** Compute a string length that is limited to what can be stored in
** lower 30 bits of a 32-bit signed integer.
**
** The value returned will never be negative.  Nor will it ever be greater
** than the actual length of the string.  For very long strings (greater
** than 1GiB) the value returned might be less than the true string length.
*/
int multiplexStrlen30(const char *z){
  const char *z2 = z;
  if( z==0 ) return 0;
  while( *z2 ){ z2++; }
  return 0x3fffffff & (int)(z2 - z);
}




























































/* Translate an sqlite3_file* that is really a multiplexGroup* into
** the sqlite3_file* for the underlying original VFS.
*/
static sqlite3_file *multiplexSubOpen(multiplexConn *pConn, int iChunk, int *rc, int *pOutFlags){
  multiplexGroup *pGroup = pConn->pGroup;
  sqlite3_vfs *pOrigVfs = gMultiplex.pOrigVfs;        /* Real VFS */
................................................................................
static int multiplexOpen(
  sqlite3_vfs *pVfs,         /* The multiplex VFS */
  const char *zName,         /* Name of file to be opened */
  sqlite3_file *pConn,       /* Fill in this file descriptor */
  int flags,                 /* Flags to control the opening */
  int *pOutFlags             /* Flags showing results of opening */
){
  int rc;                                        /* Result code */
  multiplexConn *pMultiplexOpen;                 /* The new multiplex file descriptor */
  multiplexGroup *pGroup;                        /* Corresponding multiplexGroup object */
  sqlite3_file *pSubOpen;                        /* Real file descriptor */
  sqlite3_vfs *pOrigVfs = gMultiplex.pOrigVfs;   /* Real VFS */
  int nName = multiplexStrlen30(zName);
  int i;
  int sz;

  UNUSED_PARAMETER(pVfs);

  /* We need to create a group structure and manage
  ** access to this group of files.
  */
  multiplexEnter();
  pMultiplexOpen = (multiplexConn*)pConn;












  /* allocate space for group */

  sz = sizeof(multiplexGroup)                                /* multiplexGroup */
     + (sizeof(sqlite3_file *)*SQLITE_MULTIPLEX_MAX_CHUNKS)  /* pReal[] */
     + (pOrigVfs->szOsFile*SQLITE_MULTIPLEX_MAX_CHUNKS)      /* *pReal */
     + SQLITE_MULTIPLEX_MAX_CHUNKS                           /* bOpen[] */
     + nName + 1;                                            /* zName */
#ifndef SQLITE_MULTIPLEX_EXT_OVWR
  sz += SQLITE_MULTIPLEX_EXT_SZ;
  assert(nName+SQLITE_MULTIPLEX_EXT_SZ < pOrigVfs->mxPathname);
#else
  assert(nName >= SQLITE_MULTIPLEX_EXT_SZ);
  assert(nName < pOrigVfs->mxPathname);
#endif
  pGroup = sqlite3_malloc( sz );
  if( pGroup==0 ){
    rc=SQLITE_NOMEM;
  }else{




    /* assign pointers to extra space allocated */
    char *p = (char *)&pGroup[1];
    pMultiplexOpen->pGroup = pGroup;
    memset(pGroup, 0, sz);
    pGroup->bEnabled = -1;
    pGroup->nChunkSize = SQLITE_MULTIPLEX_CHUNK_SIZE;
    pGroup->nMaxChunks = SQLITE_MULTIPLEX_MAX_CHUNKS;
................................................................................
        sqlite3_snprintf(SQLITE_MULTIPLEX_EXT_SZ+1, 
            gMultiplex.zName+nName, 
            SQLITE_MULTIPLEX_EXT_FMT, i);
#endif
    }
    rc2 = pOrigVfs->xAccess(pOrigVfs, gMultiplex.zName, 
        SQLITE_ACCESS_EXISTS, &exists);
    if( rc2==SQLITE_OK && exists){
      /* if it exists, delete it */
      rc2 = pOrigVfs->xDelete(pOrigVfs, gMultiplex.zName, syncDir);
      if( rc2!=SQLITE_OK ) rc = rc2;
    }else{
      /* stop at first "gap" */
      break;
    }

