || pIter->eType==RBU_PK_NONE ){
          zSql = sqlite3_mprintf(
              "SELECT %s, rbu_control FROM %s.'rbu_tmp_%q' ORDER BY %s%s",
              zCollist, p->zStateDb, pIter->zTbl,
              zCollist, zLimit
          );
        }else{
          zSql = sqlite3_mprintf(
              "SELECT %s, rbu_control FROM 'data_%q' "
              "WHERE typeof(rbu_control)='integer' AND rbu_control!=1 "
              "UNION ALL "
              "SELECT %s, rbu_control FROM %s.'rbu_tmp_%q' "
              "ORDER BY %s%s",
              zCollist, pIter->zTbl, 
              zCollist, p->zStateDb, pIter->zTbl, 
              zCollist, zLimit
          );
        }
        p->rc = prepareFreeAndCollectError(p->dbRbu, &pIter->pSelect, pz, zSql);
      }

      sqlite3_free(zImposterCols);
      sqlite3_free(zImposterPK);
      sqlite3_free(zWhere);
      sqlite3_free(zBind);
    }else{
      int bRbuRowid = (pIter->eType==RBU_PK_VTAB || pIter->eType==RBU_PK_NONE);
      const char *zTbl = pIter->zTbl;       /* Table this step applies to */
      const char *zWrite;                   /* Imposter table name */

      char *zBindings = rbuObjIterGetBindlist(p, pIter->nTblCol + bRbuRowid);
      char *zWhere = rbuObjIterGetWhere(p, pIter);
      char *zOldlist = rbuObjIterGetOldlist(p, pIter, "old");
      char *zNewlist = rbuObjIterGetOldlist(p, pIter, "new");

      zCollist = rbuObjIterGetCollist(p, pIter);
      pIter->nCol = pIter->nTblCol;

      /* Create the SELECT statement to read keys from data_xxx */
      if( p->rc==SQLITE_OK ){
        p->rc = prepareFreeAndCollectError(p->dbRbu, &pIter->pSelect, pz,
            sqlite3_mprintf(
              "SELECT %s, rbu_control%s FROM 'data_%q'%s", 
              zCollist, (bRbuRowid ? ", rbu_rowid" : ""), zTbl, zLimit
            )
        );
      }

      /* Create the imposter table or tables (if required). */
      rbuCreateImposterTable(p, pIter);
      rbuCreateImposterTable2(p, pIter);
      zWrite = (pIter->eType==RBU_PK_VTAB ? "" : "rbu_imp_");

      /* Create the INSERT statement to write to the target PK b-tree */
      if( p->rc==SQLITE_OK ){
        p->rc = prepareFreeAndCollectError(p->dbMain, &pIter->pInsert, pz,
            sqlite3_mprintf(
              "INSERT INTO \"%s%w\"(%s%s) VALUES(%s)", 
              zWrite, zTbl, zCollist, (bRbuRowid ? ", _rowid_" : ""), zBindings
            )
        );
      }

      /* Create the DELETE statement to write to the target PK b-tree */
      if( p->rc==SQLITE_OK ){
        p->rc = prepareFreeAndCollectError(p->dbMain, &pIter->pDelete, pz,
................................................................................
            sqlite3_mprintf(
              "DELETE FROM \"%s%w\" WHERE %s", zWrite, zTbl, zWhere
            )
        );
      }

      if( pIter->abIndexed ){
        const char *zRbuRowid = "";
        if( pIter->eType==RBU_PK_EXTERNAL || pIter->eType==RBU_PK_NONE ){
          zRbuRowid = ", rbu_rowid";
        }

        /* Create the rbu_tmp_xxx table and the triggers to populate it. */
        rbuMPrintfExec(p, p->dbRbu,
            "CREATE TABLE IF NOT EXISTS %s.'rbu_tmp_%q' AS "
            "SELECT *%s FROM 'data_%q' WHERE 0;"
            , p->zStateDb
            , zTbl, (pIter->eType==RBU_PK_EXTERNAL ? ", 0 AS rbu_rowid" : "")
            , zTbl
        );

        rbuMPrintfExec(p, p->dbMain,
            "CREATE TEMP TRIGGER rbu_delete_tr BEFORE DELETE ON \"%s%w\" "
            "BEGIN "
            "  SELECT rbu_tmp_insert(2, %s);"
            "END;"

            "CREATE TEMP TRIGGER rbu_update1_tr BEFORE UPDATE ON \"%s%w\" "
            "BEGIN "
            "  SELECT rbu_tmp_insert(2, %s);"
            "END;"

            "CREATE TEMP TRIGGER rbu_update2_tr AFTER UPDATE ON \"%s%w\" "
            "BEGIN "
            "  SELECT rbu_tmp_insert(3, %s);"
            "END;",
            zWrite, zTbl, zOldlist,
            zWrite, zTbl, zOldlist,
            zWrite, zTbl, zNewlist
        );

        if( pIter->eType==RBU_PK_EXTERNAL || pIter->eType==RBU_PK_NONE ){
          rbuMPrintfExec(p, p->dbMain,
              "CREATE TEMP TRIGGER rbu_insert_tr AFTER INSERT ON \"%s%w\" "
              "BEGIN "
              "  SELECT rbu_tmp_insert(0, %s);"
              "END;",
              zWrite, zTbl, zNewlist
          );
        }

        rbuObjIterPrepareTmpInsert(p, pIter, zCollist, zRbuRowid);
      }

      sqlite3_free(zWhere);
      sqlite3_free(zOldlist);
      sqlite3_free(zNewlist);
      sqlite3_free(zBindings);
    }
................................................................................
  return p->rc;
}

/*
** Set output variable *ppStmt to point to an UPDATE statement that may
** be used to update the imposter table for the main table b-tree of the
** table object that pIter currently points to, assuming that the 
** rbu_control column of the data_xyz table contains zMask.
** 
** If the zMask string does not specify any columns to update, then this
** is not an error. Output variable *ppStmt is set to NULL in this case.
*/
static int rbuGetUpdateStmt(
  sqlite3rbu *p,                  /* RBU handle */
  RbuObjIter *pIter,              /* Object iterator */
  const char *zMask,              /* rbu_control value ('x.x.') */
  sqlite3_stmt **ppStmt           /* OUT: UPDATE statement handle */
){
  RbuUpdateStmt **pp;
  RbuUpdateStmt *pUp = 0;
  int nUp = 0;

  /* In case an error occurs */
  *ppStmt = 0;

  /* Search for an existing statement. If one is found, shift it to the front
  ** of the LRU queue and return immediately. Otherwise, leave nUp pointing
  ** to the number of statements currently in the cache and pUp to the
  ** last object in the list.  */
  for(pp=&pIter->pRbuUpdate; *pp; pp=&((*pp)->pNext)){
    pUp = *pp;
    if( strcmp(pUp->zMask, zMask)==0 ){
      *pp = pUp->pNext;
      pUp->pNext = pIter->pRbuUpdate;
      pIter->pRbuUpdate = pUp;
      *ppStmt = pUp->pUpdate; 
      return SQLITE_OK;
    }
    nUp++;
  }
  assert( pUp==0 || pUp->pNext==0 );

  if( nUp>=SQLITE_RBU_UPDATE_CACHESIZE ){
    for(pp=&pIter->pRbuUpdate; *pp!=pUp; pp=&((*pp)->pNext));
    *pp = 0;
    sqlite3_finalize(pUp->pUpdate);
    pUp->pUpdate = 0;
  }else{
    pUp = (RbuUpdateStmt*)rbuMalloc(p, sizeof(RbuUpdateStmt)+pIter->nTblCol+1);
  }

  if( pUp ){
    char *zWhere = rbuObjIterGetWhere(p, pIter);
    char *zSet = rbuObjIterGetSetlist(p, pIter, zMask);
    char *zUpdate = 0;

    pUp->zMask = (char*)&pUp[1];
    memcpy(pUp->zMask, zMask, pIter->nTblCol);
    pUp->pNext = pIter->pRbuUpdate;
    pIter->pRbuUpdate = pUp;

    if( zSet ){
      const char *zPrefix = "";

      if( pIter->eType!=RBU_PK_VTAB ) zPrefix = "rbu_imp_";
      zUpdate = sqlite3_mprintf("UPDATE \"%s%w\" SET %s WHERE %s", 
          zPrefix, pIter->zTbl, zSet, zWhere
      );
      p->rc = prepareFreeAndCollectError(
          p->dbMain, &pUp->pUpdate, &p->zErrmsg, zUpdate
      );
      *ppStmt = pUp->pUpdate;
................................................................................
    sqlite3_free(zWhere);
    sqlite3_free(zSet);
  }

  return p->rc;
}

static sqlite3 *rbuOpenDbhandle(sqlite3rbu *p, const char *zName){
  sqlite3 *db = 0;
  if( p->rc==SQLITE_OK ){
    const int flags = SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|SQLITE_OPEN_URI;
    p->rc = sqlite3_open_v2(zName, &db, flags, p->zVfsName);
    if( p->rc ){
      p->zErrmsg = sqlite3_mprintf("%s", sqlite3_errmsg(db));
      sqlite3_close(db);
................................................................................
      db = 0;
    }
  }
  return db;
}

/*
** Open the database handle and attach the RBU database as "rbu". If an
** error occurs, leave an error code and message in the RBU handle.
*/
static void rbuOpenDatabase(sqlite3rbu *p){
  assert( p->rc==SQLITE_OK );
  assert( p->dbMain==0 && p->dbRbu==0 );

  p->eStage = 0;
  p->dbMain = rbuOpenDbhandle(p, p->zTarget);
  p->dbRbu = rbuOpenDbhandle(p, p->zRbu);

  /* If using separate RBU and state databases, attach the state database to
  ** the RBU db handle now.  */
  if( p->zState ){
    rbuMPrintfExec(p, p->dbRbu, "ATTACH %Q AS stat", p->zState);
    memcpy(p->zStateDb, "stat", 4);
  }else{
    memcpy(p->zStateDb, "main", 4);
  }

  if( p->rc==SQLITE_OK ){
    p->rc = sqlite3_create_function(p->dbMain, 
        "rbu_tmp_insert", -1, SQLITE_UTF8, (void*)p, rbuTmpInsertFunc, 0, 0
    );
  }

  if( p->rc==SQLITE_OK ){
    p->rc = sqlite3_file_control(p->dbMain, "main", SQLITE_FCNTL_RBU, (void*)p);
  }
  rbuMPrintfExec(p, p->dbMain, "SELECT * FROM sqlite_master");

  /* Mark the database file just opened as an RBU target database. If 
  ** this call returns SQLITE_NOTFOUND, then the RBU vfs is not in use.
  ** This is an error.  */
  if( p->rc==SQLITE_OK ){
    p->rc = sqlite3_file_control(p->dbMain, "main", SQLITE_FCNTL_RBU, (void*)p);
  }

  if( p->rc==SQLITE_NOTFOUND ){
    p->rc = SQLITE_ERROR;
    p->zErrmsg = sqlite3_mprintf("rbu vfs not found");
  }
}

/*
** This routine is a copy of the sqlite3FileSuffix3() routine from the core.
** It is a no-op unless SQLITE_ENABLE_8_3_NAMES is defined.
**
................................................................................
** Examples:
**
**     test.db-journal    =>   test.nal
**     test.db-wal        =>   test.wal
**     test.db-shm        =>   test.shm
**     test.db-mj7f3319fa =>   test.9fa
*/
static void rbuFileSuffix3(const char *zBase, char *z){
#ifdef SQLITE_ENABLE_8_3_NAMES
#if SQLITE_ENABLE_8_3_NAMES<2
  if( sqlite3_uri_boolean(zBase, "8_3_names", 0) )
#endif
  {
    int i, sz;
    sz = sqlite3Strlen30(z);
................................................................................
/*
** Return the current wal-index header checksum for the target database 
** as a 64-bit integer.
**
** The checksum is store in the first page of xShmMap memory as an 8-byte 
** blob starting at byte offset 40.
*/
static i64 rbuShmChecksum(sqlite3rbu *p){
  i64 iRet = 0;
  if( p->rc==SQLITE_OK ){
    sqlite3_file *pDb = p->pTargetFd->pReal;
    u32 volatile *ptr;
    p->rc = pDb->pMethods->xShmMap(pDb, 0, 32*1024, 0, (void volatile**)&ptr);
    if( p->rc==SQLITE_OK ){
      iRet = ((i64)ptr[10] << 32) + ptr[11];
................................................................................
  return iRet;
}

