/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* vim: set ts=2 et sw=2 tw=80: */ #if !defined(ORG_FOSSIL_SCM_FSL_DB_H_INCLUDED) #define ORG_FOSSIL_SCM_FSL_DB_H_INCLUDED /* Copyright 2013-2021 The Libfossil Authors, see LICENSES/BSD-2-Clause.txt SPDX-License-Identifier: BSD-2-Clause-FreeBSD SPDX-FileCopyrightText: 2021 The Libfossil Authors SPDX-ArtifactOfProjectName: Libfossil SPDX-FileType: Code Heavily indebted to the Fossil SCM project (https://fossil-scm.org). ****************************************************************************** This file declares public APIs for working with fossil's database abstraction layer. */ #include "core.h" /* MUST come first b/c of config macros */ /* We don't _really_ want to include sqlite3.h at this point, but if we do not then we have to typedef the sqlite3 struct here and that breaks when client code includes both this file and sqlite3.h. */ #include "sqlite3.h" #if defined(__cplusplus) extern "C" { #endif #if 0 /** Potential TODO. Maybe not needed - v1 uses only(?) 1 hook and we can do that w/o hooks. */ typedef int (*fsl_commit_hook_f)( void * state ); /** Potential TODO */ struct fsl_commit_hook { fsl_commit_hook_f hook; int sequence; void * state; }; #define fsl_commit_hook_empty_m {NULL,0,NULL} typedef struct fsl_commit_hook fsl_commit_hook; /* extern const fsl_commit_hook fsl_commit_hook_empty; */ /** Potential TODO. */ FSL_EXPORT int fsl_db_before_commit_hook( fsl_db * const db, fsl_commit_hook_f f, int sequence, void * state ); #endif #if 0 /* We can't do this because it breaks when clients include both this header and sqlite3.h. Is there a solution which lets us _not_ include sqlite3.h from this file and also compiles when clients include both? */ #if !defined(SQLITE_OK) /** Placeholder for sqlite3/4 type. We currently use v3 but will almost certainly switch to v4 at some point. Before we can do that we need an upgrade/migration path. */ typedef struct sqlite3 sqlite3; #endif #endif /** Flags for use with fsl_db_open() and friends. */ enum fsl_open_flags_e { /** The "no flags" value. */ FSL_OPEN_F_NONE = 0, /** Flag for fsl_db_open() specifying that the db should be opened in read-only mode. */ FSL_OPEN_F_RO = 0x01, /** Flag for fsl_db_open() specifying that the db should be opened in read-write mode, but should not create the db if it does not already exist. */ FSL_OPEN_F_RW = 0x02, /** Flag for fsl_db_open() specifying that the db should be opened in read-write mode, creating the db if it does not already exist. ACHTUNG: this flag propagates from an OPEN'd db handle to the ATTACH SQL command run via that handle, such that ATTACHing a non-existing db file will fail if the FSL_OPEN_F_CREATE flag is _not_ used. Historically (prior to 2022-01-01), fsl_db_open() would automatically apply this flag to DBs named ":memory:" or "" (unnamed temp dbs), but that ended up causing a full day of confusion, hair-pulling, and bug-hunting when lib-level code was migrated from an anonymous temp db to a "real" db and ATTACH suddenly failed. As of 2022-01-01, fsl_db_open() always takes the open-mode flags as provided by the client, regardless of the DB name, and never automatically rewrites them to include FSL_OPEN_F_CREATE. */ FSL_OPEN_F_CREATE = 0x04, /** Shorthand for RW+CREATE flags. */ FSL_OPEN_F_RWC = FSL_OPEN_F_RW | FSL_OPEN_F_CREATE, /** Currently unused. It "should" be used to tell fsl_repo_open_xxx() to confirm that the db is a repository, but how to propagate that through the corresponding APIs is not currently clear. */ FSL_OPEN_F_SCHEMA_VALIDATE = 0x20, /** Used by fsl_db_open() to to tell the underlying db connection to trace all SQL to stdout. This is often useful for testing, debugging, and learning about what's going on behind the scenes. */ FSL_OPEN_F_TRACE_SQL = 0x40 }; /** A level of indirection to "hide" the actual db driver implementation from the public API. Whether or not the API uses/will use sqlite3 or 4 is "officially unspecified." We currently use 3 because (A) it bootstraps development and testing by letting us use existing fossil repos for and (B) it reduces the number of potential problems when porting SQL-heavy code from the fossil(1) tree. Clients should try not to rely on the underlying db driver API, but may need it for some uses (e.g. binding custom SQL functions). Sidebar: at the time this port was initiated, sqlite4 was in an experimental stage to explore a new storage engine which, it was hoped, would speed up sqlite considerably. It ended up never leaving that stage because the performance gains of the storage engine did not justify such a significant upheaval. Even so, sqlite4 "might" come around sometime within the lifetime of this project, so it behooves us to abstract away this type from the public API. */ typedef sqlite3 fsl_dbh_t; /** An on-close hook for fsl_db objects. It is called from fsl_db_close(), passed the db and the state object defined in the fsl_db::hook::close. This is called early on in the closing process, before the close is completed, so it may (technically speaking) still perform db operations, but it must never start a new transaction (unless it also closes it) nor may it close the db object. If either of those conditions is violated, results are undefined. The intent is to enable to listener to, e.g., clear any buffers or caches which may refer to db-side content. Note that this is _not_ called when a DETACH'ing database, as this API does not have any insight into when ATTACH and DETACH are used. @see fsl_db_hook_close() */ typedef void (*fsl_db_hook_close_f)(fsl_db *db, void *state); /** A flag type for use with fsl_db_hook_transaction_f() implementations. */ enum fsl_db_hook_transaction_e { /** Indicates that this is the start of a transaction. */ FSL_DB_TRANSACTION_BEGIN = 0, /** Indicates that the transaction is being committed. */ FSL_DB_TRANSACTION_COMMIT, /** Indicates that the transaction is about to be rolled back Whether or not this indicates an error is context-dependent. */ FSL_DB_TRANSACTION_ROLLING_BACK, /** Indicates that the transaction was just rolled back. Whether or not this indicates an error is context-dependent. */ FSL_DB_TRANSACTION_ROLLED_BACK }; typedef enum fsl_db_hook_transaction_e fsl_db_hook_transaction_e; /** An on-transaction-start/end hook for fsl_db objects. Each fsl_db instance may have a single one of these installed and it gets called via fsl_db_transaction_begin(), fsl_db_transaction_end(), and fsl_db_rollback_force(). Its first argument is the db instance. Its second argument is the type of operation being notified for: - FSL_DB_TRANSACTION_BEGIN is passed, with an rc of 0, immediately after fsl_db_transaction_begin() starts the transaction. If this function returns non-0, the transaction is _immediately_ rolled back (but this callback is not called again for this failure), and its return value because the result of fsl_db_transaction_begin(). - FSL_DB_TRANSACTION_COMMIT is called, with an rc of 0, immediately before fsl_db_transaction_end() runs COMMIT on the db. If it returns non-0, the pending COMMIT is replaced with a ROLLBACK and that result code becomes the result of fsl_db_transaction_end(). - FSL_DB_TRANSACTION_ROLLING_BACK is called, with an unspecified rc, immediately before fsl_db_transaction_end() runs ROLLBACK on the db. If it returns non-0, that result becomes the result of fsl_db_transaction_end() but it does not cancel the pending db-side ROLLBACK. Note that only one of FSL_DB_TRANSACTION_COMMIT or FSL_DB_TRANSACTION_ROLLING_BACK is invoked for a given call to fsl_db_transaction_end(). If FSL_DB_TRANSACTION_COMMIT returns non-zero, no FSL_DB_TRANSACTION_ROLLING_BACK invocation is made. - FSL_DB_TRANSACTION_ROLLED_BACK is called, with an unspecified rc, immediately after fsl_db_transaction_end() has run a ROLLBACK (either because it was initially told to roll back or because the FSL_DB_TRANSACTION_COMMIT invocation of this function returned non-0). The rc passed to it is 0 if everything is was "okay" up until that point and non-0 if some earlier step in the commit or rollback process failed. If this function returns non-0 