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Overview
Comment:Add the "fossil git export" command, designed to simplify making a Git mirror of a working Fossil repository.
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA3-256: 702959420fa6a5878fd0dc2db0b5b88d19c461d8a42f88b88b5e7a01efc9af83
User & Date: drh 2019-03-16 00:58:05
Context
2019-03-16
01:07
Add a README.md file for the sake of the GitHub test mirror. check-in: ced33d1a user: drh tags: trunk
00:58
Add the "fossil git export" command, designed to simplify making a Git mirror of a working Fossil repository. check-in: 70295942 user: drh tags: trunk
00:26
Enhance the "fossil git export" command so that it also exports tags as lightweight Git tags. Closed-Leaf check-in: 4f19d67b user: drh tags: mirror-cmd
2019-03-14
13:52
When doing a "fossil stash" make sure that the stash has committed before deleting changes from disk, so that the changes can be recovered if something goes wrong. check-in: 60af514d user: drh tags: trunk
Changes
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Changes to src/export.c.

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*/
static struct {
  const char *zTrunkName;     /* Name of trunk branch */
} gexport;

#if INTERFACE
/*
** struct mark_t
**   holds information for translating between git commits
**   and fossil commits.
**   -git_name: This is the mark name that identifies the commit to git.
**              It will always begin with a ':'.
**   -rid: The unique object ID that identifies this commit within the
**         repository database.
**   -uuid: The SHA-1/SHA-3 of artifact corresponding to rid.
*/
struct mark_t{
  char *name;
  int rid;


  char uuid[65];
};
#endif

/*
** Output a "committer" record for the given user.
** NOTE: the given user name may be an email itself.
*/
................................................................................
      return NULL;
    }
  }
  return zMark;
}

/*
** parse_mark()
**   Create a new (mark,rid,uuid) entry in the 'xmark' table given a line
**   from a marks file.  Return the cross-ref information as a struct mark_t
**   in *mark.
**   This function returns -1 in the case that the line is blank, malformed, or
**   the rid/uuid named in 'line' does not match what is in the repository
**   database.  Otherwise, 0 is returned.

**   mark->name is dynamically allocated, and owned by the caller.
*/
int parse_mark(char *line, struct mark_t *mark){
  char *cur_tok;
  char type_;
  cur_tok = strtok(line, " \t");
  if( !cur_tok || strlen(cur_tok)<2 ){
    return -1;
................................................................................

  /* insert a cross-ref into the 'xmark' table */
  insert_commit_xref(mark->rid, mark->name, mark->uuid);
  return 0;
}

/*
** import_marks()
**   Import the marks specified in file 'f' into the 'xmark' table.
**   If 'blobs' is non-null, insert all blob marks into it.
**   If 'vers' is non-null, insert all commit marks into it.
**   If 'unused_marks' is non-null, upon return of this function, all values
**   x >= *unused_marks are free to use as marks, i.e. they do not clash with
**   any marks appearing in the marks file.

**   Each line in the file must be at most 100 characters in length.  This
**   seems like a reasonable maximum for a 40-character uuid, and 1-13
**   character rid.

**   The function returns -1 if any of the lines in file 'f' are malformed,
**   or the rid/uuid information doesn't match what is in the repository
**   database.  Otherwise, 0 is returned.
*/
int import_marks(FILE* f, Bag *blobs, Bag *vers, unsigned int *unused_mark){
  char line[101];
  while(fgets(line, sizeof(line), f)){
    struct mark_t mark;
    if( strlen(line)==100 && line[99]!='\n' ){
      /* line too long */
................................................................................
      do{
        export_mark(f, rid, 'c');
      }while( (rid = bag_next(vers, rid))!=0 );
    }
  }
}

/*
** COMMAND: export
**
** Usage: %fossil export --git ?OPTIONS? ?REPOSITORY?
**
** Write an export of all check-ins to standard output.  The export is
** written in the git-fast-export file format assuming the --git option is
** provided.  The git-fast-export format is currently the only VCS
** interchange format supported, though other formats may be added in
** the future.
................................................................................
**   --export-marks FILE          export rids of exported data to FILE
**   --import-marks FILE          read rids of data to ignore from FILE
**   --rename-trunk NAME          use NAME as name of exported trunk branch
**   --repository|-R REPOSITORY   export the given REPOSITORY
**
** See also: import
*/





void export_cmd(void){
  Stmt q, q2, q3;
  Bag blobs, vers;
  unsigned int unused_mark = 1;
  const char *markfile_in;
  const char *markfile_out;