/*
** This function is called as part of initializing or reinitializing an
** incremental checkpoint. 
**
** It populates the sqlite3rbu.aFrame[] array with the set of 
** (wal frame -> db page) copy operations required to checkpoint the 
** current wal file, and obtains the set of shm locks required to safely 
** perform the copy operations directly on the file-system.
**
** If argument pState is not NULL, then the incremental checkpoint is
** being resumed. In this case, if the checksum of the wal-index-header
** following recovery is not the same as the checksum saved in the RbuState
** object, then the rbu handle is set to DONE state. This occurs if some
** other client appends a transaction to the wal file in the middle of
** an incremental checkpoint.
*/
static void rbuSetupCheckpoint(sqlite3rbu *p, RbuState *pState){

  /* If pState is NULL, then the wal file may not have been opened and
  ** recovered. Running a read-statement here to ensure that doing so
  ** does not interfere with the "capture" process below.  */
  if( pState==0 ){
    p->eStage = 0;
    if( p->rc==SQLITE_OK ){
      p->rc = sqlite3_exec(p->dbMain, "SELECT * FROM sqlite_master", 0, 0, 0);
    }
  }

  /* Assuming no error has occurred, run a "restart" checkpoint with the
  ** sqlite3rbu.eStage variable set to CAPTURE. This turns on the following
  ** special behaviour in the rbu VFS:
  **
  **   * If the exclusive shm WRITER or READ0 lock cannot be obtained,
  **     the checkpoint fails with SQLITE_BUSY (normally SQLite would
  **     proceed with running a passive checkpoint instead of failing).
  **
  **   * Attempts to read from the *-wal file or write to the database file
  **     do not perform any IO. Instead, the frame/page combinations that
  **     would be read/written are recorded in the sqlite3rbu.aFrame[]
  **     array.
  **
  **   * Calls to xShmLock(UNLOCK) to release the exclusive shm WRITER, 
  **     READ0 and CHECKPOINT locks taken as part of the checkpoint are
  **     no-ops. These locks will not be released until the connection
  **     is closed.
  **
................................................................................
  ** array populated with a set of (frame -> page) mappings. Because the 
  ** WRITER, CHECKPOINT and READ0 locks are still held, it is safe to copy 
  ** data from the wal file into the database file according to the 
  ** contents of aFrame[].
  */
  if( p->rc==SQLITE_OK ){
    int rc2;
    p->eStage = RBU_STAGE_CAPTURE;
    rc2 = sqlite3_exec(p->dbMain, "PRAGMA main.wal_checkpoint=restart", 0, 0,0);
    if( rc2!=SQLITE_INTERNAL ) p->rc = rc2;
  }

  if( p->rc==SQLITE_OK ){
    p->eStage = RBU_STAGE_CKPT;
    p->nStep = (pState ? pState->nRow : 0);
    p->aBuf = rbuMalloc(p, p->pgsz);
    p->iWalCksum = rbuShmChecksum(p);
  }

  if( p->rc==SQLITE_OK && pState && pState->iWalCksum!=p->iWalCksum ){
    p->rc = SQLITE_DONE;
    p->eStage = RBU_STAGE_DONE;
  }
}

/*
** Called when iAmt bytes are read from offset iOff of the wal file while
** the rbu object is in capture mode. Record the frame number of the frame
** being read in the aFrame[] array.
*/
static int rbuCaptureWalRead(sqlite3rbu *pRbu, i64 iOff, int iAmt){
  const u32 mReq = (1<<WAL_LOCK_WRITE)|(1<<WAL_LOCK_CKPT)|(1<<WAL_LOCK_READ0);
  u32 iFrame;

  if( pRbu->mLock!=mReq ){
    pRbu->rc = SQLITE_BUSY;
    return SQLITE_INTERNAL;
  }

  pRbu->pgsz = iAmt;
  if( pRbu->nFrame==pRbu->nFrameAlloc ){
    int nNew = (pRbu->nFrameAlloc ? pRbu->nFrameAlloc : 64) * 2;
    RbuFrame *aNew;
    aNew = (RbuFrame*)sqlite3_realloc(pRbu->aFrame, nNew * sizeof(RbuFrame));
    if( aNew==0 ) return SQLITE_NOMEM;
    pRbu->aFrame = aNew;
    pRbu->nFrameAlloc = nNew;
  }

  iFrame = (u32)((iOff-32) / (i64)(iAmt+24)) + 1;
  if( pRbu->iMaxFrame<iFrame ) pRbu->iMaxFrame = iFrame;
  pRbu->aFrame[pRbu->nFrame].iWalFrame = iFrame;
  pRbu->aFrame[pRbu->nFrame].iDbPage = 0;
  pRbu->nFrame++;
  return SQLITE_OK;
}

/*
** Called when a page of data is written to offset iOff of the database
** file while the rbu handle is in capture mode. Record the page number 
** of the page being written in the aFrame[] array.
*/
static int rbuCaptureDbWrite(sqlite3rbu *pRbu, i64 iOff){
  pRbu->aFrame[pRbu->nFrame-1].iDbPage = (u32)(iOff / pRbu->pgsz) + 1;
  return SQLITE_OK;
}

/*
** This is called as part of an incremental checkpoint operation. Copy
** a single frame of data from the wal file into the database file, as
** indicated by the RbuFrame object.
*/
static void rbuCheckpointFrame(sqlite3rbu *p, RbuFrame *pFrame){
  sqlite3_file *pWal = p->pTargetFd->pWalFd->pReal;
  sqlite3_file *pDb = p->pTargetFd->pReal;
  i64 iOff;

  assert( p->rc==SQLITE_OK );
  iOff = (i64)(pFrame->iWalFrame-1) * (p->pgsz + 24) + 32 + 24;
  p->rc = pWal->pMethods->xRead(pWal, p->aBuf, p->pgsz, iOff);
................................................................................
  p->rc = pDb->pMethods->xWrite(pDb, p->aBuf, p->pgsz, iOff);
}


/*
** Take an EXCLUSIVE lock on the database file.
*/
static void rbuLockDatabase(sqlite3rbu *p){
  sqlite3_file *pReal = p->pTargetFd->pReal;
  assert( p->rc==SQLITE_OK );
  p->rc = pReal->pMethods->xLock(pReal, SQLITE_LOCK_SHARED);
  if( p->rc==SQLITE_OK ){
    p->rc = pReal->pMethods->xLock(pReal, SQLITE_LOCK_EXCLUSIVE);
  }
}

/*
** The RBU handle is currently in RBU_STAGE_OAL state, with a SHARED lock
** on the database file. This proc moves the *-oal file to the *-wal path,
** then reopens the database file (this time in vanilla, non-oal, WAL mode).
** If an error occurs, leave an error code and error message in the rbu 
** handle.
*/
static void rbuMoveOalFile(sqlite3rbu *p){
  const char *zBase = sqlite3_db_filename(p->dbMain, "main");

  char *zWal = sqlite3_mprintf("%s-wal", zBase);
  char *zOal = sqlite3_mprintf("%s-oal", zBase);

  assert( p->eStage==RBU_STAGE_MOVE );
  assert( p->rc==SQLITE_OK && p->zErrmsg==0 );
  if( zWal==0 || zOal==0 ){
    p->rc = SQLITE_NOMEM;
  }else{
    /* Move the *-oal file to *-wal. At this point connection p->db is
    ** holding a SHARED lock on the target database file (because it is
    ** in WAL mode). So no other connection may be writing the db. 
    **
    ** In order to ensure that there are no database readers, an EXCLUSIVE
    ** lock is obtained here before the *-oal is moved to *-wal.
    */
    rbuLockDatabase(p);
    if( p->rc==SQLITE_OK ){
      rbuFileSuffix3(zBase, zWal);
      rbuFileSuffix3(zBase, zOal);

      /* Re-open the databases. */
      rbuObjIterFinalize(&p->objiter);
      sqlite3_close(p->dbMain);
      sqlite3_close(p->dbRbu);
      p->rc = rename(zOal, zWal) ? SQLITE_IOERR : SQLITE_OK;
      if( p->rc==SQLITE_OK ){
        p->dbMain = 0;
        p->dbRbu = 0;
        rbuOpenDatabase(p);
        rbuSetupCheckpoint(p, 0);
      }
    }
  }

  sqlite3_free(zWal);
  sqlite3_free(zOal);
}
................................................................................

/*
** The SELECT statement iterating through the keys for the current object
** (p->objiter.pSelect) currently points to a valid row. This function
** determines the type of operation requested by this row and returns
** one of the following values to indicate the result:
**
**     * RBU_INSERT
**     * RBU_DELETE
**     * RBU_IDX_DELETE
**     * RBU_UPDATE
**
** If RBU_UPDATE is returned, then output variable *pzMask is set to
** point to the text value indicating the columns to update.
**
** If the rbu_control field contains an invalid value, an error code and
** message are left in the RBU handle and zero returned.
*/
static int rbuStepType(sqlite3rbu *p, const char **pzMask){
  int iCol = p->objiter.nCol;     /* Index of rbu_control column */
  int res = 0;                    /* Return value */

  switch( sqlite3_column_type(p->objiter.pSelect, iCol) ){
    case SQLITE_INTEGER: {
      int iVal = sqlite3_column_int(p->objiter.pSelect, iCol);
      if( iVal==0 ){
        res = RBU_INSERT;
      }else if( iVal==1 ){
        res = RBU_DELETE;
      }else if( iVal==2 ){
        res = RBU_IDX_DELETE;
      }else if( iVal==3 ){
        res = RBU_IDX_INSERT;
      }
      break;
    }

    case SQLITE_TEXT: {
      const unsigned char *z = sqlite3_column_text(p->objiter.pSelect, iCol);
      if( z==0 ){
        p->rc = SQLITE_NOMEM;
      }else{
        *pzMask = (const char*)z;
      }
      res = RBU_UPDATE;

      break;
    }

    default:
      break;
  }

  if( res==0 ){
    rbuBadControlError(p);
  }
  return res;
}

#ifdef SQLITE_DEBUG
/*
** Assert that column iCol of statement pStmt is named zName.
................................................................................
  assert( 0==sqlite3_stricmp(zName, zCol) );
}
#else
# define assertColumnName(x,y,z)
#endif