but the prior rollback succeeded, this function's result becames the result value of fsl_db_transaction_end(). If an earlier step failed, that result code is kept as the fsl_db_transaction_end() result. This hook is NOT called for IMPLICIT transactions. It is only called for explicit calls to fsl_db_transaction_begin(), fsl_db_transaction_end(), and fsl_db_rollback_force(). Clients must never execute SQL-level (BEGIN, COMMIT, ROLLBACK) calls on fsl_db instances. @see fsl_db_hook_transaction() */ typedef int (*fsl_db_hook_transaction_f)(fsl_db *db, fsl_db_hook_transaction_e mode, int rc, void *state); /** Db handle wrapper class. Each instance wraps a single sqlite database handle. Though this type's interface is not opaque, it is never legal for clients to directly manipulate the members. Fossil is built upon sqlite3, but this abstraction is intended to hide that, insofar as possible, from clients so as to simplify an eventual port from v3 to v4. Clients should avoid relying on the underlying db being sqlite (or at least not rely on a specific version), but may want to register custom functions with the driver (or perform similar low-level operations) and the option is left open for them to access that handle via the fsl_db::dbh member. In practice, library clients do not ever need to use the underlying sqlite API. @see fsl_db_open(); @see fsl_db_close(); @see fsl_stmt */ struct fsl_db { /** Describes what role(s) this db connection plays in fossil (if any). This is a bitmask of fsl_dbrole_e values, and a db connection may have multiple roles. This is only used by the fsl_cx-internal API. */ int role; /** Underlying db driver handle. */ fsl_dbh_t * dbh; /** Holds error state from the underlying driver. fsl_db and fsl_stmt operations which fail at the driver level "should" update this state to include error info from the driver. fsl_cx APIs which fail at the DB level uplift this (using fsl_error_move()) so that they can pass it on up the call chain. */ fsl_error error; /** Holds the file name used when opening this db. Might not refer to a real file (e.g. might be ":memory:" or "" (similar to ":memory:" but may swap to temp storage). Design note: we currently hold the name as it is passed to the db-open routine, without canonicalizing it. That is very possibly a mistake, as it makes it impossible to properly compare the name to another arbitrary checkout-relative name for purposes of fsl_reserved_fn_check(). For purposes of fsl_cx we currently (2021-03-12) canonicalize db's which we fsl_db_open(), but not those which we ATTACH (which includes the repo and checkout dbs). We cannot reasonably canonicalize the repo db filename because it gets written into the checkout db so that the checkout knows where to find the repository. History has shown that that path needs to be stored exactly as a user entered it, which is often relative. Memory is owned by this object. */ char * filename; /** Holds the database name for use in creating queries. Might or might not be set/needed, depending on the context. Memory is owned by this object. */ char * name; /** Debugging/test counter. Closing a db with opened statements might assert() or trigger debug output when the db is closed. */ int openStatementCount; /** Counter for fsl_db_transaction_begin/end(). */ int beginCount; /** Internal flag for communicating rollback state through the call stack. If this is set to a true value, fsl_db_transaction_end() calls will behave like a rollback regardless of the value of the 2nd argument passed to that function. i.e. it propagates a rollback through pseudo-nested transactions. Potential TODO: instead of treating this like a boolean, store the error number which caused the rollback here. We'd have to go fix a lot of code for that, though :/. */ int doRollback; /** Internal change counter. Set when a transaction is started/committed. Maintenance note: it's an int because that's what sqlite3_total_changes() returns. */ int priorChanges; /** Hooks for certain events the db can notify a single listener about. The main intent of these is to eliminate this class's hard dependency on fsl_cx by farming out those dependent parts to these hooks. */ struct { struct { fsl_db_hook_close_f f; void * state; } close; struct { fsl_db_hook_transaction_f f; void * state; } transaction; } hook; /** List of SQL commands (char *) which should be executed prior to a commit. This list is cleared when the transaction counter drops to zero as the result of fsl_db_transaction_end() or fsl_db_rollback_force(). TODO? Use (fsl_stmt*) objects instead of strings? Depends on how much data we need to bind here (want to avoid an extra copy if we need to bind big stuff). That was implemented in [9d9375ac2d], but that approach prohibits multi-statement pre-commit triggers, so it was not trunked. It's still unknown whether we need multi-statement SQL in this context (==fossil's infrastructure). 2024-09-16: it turns out that this is no longer used by fsl_cx. Instead, it queues up its to-verify stuff in its own internal mechanism. We'll keep this because it potentially has uses other than the one it was originally added for (running pre-commit verification of fossil data). @see fsl_db_before_commit() */ fsl_list beforeCommit; /** Internal buffer to reduce, potentially drastically, reallocations caused via fsl_db_prepare_cached(). */ fsl_buffer cachePrepBuf; /** An internal cache of "static" queries - those which do not rely on call-time state unless that state can be bind()ed. Holds a linked list of (fsl_stmt*) instances, managed by the fsl_db_prepare_cached() and fsl_stmt_cached_yield() APIs. @see fsl_db_prepare_cached() */ fsl_stmt * cacheHead; /** A marker which tells fsl_db_close() whether or not fsl_db_malloc() allocated this instance (in which case fsl_db_close() will fsl_free() it) or not (in which case it does not fsl_free() it). */ void const * allocStamp; }; /** Empty-initialized fsl_db structure, intended for const-copy initialization. */ #define fsl_db_empty_m { \ .role = FSL_DBROLE_NONE, \ .dbh = NULL, \ .error = fsl_error_empty_m, \ .filename = NULL, \ .name = NULL, \ .openStatementCount = 0, \ .beginCount = 0, \ .doRollback = 0, \ .priorChanges = 0, \ .hook = { \ .close = { .f=NULL, .state=NULL }, \ .transaction = { .f=NULL, .state=NULL } \ }, \ .beforeCommit = fsl_list_empty_m, \ .cachePrepBuf = fsl_buffer_empty_m, \ .cacheHead = NULL, \ .allocStamp = NULL \ } /** Empty-initialized fsl_db structure, intended for copy initialization. */ FSL_EXPORT const fsl_db fsl_db_empty; /** If db is not NULL then this function returns its name (the one used to fsl_db_open() it). The bytes are valid until the db connection is closed or until someone mucks with db->filename. If len is not NULL then *len is (on success) assigned to the length of the returned string, in bytes. The string is NUL-terminated, so fetching the length (by passing a non-NULL 2nd parameter) is optional but sometimes useful to eliminate a downstream call to fsl_strlen(). Results are undefined if db is NULL or was improperly initialized. Will return NULL if db was properly initialized (via copying fsl_db_empty) but has not yet been opened. */ FSL_EXPORT char const * fsl_db_filename(fsl_db const * db, fsl_size_t * len); typedef sqlite3_stmt fsl_stmt_t; /** Represents a prepared statement handle. Intended usage: ``` fsl_stmt st = fsl_stmt_empty; int rc = fsl_db_prepare( db, &st, "..." ); if(rc){ // Error! assert(!st.stmt); // db->error might hold driver-level error details. }else{ // use st and eventually finalize it: fsl_stmt_finalize( &st ); } ``` Script binding implementations can largely avoid exposing the statement handle (and its related cleanup ordering requirements) to script code. They need to have some mechanism for binding values to SQL (or implement all the escaping themselves), but that can be done without exposing all of the statement class if desired. For example, here's some hypothetical script code: ``` var st = db.prepare(".... where i=:i and x=:x"); // st is-a Statement, but we need not add script bindings for // the whole Statement.bind() API. We can instead simplify that // to something like: try { st.exec( {i: 42, x: 3} ) // or, for a SELECT query: st.each({ bind{i:42, x:3}, rowType: 'array', // or 'object' callback: function(row,state,colNames){ print(row.join('\t')); }, state: {...callback function state...