................................................................................

  db_find_and_open_repository(0, 2);
  verify_all_options();
  if( g.argc!=2 && g.argc!=3 ){ usage("--git ?REPOSITORY?"); }

  db_multi_exec("CREATE TEMPORARY TABLE oldblob(rid INTEGER PRIMARY KEY)");
  db_multi_exec("CREATE TEMPORARY TABLE oldcommit(rid INTEGER PRIMARY KEY)");
  db_multi_exec("CREATE TEMP TABLE xmark(tname TEXT UNIQUE, trid INT, tuuid TEXT)");

  db_multi_exec("CREATE INDEX xmark_trid ON xmark(trid)");
  if( markfile_in!=0 ){
    Stmt qb,qc;
    FILE *f;
    int rid;

    f = fossil_fopen(markfile_in, "r");
................................................................................
**        tid INTEGER PRIMARY KEY,   -- Check-in id
**        tseq INT                   -- integer total order on check-ins.
**     );
**
** This table contains all check-ins of the repository in topological
** order.  "Topological order" means that every parent check-in comes
** before all of its children.  Topological order is *almost* the same
** thing as "ORDER BY event.mtime".  Differences only arrise when there
** are timewarps.  In as much as Git hates timewarps, we have to compute
** a correct topological order when doing an export.
**
** Since mtime is a usually already nearly in topological order, the
** algorithm is to start with mtime, then make adjustments as necessary
** for timewarps.  This is not a great algorithm for the general case,
** but it is very fast for the overwhelmingly common case where there
................................................................................
*/
void test_topological_sort(void){
  int n;
  db_find_and_open_repository(0, 0);
  n = topological_sort_checkins(1);
  fossil_print("%d reorderings required\n", n);
}










































































































































































































































































































































































































































































































































































































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*/
static struct {
  const char *zTrunkName;     /* Name of trunk branch */
} gexport;

#if INTERFACE
/*
** Each line in a git-fast-export "marK" file is an instance of
** this object.






*/
struct mark_t {


  char *name;       /* Name of the mark.  Also starts with ":" */
  int rid;          /* Corresponding object in the BLOB table */
  char uuid[65];    /* The GIT hash name for this object */
};
#endif

/*
** Output a "committer" record for the given user.
** NOTE: the given user name may be an email itself.
*/
................................................................................
      return NULL;
    }
  }
  return zMark;
}

/*
** Parse a single line of the mark file.  Store the result in the mark object.
**
** "line" is a single line of input.

** This function returns -1 in the case that the line is blank, malformed, or
** the rid/uuid named in 'line' does not match what is in the repository
** database.  Otherwise, 0 is returned.
**
** mark->name is dynamically allocated, and owned by the caller.
*/
int parse_mark(char *line, struct mark_t *mark){
  char *cur_tok;
  char type_;
  cur_tok = strtok(line, " \t");
  if( !cur_tok || strlen(cur_tok)<2 ){
    return -1;
................................................................................

  /* insert a cross-ref into the 'xmark' table */
  insert_commit_xref(mark->rid, mark->name, mark->uuid);
  return 0;
}

/*

** Import the marks specified in file 'f';
** If 'blobs' is non-null, insert all blob marks into it.
** If 'vers' is non-null, insert all commit marks into it.
** If 'unused_marks' is non-null, upon return of this function, all values
** x >= *unused_marks are free to use as marks, i.e. they do not clash with
** any marks appearing in the marks file.
**
** Each line in the file must be at most 100 characters in length.  This
** seems like a reasonable maximum for a 40-character uuid, and 1-13
** character rid.
**
** The function returns -1 if any of the lines in file 'f' are malformed,
** or the rid/uuid information doesn't match what is in the repository
** database.  Otherwise, 0 is returned.
*/
int import_marks(FILE* f, Bag *blobs, Bag *vers, unsigned int *unused_mark){
  char line[101];
  while(fgets(line, sizeof(line), f)){
    struct mark_t mark;
    if( strlen(line)==100 && line[99]!='\n' ){
      /* line too long */
................................................................................
      do{
        export_mark(f, rid, 'c');
      }while( (rid = bag_next(vers, rid))!=0 );
    }
  }
}