/*
** This function does the work for an sqlite3rbu_step() call.
**
** The object-iterator (p->objiter) currently points to a valid object,
** and the input cursor (p->objiter.pSelect) currently points to a valid
** input row. Perform whatever processing is required and return.
**
** If no  error occurs, SQLITE_OK is returned. Otherwise, an error code
** and message is left in the RBU handle and a copy of the error code
** returned.
*/
static int rbuStep(sqlite3rbu *p){
  RbuObjIter *pIter = &p->objiter;
  const char *zMask = 0;
  int i;
  int eType = rbuStepType(p, &zMask);

  if( eType ){
    assert( eType!=RBU_UPDATE || pIter->zIdx==0 );

    if( pIter->zIdx==0 && eType==RBU_IDX_DELETE ){
      rbuBadControlError(p);
    }
    else if( 
        eType==RBU_INSERT 
     || eType==RBU_DELETE
     || eType==RBU_IDX_DELETE 
     || eType==RBU_IDX_INSERT
    ){
      sqlite3_value *pVal;
      sqlite3_stmt *pWriter;

      assert( eType!=RBU_UPDATE );
      assert( eType!=RBU_DELETE || pIter->zIdx==0 );

      if( eType==RBU_IDX_DELETE || eType==RBU_DELETE ){
        pWriter = pIter->pDelete;
      }else{
        pWriter = pIter->pInsert;
      }

      for(i=0; i<pIter->nCol; i++){
        /* If this is an INSERT into a table b-tree and the table has an
        ** explicit INTEGER PRIMARY KEY, check that this is not an attempt
        ** to write a NULL into the IPK column. That is not permitted.  */
        if( eType==RBU_INSERT 
         && pIter->zIdx==0 && pIter->eType==RBU_PK_IPK && pIter->abTblPk[i] 
         && sqlite3_column_type(pIter->pSelect, i)==SQLITE_NULL
        ){
          p->rc = SQLITE_MISMATCH;
          p->zErrmsg = sqlite3_mprintf("datatype mismatch");
          goto step_out;
        }

        if( eType==RBU_DELETE && pIter->abTblPk[i]==0 ){
          continue;
        }

        pVal = sqlite3_column_value(pIter->pSelect, i);
        p->rc = sqlite3_bind_value(pWriter, i+1, pVal);
        if( p->rc ) goto step_out;
      }
      if( pIter->zIdx==0
       && (pIter->eType==RBU_PK_VTAB || pIter->eType==RBU_PK_NONE) 
      ){
        /* For a virtual table, or a table with no primary key, the 
        ** SELECT statement is:
        **
        **   SELECT <cols>, rbu_control, rbu_rowid FROM ....
        **
        ** Hence column_value(pIter->nCol+1).
        */
        assertColumnName(pIter->pSelect, pIter->nCol+1, "rbu_rowid");
        pVal = sqlite3_column_value(pIter->pSelect, pIter->nCol+1);
        p->rc = sqlite3_bind_value(pWriter, pIter->nCol+1, pVal);
      }
      if( p->rc==SQLITE_OK ){
        sqlite3_step(pWriter);
        p->rc = resetAndCollectError(pWriter, &p->zErrmsg);
      }
    }else{
      sqlite3_value *pVal;
      sqlite3_stmt *pUpdate = 0;
      assert( eType==RBU_UPDATE );
      rbuGetUpdateStmt(p, pIter, zMask, &pUpdate);
      if( pUpdate ){
        for(i=0; p->rc==SQLITE_OK && i<pIter->nCol; i++){
          char c = zMask[pIter->aiSrcOrder[i]];
          pVal = sqlite3_column_value(pIter->pSelect, i);
          if( pIter->abTblPk[i] || c=='x' || c=='d' ){
            p->rc = sqlite3_bind_value(pUpdate, i+1, pVal);
          }
        }
        if( p->rc==SQLITE_OK 
         && (pIter->eType==RBU_PK_VTAB || pIter->eType==RBU_PK_NONE) 
        ){
          /* Bind the rbu_rowid value to column _rowid_ */
          assertColumnName(pIter->pSelect, pIter->nCol+1, "rbu_rowid");
          pVal = sqlite3_column_value(pIter->pSelect, pIter->nCol+1);
          p->rc = sqlite3_bind_value(pUpdate, pIter->nCol+1, pVal);
        }
        if( p->rc==SQLITE_OK ){
          sqlite3_step(pUpdate);
          p->rc = resetAndCollectError(pUpdate, &p->zErrmsg);
        }
................................................................................
 step_out:
  return p->rc;
}

/*
** Increment the schema cookie of the main database opened by p->dbMain.
*/
static void rbuIncrSchemaCookie(sqlite3rbu *p){
  if( p->rc==SQLITE_OK ){
    int iCookie = 1000000;
    sqlite3_stmt *pStmt;

    p->rc = prepareAndCollectError(p->dbMain, &pStmt, &p->zErrmsg, 
        "PRAGMA schema_version"
    );
................................................................................
      ** is already a transaction open, so the prepared statement cannot
      ** throw an SQLITE_SCHEMA exception. The only database page the
      ** statement reads is page 1, which is guaranteed to be in the cache.
      ** And no memory allocations are required.  */
      if( SQLITE_ROW==sqlite3_step(pStmt) ){
        iCookie = sqlite3_column_int(pStmt, 0);
      }
      rbuFinalize(p, pStmt);
    }
    if( p->rc==SQLITE_OK ){
      rbuMPrintfExec(p, p->dbMain, "PRAGMA schema_version = %d", iCookie+1);
    }
  }
}

/*
** Update the contents of the rbu_state table within the rbu database. The
** value stored in the RBU_STATE_STAGE column is eStage. All other values
** are determined by inspecting the rbu handle passed as the first argument.
*/
static void rbuSaveState(sqlite3rbu *p, int eStage){
  if( p->rc==SQLITE_OK || p->rc==SQLITE_DONE ){
    sqlite3_stmt *pInsert = 0;
    int rc;

    assert( p->zErrmsg==0 );
    rc = prepareFreeAndCollectError(p->dbRbu, &pInsert, &p->zErrmsg, 
        sqlite3_mprintf(
          "INSERT OR REPLACE INTO %s.rbu_state(k, v) VALUES "
          "(%d, %d), "
          "(%d, %Q), "
          "(%d, %Q), "
          "(%d, %d), "
          "(%d, %d), "
          "(%d, %lld), "
          "(%d, %lld), "
          "(%d, %lld) ",
          p->zStateDb,
          RBU_STATE_STAGE, eStage,
          RBU_STATE_TBL, p->objiter.zTbl, 
          RBU_STATE_IDX, p->objiter.zIdx, 
          RBU_STATE_ROW, p->nStep, 
          RBU_STATE_PROGRESS, p->nProgress,
          RBU_STATE_CKPT, p->iWalCksum,
          RBU_STATE_COOKIE, (i64)p->pTargetFd->iCookie,
          RBU_STATE_OALSZ, p->iOalSz
      )
    );
    assert( pInsert==0 || rc==SQLITE_OK );

    if( rc==SQLITE_OK ){
      sqlite3_step(pInsert);
      rc = sqlite3_finalize(pInsert);
................................................................................
    }
    if( rc!=SQLITE_OK ) p->rc = rc;
  }
}


/*
** Step the RBU object.
*/
SQLITE_API int SQLITE_STDCALL sqlite3rbu_step(sqlite3rbu *p){
  if( p ){
    switch( p->eStage ){
      case RBU_STAGE_OAL: {
        RbuObjIter *pIter = &p->objiter;
        while( p->rc==SQLITE_OK && pIter->zTbl ){

          if( pIter->bCleanup ){
            /* Clean up the rbu_tmp_xxx table for the previous table. It 
            ** cannot be dropped as there are currently active SQL statements.
            ** But the contents can be deleted.  */
            if( pIter->abIndexed ){
              rbuMPrintfExec(p, p->dbRbu, 
                  "DELETE FROM %s.'rbu_tmp_%q'", p->zStateDb, pIter->zTbl
              );
            }
          }else{
            rbuObjIterPrepareAll(p, pIter, 0);

            /* Advance to the next row to process. */
            if( p->rc==SQLITE_OK ){
              int rc = sqlite3_step(pIter->pSelect);
              if( rc==SQLITE_ROW ){
                p->nProgress++;
                p->nStep++;
                return rbuStep(p);
              }
              p->rc = sqlite3_reset(pIter->pSelect);
              p->nStep = 0;
            }
          }

          rbuObjIterNext(p, pIter);
        }

        if( p->rc==SQLITE_OK ){
          assert( pIter->zTbl==0 );
          rbuSaveState(p, RBU_STAGE_MOVE);
          rbuIncrSchemaCookie(p);
          if( p->rc==SQLITE_OK ){
            p->rc = sqlite3_exec(p->dbMain, "COMMIT", 0, 0, &p->zErrmsg);
          }
          if( p->rc==SQLITE_OK ){
            p->rc = sqlite3_exec(p->dbRbu, "COMMIT", 0, 0, &p->zErrmsg);
          }
          p->eStage = RBU_STAGE_MOVE;
        }
        break;
      }

      case RBU_STAGE_MOVE: {
        if( p->rc==SQLITE_OK ){
          rbuMoveOalFile(p);
          p->nProgress++;
        }
        break;
      }

      case RBU_STAGE_CKPT: {
        if( p->rc==SQLITE_OK ){
          if( p->nStep>=p->nFrame ){
            sqlite3_file *pDb = p->pTargetFd->pReal;
  
            /* Sync the db file */
            p->rc = pDb->pMethods->xSync(pDb, SQLITE_SYNC_NORMAL);
  
................................................................................
              p->rc = pDb->pMethods->xShmMap(pDb, 0, 32*1024, 0, &ptr);
              if( p->rc==SQLITE_OK ){
                ((u32 volatile*)ptr)[24] = p->iMaxFrame;
              }
            }
  
            if( p->rc==SQLITE_OK ){
              p->eStage = RBU_STAGE_DONE;
              p->rc = SQLITE_DONE;
            }
          }else{
            RbuFrame *pFrame = &p->aFrame[p->nStep];
            rbuCheckpointFrame(p, pFrame);
            p->nStep++;
          }
          p->nProgress++;
        }
        break;
      }

................................................................................
    return p->rc;
  }else{
    return SQLITE_NOMEM;
  }
}

/*
** Free an RbuState object allocated by rbuLoadState().
*/
static void rbuFreeState(RbuState *p){
  if( p ){
    sqlite3_free(p->zTbl);
    sqlite3_free(p->zIdx);
    sqlite3_free(p);
  }
}

/*
** Allocate an RbuState object and load the contents of the rbu_state 
** table into it. Return a pointer to the new object. It is the 
** responsibility of the caller to eventually free the object using
** sqlite3_free().
**
** If an error occurs, leave an error code and message in the rbu handle
** and return NULL.
*/
static RbuState *rbuLoadState(sqlite3rbu *p){
  RbuState *pRet = 0;
  sqlite3_stmt *pStmt = 0;
  int rc;
  int rc2;

  pRet = (RbuState*)rbuMalloc(p, sizeof(RbuState));
  if( pRet==0 ) return 0;

  rc = prepareFreeAndCollectError(p->dbRbu, &pStmt, &p->zErrmsg, 
      sqlite3_mprintf("SELECT k, v FROM %s.rbu_state", p->zStateDb)
  );
  while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
    switch( sqlite3_column_int(pStmt, 0) ){
      case RBU_STATE_STAGE:
        pRet->eStage = sqlite3_column_int(pStmt, 1);
        if( pRet->eStage!=RBU_STAGE_OAL
         && pRet->eStage!=RBU_STAGE_MOVE
         && pRet->eStage!=RBU_STAGE_CKPT
        ){
          p->rc = SQLITE_CORRUPT;
        }
        break;

      case RBU_STATE_TBL:
        pRet->zTbl = rbuStrndup((char*)sqlite3_column_text(pStmt, 1), &rc);
        break;

      case RBU_STATE_IDX:
        pRet->zIdx = rbuStrndup((char*)sqlite3_column_text(pStmt, 1), &rc);
        break;

      case RBU_STATE_ROW:
        pRet->nRow = sqlite3_column_int(pStmt, 1);
        break;

      case RBU_STATE_PROGRESS:
        pRet->nProgress = sqlite3_column_int64(pStmt, 1);
        break;

      case RBU_STATE_CKPT:
        pRet->iWalCksum = sqlite3_column_int64(pStmt, 1);
        break;

      case RBU_STATE_COOKIE:
        pRet->iCookie = (u32)sqlite3_column_int64(pStmt, 1);
        break;

      case RBU_STATE_OALSZ:
        pRet->iOalSz = (u32)sqlite3_column_int64(pStmt, 1);
        break;

      default:
        rc = SQLITE_CORRUPT;
        break;
    }
................................................................................
}