} }); } finally { st.finalize(); // It is critical that st gets finalized before its DB, and // that'shard to guaranty if we leave st to the garbage collector! } // see below for another (less messy) alternative ``` Ideally, script code should not have direct access to the Statement because managing lifetimes can be difficult in the face of flow-control changes caused by exceptions (as the above example demonstrates). Statements can be completely hidden from clients if the DB wrapper is written to support it. For example, in pseudo-JavaScript that might look like: ``` db.exec("...where i=? AND x=?", 42, 3); db.each({sql:"select ... where id0) or not (fsl_stmt_col_count()==0) without having to know the contents of the query. - fsl_db_prepare_cached() can be used to cache often-used or expensive-to-prepare queries within the context of their parent db handle. */ FSL_EXPORT int fsl_db_prepare( fsl_db * const db, fsl_stmt * const tgt, char const * sql, ... ); /** va_list counterpart of fsl_db_prepare(). */ FSL_EXPORT int fsl_db_preparev( fsl_db * const db, fsl_stmt * const tgt, char const * sql, va_list args ); /** A special-purpose variant of fsl_db_prepare() which caches statements based on their SQL code. This works very much like fsl_db_prepare() and friends except that it can return the same statement (via *st) multiple times (statements with identical SQL are considered equivalent for caching purposes). Clients need not explicitly pass the returned statement to fsl_stmt_finalize() - the db holds these statements and will finalize them when it is closed. It is legal to pass them to finalize, in which case they will be cleaned up immediately but that also invalidates _all_ pointers to the shared instances. If client code does not call fsl_stmt_finalize(), it MUST pass the statement pointer to fsl_stmt_cached_yield(st) after is done with it. That makes the query available for use again with this routine. If a cached query is not yielded via fsl_stmt_cached_yield() then this routine will return FSL_RC_ACCESS on subsequent requests for that SQL to prevent that recursive (mis)use of the statement causes problems. This routine is intended to be used in oft-called routines where the cost of re-creating statements on each execution could be prohibitive (or at least a bummer). Returns 0 on success, FSL_RC_MISUSE if any arguments are invalid. On error, *st is not written to. On other error's db->error might be updated with more useful information. See the Caveats section below for more details. Its intended usage looks like: ``` fsl_stmt * st = NULL; int rc = fsl_db_prepare_cached(myDb, &st, "SELECT ..."); if(rc) { assert(!st); ...error... } else { ...use it, and _be sure_ to yield it when done:... fsl_stmt_cached_yield(st); } ``` Though this function allows a formatted SQL string, caching is generally only useful with statements which have "static" SQL, i.e. no call-dependent values embedded within the SQL. It _can_, however, contain bind() placeholders which get reset for each use. Note that fsl_stmt_cached_yield() resets the statement, so most uses of cached statements do not require that the client explicitly reset cached statements (doing so is harmless, however). Caveats: Cached queries must not be used in contexts where recursion might cause the same query to be returned from this function while it is being processed at another level in the execution stack. Results would be undefined. Caching is primarily intended for often-used routines which bind and fetch simple values, and not for queries which bind large inlined values or might invoke recursion. Because of the potential for recursive breakage, this function flags queries it doles out and requires that clients call fsl_stmt_cached_yield() to un-flag them for re-use. It will return FSL_RC_ACCESS if an attempt is made to (re)prepare a statement for which a fsl_stmt_cached_yield() is pending, and db->error will be populated with a (long) error string descripting the problem and listing the SQL which caused the collision/misuse. Design note: for the recursion/parallel use case we "could" reimplement this to dole out a new statement (e.g. by appending " -- a_number" to the SQL to bypass the collision) and free it in fsl_stmt_cached_yield(), but that (A) gets uglier than it needs to be and (B) is not needed unless/until we really need cached queries in spots which would normally break them. The whole recursion problem is still theoretical at this point but could easily affect small, often-used queries without recursion. @see fsl_db_stmt_cache_clear() @see fsl_stmt_cached_yield() */ FSL_EXPORT int fsl_db_prepare_cached( fsl_db * const db, fsl_stmt ** st, char const * sql, ... ); /** The va_list counterpart of fsl_db_prepare_cached(). */ FSL_EXPORT int fsl_db_preparev_cached( fsl_db * const db, fsl_stmt ** st, char const * sql, va_list args ); /** "Yields" a statement which was prepared with fsl_db_prepare_cached(), such that that routine can once again use/re-issue that statement. Statements prepared this way must be yielded in order to prevent that recursion causes difficult-to-track errors when a given cached statement is used concurrently in different code contexts. If st is not NULL then this also calls fsl_stmt_reset() on the statement (because that simplifies usage of cached statements). Returns 0 on success, FSL_RC_MISUSE if !st or if st does not appear to have been doled out from fsl_db_prepare_cached(). @see fsl_db_prepare_cached() @see fsl_db_stmt_cache_clear() */ FSL_EXPORT int fsl_stmt_cached_yield( fsl_stmt * const st ); /** A special-purposes utility which schedules SQL to be executed the next time fsl_db_transaction_end() commits a transaction for the given db. A commit or rollback will clear all before-commit SQL whether it executes them or not. This should not be used as a general-purpose trick, and is intended only for use in very limited parts of the Fossil infrastructure. Before-commit code is only executed if the db has made changes since the transaction began. If no changes are recorded then before-commit triggers are _not_ run. This is a historical behaviour which is up for debate. This function does not prepare the SQL, so it does not catch errors which happen at prepare-time. Preparation is done (if ever) just before the next transaction is committed. Returns 0 on success, non-0 on error. Potential TODO: instead of storing the raw SQL, prepare the statements here and store the statement handles. The main benefit would be that this routine could report preport preparation errors (which otherwise cause the the commit to fail). The down-side is that it prohibits the use of multi-statement pre-commit code. We have an implementation of this somewhere early on in the libfossil tree, but it was not integrated because of the inability to use multi-statement SQL with it. */ FSL_EXPORT int fsl_db_before_commit( fsl_db * const db, char const * const sql, ... ); /** va_list counterpart to fsl_db_before_commit(). */ FSL_EXPORT int fsl_db_before_commitv( fsl_db * const db, char const * const sql, va_list args ); /** Frees memory associated with stmt but does not free stmt unless it was allocated by fsl_stmt_malloc() (these objects are normally stack-allocated, and such object must be initialized by copying fsl_stmt_empty so that this function knows whether or not to fsl_free() them). Returns FSL_RC_MISUSE if !stmt or it has already been finalized (but was not freed). */ FSL_EXPORT int fsl_stmt_finalize( fsl_stmt * const stmt ); /** "Steps" the given SQL cursor one time. The return values FSL_RC_STEP_ROW and FSL_RC_STEP_DONE are both success cases, the former indicating that one row has been fetched and the latter indicating that either no rows are left to fetch or the statement is a non-fetching query. On error some other non-zero code will be returned. On a db