/* This is the original header command (and hence documentation) for
** the "fossil export" command:
** 
** Usage: %fossil export --git ?OPTIONS? ?REPOSITORY?
**
** Write an export of all check-ins to standard output.  The export is
** written in the git-fast-export file format assuming the --git option is
** provided.  The git-fast-export format is currently the only VCS
** interchange format supported, though other formats may be added in
** the future.
................................................................................
**   --export-marks FILE          export rids of exported data to FILE
**   --import-marks FILE          read rids of data to ignore from FILE
**   --rename-trunk NAME          use NAME as name of exported trunk branch
**   --repository|-R REPOSITORY   export the given REPOSITORY
**
** See also: import
*/
/*
** COMMAND: export*
**
** This command is deprecated.  Use "fossil git export" instead.
*/
void export_cmd(void){
  Stmt q, q2, q3;
  Bag blobs, vers;
  unsigned int unused_mark = 1;
  const char *markfile_in;
  const char *markfile_out;

................................................................................

  db_find_and_open_repository(0, 2);
  verify_all_options();
  if( g.argc!=2 && g.argc!=3 ){ usage("--git ?REPOSITORY?"); }

  db_multi_exec("CREATE TEMPORARY TABLE oldblob(rid INTEGER PRIMARY KEY)");
  db_multi_exec("CREATE TEMPORARY TABLE oldcommit(rid INTEGER PRIMARY KEY)");
  db_multi_exec("CREATE TEMP TABLE xmark(tname TEXT UNIQUE, trid INT,"
                " tuuid TEXT)");
  db_multi_exec("CREATE INDEX xmark_trid ON xmark(trid)");
  if( markfile_in!=0 ){
    Stmt qb,qc;
    FILE *f;
    int rid;

    f = fossil_fopen(markfile_in, "r");
................................................................................
**        tid INTEGER PRIMARY KEY,   -- Check-in id
**        tseq INT                   -- integer total order on check-ins.
**     );
**
** This table contains all check-ins of the repository in topological
** order.  "Topological order" means that every parent check-in comes
** before all of its children.  Topological order is *almost* the same
** thing as "ORDER BY event.mtime".  Differences only arise when there
** are timewarps.  In as much as Git hates timewarps, we have to compute
** a correct topological order when doing an export.
**
** Since mtime is a usually already nearly in topological order, the
** algorithm is to start with mtime, then make adjustments as necessary
** for timewarps.  This is not a great algorithm for the general case,
** but it is very fast for the overwhelmingly common case where there
................................................................................
*/
void test_topological_sort(void){
  int n;
  db_find_and_open_repository(0, 0);
  n = topological_sort_checkins(1);
  fossil_print("%d reorderings required\n", n);
}

/***************************************************************************
** Implementation of the "fossil git" command follows.  We hope that the
** new code that follows will largely replace the legacy "fossil export"
** and "fossil import" code above.
*/

/*
** Convert characters of z[] that are not allowed to be in branch or
** tag names into "_".
*/
static void gitmirror_sanitize_name(char *z){
  static unsigned char aSafe[] = {
     /* x0 x1 x2 x3 x4 x5 x6 x7 x8  x9 xA xB xC xD xE xF */
         0, 0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0,  /* 0x */
         0, 0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0,  /* 1x */
         0, 1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1,  /* 2x */
         1, 1, 1, 1, 1, 1, 1, 1, 1,  1, 0, 1, 1, 1, 1, 0,  /* 3x */
         0, 1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1,  /* 4x */
         1, 1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 0, 0, 1, 0, 1,  /* 5x */
         1, 1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1,  /* 6x */
         1, 1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 0, 0,  /* 7x */
  };
  unsigned char *zu = (unsigned char*)z;
  int i;
  for(i=0; zu[i]; i++){
    if( zu[i]>0x7f || !aSafe[zu[i]] ){
      zu[i] = '_';
    }else if( zu[i]=='/' && (i==0 || zu[i+1]==0 || zu[i+1]=='/') ){
      zu[i] = '_';
    }else if( zu[i]=='.' && (zu[i+1]==0 || zu[i+1]=='.'
                             || (i>0 && zu[i-1]=='.')) ){
      zu[i] = '_';
    }
  }
}