/*
** Compare strings z1 and z2, returning 0 if they are identical, or non-zero
** otherwise. Either or both argument may be NULL. Two NULL values are
** considered equal, and NULL is considered distinct from all other values.
*/
static int rbuStrCompare(const char *z1, const char *z2){
  if( z1==0 && z2==0 ) return 0;
  if( z1==0 || z2==0 ) return 1;
  return (sqlite3_stricmp(z1, z2)!=0);
}

/*
** This function is called as part of sqlite3rbu_open() when initializing
** an rbu handle in OAL stage. If the rbu update has not started (i.e.
** the rbu_state table was empty) it is a no-op. Otherwise, it arranges
** things so that the next call to sqlite3rbu_step() continues on from
** where the previous rbu handle left off.
**
** If an error occurs, an error code and error message are left in the
** rbu handle passed as the first argument.
*/
static void rbuSetupOal(sqlite3rbu *p, RbuState *pState){
  assert( p->rc==SQLITE_OK );
  if( pState->zTbl ){
    RbuObjIter *pIter = &p->objiter;
    int rc = SQLITE_OK;

    while( rc==SQLITE_OK && pIter->zTbl && (pIter->bCleanup 
       || rbuStrCompare(pIter->zIdx, pState->zIdx)
       || rbuStrCompare(pIter->zTbl, pState->zTbl) 
    )){
      rc = rbuObjIterNext(p, pIter);
    }

    if( rc==SQLITE_OK && !pIter->zTbl ){
      rc = SQLITE_ERROR;
      p->zErrmsg = sqlite3_mprintf("rbu_state mismatch error");
    }

    if( rc==SQLITE_OK ){
      p->nStep = pState->nRow;
      rc = rbuObjIterPrepareAll(p, &p->objiter, p->nStep);
    }

    p->rc = rc;
  }
}

/*
** If there is a "*-oal" file in the file-system corresponding to the
** target database in the file-system, delete it. If an error occurs,
** leave an error code and error message in the rbu handle.
*/
static void rbuDeleteOalFile(sqlite3rbu *p){
  char *zOal = sqlite3_mprintf("%s-oal", p->zTarget);
  assert( p->rc==SQLITE_OK && p->zErrmsg==0 );
  unlink(zOal);
  sqlite3_free(zOal);
}

/*
** Allocate a private rbu VFS for the rbu handle passed as the only
** argument. This VFS will be used unless the call to sqlite3rbu_open()
** specified a URI with a vfs=? option in place of a target database
** file name.
*/
static void rbuCreateVfs(sqlite3rbu *p){
  int rnd;
  char zRnd[64];

  assert( p->rc==SQLITE_OK );
  sqlite3_randomness(sizeof(int), (void*)&rnd);
  sprintf(zRnd, "rbu_vfs_%d", rnd);
  p->rc = sqlite3rbu_create_vfs(zRnd, 0);
  if( p->rc==SQLITE_OK ){
    sqlite3_vfs *pVfs = sqlite3_vfs_find(zRnd);
    assert( pVfs );
    p->zVfsName = pVfs->zName;
  }
}

/*
** Destroy the private VFS created for the rbu handle passed as the only
** argument by an earlier call to rbuCreateVfs().
*/
static void rbuDeleteVfs(sqlite3rbu *p){
  if( p->zVfsName ){
    sqlite3rbu_destroy_vfs(p->zVfsName);
    p->zVfsName = 0;
  }
}

/*
** Open and return a new RBU handle. 
*/
SQLITE_API sqlite3rbu *SQLITE_STDCALL sqlite3rbu_open(
  const char *zTarget, 
  const char *zRbu,
  const char *zState
){
  sqlite3rbu *p;
  int nTarget = strlen(zTarget);
  int nRbu = strlen(zRbu);
  int nState = zState ? strlen(zState) : 0;

  p = (sqlite3rbu*)sqlite3_malloc(sizeof(sqlite3rbu)+nTarget+1+nRbu+1+nState+1);
  if( p ){
    RbuState *pState = 0;

    /* Create the custom VFS. */
    memset(p, 0, sizeof(sqlite3rbu));
    rbuCreateVfs(p);

    /* Open the target database */
    if( p->rc==SQLITE_OK ){
      p->zTarget = (char*)&p[1];
      memcpy(p->zTarget, zTarget, nTarget+1);
      p->zRbu = &p->zTarget[nTarget+1];
      memcpy(p->zRbu, zRbu, nRbu+1);
      if( zState ){
        p->zState = &p->zRbu[nRbu+1];
        memcpy(p->zState, zState, nState+1);
      }
      rbuOpenDatabase(p);
    }

    /* If it has not already been created, create the rbu_state table */
    rbuMPrintfExec(p, p->dbRbu, RBU_CREATE_STATE, p->zStateDb);

    if( p->rc==SQLITE_OK ){
      pState = rbuLoadState(p);
      assert( pState || p->rc!=SQLITE_OK );
      if( p->rc==SQLITE_OK ){

        if( pState->eStage==0 ){ 
          rbuDeleteOalFile(p);
          p->eStage = RBU_STAGE_OAL;
        }else{
          p->eStage = pState->eStage;
        }
        p->nProgress = pState->nProgress;
        p->iOalSz = pState->iOalSz;
      }
    }
    assert( p->rc!=SQLITE_OK || p->eStage!=0 );

    if( p->rc==SQLITE_OK && p->pTargetFd->pWalFd ){
      if( p->eStage==RBU_STAGE_OAL ){
        p->rc = SQLITE_ERROR;
        p->zErrmsg = sqlite3_mprintf("cannot update wal mode database");
      }else if( p->eStage==RBU_STAGE_MOVE ){
        p->eStage = RBU_STAGE_CKPT;
        p->nStep = 0;
      }
    }

    if( p->rc==SQLITE_OK
     && (p->eStage==RBU_STAGE_OAL || p->eStage==RBU_STAGE_MOVE)
     && pState->eStage!=0 && p->pTargetFd->iCookie!=pState->iCookie
    ){   
      /* At this point (pTargetFd->iCookie) contains the value of the
      ** change-counter cookie (the thing that gets incremented when a 
      ** transaction is committed in rollback mode) currently stored on 
      ** page 1 of the database file. */
      p->rc = SQLITE_BUSY;
      p->zErrmsg = sqlite3_mprintf("database modified during rbu update");
    }

    if( p->rc==SQLITE_OK ){
      if( p->eStage==RBU_STAGE_OAL ){

        /* Open transactions both databases. The *-oal file is opened or
        ** created at this point. */
        p->rc = sqlite3_exec(p->dbMain, "BEGIN IMMEDIATE", 0, 0, &p->zErrmsg);
        if( p->rc==SQLITE_OK ){
          p->rc = sqlite3_exec(p->dbRbu, "BEGIN IMMEDIATE", 0, 0, &p->zErrmsg);
        }
  
        /* Point the object iterator at the first object */
        if( p->rc==SQLITE_OK ){
          p->rc = rbuObjIterFirst(p, &p->objiter);
        }

        /* If the RBU database contains no data_xxx tables, declare the RBU
        ** update finished.  */
        if( p->rc==SQLITE_OK && p->objiter.zTbl==0 ){
          p->rc = SQLITE_DONE;
        }

        if( p->rc==SQLITE_OK ){
          rbuSetupOal(p, pState);
        }

      }else if( p->eStage==RBU_STAGE_MOVE ){
        /* no-op */
      }else if( p->eStage==RBU_STAGE_CKPT ){
        rbuSetupCheckpoint(p, pState);
      }else if( p->eStage==RBU_STAGE_DONE ){
        p->rc = SQLITE_DONE;
      }else{
        p->rc = SQLITE_CORRUPT;
      }
    }

    rbuFreeState(pState);
  }

  return p;
}


/*
** Return the database handle used by pRbu.
*/
SQLITE_API sqlite3 *SQLITE_STDCALL sqlite3rbu_db(sqlite3rbu *pRbu, int bRbu){
  sqlite3 *db = 0;
  if( pRbu ){
    db = (bRbu ? pRbu->dbRbu : pRbu->dbMain);
  }
  return db;
}


/*
** If the error code currently stored in the RBU handle is SQLITE_CONSTRAINT,
** then edit any error message string so as to remove all occurrences of
** the pattern "rbu_imp_[0-9]*".
*/
static void rbuEditErrmsg(sqlite3rbu *p){
  if( p->rc==SQLITE_CONSTRAINT && p->zErrmsg ){
    int i;
    int nErrmsg = strlen(p->zErrmsg);
    for(i=0; i<(nErrmsg-8); i++){
      if( memcmp(&p->zErrmsg[i], "rbu_imp_", 8)==0 ){
        int nDel = 8;
        while( p->zErrmsg[i+nDel]>='0' && p->zErrmsg[i+nDel]<='9' ) nDel++;
        memmove(&p->zErrmsg[i], &p->zErrmsg[i+nDel], nErrmsg + 1 - i - nDel);
        nErrmsg -= nDel;
      }
    }
  }
}

/*
** Close the RBU handle.
*/
SQLITE_API int SQLITE_STDCALL sqlite3rbu_close(sqlite3rbu *p, char **pzErrmsg){
  int rc;
  if( p ){

    /* Commit the transaction to the *-oal file. */
    if( p->rc==SQLITE_OK && p->eStage==RBU_STAGE_OAL ){
      p->rc = sqlite3_exec(p->dbMain, "COMMIT", 0, 0, &p->zErrmsg);
    }

    rbuSaveState(p, p->eStage);

    if( p->rc==SQLITE_OK && p->eStage==RBU_STAGE_OAL ){
      p->rc = sqlite3_exec(p->dbRbu, "COMMIT", 0, 0, &p->zErrmsg);
    }

    /* Close any open statement handles. */
    rbuObjIterFinalize(&p->objiter);

    /* Close the open database handle and VFS object. */
    sqlite3_close(p->dbMain);
    sqlite3_close(p->dbRbu);
    rbuDeleteVfs(p);
    sqlite3_free(p->aBuf);
    sqlite3_free(p->aFrame);

    rbuEditErrmsg(p);
    rc = p->rc;
    *pzErrmsg = p->zErrmsg;
    sqlite3_free(p);
  }else{
    rc = SQLITE_NOMEM;
    *pzErrmsg = 0;
  }
  return rc;
}

/*
** Return the total number of key-value operations (inserts, deletes or 
** updates) that have been performed on the target database since the
** current RBU update was started.
*/
SQLITE_API sqlite3_int64 SQLITE_STDCALL sqlite3rbu_progress(sqlite3rbu *pRbu){
  return pRbu->nProgress;
}

