SQLite

    **   "<path to db>-walNN"
    **
    ** where NN is a decimal number. The NN naming schemes are 
    ** used by the test_multiplex.c module.
    */
    nDb = sqlite3Strlen30(zPath) - 1; 
#ifdef SQLITE_ENABLE_8_3_NAMES
    while( nDb>0 && sqlite3Isalnum(zPath[nDb]) ) nDb--;
    if( nDb==0 || zPath[nDb]!='-' ) return SQLITE_OK;
#else
    while( zPath[nDb]!='-' ){
      assert( nDb>0 );
      assert( zPath[nDb]!='\n' );
      nDb--;
    }

  if( HAS_TIMER && c=='t' && n>=5 && strncmp(azArg[0], "timer", n)==0
   && nArg==2
  ){
    enableTimer = booleanValue(azArg[1]);
  }else
  
  if( c=='v' && strncmp(azArg[0], "version", n)==0 ){
    printf("SQLite %s %s\n" /*extra-version-info*/,
        sqlite3_libversion(), sqlite3_sourceid());
  }else

  if( c=='w' && strncmp(azArg[0], "width", n)==0 && nArg>1 ){
    int j;
    assert( nArg<=ArraySize(azArg) );
    for(j=1; j<nArg && j<ArraySize(p->colWidth); j++){

    /* Run commands received from standard input
    */
    if( stdin_is_interactive ){
      char *zHome;
      char *zHistory = 0;
      int nHistory;
      printf(
        "SQLite version %s %.19s\n" /*extra-version-info*/
        "Enter \".help\" for instructions\n"
        "Enter SQL statements terminated with a \";\"\n",
        sqlite3_libversion(), sqlite3_sourceid()
      );
      zHome = find_home_dir();
      if( zHome ){
        nHistory = strlen30(zHome) + 20;

** the xFileControl() interface.  It will be rounded up to a 
** multiple of MAX_PAGE_SIZE.  We default it here to 2GiB less 64KiB.
*/
#ifndef SQLITE_MULTIPLEX_CHUNK_SIZE
# define SQLITE_MULTIPLEX_CHUNK_SIZE 2147418112
#endif

/* This used to be the default limit on number of chunks, but
** it is no longer enforced.  There is currently no limit to the
** number of chunks.

**
** May be changed by calling the xFileControl() interface.
*/
#ifndef SQLITE_MULTIPLEX_MAX_CHUNKS
# define SQLITE_MULTIPLEX_MAX_CHUNKS 12
#endif












/************************ Object Definitions ******************************/

/* Forward declaration of all object types */
typedef struct multiplexGroup multiplexGroup;
typedef struct multiplexConn multiplexConn;

/*

    memset(&p[pGroup->nReal], 0, sizeof(p[0])*(iChunk+1-pGroup->nReal));
    pGroup->aReal = p;
    pGroup->nReal = iChunk+1;
  }
  if( pGroup->aReal[iChunk].z==0 ){
    char *z;
    int n = pGroup->nName;
    pGroup->aReal[iChunk].z = z = sqlite3_malloc( n+4 );
    if( z==0 ){
      return SQLITE_NOMEM;
    }
    memcpy(z, pGroup->zName, n+1);
    if( iChunk>0 ){
#ifdef SQLITE_ENABLE_8_3_NAMES

      int i;
      for(i=n-1; i>0 && i>=n-4 && z[i]!='.'; i--){}
      if( i>=n-4 ) n = i+1;
      if( pGroup->flags & (SQLITE_OPEN_MAIN_JOURNAL|SQLITE_OPEN_TEMP_JOURNAL) ){
        /* The extensions on overflow files for main databases are 001, 002,
        ** 003 and so forth.  To avoid name collisions, add 100 to the 
        ** extensions of journal files so that they are 101, 102, 103, ....
        */
        iChunk += 100;
      }
#endif
      sqlite3_snprintf(4,&z[n],"%03d",iChunk);
    }
  }
  return SQLITE_OK;
}

/* Translate an sqlite3_file* that is really a multiplexGroup* into
** the sqlite3_file* for the underlying original VFS.

  if( !pGroup->bEnabled ){
    sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, 0, &rc, NULL);
    if( pSubOpen==0 ){
      rc = SQLITE_IOERR_TRUNCATE;
    }else{
      rc = pSubOpen->pMethods->xTruncate(pSubOpen, size);
    }
  }else if( (pGroup->flags & SQLITE_OPEN_MAIN_DB)==0 ){
    int rc2;
    int i;
    sqlite3_file *pSubOpen;
    sqlite3_vfs *pOrigVfs = gMultiplex.pOrigVfs;   /* Real VFS */
    /* delete the chunks above the truncate limit */
    for(i=(int)(size / pGroup->szChunk)+1; i<pGroup->nReal; i++){
      multiplexSubClose(pGroup, i, pOrigVfs);

    sqlite3_vfs *pOrigVfs = gMultiplex.pOrigVfs;
    *pSize = 0;
    for(i=0; 1; i++){
      sqlite3_file *pSubOpen = 0;
      int exists = 0;
      rc = multiplexSubFilename(pGroup, i);
      if( rc ) break;
      if( pGroup->flags & SQLITE_OPEN_DELETEONCLOSE ){
        exists = pGroup->nReal>=i && pGroup->aReal[i].p!=0;
        rc2 = SQLITE_OK;
      }else{
        rc2 = pOrigVfs->xAccess(pOrigVfs, pGroup->aReal[i].z,
            SQLITE_ACCESS_EXISTS, &exists);
      }
      if( rc2==SQLITE_OK && exists){
        /* if it exists, open it */
        pSubOpen = multiplexSubOpen(pGroup, i, &rc, NULL);
      }else{
        /* stop at first "gap" */
        break;
      }