error this will update the underlying db's error state. This function increments stmt->rowCount by 1 if it returns FSL_RC_STEP_ROW. Returns FSL_RC_MISUSE if !stmt or stmt has not been prepared. It is only legal to call the fsl_stmt_g_xxx() and fsl_stmt_get_xxx() functions if this functon returns FSL_RC_STEP_ROW. FSL_RC_STEP_DONE is returned upon successfully ending iteration or if there is no iteration to perform (e.g. typically an UPDATE or INSERT, but see the next paragraph). Though the historical definition of non-fetching query was pretty clear, the addition of the RETURNING keyword to sqlite3's dialect means that even an INSERT or DELETE can return data. @see fsl_stmt_reset() @see fsl_stmt_reset2() @see fsl_stmt_each() */ FSL_EXPORT int fsl_stmt_step( fsl_stmt * const stmt ); /** A callback interface for use with fsl_stmt_each() and fsl_db_each(). It will be called one time for each row fetched, passed the statement object and the state parameter passed to fsl_stmt_each() resp. fsl_db_each(). If it returns non-0 then iteration stops and that code is returned UNLESS it returns FSL_RC_BREAK, in which case fsl_stmt_each() stops iteration and returns 0. i.e. implementations may return FSL_RC_BREAK to prematurly end iteration without causing an error. This callback is not called for non-fetching queries or queries which return no results, though it might (or might not) be interesting for it to do so, passing a NULL stmt for that case. stmt->rowCount can be used to determine how many times the statement has called this function. Its counting starts at 1. It is strictly illegal for a callback to pass stmt to fsl_stmt_step(), fsl_stmt_reset(), fsl_stmt_finalize(), or any similar routine which modifies its state. It must only read the current column data (or similar metatdata, e.g. column names) from the statement, e.g. using fsl_stmt_g_int32(), fsl_stmt_get_text(), or similar. */ typedef int (*fsl_stmt_each_f)( fsl_stmt * stmt, void * state ); /** Calls the given callback one time for each result row in the given statement, iterating over stmt using fsl_stmt_step(). It applies no meaning to the callbackState parameter, which gets passed as-is to the callback. See fsl_stmt_each_f() for the semantics of the callback. Returns 0 on success. Returns FSL_RC_MISUSE if !stmt or !callback. */ FSL_EXPORT int fsl_stmt_each( fsl_stmt * const stmt, fsl_stmt_each_f callback, void * callbackState ); /** Resets the given statement, analog to sqlite3_reset(). Should be called one time between fsl_stmt_step() iterations when running multiple INSERTS, UPDATES, etc. via the same statement. If resetRowCounter is true then the statement's row counter (st->rowCount) is also reset to 0, else it is left unmodified. (Most use cases don't use the row counter.) Returns 0 on success, FSL_RC_MISUSE if stmt has not been prepared or has not been cleanly initialized via copying from fsl_stmt_empty or fsl_stmt_empty_m, FSL_RC_DB if the underlying reset fails (in which case the error state of the stmt->db handle is updated to contain the error information). @see fsl_stmt_db() @see fsl_stmt_reset() */ FSL_EXPORT int fsl_stmt_reset2( fsl_stmt * const stmt, bool resetRowCounter ); /** Equivalent to fsl_stmt_reset2(stmt, 0). */ FSL_EXPORT int fsl_stmt_reset( fsl_stmt * const stmt ); /** Returns the db handle which prepared the given statement, or NULL if stmt has not been prepared. */ FSL_EXPORT fsl_db * fsl_stmt_db( fsl_stmt * const stmt ); /** Returns the SQL string used to prepare the given statement, or NULL if stmt has not been prepared. If len is not NULL then *len is set to the length of the returned string (which is NUL-terminated). The returned bytes are owned by stmt and are invalidated when it is finalized. */ FSL_EXPORT char const * fsl_stmt_sql( fsl_stmt * const stmt, fsl_size_t * const len ); /** Returns the name of the given 0-based result column index, or NULL if !stmt, stmt is not prepared, or index is out out of range. The returned bytes are owned by the statement object and may be invalidated shortly after this is called, so the caller must copy the returned value if it needs to have any useful lifetime guarantees. It's a bit more complicated than this, but assume that any API calls involving the statement handle might invalidate the column name bytes. The API guarantees that the returned value is either NULL or NUL-terminated. @see fsl_stmt_param_count() @see fsl_stmt_col_count() */ FSL_EXPORT char const * fsl_stmt_col_name(fsl_stmt * const stmt, int index); /** Returns the result column count for the given statement, or -1 if !stmt or it has not been prepared. Note that this value is cached when the statement is created. Note that non-fetching queries (e.g. INSERT and UPDATE) have a column count of 0 unless they have a RETURNING clause. Some non-SELECT constructs, e.g. PRAGMA table_info(tname) and INSERT/UPDATE/DELETE with a RETURNING clause, behave like a SELECT and have a positive column count. @see fsl_stmt_param_count() @see fsl_stmt_col_name() */ FSL_EXPORT int fsl_stmt_col_count( fsl_stmt const * const stmt ); /** Returns the bound parameter count for the given statement, or -1 if !stmt or it has not been prepared. Note that this value is cached when the statement is created. @see fsl_stmt_col_count() @see fsl_stmt_col_name() */ FSL_EXPORT int fsl_stmt_param_count( fsl_stmt const * const stmt ); /** Returns the index of the given named parameter for the given statement, or -1 if !stmt or stmt is not prepared. */ FSL_EXPORT int fsl_stmt_param_index( fsl_stmt * const stmt, char const * const param); /** Binds NULL to the given 1-based parameter index. Returns 0 on succcess. Sets the DB's error state on error. */ FSL_EXPORT int fsl_stmt_bind_null( fsl_stmt * const stmt, int index ); /** Equivalent to fsl_stmt_bind_null_name() but binds to a named parameter. */ FSL_EXPORT int fsl_stmt_bind_null_name( fsl_stmt * const stmt, char const * param ); /** Binds v to the given 1-based parameter index. Returns 0 on succcess. Sets the DB's error state on error. */ FSL_EXPORT int fsl_stmt_bind_int32( fsl_stmt * const stmt, int index, int32_t v ); /** Equivalent to fsl_stmt_bind_int32() but binds to a named parameter. */ FSL_EXPORT int fsl_stmt_bind_int32_name( fsl_stmt * const stmt, char const * param, int32_t v ); /** Binds v to the given 1-based parameter index. Returns 0 on succcess. Sets the DB's error state on error. */ FSL_EXPORT int fsl_stmt_bind_int64( fsl_stmt * const stmt, int index, int64_t v ); /** Equivalent to fsl_stmt_bind_int64() but binds to a named parameter. */ FSL_EXPORT int fsl_stmt_bind_int64_name( fsl_stmt * const stmt, char const * param, int64_t v ); /** Binds v to the given 1-based parameter index. Returns 0 on succcess. Sets the Fossil context's error state on error. */ FSL_EXPORT int fsl_stmt_bind_double( fsl_stmt * const stmt, int index, double v ); /** Equivalent to fsl_stmt_bind_double() but binds to a named parameter. */ FSL_EXPORT int fsl_stmt_bind_double_name( fsl_stmt * const stmt, char const * param, double v ); /** Binds v to the given 1-based parameter index. Returns 0 on succcess. Sets the DB's error state on error. */ FSL_EXPORT int fsl_stmt_bind_id( fsl_stmt * const stmt, int index, fsl_id_t v ); /** Equivalent to fsl_stmt_bind_id() but binds to a named parameter. */ FSL_EXPORT int fsl_stmt_bind_id_name( fsl_stmt * const stmt, char const * param, fsl_id_t v ); /** Binds the first n bytes of v as text to the given 1-based bound parameter column in the given statement. If makeCopy is true then the binding makes an copy of the data. Set makeCopy to false ONLY if you KNOW that the bytes will outlive the binding. Returns 0 on success. On error stmt's underlying db's error state is updated, hopefully with a useful error message. */ FSL_EXPORT int fsl_stmt_bind_text( fsl_stmt * const stmt, int index, char const * v, fsl_int_t n, bool makeCopy ); /** Equivalent to fsl_stmt_bind_text() but binds to a named parameter. */ FSL_EXPORT int fsl_stmt_bind_text_name( fsl_stmt * const stmt, char const * param, char const * v, fsl_int_t n, bool makeCopy ); /** Binds the first n bytes of