/**************************************************************************
** Beginning of RBU VFS shim methods. The VFS shim modifies the behaviour
** of a standard VFS in the following ways:
**
** 1. Whenever the first page of a main database file is read or 
**    written, the value of the change-counter cookie is stored in
**    rbu_file.iCookie. Similarly, the value of the "write-version"
**    database header field is stored in rbu_file.iWriteVer. This ensures
**    that the values are always trustworthy within an open transaction.
**
** 2. Whenever an SQLITE_OPEN_WAL file is opened, the (rbu_file.pWalFd)
**    member variable of the associated database file descriptor is set
**    to point to the new file. A mutex protected linked list of all main 
**    db fds opened using a particular RBU VFS is maintained at 
**    rbu_vfs.pMain to facilitate this.
**
** 3. Using a new file-control "SQLITE_FCNTL_RBU", a main db rbu_file 
**    object can be marked as the target database of an RBU update. This
**    turns on the following extra special behaviour:
**
** 3a. If xAccess() is called to check if there exists a *-wal file 
**     associated with an RBU target database currently in RBU_STAGE_OAL
**     stage (preparing the *-oal file), the following special handling
**     applies:
**
**      * if the *-wal file does exist, return SQLITE_CANTOPEN. An RBU
**        target database may not be in wal mode already.
**
**      * if the *-wal file does not exist, set the output parameter to
**        non-zero (to tell SQLite that it does exist) anyway.
**
**     Then, when xOpen() is called to open the *-wal file associated with
**     the RBU target in RBU_STAGE_OAL stage, instead of opening the *-wal
**     file, the rbu vfs opens the corresponding *-oal file instead. 
**
** 3b. The *-shm pages returned by xShmMap() for a target db file in
**     RBU_STAGE_OAL mode are actually stored in heap memory. This is to
**     avoid creating a *-shm file on disk. Additionally, xShmLock() calls
**     are no-ops on target database files in RBU_STAGE_OAL mode. This is
**     because assert() statements in some VFS implementations fail if 
**     xShmLock() is called before xShmMap().
**
** 3c. If an EXCLUSIVE lock is attempted on a target database file in any
**     mode except RBU_STAGE_DONE (all work completed and checkpointed), it 
**     fails with an SQLITE_BUSY error. This is to stop RBU connections
**     from automatically checkpointing a *-wal (or *-oal) file from within
**     sqlite3_close().
**
** 3d. In RBU_STAGE_CAPTURE mode, all xRead() calls on the wal file, and
**     all xWrite() calls on the target database file perform no IO. 
**     Instead the frame and page numbers that would be read and written
**     are recorded. Additionally, successful attempts to obtain exclusive
**     xShmLock() WRITER, CHECKPOINTER and READ0 locks on the target 
**     database file are recorded. xShmLock() calls to unlock the same
**     locks are no-ops (so that once obtained, these locks are never
**     relinquished). Finally, calls to xSync() on the target database
**     file fail with SQLITE_INTERNAL errors.
*/

static void rbuUnlockShm(rbu_file *p){
  if( p->pRbu ){
    int (*xShmLock)(sqlite3_file*,int,int,int) = p->pReal->pMethods->xShmLock;
    int i;
    for(i=0; i<SQLITE_SHM_NLOCK;i++){
      if( (1<<i) & p->pRbu->mLock ){
        xShmLock(p->pReal, i, 1, SQLITE_SHM_UNLOCK|SQLITE_SHM_EXCLUSIVE);
      }
    }
    p->pRbu->mLock = 0;
  }
}

/*
** Close an rbu file.
*/
static int rbuVfsClose(sqlite3_file *pFile){
  rbu_file *p = (rbu_file*)pFile;
  int rc;
  int i;

  /* Free the contents of the apShm[] array. And the array itself. */
  for(i=0; i<p->nShm; i++){
    sqlite3_free(p->apShm[i]);
  }
  sqlite3_free(p->apShm);
  p->apShm = 0;
  sqlite3_free(p->zDel);

  if( p->openFlags & SQLITE_OPEN_MAIN_DB ){
    rbu_file **pp;
    sqlite3_mutex_enter(p->pRbuVfs->mutex);
    for(pp=&p->pRbuVfs->pMain; *pp!=p; pp=&((*pp)->pMainNext));
    *pp = p->pMainNext;
    sqlite3_mutex_leave(p->pRbuVfs->mutex);
    rbuUnlockShm(p);
    p->pReal->pMethods->xShmUnmap(p->pReal, 0);
  }

  /* Close the underlying file handle */
  rc = p->pReal->pMethods->xClose(p->pReal);
  return rc;
}


/*
** Read and return an unsigned 32-bit big-endian integer from the buffer 
** passed as the only argument.
*/
static u32 rbuGetU32(u8 *aBuf){
  return ((u32)aBuf[0] << 24)
       + ((u32)aBuf[1] << 16)
       + ((u32)aBuf[2] <<  8)
       + ((u32)aBuf[3]);
}

/*
** Read data from an rbuVfs-file.
*/
static int rbuVfsRead(
  sqlite3_file *pFile, 
  void *zBuf, 
  int iAmt, 
  sqlite_int64 iOfst
){
  rbu_file *p = (rbu_file*)pFile;
  sqlite3rbu *pRbu = p->pRbu;
  int rc;

  if( pRbu && pRbu->eStage==RBU_STAGE_CAPTURE ){
    assert( p->openFlags & SQLITE_OPEN_WAL );
    rc = rbuCaptureWalRead(p->pRbu, iOfst, iAmt);
  }else{
    if( pRbu && pRbu->eStage==RBU_STAGE_OAL 
     && (p->openFlags & SQLITE_OPEN_WAL) 
     && iOfst>=pRbu->iOalSz 
    ){
      rc = SQLITE_OK;
      memset(zBuf, 0, iAmt);
    }else{
      rc = p->pReal->pMethods->xRead(p->pReal, zBuf, iAmt, iOfst);
    }
    if( rc==SQLITE_OK && iOfst==0 && (p->openFlags & SQLITE_OPEN_MAIN_DB) ){
      /* These look like magic numbers. But they are stable, as they are part
       ** of the definition of the SQLite file format, which may not change. */
      u8 *pBuf = (u8*)zBuf;
      p->iCookie = rbuGetU32(&pBuf[24]);
      p->iWriteVer = pBuf[19];
    }
  }
  return rc;
}

/*
** Write data to an rbuVfs-file.
*/
static int rbuVfsWrite(
  sqlite3_file *pFile, 
  const void *zBuf, 
  int iAmt, 
  sqlite_int64 iOfst
){
  rbu_file *p = (rbu_file*)pFile;
  sqlite3rbu *pRbu = p->pRbu;
  int rc;

  if( pRbu && pRbu->eStage==RBU_STAGE_CAPTURE ){
    assert( p->openFlags & SQLITE_OPEN_MAIN_DB );
    rc = rbuCaptureDbWrite(p->pRbu, iOfst);
  }else{
    if( pRbu && pRbu->eStage==RBU_STAGE_OAL 
     && (p->openFlags & SQLITE_OPEN_WAL) 
     && iOfst>=pRbu->iOalSz
    ){
      pRbu->iOalSz = iAmt + iOfst;
    }
    rc = p->pReal->pMethods->xWrite(p->pReal, zBuf, iAmt, iOfst);
    if( rc==SQLITE_OK && iOfst==0 && (p->openFlags & SQLITE_OPEN_MAIN_DB) ){
      /* These look like magic numbers. But they are stable, as they are part
      ** of the definition of the SQLite file format, which may not change. */
      u8 *pBuf = (u8*)zBuf;
      p->iCookie = rbuGetU32(&pBuf[24]);
      p->iWriteVer = pBuf[19];
    }
  }
  return rc;
}

/*
** Truncate an rbuVfs-file.
*/
static int rbuVfsTruncate(sqlite3_file *pFile, sqlite_int64 size){
  rbu_file *p = (rbu_file*)pFile;
  return p->pReal->pMethods->xTruncate(p->pReal, size);
}

/*
** Sync an rbuVfs-file.
*/
static int rbuVfsSync(sqlite3_file *pFile, int flags){
  rbu_file *p = (rbu_file *)pFile;
  if( p->pRbu && p->pRbu->eStage==RBU_STAGE_CAPTURE ){
    if( p->openFlags & SQLITE_OPEN_MAIN_DB ){
      return SQLITE_INTERNAL;
    }
    return SQLITE_OK;
  }
  return p->pReal->pMethods->xSync(p->pReal, flags);
}

/*
** Return the current file-size of an rbuVfs-file.
*/
static int rbuVfsFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){
  rbu_file *p = (rbu_file *)pFile;
  return p->pReal->pMethods->xFileSize(p->pReal, pSize);
}

/*
** Lock an rbuVfs-file.
*/
static int rbuVfsLock(sqlite3_file *pFile, int eLock){
  rbu_file *p = (rbu_file*)pFile;
  sqlite3rbu *pRbu = p->pRbu;
  int rc = SQLITE_OK;

  assert( p->openFlags & (SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_TEMP_DB) );
  if( pRbu && eLock==SQLITE_LOCK_EXCLUSIVE && pRbu->eStage!=RBU_STAGE_DONE ){
    /* Do not allow EXCLUSIVE locks. Preventing SQLite from taking this 
    ** prevents it from checkpointing the database from sqlite3_close(). */
    rc = SQLITE_BUSY;
  }else{
    rc = p->pReal->pMethods->xLock(p->pReal, eLock);
  }

  return rc;
}

/*
** Unlock an rbuVfs-file.
*/
static int rbuVfsUnlock(sqlite3_file *pFile, int eLock){
  rbu_file *p = (rbu_file *)pFile;
  return p->pReal->pMethods->xUnlock(p->pReal, eLock);
}

/*
** Check if another file-handle holds a RESERVED lock on an rbuVfs-file.
*/
static int rbuVfsCheckReservedLock(sqlite3_file *pFile, int *pResOut){
  rbu_file *p = (rbu_file *)pFile;
  return p->pReal->pMethods->xCheckReservedLock(p->pReal, pResOut);
}

/*
** File control method. For custom operations on an rbuVfs-file.
*/
static int rbuVfsFileControl(sqlite3_file *pFile, int op, void *pArg){
  rbu_file *p = (rbu_file *)pFile;
  int (*xControl)(sqlite3_file*,int,void*) = p->pReal->pMethods->xFileControl;
  int rc;

  assert( p->openFlags & (SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_TEMP_DB)
       || p->openFlags & (SQLITE_OPEN_TRANSIENT_DB|SQLITE_OPEN_TEMP_JOURNAL)
  );
  if( op==SQLITE_FCNTL_RBU ){
    sqlite3rbu *pRbu = (sqlite3rbu*)pArg;

    /* First try to find another RBU vfs lower down in the vfs stack. If
    ** one is found, this vfs will operate in pass-through mode. The lower
    ** level vfs will do the special RBU handling.  */
    rc = xControl(p->pReal, op, pArg);

    if( rc==SQLITE_NOTFOUND ){
      /* Now search for a zipvfs instance lower down in the VFS stack. If
      ** one is found, this is an error.  */
      void *dummy = 0;
      rc = xControl(p->pReal, SQLITE_FCNTL_ZIPVFS, &dummy);
      if( rc==SQLITE_OK ){
        rc = SQLITE_ERROR;
        pRbu->zErrmsg = sqlite3_mprintf("rbu/zipvfs setup error");
      }else if( rc==SQLITE_NOTFOUND ){
        pRbu->pTargetFd = p;
        p->pRbu = pRbu;
        if( p->pWalFd ) p->pWalFd->pRbu = pRbu;
        rc = SQLITE_OK;
      }
    }
    return rc;
  }

  rc = xControl(p->pReal, op, pArg);
  if( rc==SQLITE_OK && op==SQLITE_FCNTL_VFSNAME ){
    rbu_vfs *pRbuVfs = p->pRbuVfs;
    char *zIn = *(char**)pArg;
    char *zOut = sqlite3_mprintf("rbu(%s)/%z", pRbuVfs->base.zName, zIn);
    *(char**)pArg = zOut;
    if( zOut==0 ) rc = SQLITE_NOMEM;
  }

  return rc;
}

/*
** Return the sector-size in bytes for an rbuVfs-file.
*/
static int rbuVfsSectorSize(sqlite3_file *pFile){
  rbu_file *p = (rbu_file *)pFile;
  return p->pReal->pMethods->xSectorSize(p->pReal);
}

/*
** Return the device characteristic flags supported by an rbuVfs-file.
*/
static int rbuVfsDeviceCharacteristics(sqlite3_file *pFile){
  rbu_file *p = (rbu_file *)pFile;
  return p->pReal->pMethods->xDeviceCharacteristics(p->pReal);
}

