SQLite

      break;
    }
  }
  va_end(ap);
#endif /* SQLITE_UNTESTABLE */
  return rc;
}

/*
** The Pager stores the Database filename, Journal filename, and WAL filename
** consecutively in memory, in that order.  The database filename is prefixed
** by four zero bytes.  Locate the start of the database filename by searching
** backwards for the first byte following four consecutive zero bytes.
**
** This only works if the filename passed in was obtained from the Pager.
*/
static const char *databaseName(const char *zName){
  while( zName[-1]!=0 || zName[-2]!=0 || zName[-3]!=0 || zName[-4]!=0 ){
    zName--;
  }
  return zName;
}

/*
** This is a utility routine, useful to VFS implementations, that checks
** to see if a database file was a URI that contained a specific query 
** parameter, and if so obtains the value of the query parameter.
**
** The zFilename argument is the filename pointer passed into the xOpen()
** method of a VFS implementation.  The zParam argument is the name of the
** query parameter we seek.  This routine returns the value of the zParam
** parameter if it exists.  If the parameter does not exist, this routine
** returns a NULL pointer.
*/
const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam){
  if( zFilename==0 || zParam==0 ) return 0;
  zFilename = databaseName(zFilename);
  zFilename += sqlite3Strlen30(zFilename) + 1;
  while( zFilename[0] ){
    int x = strcmp(zFilename, zParam);
    zFilename += sqlite3Strlen30(zFilename) + 1;
    if( x==0 ) return zFilename;
    zFilename += sqlite3Strlen30(zFilename) + 1;
  }
  return 0;
}

/*
** Return a pointer to the name of Nth query parameter of the filename.
*/
const char *sqlite3_uri_key(const char *zFilename, int N){
  if( zFilename==0 || N<0 ) return 0;
  zFilename = databaseName(zFilename);
  zFilename += sqlite3Strlen30(zFilename) + 1;
  while( zFilename[0] && (N--)>0 ){
    zFilename += sqlite3Strlen30(zFilename) + 1;
    zFilename += sqlite3Strlen30(zFilename) + 1;
  }
  return zFilename[0] ? zFilename : 0;
}

  sqlite3_int64 v;
  if( z && sqlite3DecOrHexToI64(z, &v)==0 ){
    bDflt = v;
  }
  return bDflt;
}




















/*
** Translate a filename that was handed to a VFS routine into the corresponding
** database, journal, or WAL file.
**
** It is an error to pass this routine a filename string that was not
** passed into the VFS from the SQLite core.  Doing so is similar to
** passing free() a pointer that was not obtained from malloc() - it is
** an error that we cannot easily detect but that will likely cause memory
** corruption.
*/
const char *sqlite3_filename_database(const char *zFilename){
  return databaseName(zFilename);
  return sqlite3_uri_parameter(zFilename - 3, "\003");
}
const char *sqlite3_filename_journal(const char *zFilename){
  zFilename = databaseName(zFilename);
  zFilename += sqlite3Strlen30(zFilename) + 1;
  while( zFilename[0] ){
    zFilename += sqlite3Strlen30(zFilename) + 1;
    zFilename += sqlite3Strlen30(zFilename) + 1;
  }
  return zFilename + 1;
}
const char *sqlite3_filename_wal(const char *zFilename){
#ifdef SQLITE_OMIT_WAL
  return 0;
#else
  zFilename = sqlite3_filename_journal(zFilename);
  zFilename += sqlite3Strlen30(zFilename) + 1;
  return zFilename;
#endif
}

/*
** Return the Btree pointer identified by zDbName.  Return NULL if not found.
*/
Btree *sqlite3DbNameToBtree(sqlite3 *db, const char *zDbName){
  int iDb = zDbName ? sqlite3FindDbName(db, zDbName) : 0;

  ** file name. The layout in memory is as follows:
  **
  **     Pager object                    (sizeof(Pager) bytes)
  **     PCache object                   (sqlite3PcacheSize() bytes)
  **     Database file handle            (pVfs->szOsFile bytes)
  **     Sub-journal file handle         (journalFileSize bytes)
  **     Main journal file handle        (journalFileSize bytes)
  **     \0\0\0\0 database prefix        (4 bytes)
  **     Database file name              (nPathname+1 bytes)
  **     URI query parameters            (nUriByte bytes)
  **     Journal filename                (nPathname+8+1 bytes)