v as a blob to the given 1-based bound parameter column in the given statement. See fsl_stmt_bind_text() for the semantics of the makeCopy parameter and return value. */ FSL_EXPORT int fsl_stmt_bind_blob( fsl_stmt * const stmt, int index, void const * v, fsl_size_t len, bool makeCopy ); /** Equivalent to fsl_stmt_bind_blob() but binds to a named parameter. */ FSL_EXPORT int fsl_stmt_bind_blob_name( fsl_stmt * const stmt, char const * param, void const * v, fsl_int_t len, bool makeCopy ); /** Gets an integer value from the given 0-based result set column, assigns *v to that value, and returns 0 on success. Returns FSL_RC_RANGE if index is out of range for stmt, FSL_RC_MISUSE if stmt has no result columns. */ FSL_EXPORT int fsl_stmt_get_int32( fsl_stmt * const stmt, int index, int32_t * v ); /** Gets an integer value from the given 0-based result set column, assigns *v to that value, and returns 0 on success. Returns FSL_RC_RANGE if index is out of range for stmt, FSL_RC_MISUSE if stmt has no result columns. */ FSL_EXPORT int fsl_stmt_get_int64( fsl_stmt * const stmt, int index, int64_t * v ); /** The fsl_id_t counterpart of fsl_stmt_get_int32(). Depending on the sizeof(fsl_id_t), it behaves as one of fsl_stmt_get_int32() or fsl_stmt_get_int64(). */ FSL_EXPORT int fsl_stmt_get_id( fsl_stmt * const stmt, int index, fsl_id_t * v ); /** Convenience form of fsl_stmt_get_id() which returns the value directly but cannot report errors. It returns -1 on error, but that is not unambiguously an error value. */ FSL_EXPORT fsl_id_t fsl_stmt_g_id( fsl_stmt * const stmt, int index ); /** Convenience form of fsl_stmt_get_int32() which returns the value directly but cannot report errors. It returns 0 on error, but that is not unambiguously an error. */ FSL_EXPORT int32_t fsl_stmt_g_int32( fsl_stmt * const stmt, int index ); /** Convenience form of fsl_stmt_get_int64() which returns the value directly but cannot report errors. It returns 0 on error, but that is not unambiguously an error. */ FSL_EXPORT int64_t fsl_stmt_g_int64( fsl_stmt * const stmt, int index ); /** Convenience form of fsl_stmt_get_double() which returns the value directly but cannot report errors. It returns 0 on error, but that is not unambiguously an error. */ FSL_EXPORT double fsl_stmt_g_double( fsl_stmt * const stmt, int index ); /** Convenience form of fsl_stmt_get_text() which returns the value directly but cannot report errors. It returns NULL on error, but that is not unambiguously an error because it also returns NULL if the column contains an SQL NULL value. If outLen is not NULL then it is set to the byte length of the returned string. */ FSL_EXPORT char const * fsl_stmt_g_text( fsl_stmt * const stmt, int index, fsl_size_t * outLen ); /** Gets double value from the given 0-based result set column, assigns *v to that value, and returns 0 on success. Returns FSL_RC_RANGE if index is out of range for stmt, FSL_RC_MISUSE if stmt has no result columns. */ FSL_EXPORT int fsl_stmt_get_double( fsl_stmt * const stmt, int index, double * v ); /** Gets a string value from the given 0-based result set column, assigns *out (if out is not NULL) to that value, assigns *outLen (if outLen is not NULL) to *out's length in bytes, and returns 0 on success. Ownership of the string memory is unchanged - it is owned by the statement and the caller should immediately copy it if it will be needed for much longer. Returns FSL_RC_RANGE if index is out of range for stmt, FSL_RC_MISUSE if stmt has no result columns. Returns FSL_RC_OOM if fetching the text from the underlying statement handle fails due to an allocation error. */ FSL_EXPORT int fsl_stmt_get_text( fsl_stmt * const stmt, int index, char const **out, fsl_size_t * outLen ); /** The Blob counterpart of fsl_stmt_get_text(). Identical to that function except that its output result (3rd paramter) type differs, and it fetches the data as a raw blob, without any sort of string interpretation. Returns FSL_RC_RANGE if index is out of range for stmt, FSL_RC_MISUSE if stmt has no result columns. Returns FSL_RC_OOM if fetching the text from the underlying statement handle fails due to an allocation error. */ FSL_EXPORT int fsl_stmt_get_blob( fsl_stmt * const stmt, int index, void const **out, fsl_size_t * outLen ); /** Executes multiple SQL statements, ignoring any results they might collect. Returns 0 on success, non-0 on error. On error db->error might be updated to report the problem. */ FSL_EXPORT int fsl_db_exec_multi( fsl_db * const db, const char * sql, ...); /** va_list counterpart of db_exec_multi(). */ FSL_EXPORT int fsl_db_exec_multiv( fsl_db * const db, const char * sql, va_list args); /** Executes a single SQL statement, skipping over any results it may have. Returns 0 on success. On error db's error state may be updated. Note that this function translates FSL_RC_STEP_DONE and FSL_RC_STEP_ROW to 0. For cases where those particular result codes are significant, use fsl_db_prepare() and fsl_stmt_step() (for which this function is just a proxy). */ FSL_EXPORT int fsl_db_exec( fsl_db * const db, char const * sql, ... ); /** va_list counterpart of fs_db_exec(). */ FSL_EXPORT int fsl_db_execv( fsl_db * const db, char const * sql, va_list args ); /** Begins a transaction on the given db. Nested transactions are not directly supported but the db handle keeps track of open/close counts, such that fsl_db_transaction_end() will not actually do anything until the transaction begin/end counter goes to 0. Returns FSL_RC_MISUSE if !db or the db is not connected, else the result of the underlying db call(s). Transactions are an easy way to implement "dry-run" mode for some types of applications. For example: ``` char dryRunMode = ...; fsl_db_transaction_begin(db); ...do your stuff... fsl_db_transaction_end(db, dryRunMode ? 1 : 0); ``` Here's a tip for propagating error codes when using transactions: ``` ... if(rc) fsl_db_transaction_end(db, 1); else rc = fsl_db_transaction_end(db, 0); ``` That ensures that we propagate rc in the face of a rollback but we also capture the rc for a commit (which might yet fail). Note that a rollback in and of itself is not an error (though it also might fail, that would be "highly unusual" and indicative of other problems), and we certainly don't want to overwrite that precious non-0 rc with a successful return result from a rollback (which would, in effect, hide the error from the client). */ FSL_EXPORT int fsl_db_transaction_begin(fsl_db * const db); /** Equivalent to fsl_db_transaction_end(db, 0). */ FSL_EXPORT int fsl_db_transaction_commit(fsl_db * const db); /** Equivalent to fsl_db_transaction_end(db, 1). */ FSL_EXPORT int fsl_db_transaction_rollback(fsl_db * const db); /** Forces a rollback of any pending transaction in db, regardless of the internal transaction begin/end counter. Returns FSL_RC_MISUSE if db is not opened, else returns the value of the underlying ROLLBACK call. This also re-sets/frees any transaction-related state held by db (e.g. db->beforeCommit). Use with care, as this mucks about with db state in a way which is not all that pretty and it may confuse downstream code. Returns 0 on success. Never, ever use this. In 8+ years it has never proven necessary to use this function, and doing so can easily lead to a mismatch in transaction-using code and the transaction stack level. */ FSL_EXPORT int fsl_db_rollback_force(fsl_db * const db); /** Decrements the transaction counter incremented by fsl_db_transaction_begin() and commits or rolls back the transaction if the counter goes to 0. If doRollback is true then this rolls back (or schedules a rollback of) a transaction started by fsl_db_transaction_begin(). If doRollback is false is commits (or schedules a commit). If db fsl_db_transaction_begin() is used in a nested manner and doRollback is true for any one of the nested calls, then that value will be remembered, such that the downstream calls to this function within the same transaction will behave like a rollback even if they pass 0 for the second argument. Returns FSL_RC_MISUSE if db is not opened, 0 if the transaction counter is above 0, else