/*
** Take or release a shared-memory lock.
*/
static int rbuVfsShmLock(sqlite3_file *pFile, int ofst, int n, int flags){
  rbu_file *p = (rbu_file*)pFile;
  sqlite3rbu *pRbu = p->pRbu;
  int rc = SQLITE_OK;

#ifdef SQLITE_AMALGAMATION
    assert( WAL_CKPT_LOCK==1 );
#endif

  assert( p->openFlags & (SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_TEMP_DB) );
  if( pRbu && (pRbu->eStage==RBU_STAGE_OAL || pRbu->eStage==RBU_STAGE_MOVE) ){
    /* Magic number 1 is the WAL_CKPT_LOCK lock. Preventing SQLite from
    ** taking this lock also prevents any checkpoints from occurring. 
    ** todo: really, it's not clear why this might occur, as 
    ** wal_autocheckpoint ought to be turned off.  */
    if( ofst==WAL_LOCK_CKPT && n==1 ) rc = SQLITE_BUSY;
  }else{
    int bCapture = 0;
    if( n==1 && (flags & SQLITE_SHM_EXCLUSIVE)
     && pRbu && pRbu->eStage==RBU_STAGE_CAPTURE
     && (ofst==WAL_LOCK_WRITE || ofst==WAL_LOCK_CKPT || ofst==WAL_LOCK_READ0)
    ){
      bCapture = 1;
    }

    if( bCapture==0 || 0==(flags & SQLITE_SHM_UNLOCK) ){
      rc = p->pReal->pMethods->xShmLock(p->pReal, ofst, n, flags);
      if( bCapture && rc==SQLITE_OK ){
        pRbu->mLock |= (1 << ofst);
      }
    }
  }

  return rc;
}

/*
** Obtain a pointer to a mapping of a single 32KiB page of the *-shm file.
*/
static int rbuVfsShmMap(
  sqlite3_file *pFile, 
  int iRegion, 
  int szRegion, 
  int isWrite, 
  void volatile **pp
){
  rbu_file *p = (rbu_file*)pFile;
  int rc = SQLITE_OK;
  int eStage = (p->pRbu ? p->pRbu->eStage : 0);

  /* If not in RBU_STAGE_OAL, allow this call to pass through. Or, if this
  ** rbu is in the RBU_STAGE_OAL state, use heap memory for *-shm space 
  ** instead of a file on disk.  */
  assert( p->openFlags & (SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_TEMP_DB) );
  if( eStage==RBU_STAGE_OAL || eStage==RBU_STAGE_MOVE ){
    if( iRegion<=p->nShm ){
      int nByte = (iRegion+1) * sizeof(char*);
      char **apNew = (char**)sqlite3_realloc(p->apShm, nByte);
      if( apNew==0 ){
        rc = SQLITE_NOMEM;
      }else{
        memset(&apNew[p->nShm], 0, sizeof(char*) * (1 + iRegion - p->nShm));
................................................................................

  return rc;
}

/*
** Memory barrier.
*/
static void rbuVfsShmBarrier(sqlite3_file *pFile){
  rbu_file *p = (rbu_file *)pFile;
  p->pReal->pMethods->xShmBarrier(p->pReal);
}

/*
** The xShmUnmap method.
*/
static int rbuVfsShmUnmap(sqlite3_file *pFile, int delFlag){
  rbu_file *p = (rbu_file*)pFile;
  int rc = SQLITE_OK;
  int eStage = (p->pRbu ? p->pRbu->eStage : 0);

  assert( p->openFlags & (SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_TEMP_DB) );
  if( eStage==RBU_STAGE_OAL || eStage==RBU_STAGE_MOVE ){
    /* no-op */
  }else{
    /* Release the checkpointer and writer locks */
    rbuUnlockShm(p);
    rc = p->pReal->pMethods->xShmUnmap(p->pReal, delFlag);
  }
  return rc;
}

/*
** Given that zWal points to a buffer containing a wal file name passed to 
** either the xOpen() or xAccess() VFS method, return a pointer to the
** file-handle opened by the same database connection on the corresponding
** database file.
*/
static rbu_file *rbuFindMaindb(rbu_vfs *pRbuVfs, const char *zWal){
  rbu_file *pDb;
  sqlite3_mutex_enter(pRbuVfs->mutex);
  for(pDb=pRbuVfs->pMain; pDb && pDb->zWal!=zWal; pDb=pDb->pMainNext);
  sqlite3_mutex_leave(pRbuVfs->mutex);
  return pDb;
}

/*
** Open an rbu file handle.
*/
static int rbuVfsOpen(
  sqlite3_vfs *pVfs,
  const char *zName,
  sqlite3_file *pFile,
  int flags,
  int *pOutFlags
){
  static sqlite3_io_methods rbuvfs_io_methods = {
    2,                            /* iVersion */
    rbuVfsClose,                  /* xClose */
    rbuVfsRead,                   /* xRead */
    rbuVfsWrite,                  /* xWrite */
    rbuVfsTruncate,               /* xTruncate */
    rbuVfsSync,                   /* xSync */
    rbuVfsFileSize,               /* xFileSize */
    rbuVfsLock,                   /* xLock */
    rbuVfsUnlock,                 /* xUnlock */
    rbuVfsCheckReservedLock,      /* xCheckReservedLock */
    rbuVfsFileControl,            /* xFileControl */
    rbuVfsSectorSize,             /* xSectorSize */
    rbuVfsDeviceCharacteristics,  /* xDeviceCharacteristics */
    rbuVfsShmMap,                 /* xShmMap */
    rbuVfsShmLock,                /* xShmLock */
    rbuVfsShmBarrier,             /* xShmBarrier */
    rbuVfsShmUnmap                /* xShmUnmap */
  };
  rbu_vfs *pRbuVfs = (rbu_vfs*)pVfs;
  sqlite3_vfs *pRealVfs = pRbuVfs->pRealVfs;
  rbu_file *pFd = (rbu_file *)pFile;
  int rc = SQLITE_OK;
  const char *zOpen = zName;

  memset(pFd, 0, sizeof(rbu_file));
  pFd->pReal = (sqlite3_file*)&pFd[1];
  pFd->pRbuVfs = pRbuVfs;
  pFd->openFlags = flags;
  if( zName ){
    if( flags & SQLITE_OPEN_MAIN_DB ){
      /* A main database has just been opened. The following block sets
      ** (pFd->zWal) to point to a buffer owned by SQLite that contains
      ** the name of the *-wal file this db connection will use. SQLite
      ** happens to pass a pointer to this buffer when using xAccess()
................................................................................
      }else{
        while( *z==0 ) z++;
      }
      z += (n + 8 + 1);
      pFd->zWal = z;
    }
    else if( flags & SQLITE_OPEN_WAL ){
      rbu_file *pDb = rbuFindMaindb(pRbuVfs, zName);
      if( pDb ){
        if( pDb->pRbu && pDb->pRbu->eStage==RBU_STAGE_OAL ){
          /* This call is to open a *-wal file. Intead, open the *-oal. This
          ** code ensures that the string passed to xOpen() is terminated by a
          ** pair of '\0' bytes in case the VFS attempts to extract a URI 
          ** parameter from it.  */
          int nCopy = strlen(zName);
          char *zCopy = sqlite3_malloc(nCopy+2);
          if( zCopy ){
................................................................................
            zCopy[nCopy-3] = 'o';
            zCopy[nCopy] = '\0';
            zCopy[nCopy+1] = '\0';
            zOpen = (const char*)(pFd->zDel = zCopy);
          }else{
            rc = SQLITE_NOMEM;
          }
          pFd->pRbu = pDb->pRbu;
        }
        pDb->pWalFd = pFd;
      }
    }
  }

  if( rc==SQLITE_OK ){
    rc = pRealVfs->xOpen(pRealVfs, zOpen, pFd->pReal, flags, pOutFlags);
  }
  if( pFd->pReal->pMethods ){
    /* The xOpen() operation has succeeded. Set the sqlite3_file.pMethods
    ** pointer and, if the file is a main database file, link it into the
    ** mutex protected linked list of all such files.  */
    pFile->pMethods = &rbuvfs_io_methods;
    if( flags & SQLITE_OPEN_MAIN_DB ){
      sqlite3_mutex_enter(pRbuVfs->mutex);
      pFd->pMainNext = pRbuVfs->pMain;
      pRbuVfs->pMain = pFd;
      sqlite3_mutex_leave(pRbuVfs->mutex);
    }
  }else{
    sqlite3_free(pFd->zDel);
  }

  return rc;
}

/*
** Delete the file located at zPath.
*/
static int rbuVfsDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
  sqlite3_vfs *pRealVfs = ((rbu_vfs*)pVfs)->pRealVfs;
  return pRealVfs->xDelete(pRealVfs, zPath, dirSync);
}

/*
** Test for access permissions. Return true if the requested permission
** is available, or false otherwise.
*/
static int rbuVfsAccess(
  sqlite3_vfs *pVfs, 
  const char *zPath, 
  int flags, 
  int *pResOut
){
  rbu_vfs *pRbuVfs = (rbu_vfs*)pVfs;
  sqlite3_vfs *pRealVfs = pRbuVfs->pRealVfs;
  int rc;

  rc = pRealVfs->xAccess(pRealVfs, zPath, flags, pResOut);

  /* If this call is to check if a *-wal file associated with an RBU target
  ** database connection exists, and the RBU update is in RBU_STAGE_OAL,
  ** the following special handling is activated:
  **
  **   a) if the *-wal file does exist, return SQLITE_CANTOPEN. This
  **      ensures that the RBU extension never tries to update a database
  **      in wal mode, even if the first page of the database file has
  **      been damaged. 
  **
  **   b) if the *-wal file does not exist, claim that it does anyway,
  **      causing SQLite to call xOpen() to open it. This call will also
  **      be intercepted (see the rbuVfsOpen() function) and the *-oal
  **      file opened instead.
  */
  if( rc==SQLITE_OK && flags==SQLITE_ACCESS_EXISTS ){
    rbu_file *pDb = rbuFindMaindb(pRbuVfs, zPath);
    if( pDb && pDb->pRbu && pDb->pRbu->eStage==RBU_STAGE_OAL ){
      if( *pResOut ){
        rc = SQLITE_CANTOPEN;
      }else{
        *pResOut = 1;
      }
    }
  }
................................................................................
}

/*
** Populate buffer zOut with the full canonical pathname corresponding
** to the pathname in zPath. zOut is guaranteed to point to a buffer
** of at least (DEVSYM_MAX_PATHNAME+1) bytes.
*/
static int rbuVfsFullPathname(
  sqlite3_vfs *pVfs, 
  const char *zPath, 
  int nOut, 
  char *zOut
){
  sqlite3_vfs *pRealVfs = ((rbu_vfs*)pVfs)->pRealVfs;
  return pRealVfs->xFullPathname(pRealVfs, zPath, nOut, zOut);
}

#ifndef SQLITE_OMIT_LOAD_EXTENSION
/*
** Open the dynamic library located at zPath and return a handle.
*/
static void *rbuVfsDlOpen(sqlite3_vfs *pVfs, const char *zPath){
  sqlite3_vfs *pRealVfs = ((rbu_vfs*)pVfs)->pRealVfs;
  return pRealVfs->xDlOpen(pRealVfs, zPath);
}

/*
** Populate the buffer zErrMsg (size nByte bytes) with a human readable
** utf-8 string describing the most recent error encountered associated 
** with dynamic libraries.
*/
static void rbuVfsDlError(sqlite3_vfs *pVfs, int nByte, char *zErrMsg){
  sqlite3_vfs *pRealVfs = ((rbu_vfs*)pVfs)->pRealVfs;
  pRealVfs->xDlError(pRealVfs, nByte, zErrMsg);
}