** Compute a string length that is limited to what can be stored in
** lower 30 bits of a 32-bit signed integer.
**
** The value returned will never be negative.  Nor will it ever be greater
** than the actual length of the string.  For very long strings (greater
** than 1GiB) the value returned might be less than the true string length.
*/
static int multiplexStrlen30(const char *z){
  const char *z2 = z;
  if( z==0 ) return 0;
  while( *z2 ){ z2++; }
  return 0x3fffffff & (int)(z2 - z);
}

/*
** Create a temporary file name in zBuf.  zBuf must be big enough to
** hold at pOrigVfs->mxPathname characters.  This function departs
** from the traditional temporary name generation in the os_win
** and os_unix VFS in several ways, but is necessary so that 
** the file name is known for temporary files (like those used 
** during vacuum.)
**
** N.B. This routine assumes your underlying VFS is ok with using
** "/" as a directory seperator.  This is the default for UNIXs
** and is allowed (even mixed) for most versions of Windows.
*/
static int multiplexGetTempname(sqlite3_vfs *pOrigVfs, int nBuf, char *zBuf){
  static char zChars[] =
    "abcdefghijklmnopqrstuvwxyz"
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "0123456789";
  int i,j;
  int attempts = 0;
  int exists = 0;
  int rc = SQLITE_ERROR;

  /* Check that the output buffer is large enough for 
  ** pVfs->mxPathname characters.
  */
  if( pOrigVfs->mxPathname <= nBuf ){

    /* sqlite3_temp_directory should always be less than
    ** pVfs->mxPathname characters.
    */
    sqlite3_snprintf(pOrigVfs->mxPathname,
                     zBuf,
                     "%s/",
                     sqlite3_temp_directory ? sqlite3_temp_directory : ".");

    /* Check that the output buffer is large enough for the temporary file 
    ** name.
    */
    j = multiplexStrlen30(zBuf);
    if( (j + 8 + 1 + 3 + 1) <= nBuf ){
      /* Make 3 attempts to generate a unique name. */
      do {
        attempts++;
        sqlite3_randomness(8, &zBuf[j]);
        for(i=0; i<8; i++){
          zBuf[j+i] = (char)zChars[ ((unsigned char)zBuf[j+i])%(sizeof(zChars)-1) ];
        }
        memcpy(&zBuf[j+i], ".tmp", 5);
        rc = pOrigVfs->xAccess(pOrigVfs, zBuf, SQLITE_ACCESS_EXISTS, &exists);
      } while ( (rc==SQLITE_OK) && exists && (attempts<3) );
      if( rc==SQLITE_OK && exists ){
        rc = SQLITE_ERROR;
      }
    }
  }

  return rc;
}

/* Translate an sqlite3_file* that is really a multiplexGroup* into
** the sqlite3_file* for the underlying original VFS.
*/
static sqlite3_file *multiplexSubOpen(multiplexConn *pConn, int iChunk, int *rc, int *pOutFlags){
  multiplexGroup *pGroup = pConn->pGroup;
  sqlite3_vfs *pOrigVfs = gMultiplex.pOrigVfs;        /* Real VFS */
................................................................................
static int multiplexOpen(
  sqlite3_vfs *pVfs,         /* The multiplex VFS */
  const char *zName,         /* Name of file to be opened */
  sqlite3_file *pConn,       /* Fill in this file descriptor */
  int flags,                 /* Flags to control the opening */
  int *pOutFlags             /* Flags showing results of opening */
){
  int rc = SQLITE_OK;                            /* Result code */
  multiplexConn *pMultiplexOpen;                 /* The new multiplex file descriptor */
  multiplexGroup *pGroup;                        /* Corresponding multiplexGroup object */
  sqlite3_file *pSubOpen;                        /* Real file descriptor */
  sqlite3_vfs *pOrigVfs = gMultiplex.pOrigVfs;   /* Real VFS */
  int nName;
  int i;
  int sz;

  UNUSED_PARAMETER(pVfs);

  /* We need to create a group structure and manage
  ** access to this group of files.
  */
  multiplexEnter();
  pMultiplexOpen = (multiplexConn*)pConn;