/*
** Quote a filename as a C-style string using \\ and \" if necessary.
** If quoting is not necessary, just return a copy of the input string.
**
** The return value is a held in memory obtained from fossil_malloc()
** and must be freed by the caller.
*/
static char *gitmirror_quote_filename_if_needed(const char *zIn){
  int i, j;
  char c;
  int nSpecial = 0;
  char *zOut;
  for(i=0; (c = zIn[i])!=0; i++){
    if( c=='\\' || c=='"' || c=='\n' ){
      nSpecial++;
    }
  }
  if( nSpecial==0 ){
    return fossil_strdup(zIn);
  }
  zOut = fossil_malloc( i+nSpecial+3 );
  zOut[0] = '"';
  for(i=0, j=1; (c = zIn[i])!=0; i++){
    if( c=='\\' || c=='"' || c=='\n' ){
      zOut[j++] = '\\';
      if( c=='\n' ){
        zOut[j++] = 'n';
      }else{
        zOut[j++] = c;
      }
    }else{
      zOut[j++] = c;
    }
  }
  zOut[j++] = '"';
  zOut[j] = 0;
  return zOut;
}

/*
** Locate the mark for a UUID.
**
** If the mark does not exist and if the bCreate flag is false, then
** return 0.  If the mark does not exist and the bCreate flag is true,
** then create the mark.
*/
static int gitmirror_find_mark(const char *zUuid, int bCreate){
  int iMark;
  static Stmt sFind, sIns;
  db_static_prepare(&sFind,
    "SELECT id FROM mirror.mmark WHERE uuid=:uuid"
  );
  db_bind_text(&sFind, ":uuid", zUuid);
  if( db_step(&sFind)==SQLITE_ROW ){
    iMark = db_column_int(&sFind, 0);
    db_reset(&sFind);
    return iMark;
  }
  db_reset(&sFind);
  if( !bCreate ) return 0;
  db_static_prepare(&sIns,
    "INSERT INTO mirror.mmark(uuid) VALUES(:uuid)"
  );
  db_bind_text(&sIns, ":uuid", zUuid);
  db_step(&sIns);
  db_reset(&sIns);
  return db_last_insert_rowid();
}

/* This is the SHA3-256 hash of an empty file */
static const char zEmptySha3[] = 
  "a7ffc6f8bf1ed76651c14756a061d662f580ff4de43b49fa82d80a4b80f8434a";

/*
** Export a single file named by zUuid.
*/
static void gitmirror_send_file(FILE *xCmd, const char *zUuid){
  int iMark;
  int rid;
  int rc;
  Blob data;
  rid = fast_uuid_to_rid(zUuid);
  if( rid<0 ){
    zUuid = zEmptySha3;
  }else{
    rc = content_get(rid, &data);
    if( rc==0 ){
      blob_init(&data, 0, 0);
      zUuid = zEmptySha3;
    }
  }
  iMark = gitmirror_find_mark(zUuid, 1);
  fprintf(xCmd, "blob\nmark :%d\ndata %d\n", iMark, blob_size(&data));
  fwrite(blob_buffer(&data), 1, blob_size(&data), xCmd);
  fprintf(xCmd, "\n");
  blob_reset(&data);
}

/*
** Transfer a check-in over to the mirror.  "rid" is the BLOB.RID for
** the check-in to export.
**
** If any ancestor of the check-in has not yet been exported, then
** invoke this routine recursively to export the ancestor first.
** This can only happen on a timewarp, so deep nesting is unlikely.
**
** Before sending the check-in, first make sure all associated files
** have already been exported, and send "blob" records for any that
** have not been.  Update the MIRROR.MMARK table so that it holds the
** marks for the exported files. 
*/
static void gitmirror_send_checkin(
  FILE *xCmd,           /* Write fast-import text on this pipe */
  int rid,              /* BLOB.RID for the check-in to export */
  const char *zUuid,    /* BLOB.UUID for the check-in to export */
  int *pnLimit,         /* Stop when the counter reaches zero */
  int fManifest         /* MFESTFLG_* values */
){
  Manifest *pMan;       /* The check-in to be output */
  int i;                /* Loop counter */
  int iParent;          /* Which immediate ancestor is primary.  -1 for none */
  Stmt q;               /* An SQL query */
  char *zBranch;        /* The branch of the check-in */
  int iMark;            /* The mark for the check-in */
  Blob sql;             /* String of SQL for part of the query */
  Blob comment;         /* The comment text for the check-in */

  pMan = manifest_get(rid, CFTYPE_MANIFEST, 0);
  if( pMan==0 ){
    /* Must be a phantom.  Return without doing anything, and in particular
    ** without creating a mark for this check-in. */
    return;
  }