  **     WAL filename                    (nPathname+4+1 bytes)
  **     \0\0\0 terminator               (3 bytes)
  **
  ** Some 3rd-party software, over which we have no control, depends on
  ** the specific order of the filenames and the \0 separators between them
  ** so that it can (for example) find the database filename given the WAL
  ** filename without using the sqlite3_filename_database() API.  This is a
  ** misuse of SQLite and a bug in the 3rd-party software, but the 3rd-party
  ** software is in widespread use, so we try to avoid changing the filename
  ** order and formatting if possible.  In particular, the details of the
  ** filename format expected by 3rd-party software should be as follows:
  **
  **   - Main Database Path
  **   - \0
  **   - Multiple URI components consisting of:
  **     - Key
  **     - \0
  **     - Value
  **     - \0
  **   - \0
  **   - Journal Path
  **   - \0
  **   - WAL Path (zWALName)
  **   - \0
  */
  pPtr = (u8 *)sqlite3MallocZero(
    ROUND8(sizeof(*pPager)) +            /* Pager structure */
    ROUND8(pcacheSize) +                 /* PCache object */
    ROUND8(pVfs->szOsFile) +             /* The main db file */
    journalFileSize * 2 +                /* The two journal files */
    4 +                                  /* Database prefix */
    nPathname + 1 +                      /* database filename */
    nUriByte +                           /* query parameters */
    nPathname + 8 + 1 +                  /* Journal filename */
#ifndef SQLITE_OMIT_WAL

    nPathname + 4 + 1 +                  /* WAL filename */
#endif



    3                                    /* Terminator */
  );
  assert( EIGHT_BYTE_ALIGNMENT(SQLITE_INT_TO_PTR(journalFileSize)) );
  if( !pPtr ){
    sqlite3DbFree(0, zPathname);
    return SQLITE_NOMEM_BKPT;
  }
  pPager = (Pager*)pPtr;                  pPtr += ROUND8(sizeof(*pPager));
  pPager->pPCache = (PCache*)pPtr;        pPtr += ROUND8(pcacheSize);
  pPager->fd = (sqlite3_file*)pPtr;       pPtr += ROUND8(pVfs->szOsFile);
  pPager->sjfd = (sqlite3_file*)pPtr;     pPtr += journalFileSize;
  pPager->jfd =  (sqlite3_file*)pPtr;     pPtr += journalFileSize;
  assert( EIGHT_BYTE_ALIGNMENT(pPager->jfd) );

  /* Fill in the Pager.zFilename and pPager.zQueryParam fields */
                                          pPtr += 4;  /* Skip zero prefix */
  pPager->zFilename = (char*)pPtr;
  if( nPathname>0 ){
    memcpy(pPtr, zPathname, nPathname);   pPtr += nPathname + 1;
    if( zUri ){
      memcpy(pPtr, zUri, nUriByte);       pPtr += nUriByte;
    }else{
                                          pPtr++;
    }
  }


  /* Fill in Pager.zJournal */

  if( nPathname>0 ){
    pPager->zJournal = (char*)pPtr;
    memcpy(pPtr, zPathname, nPathname);   pPtr += nPathname;
    memcpy(pPtr, "-journal",8);           pPtr += 8 + 1;
#ifdef SQLITE_ENABLE_8_3_NAMES
    sqlite3FileSuffix3(zFilename,pPager->zJournal);
    pPtr = (u8*)(pPager->zJournal + sqlite3Strlen30(pPager->zJournal)+1);
#endif
  }else{
    pPager->zJournal = 0;

  }

#ifndef SQLITE_OMIT_WAL
  /* Fill in Pager.zWal */

  if( nPathname>0 ){
    pPager->zWal = (char*)pPtr;
    memcpy(pPtr, zPathname, nPathname);   pPtr += nPathname;
    memcpy(pPtr, "-wal", 4);              pPtr += 4 + 1;
#ifdef SQLITE_ENABLE_8_3_NAMES
    sqlite3FileSuffix3(zFilename, pPager->zWal);
    pPtr = (u8*)(pPager->zWal + sqlite3Strlen30(pPager->zWal)+1);
#endif
  }else{
    pPager->zWal = 0;

  }
#endif












  if( nPathname ) sqlite3DbFree(0, zPathname);
  pPager->pVfs = pVfs;
  pPager->vfsFlags = vfsFlags;

  /* Open the pager file.
  */
  if( zFilename && zFilename[0] ){

** shared cache, it uses nullIfMemDb==0 so that in-memory databases can
** participate in shared-cache.
**
** The return value to this routine is always safe to use with
** sqlite3_uri_parameter() and sqlite3_filename_database() and friends.
*/
const char *sqlite3PagerFilename(const Pager *pPager, int nullIfMemDb){
  static const char zFake[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
  return (nullIfMemDb && pPager->memDb) ? &zFake[4] : pPager->zFilename;
}

/*
** Return the VFS structure for the pager.
*/
sqlite3_vfs *sqlite3PagerVfs(Pager *pPager){
  return pPager->pVfs;