  /* If the second argument to this function is NULL, generate a 
  ** temporary file name to use.  This will be handled by the
  ** original xOpen method.  We just need to allocate space for
  ** it.
  */
  if( !zName ){
    rc = multiplexGetTempname(pOrigVfs, pOrigVfs->mxPathname, gMultiplex.zName);
    zName = gMultiplex.zName;
  }

  if( rc==SQLITE_OK ){
    /* allocate space for group */
    nName = multiplexStrlen30(zName);
    sz = sizeof(multiplexGroup)                                /* multiplexGroup */
       + (sizeof(sqlite3_file *)*SQLITE_MULTIPLEX_MAX_CHUNKS)  /* pReal[] */
       + (pOrigVfs->szOsFile*SQLITE_MULTIPLEX_MAX_CHUNKS)      /* *pReal */
       + SQLITE_MULTIPLEX_MAX_CHUNKS                           /* bOpen[] */
       + nName + 1;                                            /* zName */
#ifndef SQLITE_MULTIPLEX_EXT_OVWR
    sz += SQLITE_MULTIPLEX_EXT_SZ;
    assert(nName+SQLITE_MULTIPLEX_EXT_SZ < pOrigVfs->mxPathname);
#else
    assert(nName >= SQLITE_MULTIPLEX_EXT_SZ);
    assert(nName < pOrigVfs->mxPathname);
#endif
    pGroup = sqlite3_malloc( sz );
    if( pGroup==0 ){
      rc=SQLITE_NOMEM;

    }
  }

  if( rc==SQLITE_OK ){
    /* assign pointers to extra space allocated */
    char *p = (char *)&pGroup[1];
    pMultiplexOpen->pGroup = pGroup;
    memset(pGroup, 0, sz);
    pGroup->bEnabled = -1;
    pGroup->nChunkSize = SQLITE_MULTIPLEX_CHUNK_SIZE;
    pGroup->nMaxChunks = SQLITE_MULTIPLEX_MAX_CHUNKS;
................................................................................
        sqlite3_snprintf(SQLITE_MULTIPLEX_EXT_SZ+1, 
            gMultiplex.zName+nName, 
            SQLITE_MULTIPLEX_EXT_FMT, i);
#endif
    }
    rc2 = pOrigVfs->xAccess(pOrigVfs, gMultiplex.zName, 
        SQLITE_ACCESS_EXISTS, &exists);
    if( rc2==SQLITE_OK && exists ){
      /* if it exists, delete it */
      rc2 = pOrigVfs->xDelete(pOrigVfs, gMultiplex.zName, syncDir);
      if( rc2!=SQLITE_OK ) rc = rc2;
    }else{
      /* stop at first "gap" */
      break;
    }

      }
    } {1 {disk I/O error}}
    do_test multiplex-5.6.4.$jmode {
      db close
    } {}
  }
}









































catch { sqlite3_multiplex_shutdown }
finish_test

      }
    } {1 {disk I/O error}}
    do_test multiplex-5.6.4.$jmode {
      db close
    } {}
  }
}

#-------------------------------------------------------------------------
# Test that you can vacuum a multiplex'ed DB.  

ifcapable vacuum {

do_test multiplex-6.0.0 {
  multiplex_delete test.db
  sqlite3_multiplex_initialize "" 1
  sqlite3 db test.db
  multiplex_set db main 4096 16
} {SQLITE_OK}

do_test multiplex-6.1.0 {
  execsql {
    PRAGMA page_size=1024;
    PRAGMA journal_mode=DELETE;
    PRAGMA auto_vacuum=OFF;
  }
  execsql {
    CREATE TABLE t1(a, b);
    INSERT INTO t1 VALUES(1, randomblob($g_chunk_size));
    INSERT INTO t1 VALUES(2, randomblob($g_chunk_size));
  }
} {}
do_test multiplex-6.2.1 { file size [multiplex_name test.db 0] } [list $g_chunk_size]
do_test multiplex-6.2.2 { file size [multiplex_name test.db 1] } [list $g_chunk_size]

do_test multiplex-6.3.0 {
  execsql { VACUUM }
} {}

do_test multiplex-6.99 {
  db close
  multiplex_delete test.db
  sqlite3_multiplex_shutdown
} {SQLITE_OK}

}


catch { sqlite3_multiplex_shutdown }
finish_test