the result of the (potentially many) underlying database operations. Unfortunate low-level co-dependency: if db->f is not NULL then this function may perform extra repository-related post-processing on any commit, and checking the result code is particularly important for those cases. Sidebar: this APIs pseudo-nested transaction support was initially a direct port of that from fossil(1). sqlite3 added SAVEPOINT support, which is essentially named, nested transaction, much later on. That support may have been a better basis for this API, but it didn't exist at the time and an overhaul would be both time-consuming and risk all sorts of new bugs. SAVEPOINTS: https://sqlite.org/lang_savepoint.html Though this API does not prohibit the use of savepoints (like it does direct use of BEGIN/COMMIT/ROLLBACK from SQL code), it is untested with them and undesired side effects vis a vis this API's transaction support cannot be entirely ruled out. */ FSL_EXPORT int fsl_db_transaction_end(fsl_db * const db, bool doRollback); /** Returns the given db's current transaction depth. If the value is negative, its absolute value represents the depth but indicates that a rollback is pending. If it is positive, the transaction is still in a "good" state. If it is 0, no transaction is active. */ FSL_EXPORT int fsl_db_transaction_level(fsl_db * const db); /** Runs the given SQL query on the given db and returns true if the query returns any rows, else false. Returns 0 for any error as well. */ FSL_EXPORT bool fsl_db_exists(fsl_db * const db, char const * sql, ... ); /** va_list counterpart of fsl_db_exists(). */ FSL_EXPORT bool fsl_db_existsv(fsl_db * const db, char const * sql, va_list args ); /** Runs a fetch-style SQL query against DB and returns the first column of the first result row via *rv. If the query returns no rows, *rv is not modified. The intention is that the caller sets *rv to his preferred default (or sentinel) value before calling this. The format string (the sql parameter) accepts all formatting options supported by fsl_appendf(). Returns 0 on success. On error db's error state is updated and *rv is not modified. Returns FSL_RC_MISUSE without side effects if !db, !rv, !sql, or !*sql. */ FSL_EXPORT int fsl_db_get_int32( fsl_db * const db, int32_t * rv, char const * sql, ... ); /** va_list counterpart of fsl_db_get_int32(). */ FSL_EXPORT int fsl_db_get_int32v( fsl_db * const db, int32_t * rv, char const * sql, va_list args); /** Convenience form of fsl_db_get_int32() which returns the value directly but provides no way of checking for errors. On error, or if no result is found, defaultValue is returned. */ FSL_EXPORT int32_t fsl_db_g_int32( fsl_db * const db, int32_t defaultValue, char const * sql, ... ); /** The int64 counterpart of fsl_db_get_int32(). See that function for the semantics. */ FSL_EXPORT int fsl_db_get_int64( fsl_db * const db, int64_t * rv, char const * sql, ... ); /** va_list counterpart of fsl_db_get_int64(). */ FSL_EXPORT int fsl_db_get_int64v( fsl_db * const db, int64_t * rv, char const * sql, va_list args); /** Convenience form of fsl_db_get_int64() which returns the value directly but provides no way of checking for errors. On error, or if no result is found, defaultValue is returned. */ FSL_EXPORT int64_t fsl_db_g_int64( fsl_db * const db, int64_t defaultValue, char const * sql, ... ); /** The fsl_id_t counterpart of fsl_db_get_int32(). See that function for the semantics. */ FSL_EXPORT int fsl_db_get_id( fsl_db * const db, fsl_id_t * rv, char const * sql, ... ); /** va_list counterpart of fsl_db_get_id(). */ FSL_EXPORT int fsl_db_get_idv( fsl_db * const db, fsl_id_t * rv, char const * sql, va_list args); /** Convenience form of fsl_db_get_id() which returns the value directly but provides no way of checking for errors. On error, or if no result is found, defaultValue is returned. */ FSL_EXPORT fsl_id_t fsl_db_g_id( fsl_db * const db, fsl_id_t defaultValue, char const * sql, ... ); /** The fsl_size_t counterpart of fsl_db_get_int32(). See that function for the semantics. If this function would fetch a negative value, it returns FSL_RC_RANGE and *rv is not modified. */ FSL_EXPORT int fsl_db_get_size( fsl_db * const db, fsl_size_t * rv, char const * sql, ... ); /** va_list counterpart of fsl_db_get_size(). */ FSL_EXPORT int fsl_db_get_sizev( fsl_db * const db, fsl_size_t * rv, char const * sql, va_list args); /** Convenience form of fsl_db_get_size() which returns the value directly but provides no way of checking for errors. On error, or if no result is found, defaultValue is returned. */ FSL_EXPORT fsl_size_t fsl_db_g_size( fsl_db * const db, fsl_size_t defaultValue, char const * sql, ... ); /** The double counterpart of fsl_db_get_int32(). See that function for the semantics. */ FSL_EXPORT int fsl_db_get_double( fsl_db * const db, double * rv, char const * sql, ... ); /** va_list counterpart of fsl_db_get_double(). */ FSL_EXPORT int fsl_db_get_doublev( fsl_db * const db, double * rv, char const * sql, va_list args); /** Convenience form of fsl_db_get_double() which returns the value directly but provides no way of checking for errors. On error, or if no result is found, defaultValue is returned. */ FSL_EXPORT double fsl_db_g_double( fsl_db * const db, double defaultValue, char const * sql, ... ); /** The C-string counterpart of fsl_db_get_int32(). On success *rv will be set to a dynamically allocated string copied from the first column of the first result row. If rvLen is not NULL then *rvLen will be assigned the byte-length of that string. If no row is found, *rv is set to NULL and *rvLen (if not NULL) is set to 0, and 0 is returned. Note that NULL is also a legal result (an SQL NULL translates as a NULL string), The caller must eventually free the returned string value using fsl_free(). */ FSL_EXPORT int fsl_db_get_text( fsl_db * const db, char ** rv, fsl_size_t * rvLen, char const * sql, ... ); /** va_list counterpart of fsl_db_get_text(). */ FSL_EXPORT int fsl_db_get_textv( fsl_db * const db, char ** rv, fsl_size_t * rvLen, char const * sql, va_list args ); /** Convenience form of fsl_db_get_text() which returns the value directly but provides no way of checking for errors. On error, or if no result is found, NULL is returned. The returned string must eventually be passed to fsl_free() to free it. If len is not NULL then if non-NULL is returned, *len will be assigned the byte-length of the returned string. */ FSL_EXPORT char * fsl_db_g_text( fsl_db * const db, fsl_size_t * len, char const * sql, ... ); /** The Blob counterpart of fsl_db_get_text(). Identical to that function except that its output result (2nd paramter) type differs, and it fetches the data as a raw blob, without any sort of string interpretation. The returned *rv memory must eventually be passed to fsl_free() to free it. If len is not NULL then on success *len will be set to the byte length of the returned blob. If no row is found, *rv is set to NULL and *rvLen (if not NULL) is set to 0, and 0 is returned. Note that NULL is also a legal result (an SQL NULL translates as a NULL string), */ FSL_EXPORT int fsl_db_get_blob( fsl_db * const db, void ** rv, fsl_size_t * len, char const * sql, ... ); /** va_list counterpart of fsl_db_get_blob(). */ FSL_EXPORT int fsl_db_get_blobv( fsl_db * const db, void ** rv, fsl_size_t * stmtLen, char const * sql, va_list args ); /** Convenience form of fsl_db_get_blob() which returns the value directly but provides no way of checking for errors. On error, or if no result is found, NULL is returned. */ FSL_EXPORT void * fsl_db_g_blob( fsl_db * const db, fsl_size_t * len, char const * sql, ... ); /** Similar to fsl_db_get_text() and fsl_db_get_blob(), but writes its result to tgt, appending its results to the given buffer. If asBlob is true then the underlying BLOB API is used to populate the buffer, else the underlying STRING/TEXT API is used. For many purposes there will be no difference, but if you know you might have binary data, be sure to pass a true value for asBlob to avoid any potential encoding-related problems. Results are undefined if any pointer argument is NULL. Returns FSL_RC_MISUSE if the SQL is an empty string. */ FSL_EXPORT int fsl_db_get_buffer( fsl_db * const db, fsl_buffer * const tgt, bool asBlob, char const * sql, ... ); /** va_list counterpart of fsl_db_get_buffer(). */ FSL_EXPORT int fsl_db_get_bufferv( fsl_db * const db, fsl_buffer * const tgt, bool asBlob, char const * sql, va_list args ); /** Expects sql to be a SELECT-style query which (potentially) returns a result set. For each row in the set callback() is called, as described for fsl_stmt_each(). Returns 0 on success. The callback is _not_ called for queries which return no rows. If clients need to know if rows were returned, they can add a counter to their callbackState and increment it from the callback. Returns FSL_RC_MISUSE if db is not opened, !callback, !sql. Returns FSL_RC_RANGE if !