  /* Check to see if any parent logins have not yet been processed, and
  ** if so, create them */
  for(i=0; i<pMan->nParent; i++){
    int iMark = gitmirror_find_mark(pMan->azParent[i], 0);
    if( iMark<=0 ){
      int prid = db_int(0, "SELECT rid FROM blob WHERE uuid=%Q",
                        pMan->azParent[i]);
      gitmirror_send_checkin(xCmd, prid, pMan->azParent[i], pnLimit, fManifest);
      if( *pnLimit<=0 ){
        manifest_destroy(pMan);
        return;
      }
    }
  }

  /* Make sure all necessary files have been exported */
  db_prepare(&q,
    "SELECT uuid FROM files_of_checkin(%Q)"
    " WHERE uuid NOT IN (SELECT uuid FROM mirror.mmark)",
    zUuid
  );
  while( db_step(&q)==SQLITE_ROW ){
    const char *zFUuid = db_column_text(&q, 0);
    gitmirror_send_file(xCmd, zFUuid);
  }
  db_finalize(&q);

  /* Figure out which branch this check-in is a member of */
  zBranch = db_text(0,
    "SELECT value FROM tagxref WHERE tagid=%d AND tagtype>0 AND rid=%d",
    TAG_BRANCH, rid
  );
  if( fossil_strcmp(zBranch,"trunk")==0 ){
    fossil_free(zBranch);
    zBranch = mprintf("master");
  }else if( zBranch==0 ){
    zBranch = mprintf("unknown");
  }else{
    gitmirror_sanitize_name(zBranch);
  }

  /* Export the check-in */
  fprintf(xCmd, "commit refs/heads/%s\n", zBranch);
  fossil_free(zBranch);
  iMark = gitmirror_find_mark(zUuid, 1);
  fprintf(xCmd, "mark :%d\n", iMark);
  fprintf(xCmd, "committer %s <%s@noemail.net> %lld +0000\n",
     pMan->zUser, pMan->zUser, 
     (sqlite3_int64)((pMan->rDate-2440587.5)*86400.0)
  );
  blob_init(&comment, pMan->zComment, -1);
  if( blob_size(&comment)==0 ){
    blob_append(&comment, "(no comment)", -1);
  }
  blob_appendf(&comment, "\n\nFossilOrigin-Name: %s", zUuid);
  fprintf(xCmd, "data %d\n%s\n", blob_size(&comment), blob_str(&comment));
  blob_reset(&comment);
  iParent = -1;  /* Which ancestor is the primary parent */
  for(i=0; i<pMan->nParent; i++){
    int iOther = gitmirror_find_mark(pMan->azParent[i], 0);
    if( iOther==0 ) continue;
    if( iParent<0 ){
      iParent = i;
      fprintf(xCmd, "from :%d\n", iOther);
    }else{
      fprintf(xCmd, "merge :%d\n", iOther);
    }
  }
  if( iParent>=0 ){
    db_prepare(&q,
      "SELECT filename FROM files_of_checkin(%Q)"
      " EXCEPT SELECT filename FROM files_of_checkin(%Q)",
      pMan->azParent[iParent], zUuid
    );
    while( db_step(&q)==SQLITE_ROW ){
      fprintf(xCmd, "D %s\n", db_column_text(&q,0));
    }
    db_finalize(&q);
  }
  blob_init(&sql, 0, 0);
  blob_append_sql(&sql,
    "SELECT filename, uuid, perm FROM files_of_checkin(%Q)",
    zUuid
  );
  if( pMan->nParent ){
    blob_append_sql(&sql,
      " EXCEPT SELECT filename, uuid, perm FROM files_of_checkin(%Q)",
      pMan->azParent[0]);
  }
  db_prepare(&q,
     "SELECT x.filename, x.perm, mmark.id FROM (%s) AS x, mirror.mmark"
     " WHERE mmark.uuid=x.uuid",
     blob_sql_text(&sql)
  );
  blob_reset(&sql);
  while( db_step(&q)==SQLITE_ROW ){
    const char *zFilename = db_column_text(&q,0);
    const char *zMode = db_column_text(&q,1);
    int iMark = db_column_int(&q,2);
    const char *zGitMode = "100644";
    char *zFNQuoted = 0;
    if( zMode ){
      if( strchr(zMode,'x') ) zGitMode = "100755";
      if( strchr(zMode,'l') ) zGitMode = "120000";
    }
    zFNQuoted = gitmirror_quote_filename_if_needed(zFilename);
    fprintf(xCmd,"M %s :%d %s\n", zGitMode, iMark, zFNQuoted);
    fossil_free(zFNQuoted);
  }
  db_finalize(&q);