/*
** Return a pointer to the symbol zSymbol in the dynamic library pHandle.
*/
static void (*rbuVfsDlSym(
  sqlite3_vfs *pVfs, 
  void *pArg, 
  const char *zSym
))(void){
  sqlite3_vfs *pRealVfs = ((rbu_vfs*)pVfs)->pRealVfs;
  return pRealVfs->xDlSym(pRealVfs, pArg, zSym);
}

/*
** Close the dynamic library handle pHandle.
*/
static void rbuVfsDlClose(sqlite3_vfs *pVfs, void *pHandle){
  sqlite3_vfs *pRealVfs = ((rbu_vfs*)pVfs)->pRealVfs;
  return pRealVfs->xDlClose(pRealVfs, pHandle);
}
#endif /* SQLITE_OMIT_LOAD_EXTENSION */

/*
** Populate the buffer pointed to by zBufOut with nByte bytes of 
** random data.
*/
static int rbuVfsRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
  sqlite3_vfs *pRealVfs = ((rbu_vfs*)pVfs)->pRealVfs;
  return pRealVfs->xRandomness(pRealVfs, nByte, zBufOut);
}

/*
** Sleep for nMicro microseconds. Return the number of microseconds 
** actually slept.
*/
static int rbuVfsSleep(sqlite3_vfs *pVfs, int nMicro){
  sqlite3_vfs *pRealVfs = ((rbu_vfs*)pVfs)->pRealVfs;
  return pRealVfs->xSleep(pRealVfs, nMicro);
}

/*
** Return the current time as a Julian Day number in *pTimeOut.
*/
static int rbuVfsCurrentTime(sqlite3_vfs *pVfs, double *pTimeOut){
  sqlite3_vfs *pRealVfs = ((rbu_vfs*)pVfs)->pRealVfs;
  return pRealVfs->xCurrentTime(pRealVfs, pTimeOut);
}

/*
** No-op.
*/
static int rbuVfsGetLastError(sqlite3_vfs *pVfs, int a, char *b){
  return 0;
}

/*
** Deregister and destroy an RBU vfs created by an earlier call to
** sqlite3rbu_create_vfs().
*/
SQLITE_API void SQLITE_STDCALL sqlite3rbu_destroy_vfs(const char *zName){
  sqlite3_vfs *pVfs = sqlite3_vfs_find(zName);
  if( pVfs && pVfs->xOpen==rbuVfsOpen ){
    sqlite3_mutex_free(((rbu_vfs*)pVfs)->mutex);
    sqlite3_vfs_unregister(pVfs);
    sqlite3_free(pVfs);
  }
}

/*
** Create an RBU VFS named zName that accesses the underlying file-system
** via existing VFS zParent. The new object is registered as a non-default
** VFS with SQLite before returning.
*/
SQLITE_API int SQLITE_STDCALL sqlite3rbu_create_vfs(const char *zName, const char *zParent){

  /* Template for VFS */
  static sqlite3_vfs vfs_template = {
    1,                            /* iVersion */
    0,                            /* szOsFile */
    0,                            /* mxPathname */
    0,                            /* pNext */
    0,                            /* zName */
    0,                            /* pAppData */
    rbuVfsOpen,                   /* xOpen */
    rbuVfsDelete,                 /* xDelete */
    rbuVfsAccess,                 /* xAccess */
    rbuVfsFullPathname,           /* xFullPathname */

#ifndef SQLITE_OMIT_LOAD_EXTENSION
    rbuVfsDlOpen,                 /* xDlOpen */
    rbuVfsDlError,                /* xDlError */
    rbuVfsDlSym,                  /* xDlSym */
    rbuVfsDlClose,                /* xDlClose */
#else
    0, 0, 0, 0,
#endif

    rbuVfsRandomness,             /* xRandomness */
    rbuVfsSleep,                  /* xSleep */
    rbuVfsCurrentTime,            /* xCurrentTime */
    rbuVfsGetLastError,           /* xGetLastError */
    0,                            /* xCurrentTimeInt64 (version 2) */
    0, 0, 0                       /* Unimplemented version 3 methods */
  };

  rbu_vfs *pNew = 0;              /* Newly allocated VFS */
  int nName;
  int rc = SQLITE_OK;

  int nByte;
  nName = strlen(zName);
  nByte = sizeof(rbu_vfs) + nName + 1;
  pNew = (rbu_vfs*)sqlite3_malloc(nByte);
  if( pNew==0 ){
    rc = SQLITE_NOMEM;
  }else{
    sqlite3_vfs *pParent;           /* Parent VFS */
    memset(pNew, 0, nByte);
    pParent = sqlite3_vfs_find(zParent);
    if( pParent==0 ){
      rc = SQLITE_NOTFOUND;
    }else{
      char *zSpace;
      memcpy(&pNew->base, &vfs_template, sizeof(sqlite3_vfs));
      pNew->base.mxPathname = pParent->mxPathname;
      pNew->base.szOsFile = sizeof(rbu_file) + pParent->szOsFile;
      pNew->pRealVfs = pParent;
      pNew->base.zName = (const char*)(zSpace = (char*)&pNew[1]);
      memcpy(zSpace, zName, nName);

      /* Allocate the mutex and register the new VFS (not as the default) */
      pNew->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_RECURSIVE);
      if( pNew->mutex==0 ){
................................................................................

  return rc;
}


/**************************************************************************/

#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_RBU) */

/************** End of sqlite3rbu.c ******************************************/
/************** Begin file dbstat.c ******************************************/
/*
** 2010 July 12
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
................................................................................
**
** The dbstat virtual table is used to extract low-level formatting
** information from an SQLite database in order to implement the
** "sqlite3_analyzer" utility.  See the ../tool/spaceanal.tcl script
** for an example implementation.
*/

/* #include "sqliteInt.h"   ** Requires access to internal data structures ** */
#if (defined(SQLITE_ENABLE_DBSTAT_VTAB) || defined(SQLITE_TEST)) \
    && !defined(SQLITE_OMIT_VIRTUALTABLE)

/*
** Page paths:
** 
**   The value of the 'path' column describes the path taken from the 

**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.8.11"
#define SQLITE_VERSION_NUMBER 3008011
#define SQLITE_SOURCE_ID      "2015-07-08 16:22:42 5348ffc3fda5168c1e9e14aa88b0c6aedbda7c94"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version, sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
................................................................................
** circumstances in order to fix a problem with priority inversion.
** Applications should <em>not</em> use this file-control.
**
** <li>[[SQLITE_FCNTL_ZIPVFS]]
** The [SQLITE_FCNTL_ZIPVFS] opcode is implemented by zipvfs only. All other
** VFS should return SQLITE_NOTFOUND for this opcode.
**
** <li>[[SQLITE_FCNTL_OTA]]
** The [SQLITE_FCNTL_OTA] opcode is implemented by the special VFS used by
** the OTA extension only.  All other VFS should return SQLITE_NOTFOUND for
** this opcode.  
** </ul>
*/
#define SQLITE_FCNTL_LOCKSTATE               1
#define SQLITE_FCNTL_GET_LOCKPROXYFILE       2
#define SQLITE_FCNTL_SET_LOCKPROXYFILE       3
#define SQLITE_FCNTL_LAST_ERRNO              4
................................................................................
#define SQLITE_FCNTL_TRACE                  19
#define SQLITE_FCNTL_HAS_MOVED              20
#define SQLITE_FCNTL_SYNC                   21
#define SQLITE_FCNTL_COMMIT_PHASETWO        22
#define SQLITE_FCNTL_WIN32_SET_HANDLE       23
#define SQLITE_FCNTL_WAL_BLOCK              24
#define SQLITE_FCNTL_ZIPVFS                 25
#define SQLITE_FCNTL_OTA                    26

/* deprecated names */
#define SQLITE_GET_LOCKPROXYFILE      SQLITE_FCNTL_GET_LOCKPROXYFILE
#define SQLITE_SET_LOCKPROXYFILE      SQLITE_FCNTL_SET_LOCKPROXYFILE
#define SQLITE_LAST_ERRNO             SQLITE_FCNTL_LAST_ERRNO

**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.8.11"
#define SQLITE_VERSION_NUMBER 3008011
#define SQLITE_SOURCE_ID      "2015-07-23 20:44:49 017c5019e1ce042025d4f327e50ec50af49f9fa4"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version, sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
................................................................................
** circumstances in order to fix a problem with priority inversion.
** Applications should <em>not</em> use this file-control.
**
** <li>[[SQLITE_FCNTL_ZIPVFS]]
** The [SQLITE_FCNTL_ZIPVFS] opcode is implemented by zipvfs only. All other
** VFS should return SQLITE_NOTFOUND for this opcode.
**
** <li>[[SQLITE_FCNTL_RBU]]
** The [SQLITE_FCNTL_RBU] opcode is implemented by the special VFS used by
** the RBU extension only.  All other VFS should return SQLITE_NOTFOUND for
** this opcode.  
** </ul>
*/
#define SQLITE_FCNTL_LOCKSTATE               1
#define SQLITE_FCNTL_GET_LOCKPROXYFILE       2
#define SQLITE_FCNTL_SET_LOCKPROXYFILE       3
#define SQLITE_FCNTL_LAST_ERRNO              4
................................................................................
#define SQLITE_FCNTL_TRACE                  19
#define SQLITE_FCNTL_HAS_MOVED              20
#define SQLITE_FCNTL_SYNC                   21
#define SQLITE_FCNTL_COMMIT_PHASETWO        22
#define SQLITE_FCNTL_WIN32_SET_HANDLE       23
#define SQLITE_FCNTL_WAL_BLOCK              24
#define SQLITE_FCNTL_ZIPVFS                 25
#define SQLITE_FCNTL_RBU                    26

/* deprecated names */
#define SQLITE_GET_LOCKPROXYFILE      SQLITE_FCNTL_GET_LOCKPROXYFILE
#define SQLITE_SET_LOCKPROXYFILE      SQLITE_FCNTL_SET_LOCKPROXYFILE
#define SQLITE_LAST_ERRNO             SQLITE_FCNTL_LAST_ERRNO

){
  if( argc!=2 ){
    return Th_WrongNumArgs(interp, "puts STRING");
  }
  sendText((char*)argv[1], argl[1], *(unsigned int*)pConvert);
  return TH_OK;
}































/*
** TH1 command: decorate STRING
** TH1 command: wiki STRING
**
** Render the input string as wiki.  For the decorate command, only links
** are handled.
................................................................................
    {"httpize",       httpizeCmd,           0},
    {"hascap",        hascapCmd,            (void*)&zeroInt},
    {"hasfeature",    hasfeatureCmd,        0},
    {"html",          putsCmd,              (void*)&aFlags[0]},
    {"htmlize",       htmlizeCmd,           0},
    {"http",          httpCmd,              0},
    {"linecount",     linecntCmd,           0},

    {"puts",          putsCmd,              (void*)&aFlags[1]},
    {"query",         queryCmd,             0},
    {"randhex",       randhexCmd,           0},
    {"regexp",        regexpCmd,            0},
    {"reinitialize",  reinitializeCmd,      0},
    {"render",        renderCmd,            0},
    {"repository",    repositoryCmd,        0},

){
  if( argc!=2 ){
    return Th_WrongNumArgs(interp, "puts STRING");
  }
  sendText((char*)argv[1], argl[1], *(unsigned int*)pConvert);
  return TH_OK;
}

/*
** TH1 command: markdown STRING
**
** Renders the input string as markdown.  The result is a two-element list.
** The first element is the text-only title string.  The second element
** contains the body, rendered as HTML.
*/
static int markdownCmd(
  Th_Interp *interp,
  void *p,
  int argc,
  const char **argv,
  int *argl
){
  Blob src, title, body;
  char *zValue = 0;
  int nValue = 0;
  if( argc!=2 ){
    return Th_WrongNumArgs(interp, "markdown STRING");
  }
  blob_zero(&src);
  blob_init(&src, (char*)argv[1], argl[1]);
  blob_zero(&title); blob_zero(&body);
  markdown_to_html(&src, &title, &body);
  Th_ListAppend(interp, &zValue, &nValue, blob_str(&title), blob_size(&title));
  Th_ListAppend(interp, &zValue, &nValue, blob_str(&body), blob_size(&body));
  Th_SetResult(interp, zValue, nValue);
  return TH_OK;
}