*sql. */ FSL_EXPORT int fsl_db_each( fsl_db * const db, fsl_stmt_each_f callback, void * callbackState, char const * sql, ... ); /** va_list counterpart to fsl_db_each(). */ FSL_EXPORT int fsl_db_eachv( fsl_db * const db, fsl_stmt_each_f callback, void * callbackState, char const * sql, va_list args ); /** Returns the given Julian date value formatted as an ISO8601 string (with a fractional seconds part if msPrecision is true, else without it). Returns NULL if !db, db is not connected, j is less than 0, or on allocation error. The returned memory must eventually be freed using fsl_free(). If localTime is true then the value is converted to the local time, otherwise it is not. @see fsl_db_unix_to_iso8601() @see fsl_julian_to_iso8601() @see fsl_iso8601_to_julian() */ FSL_EXPORT char * fsl_db_julian_to_iso8601( fsl_db * const db, double j, bool msPrecision, bool localTime ); /** Returns the given Julian date value formatted as an ISO8601 string (with a fractional seconds part if msPrecision is true, else without it). Returns NULL if !db, db is not connected, j is less than 0, or on allocation error. The returned memory must eventually be freed using fsl_free(). If localTime is true then the value is converted to the local time, otherwise it is not. @see fsl_db_julian_to_iso8601() @see fsl_julian_to_iso8601() @see fsl_iso8601_to_julian() */ FSL_EXPORT char * fsl_db_unix_to_iso8601( fsl_db * const db, fsl_time_t j, bool localTime ); /** Returns the current time in Julian Date format. Returns a negative value if !db or db is not opened. */ FSL_EXPORT double fsl_db_julian_now(fsl_db * const db); /** Uses the given db to convert the given time string to Julian Day format. If it cannot be converted, a negative value is returned. The str parameter can be anything suitable for passing to sqlite's: SELECT julianday(str) Note that this routine will escape str for use with SQL - the caller must not do so. @see fsl_julian_to_iso8601() @see fsl_iso8601_to_julian() */ FSL_EXPORT double fsl_db_string_to_julian(fsl_db * const db, char const * str); /** Opens the given db file and populates db with its handle. db must have been cleanly initialized by copy-initializing it from fsl_db_empty (or fsl_db_empty_m) or by allocating it using fsl_db_malloc(). Failure to do so will lead to undefined behaviour. openFlags may be a mask of FSL_OPEN_F_xxx values, but not all are used/supported here. If FSL_OPEN_F_CREATE is _not_ set in openFlags and dbFile does not exist, it will return FSL_RC_NOT_FOUND. The existence of FSL_OPEN_F_CREATE in the flags will cause this routine to try to create the file if needed. If conflicting flags are specified (e.g. FSL_OPEN_F_RO and FSL_OPEN_F_RWC) then which one takes precedence is unspecified and possibly unpredictable. As a special case, if dbFile is ":memory:" (for an in-memory database) or "" (empty string, for a "temporary" database) then it is is passed through without any filesystem-related checks and the openFlags are ignored. See this page for the differences between ":memory:" and "": https://www.sqlite.org/inmemorydb.html Returns FSL_RC_MISUSE if !db, !dbFile, !*dbFile, or if db->dbh is not NULL (i.e. if it is already opened or its memory was default-initialized (use fsl_db_empty to cleanly copy-initialize new stack-allocated instances). On error db->dbh will be NULL, but db->error might contain error details. Regardless of success or failure, db should be passed to fsl_db_close() to free up all memory associated with it. It is not closed automatically by this function because doing so cleans up the error state, which the caller will presumably want to have. If db->f is not NULL when this is called then it is assumed that db should be plugged in to the Fossil repository system, and the following additional things happen: - A number of SQL functions are registered with the db. Details are below. - If FSL_OPEN_F_SCHEMA_VALIDATE is set in openFlags then the db is validated to see if it has a fossil schema. If that validation fails, FSL_RC_REPO_NEEDS_REBUILD or FSL_RC_NOT_A_REPO will be returned and db's error state will be updated. db->f does not need to be set for that check to work. If db->f is not NULL when this function is called then any error triggered during opening is _copied_ into db->f's error state. @see fsl_db_close() @see fsl_db_prepare() @see fsl_db_malloc() */ FSL_EXPORT int fsl_db_open( fsl_db * const db, char const * dbFile, int openFlags ); /** Closes the given db handle and frees any resources owned by db. Results are undefined if db is NULL. If db is not opened, this is a harmless no-op. If db was allocated using fsl_db_malloc() (as determined by examining db->allocStamp) then this routine also fsl_free()s it, otherwise it is assumed to either be on the stack or part of a larger struct and is not freed. If db has any pending transactions, they are rolled back by this function. */ FSL_EXPORT void fsl_db_close( fsl_db * const db ); /** If db is an opened db handle, this registers a debugging function with the db which traces all SQL to the given FILE handle (defaults to stdout if outStream is NULL). This mechanism is only intended for debugging and exploration of how Fossil works. Tracing is often as easy way to ensure that a given code block is getting run. As a special case, if db->f is not NULL _before_ it is is fsl_db_open()ed, then this function automatically gets installed if the SQL tracing option is enabled for that fsl_cx instance before the db is opened. This is a no-op if db is not opened. TODOs: - Expand this API to take a client-side callback and state object, rather than a FILE pointer. - Provide a toggle for the tracing level: with and without "expanded" SQL. Expanding the SQL to include its bound values is far more expensive (but also far more informative). */ FSL_EXPORT void fsl_db_sqltrace_enable( fsl_db * const db, FILE * outStream ); /** Returns the row ID of the most recent insertion, or -1 if !db, db is not connected, or 0 if no inserts have been performed. */ FSL_EXPORT fsl_id_t fsl_db_last_insert_id(fsl_db * const db); /** Returns non-0 (true) if the database (which must be open) table identified by zTableName has a column named zColName (case-sensitive), else returns 0. */ FSL_EXPORT bool fsl_db_table_has_column( fsl_db * const db, char const *zTableName, char const *zColName ); /** If a db name has been associated with db then it is returned, otherwise NULL is returned. A db has no name by default, but fsl_cx-used ones get their database name assigned to them (e.g. "main" for the main db). */ FSL_EXPORT char const * fsl_db_name(fsl_db const * const db); /** Returns a db name string for the given fsl_db_role value. The string is static, guaranteed to live as long as the app. It returns NULL if passed FSL_DBROLE_NONE or some value out of range for the enum. */ FSL_EXPORT const char * fsl_db_role_name(enum fsl_dbrole_e r); /** Allocates a new fsl_db instance(). Returns NULL on allocation error. Note that fsl_db instances can often be used from the stack - allocating them dynamically is an uncommon case necessary for script bindings. Achtung: the returned value's allocStamp member is used for determining if fsl_db_close() should free the value or not. Thus if clients copy over this value without adjusting allocStamp back to its original value, the library will likely leak the instance. Been there, done that. */ FSL_EXPORT fsl_db * fsl_db_malloc(void); /** The fsl_stmt counterpart of fsl_db_malloc(). See that function for when you might want to use this and a caveat involving the allocStamp member of the returned value. fsl_stmt_finalize() will free statements created with this function. */ FSL_EXPORT fsl_stmt * fsl_stmt_malloc(void); /** ATTACHes the file zDbName to db using the databbase name zLabel. Returns 0 on success. Returns FSL_RC_MISUSE if any argument is NULL or any string argument starts with a NUL byte, else it returns the result of fsl_db_exec() which attaches the db. On db-level errors db's error state will be updated. */ FSL_EXPORT int fsl_db_attach(fsl_db * const db, const char *zDbName, const char *zLabel); /** The converse of fsl_db_detach(). Must be passed the same arguments which were passed as the 1st and 3rd arguments to fsl_db_attach(). Returns 0 on success, FSL_RC_MISUSE if !db, !zLabel, or !