  /* Include Fossil-generated auxiliary files in the check-in */
  if( fManifest & MFESTFLG_RAW ){
    Blob manifest;
    content_get(rid, &manifest);
    fprintf(xCmd,"M 100644 inline manifest\ndata %d\n%s\n",
      blob_size(&manifest), blob_str(&manifest));
    blob_reset(&manifest);
  }
  if( fManifest & MFESTFLG_UUID ){
    int n = (int)strlen(zUuid);
    fprintf(xCmd,"M 100644 inline manifest.uuid\ndata %d\n%s\n", n, zUuid);
  }
  if( fManifest & MFESTFLG_TAGS ){
    Blob tagslist;
    blob_init(&tagslist, 0, 0);
    get_checkin_taglist(rid, &tagslist);
    fprintf(xCmd,"M 100644 inline manifest.tags\ndata %d\n%s\n",
      blob_size(&tagslist), blob_str(&tagslist));
    blob_reset(&tagslist);
  }

  /* The check-in is finished, so decrement the counter */
  (*pnLimit)--;
}

/*
** Implementation of the "fossil git export" command.
*/
void gitmirror_export_command(void){
  const char *zLimit;             /* Text of the --limit flag */
  int nLimit = 0x7fffffff;        /* Numeric value of the --limit flag */
  int nTotal = 0;                 /* Total number of check-ins to export */
  char *zMirror;                  /* Name of the mirror */
  char *z;                        /* Generic string */
  char *zCmd;                     /* git command to run as a subprocess */
  const char *zDebug = 0;         /* Value of the --debug flag */
  double rEnd;                    /* time of most recent export */
  int rc;                         /* Result code */
  int fManifest;                  /* Current "manifest" setting */
  FILE *xCmd;                     /* Pipe to the "git fast-import" command */
  FILE *pIn, *pOut;               /* Git mark files */
  Stmt q;                         /* Queries */
  char zLine[200];                /* One line of a mark file */

  zDebug = find_option("debug",0,1);
  db_find_and_open_repository(0, 0);
  zLimit = find_option("limit", 0, 1);
  if( zLimit ){
    nLimit = (unsigned int)atoi(zLimit);
    if( nLimit<=0 ) fossil_fatal("--limit must be positive");
  }
  verify_all_options();
  if( g.argc!=4 ){ usage("export MIRROR"); }
  zMirror = g.argv[3];

  /* Make sure the GIT repository directory exists */
  rc = file_mkdir(zMirror, ExtFILE, 0);
  if( rc ) fossil_fatal("cannot create directory \"%s\"", zMirror);

  /* Make sure GIT has been initialized */
  z = mprintf("%s/.git", zMirror);
  if( !file_isdir(z, ExtFILE) ){
    zCmd = mprintf("git init '%s'",zMirror);
    fossil_print("%s\n", zCmd);
    rc = fossil_system(zCmd);
    if( rc ){
      fossil_fatal("command failed: \"%s\"", zCmd);
    }
    fossil_free(zCmd);
  }
  fossil_free(z);
  
  /* Make sure the .mirror_state subdirectory exists */
  z = mprintf("%s/.mirror_state", zMirror);
  rc = file_mkdir(z, ExtFILE, 0);
  if( rc ) fossil_fatal("cannot create directory \"%s\"", z);
  fossil_free(z);