/*
** TH1 command: decorate STRING
** TH1 command: wiki STRING
**
** Render the input string as wiki.  For the decorate command, only links
** are handled.
................................................................................
    {"httpize",       httpizeCmd,           0},
    {"hascap",        hascapCmd,            (void*)&zeroInt},
    {"hasfeature",    hasfeatureCmd,        0},
    {"html",          putsCmd,              (void*)&aFlags[0]},
    {"htmlize",       htmlizeCmd,           0},
    {"http",          httpCmd,              0},
    {"linecount",     linecntCmd,           0},
    {"markdown",      markdownCmd,          0},
    {"puts",          putsCmd,              (void*)&aFlags[1]},
    {"query",         queryCmd,             0},
    {"randhex",       randhexCmd,           0},
    {"regexp",        regexpCmd,            0},
    {"reinitialize",  reinitializeCmd,      0},
    {"render",        renderCmd,            0},
    {"repository",    repositoryCmd,        0},

#   http://www.hwaci.com/drh/
#
############################################################################
#
# TH1 Commands
#





fossil test-th-eval --open-config "setting th1-hooks"
set th1Hooks [expr {$RESULT eq "1"}]

###############################################################################

fossil test-th-eval --open-config "setting abc"
test th1-setting-1 {$RESULT eq ""}
................................................................................
# NOTE: This test may fail if the command names do not always come
#       out in a deterministic order from TH1.
#
fossil test-th-eval "info commands"
test th1-info-commands-1 {$RESULT eq {linecount htmlize date stime\
enable_output uplevel http expr glob_match utime styleFooter catch if\
tclReady searchable reinitialize combobox lindex query html anoncap randhex\
llength for set break regexp styleHeader puts return checkout decorate\
artifact trace wiki proc hascap globalState continue getParameter\
hasfeature setting lsearch breakpoint upvar render repository string unset\
setParameter list error info rename anycap httpize}}

###############################################################################

fossil test-th-eval "info vars"
test th1-info-vars-1 {$RESULT eq ""}
................................................................................
fossil test-th-eval {string is integer 0xC0DEF00D}
test th1-string-is-30 {$RESULT eq "1"}

###############################################################################

fossil test-th-eval {string is integer 0xC0DEF00Z}
test th1-string-is-31 {$RESULT eq "0"}

#   http://www.hwaci.com/drh/
#
############################################################################
#
# TH1 Commands
#

set dir [file dirname [info script]]

###############################################################################

fossil test-th-eval --open-config "setting th1-hooks"
set th1Hooks [expr {$RESULT eq "1"}]

###############################################################################

fossil test-th-eval --open-config "setting abc"
test th1-setting-1 {$RESULT eq ""}
................................................................................
# NOTE: This test may fail if the command names do not always come
#       out in a deterministic order from TH1.
#
fossil test-th-eval "info commands"
test th1-info-commands-1 {$RESULT eq {linecount htmlize date stime\
enable_output uplevel http expr glob_match utime styleFooter catch if\
tclReady searchable reinitialize combobox lindex query html anoncap randhex\
llength for set break regexp markdown styleHeader puts return checkout\
decorate artifact trace wiki proc hascap globalState continue getParameter\
hasfeature setting lsearch breakpoint upvar render repository string unset\
setParameter list error info rename anycap httpize}}

###############################################################################

fossil test-th-eval "info vars"
test th1-info-vars-1 {$RESULT eq ""}
................................................................................
fossil test-th-eval {string is integer 0xC0DEF00D}
test th1-string-is-30 {$RESULT eq "1"}

###############################################################################

fossil test-th-eval {string is integer 0xC0DEF00Z}
test th1-string-is-31 {$RESULT eq "0"}

###############################################################################

fossil test-th-eval {markdown}
test th1-markdown-1 {$RESULT eq \
{TH_ERROR: wrong # args: should be "markdown STRING"}}

###############################################################################

fossil test-th-eval {markdown one two}
test th1-markdown-2 {$RESULT eq \
{TH_ERROR: wrong # args: should be "markdown STRING"}}

###############################################################################

fossil test-th-eval {markdown "*This is a test.*"}
test th1-markdown-3 {[normalize_result] eq {{} {<div class="markdown">

<p><em>This is a test.</em></p>

</div>
}}}

###############################################################################

fossil test-th-eval {markdown "Test1\n=====\n*This is a test.*"}
test th1-markdown-4 {[normalize_result] eq {Test1 {<div class="markdown">

<h1>Test1</h1>
<p><em>This is a test.</em></p>

</div>
}}}

###############################################################################

set markdown [read_file [file join $dir markdown-test1.md]]
fossil test-th-eval [string map \
    [list %markdown% $markdown] {markdown {%markdown%}}]
test th1-markdown-5 {[normalize_result] eq \
{{Markdown Formatter Test Document} {<div class="markdown">

<h1>Markdown Formatter Test Document</h1>
<p>This document is designed to test the markdown formatter.</p>

<ul>
<li>A bullet item.

<ul>
<li>A subitem</li>
</ul></li>
<li>Second bullet</li>
</ul>

<p>More text</p>

<ol>
<li>Enumeration
1.1.  Subitem 1
1.2.  Subitem 2</li>
<li>Second enumeration.</li>
</ol>

<p>Another paragraph.</p>

<h2>Other Features</h2>
<p>Text can show <em>emphasis</em> or <em>emphasis</em> or <strong>strong emphassis</strong>.</p>

</div>
}}}

<title>Change Log</title>

<h2>Changes for Version 1.34 (2015-??-??)</h2>


  *  Fix --hard option to mv/rm to enable them to work properly with certain
     relative paths.
  *  Make the clean command undoable for files less than 10MiB.


  *  Add minimal <nowiki>[lsearch]</nowiki> command to TH1. Only exact
     case-sensitive matching is supported.
  *  Add the <nowiki>[glob_match]</nowiki> command to TH1.

  *  Add the <nowiki>[tclIsSafe] and [tclMakeSafe]</nowiki> TH1 commands to
     the Tcl integration subsystem.
  *  Add 'double', 'integer', and 'list' classes to the
     <nowiki>[string is]</nowiki> command in TH1.
  *  Update internal Unicode character tables, used in regular expression
     handling, from version 7.0 to 8.0.

<title>Change Log</title>

<h2>Changes for Version 1.34 (2015-??-??)</h2>

  *  Fix --hard option to [/help?cmd=mv|fossil mv] and [/help?cmd=rm|fossil rm]
     to enable them to work properly with certain relative paths.


  *  Make the [/help?cmd=clean|fossil clean] command undoable for files less
     than 10MiB.
  *  Add minimal <nowiki>[lsearch]</nowiki> command to TH1. Only exact
     case-sensitive matching is supported.
  *  Add the <nowiki>[glob_match]</nowiki> and <nowiki>[markdown]</nowiki>
     commands to TH1.
  *  Add the <nowiki>[tclIsSafe] and [tclMakeSafe]</nowiki> TH1 commands to
     the Tcl integration subsystem.
  *  Add 'double', 'integer', and 'list' classes to the
     <nowiki>[string is]</nowiki> command in TH1.
  *  Update internal Unicode character tables, used in regular expression
     handling, from version 7.0 to 8.0.

<tt>manifest</tt>. The most important is <tt>ignore-glob</tt> which
specifies which files should be ignored when looking for unmanaged files
with the <tt>extras</tt> command.

Because these options can change over time, and the inconvenience of
replicating changes, these settings are "versionable". As well as being
able to be set using the <tt>settings</tt> command or the web interface,
you can created versioned files in the <tt>.fossil-settings</tt>

directory named with the setting name. The contents of the file is the
value of the setting, and these files are checked in, committed, merged,
and so on, as with any other file.

Where a setting is a list of values, such as <tt>ignore-glob</tt>, you
can use a newline as a separator as well as a comma.

For example, to set the list of ignored files, create a
<tt>.fossil-settings/ignore-glob</tt> file where each line contains a
glob for ignored files.

If you set the value of a setting using the <tt>settings</tt> command as
well as a versioned file, the versioned setting will take precedence. A
warning will be displayed.

<tt>manifest</tt>. The most important is <tt>ignore-glob</tt> which
specifies which files should be ignored when looking for unmanaged files
with the <tt>extras</tt> command.

Because these options can change over time, and the inconvenience of
replicating changes, these settings are "versionable". As well as being
able to be set using the <tt>settings</tt> command or the web interface,
you can create versioned files in the <tt>.fossil-settings</tt>
subdirectory of the check-out root, named with the setting name.
The contents of the file is the
value of the setting, and these files are checked in, committed, merged,
and so on, as with any other file.

Where a setting is a list of values, such as <tt>ignore-glob</tt>, you
can use a newline as a separator as well as a comma.

For example, to set the list of ignored files, create a
<tt>.fossil-settings/ignore-glob</tt> file where each line contains a
glob for ignored files.

If you set the value of a setting using the <tt>settings</tt> command as
well as a versioned file, the versioned setting will take precedence. A
warning will be displayed.

  *  hascap
  *  hasfeature
  *  html
  *  htmlize
  *  http
  *  httpize
  *  linecount

  *  puts
  *  query
  *  randhex
  *  regexp
  *  reinitialize
  *  render
  *  repository
................................................................................
<a name="linecount"></a>TH1 linecount Command
---------------------------------------------

  *  linecount STRING MAX MIN

Returns one more than the number of \n characters in STRING.  But
never returns less than MIN or more than MAX.










<a name="puts"></a>TH1 puts Command
-----------------------------------

  *  puts STRING

Outputs the STRING unchanged.

  *  hascap
  *  hasfeature
  *  html
  *  htmlize
  *  http
  *  httpize
  *  linecount
  *  markdown
  *  puts
  *  query
  *  randhex
  *  regexp
  *  reinitialize
  *  render
  *  repository
................................................................................
<a name="linecount"></a>TH1 linecount Command
---------------------------------------------

  *  linecount STRING MAX MIN

Returns one more than the number of \n characters in STRING.  But
never returns less than MIN or more than MAX.

<a name="markdown"></a>TH1 markdown Command
---------------------------------------------

  *  markdown STRING

Renders the input string as markdown.  The result is a two-element list.
The first element contains the body, rendered as HTML.  The second element
is the text-only title string.

<a name="puts"></a>TH1 puts Command
-----------------------------------

  *  puts STRING

Outputs the STRING unchanged.

from within an open check-out, you can omit the repository name:

  <b>fossil ui</b>

The latter case is a very useful short-cut when you are working on a
Fossil project and you want to quickly do some work with the web interface.
Notice that Fossil automatically finds an unused TCP port to run the
server own and automatically points your web browser to the correct
URL.  So there is never any fumbling around trying to find an open
port or to type arcane strings into your browser URL entry box.
The interface just pops right up, ready to run.

The Fossil web interface is also very easy to setup and run on a
network server, as either a CGI program or from inetd, or as an
SCGI server.  Details on how

from within an open check-out, you can omit the repository name:

  <b>fossil ui</b>

The latter case is a very useful short-cut when you are working on a
Fossil project and you want to quickly do some work with the web interface.
Notice that Fossil automatically finds an unused TCP port to run the
server on and automatically points your web browser to the correct
URL.  So there is never any fumbling around trying to find an open
port or to type arcane strings into your browser URL entry box.
The interface just pops right up, ready to run.

The Fossil web interface is also very easy to setup and run on a
network server, as either a CGI program or from inetd, or as an
SCGI server.  Details on how