*zLabel, else it returns the result of the underlying fsl_db_exec() call. */ FSL_EXPORT int fsl_db_detach(fsl_db * const db, const char *zLabel); /** Expects fmt to be a SELECT-style query. For each row in the query, the first column is fetched as a string and appended to the tgt list. Returns 0 on success, FSL_RC_MISUSE if !fmt or fmt is empty, or any number of potential FSL_RC_OOM or db-related errors. Results rows with a NULL value (resulting from an SQL NULL) are added to the list as NULL entries. Each entry appended to the list is a (char *) which must be freed using fsl_free(). To easiest way to clean up the list and its contents is: ``` fsl_list_visit_free(tgt,...); ``` On error the list may be partially populated. Complete example: ``` fsl_list li = fsl_list_empty; int rc = fsl_db_select_slist(db, &li, "SELECT uuid FROM blob WHERE rid<20"); if(!rc){ fsl_size_t i; for(i = 0;i < li.used; ++i){ char const * uuid = (char const *)li.list[i]; fsl_fprintf(stdout, "UUID: %s\n", uuid); } } fsl_list_visit_free(&li, 1); ``` Of course fsl_list_visit() may be used to traverse the list as well, as long as the visitor expects (char [const]*) list elements. */ FSL_EXPORT int fsl_db_select_slist( fsl_db * const db, fsl_list * const tgt, char const * fmt, ... ); /** The va_list counterpart of fsl_db_select_slist(). */ FSL_EXPORT int fsl_db_select_slistv( fsl_db * const db, fsl_list * const tgt, char const * fmt, va_list args ); /** Returns n bytes of random lower-case hexidecimal characters using the given db as its data source, plus a terminating NUL byte. The returned memory must eventually be freed using fsl_free(). Returns NULL if !n, db is not opened, or on a db-level error. */ FSL_EXPORT char * fsl_db_random_hex(fsl_db * const db, fsl_size_t n); /** Returns the "number of database rows that were changed or inserted or deleted by the most recently completed SQL statement" (to quote the underlying APIs). Returns 0 if db is not opened. See: https://sqlite.org/c3ref/changes.html */ FSL_EXPORT int fsl_db_changes_recent(fsl_db * const db); /** Returns "the number of row changes caused by INSERT, UPDATE or DELETE statements since the database connection was opened" (to quote the underlying APIs). Returns 0 if db is not opened. See; https://sqlite.org/c3ref/total_changes.html */ FSL_EXPORT int fsl_db_changes_total(fsl_db * const db); /** Initializes the given database file. zFilename is the name of the db file. It is created if needed, but any directory components are not created. zSchema is the base schema to install. The following arguments may be (char const *) SQL code, each of which gets run against the db after the main schema is called. The variadic argument list MUST end with NULL (0), even if there are no non-NULL entries. Returns 0 on success. On error, if err is not NULL then it is populated with any error state from the underlying (temporary) db handle. */ FSL_EXPORT int fsl_db_init( fsl_error * err, char const * zFilename, char const * zSchema, ... ); /** A fsl_stmt_each_f() impl, intended primarily for debugging, which simply outputs row data in tabular form via fsl_output(). The state argument must be a valid fsl_cx pointer. On the first row, the column names are output. Achtung: this function's expectations were changed on 2024-09-16: prior to this, stmt's db handle had access to a fsl_cx instance, but that was factored out. It now requires the state argument to be a fsl_cx. */ FSL_EXPORT int fsl_stmt_each_f_dump( fsl_stmt * const stmt, void * state ); /** Returns true if the table name specified by the final argument exists in the fossil database specified by the 2nd argument on the db connection specified by the first argument, else returns false. Trivia: this is one of the few libfossil APIs which makes use of FSL_DBROLE_TEMP. Potential TODO: this is a bit of a wonky interface. Consider changing it to eliminate the role argument, which is only really needed if we have duplicate table names across attached dbs or if we internally mess up and write a table to the wrong db. */ FSL_EXPORT bool fsl_db_table_exists(fsl_db * const db, fsl_dbrole_e whichDb, const char *zTable); /** The elipsis counterpart of fsl_stmt_bind_fmtv(). */ FSL_EXPORT int fsl_stmt_bind_fmt( fsl_stmt * const st, char const * fmt, ... ); /** Binds a series of values using a formatting string. The string may contain the following characters, each of which refers to the next argument in the args list: '-': binds a NULL and expects a NULL placeholder in the argument list (for consistency's sake). 'i': binds an int32 'I': binds an int64 'R': binds a fsl_id_t ('R' as in 'RID') 'f': binds a double 's': binds a (char const *) as text or NULL. 'S': binds a (char const *) as a blob or NULL. 'b': binds a (fsl_buffer const *) as text or NULL. 'B': binds a (fsl_buffer const *) as a blob or NULL. ' ': spaces are allowed for readability and are ignored. Returns 0 on success, any number of other FSL_RC_xxx codes on error. ACHTUNG: the "sSbB" bindings assume, because of how this API is normally used, that the memory pointed to by the given argument will outlive the pending step of the given statement, so that memory is NOT copied by the binding. Thus results are undefined if such an argument's memory is invalidated before the statement is done with it. */ FSL_EXPORT int fsl_stmt_bind_fmtv( fsl_stmt * const st, char const * fmt, va_list args ); /** Works like fsl_stmt_bind_fmt() but: 1) It calls fsl_stmt_reset() before binding the arguments. 2) If binding succeeds then it steps the given statement a single time. 3) If the result is _NOT_ FSL_RC_STEP_ROW then it also resets the statement before returning. It does not do so for FSL_RC_STEP_ROW because doing so would remove the fetched columns (and this is why it resets in step (1)). Returns 0 if stepping results in FSL_RC_STEP_DONE, FSL_RC_STEP_ROW if it produces a result row, or any number of other potential non-0 codes on error. On error, the error state of st->db is updated. Design note: the return value for FSL_RC_STEP_ROW, as opposed to returning 0, is necessary for proper statement use if the client wants to fetch any result data from the statement afterwards (which is illegal if FSL_RC_STEP_ROW was not the result). This is also why it cannot reset the statement if that result is returned. */ FSL_EXPORT int fsl_stmt_bind_stepv( fsl_stmt * const st, char const * fmt, va_list args ); /** The elipsis counterpart of fsl_stmt_bind_stepv(). */ FSL_EXPORT int fsl_stmt_bind_step( fsl_stmt * st, char const * fmt, ... ); /** Sets the on-close hook for the given db, overwriting any prior one. To clear the hook, pass NULL for the 2nd and 3rd arguments. */ FSL_EXPORT void fsl_db_hook_close( fsl_db * const db, fsl_db_hook_close_f f, void * pState ); /** Sets the on-transaction hook for the given db, overwriting any prior one. To clear the hook, pass NULL for the 2nd and 3rd arguments. */ FSL_EXPORT void fsl_db_hook_transaction( fsl_db * const db, fsl_db_hook_transaction_f f, void * pState ); #if defined(__cplusplus) } /*extern "C"*/ #endif #endif /* ORG_FOSSIL_SCM_FSL_DB_H_INCLUDED */