  /* Attach the .mirror_state/db database */
  db_multi_exec("ATTACH '%q/.mirror_state/db' AS mirror;", zMirror);
  db_begin_write();
  db_multi_exec(
    "CREATE TABLE IF NOT EXISTS mirror.mconfig(\n"
    "  key TEXT PRIMARY KEY,\n"
    "  Value ANY\n"
    ") WITHOUT ROWID;\n"
    "CREATE TABLE IF NOT EXISTS mirror.mmark(\n"
    "  id INTEGER PRIMARY KEY,\n"
    "  uuid TEXT UNIQUE,\n"
    "  githash TEXT\n"
    ");"
  );

  /* See if there is any work to be done.  Exit early if not, before starting
  ** the "git fast-import" command. */
  if( !db_exists("SELECT 1 FROM event WHERE type IN ('ci','t')"
                 " AND mtime>coalesce((SELECT value FROM mconfig"
                                        " WHERE key='start'),0.0)")
  ){
    fossil_print("no changes\n");
    return;
  }

  /* Do we need to include manifest files in the clone? */
  fManifest = db_get_manifest_setting();

  /* Change to the MIRROR directory so that the Git commands will work */
  rc = file_chdir(zMirror, 0);
  if( rc ) fossil_fatal("cannot change the working directory to \"%s\"",
                        zMirror);

  /* Start up the git fast-import command */
  if( zDebug ){
    if( fossil_strcmp(zDebug,"stdout")==0 ){
      xCmd = stdout;
    }else{
      xCmd = fopen(zDebug, "wb");
      if( xCmd==0 ) fossil_fatal("cannot open file \"%s\" for writing", zDebug);
    }
  }else{
    zCmd = mprintf("git fast-import"
              " --import-marks-if-exists=.mirror_state/in"
              " --export-marks=.mirror_state/out"
              " --quiet --done");
    fossil_print("%s\n", zCmd);
    xCmd = popen(zCmd, "w");
    if( zCmd==0 ){
      fossil_fatal("cannot start the \"git fast-import\" command");
    }
    fossil_free(zCmd);
  }

  /* Run the export */
  rEnd = 0.0;
  db_multi_exec(
    "CREATE TEMP TABLE tomirror(objid,mtime,uuid);\n"
    "INSERT INTO tomirror "
    "SELECT objid, mtime, blob.uuid FROM event, blob\n"
    " WHERE type='ci'"
    "   AND mtime>coalesce((SELECT value FROM mconfig WHERE key='start'),0.0)"
    "   AND blob.rid=event.objid"
    "   AND blob.uuid NOT IN (SELECT uuid FROM mirror.mmark);"
  );
  nTotal = db_int(0, "SELECT count(*) FROM tomirror");
  if( nLimit<nTotal ){
    nTotal = nLimit;
  }else if( nLimit>nTotal ){
    nLimit = nTotal;
  }
  db_prepare(&q,
    "SELECT objid, mtime, uuid FROM tomirror ORDER BY mtime"
  );
  while( nLimit && db_step(&q)==SQLITE_ROW ){
    int rid = db_column_int(&q, 0);
    double rMTime = db_column_double(&q, 1);
    const char *zUuid = db_column_text(&q, 2);
    if( rMTime>rEnd ) rEnd = rMTime;
    gitmirror_send_checkin(xCmd, rid, zUuid, &nLimit, fManifest);
    printf("\r%d/%d  ", nTotal-nLimit, nTotal);
    fflush(stdout);
  }
  db_finalize(&q);
  fprintf(xCmd, "done\n");
  if( zDebug ){
    if( xCmd!=stdout ) fclose(xCmd);
  }else{
    pclose(xCmd);
  }
  fossil_print("%d check-ins added to the mirror\n", nTotal-nLimit);

  /* Read the export-marks file.  Transfer the new marks over into
  ** the import-marks file.
  */
  pOut = fopen(".mirror_state/out", "rb");
  if( pOut ){
    pIn = fopen(".mirror_state/in", "ab");
    if( pIn==0 ){
      fossil_fatal("cannot open %s/.mirror_state/in for appending", zMirror);
    }
    db_prepare(&q, "UPDATE mirror.mmark SET githash=:githash WHERE id=:id");
    while( fgets(zLine, sizeof(zLine), pOut) ){
      int j, k;
      if( zLine[0]!=':' ) continue;
      db_bind_int(&q, ":id", atoi(zLine+1));
      for(j=1; zLine[j] && zLine[j]!=' '; j++){}
      if( zLine[j]!=' ' ) continue;
      j++;
      if( zLine[j]==0 ) continue;
      for(k=j; fossil_isalnum(zLine[k]); k++){}
      zLine[k] = 0;
      db_bind_text(&q, ":githash", &zLine[j]);
      db_step(&q);
      db_reset(&q);
      zLine[k] = '\n';
      fputs(zLine, pIn);
    }
    db_finalize(&q);
    fclose(pOut);
    fclose(pIn);
    file_delete(".mirror_state/out");
  }else{
    fossil_fatal("git fast-import didn't generate a marks file!");
  }
  db_multi_exec(
    "CREATE INDEX IF NOT EXISTS mirror.mmarkx1 ON mmark(githash);"
  );

  /* Do any tags that have been created since the start time */
  db_prepare(&q,
    "SELECT substr(tagname,5), githash"
    "  FROM (SELECT tagxref.tagid AS xtagid, tagname, rid, max(mtime) AS mtime"
    "          FROM tagxref JOIN tag ON tag.tagid=tagxref.tagid"
    "         WHERE tag.tagname GLOB 'sym-*'"
    "           AND tagxref.tagtype=1"
    "           AND tagxref.mtime > coalesce((SELECT value FROM mconfig"
                                        " WHERE key='start'),0.0)"
    "         GROUP BY tagxref.tagid) AS tx"
    "       JOIN blob ON tx.rid=blob.rid"
    "       JOIN mmark ON mmark.uuid=blob.uuid;"
  );
  while( db_step(&q)==SQLITE_ROW ){
    char *zTagname = fossil_strdup(db_column_text(&q,0));
    const char *zObj = db_column_text(&q,1);
    char *zTagCmd;
    gitmirror_sanitize_name(zTagname);
    zTagCmd = mprintf("git tag -f \"%s\" %s", zTagname, zObj);
    fossil_free(zTagname);
    fossil_print("%s\n", zTagCmd);
    fossil_system(zTagCmd);
    fossil_free(zTagCmd);
  }
  db_finalize(&q);

  /* Update the start time */
  db_prepare(&q, "REPLACE INTO mirror.mconfig(key,value) VALUES('start',:x)");
  db_bind_double(&q, ":x", rEnd);
  db_step(&q);
  db_finalize(&q);
  db_commit_transaction();

  /* Optionally do a "git push" */
}

/*
** COMMAND: git
**
** Usage: %fossil git SUBCOMMAND
**
** Do incremental import or export operations between Fossil and Git.
** Subcommands:
**
**   fossil git export MIRROR [OPTIONS]
**
**       Write content from the Fossil repository into the Git repository
**       in directory MIRROR.  The Git repository is created if it does not
**       already exist.  If the Git repository does already exist, then
**       new content added to fossil since the previous export is appended.
**
**       Repeat this command whenever new checkins are added to the Fossil
**       repository in order to reflect those changes into the mirror.
**
**       The MIRROR directory will contain a subdirectory named
**       ".mirror_state" that contains information that Fossil needs to
**       do incremental exports.  Do not attempt to manage or edit the files
**       in that directory since doing so can disrupt future incremental
**       exports.
**
**       Options:
**         --debug FILE        Write fast-export text to FILE rather than
**                             piping it into "git fast-import".
**         --limit N           Add no more than N new check-ins to MIRROR.
**                             Useful for debugging
**
**   fossil git import MIRROR
**
**       TBD...   
*/
void gitmirror_command(void){
  char *zCmd;
  int nCmd;
  if( g.argc<3 ){
    usage("export ARGS...");
  }
  zCmd =  g.argv[2];
  nCmd = (int)strlen(zCmd);
  if( nCmd>2 && strncmp(zCmd,"export",nCmd)==0 ){
    gitmirror_export_command();
  }else
  if( nCmd>2 && strncmp(zCmd,"import",nCmd)==0 ){
    fossil_fatal("not yet implemented - check back later");
  }else
  {
    fossil_fatal("unknown subcommand \"%s\": should be one of "
                 "\"export\", \"import\"",
                 zCmd);
  }
}