SQLite

  ckfree((char *)p->pVfs);
  ckfree((char *)p);
}

#define TESTVFS_MAX_ARGS 12

/*
** Usage:  testvfs ?-noshm? VFSNAME SCRIPT
**
** This command creates two things when it is invoked: an SQLite VFS, and
** a Tcl command. Both are named VFSNAME. The VFS is installed. It is not
** installed as the default VFS.
**
** The VFS passes all file I/O calls through to the underlying VFS.
**

  sqlite3_vfs *pVfs;              /* New VFS */
  char *zVfs;
  Tcl_Obj *pScript;
  int nScript;                    /* Number of elements in list pScript */
  Tcl_Obj **apScript;             /* Array of pScript elements */
  int nByte;                      /* Bytes of space to allocate at p */
  int i;                          /* Counter variable */
  int isNoshm = 0;                /* True if -noshm is passed */

  if( objc<3 ) goto bad_args;

  if( strcmp(Tcl_GetString(objv[1]), "-noshm")==0 ){
    isNoshm = 1;
  }
  if( objc!=3+isNoshm ) goto bad_args;
  zVfs = Tcl_GetString(objv[isNoshm+1]);
  pScript = objv[isNoshm+2];

  if( TCL_OK!=Tcl_ListObjGetElements(interp, pScript, &nScript, &apScript) ){
    return TCL_ERROR;
  }

  nByte = sizeof(Testvfs)
        + (nScript+TESTVFS_MAX_ARGS)*sizeof(Tcl_Obj *) 

  pVfs = (sqlite3_vfs *)ckalloc(sizeof(sqlite3_vfs));
  memcpy(pVfs, &tvfs_vfs, sizeof(sqlite3_vfs));
  pVfs->pAppData = (void *)p;
  pVfs->zName = p->zName;
  pVfs->mxPathname = p->pParent->mxPathname;
  pVfs->szOsFile += p->pParent->szOsFile;
  p->pVfs = pVfs;
  if( isNoshm ){
    pVfs->xShmOpen = 0;
    pVfs->xShmGet = 0;
    pVfs->xShmSize = 0;
    pVfs->xShmRelease = 0;
    pVfs->xShmClose = 0;
    pVfs->xShmLock = 0;
  }

  Tcl_CreateObjCommand(interp, zVfs, testvfs_obj_cmd, p, testvfs_obj_del);
  sqlite3_vfs_register(pVfs, 0);

  return TCL_OK;

 bad_args:
  Tcl_WrongNumArgs(interp, 1, objv, "?-noshm? VFSNAME SCRIPT");
  return TCL_ERROR;
}

int Sqlitetestvfs_Init(Tcl_Interp *interp){
  Tcl_CreateObjCommand(interp, "testvfs", testvfs_cmd, 0, 0);
  return TCL_OK;
}

#endif

    sqlite3_free(aFrame);
  }else{
    hdr.iCheck1 = 2;
    hdr.iCheck2 = 3;
  }

finished:
  if( rc==SQLITE_OK && hdr.iLastPg==0 ){
    rc = walIndexRemap(pWal, WALINDEX_MMAP_INCREMENT);
  }
  if( rc==SQLITE_OK ){
    walIndexWriteHdr(pWal, &hdr);
    memcpy(&pWal->hdr, &hdr, sizeof(hdr));
  }
  return rc;
}

/*
** Close an open wal-index.
*/
static void walIndexClose(Wal *pWal, int isDelete){

  int nByte;                      /* Number of bytes to allocate */
  int i;                          /* Iterator variable */
  int nFinal;                     /* Number of unindexed entries */
  struct WalSegment *pFinal;      /* Final (unindexed) segment */
  u8 *aTmp;                       /* Temp space used by merge-sort */
  int rc;                         /* Return code of walIndexMap() */

  rc = walIndexMap(pWal, walMappingSize(pWal->hdr.iLastPg));
  if( rc!=SQLITE_OK ){
    return rc;
  }
  aData = pWal->pWiData;
  iLast = pWal->hdr.iLastPg;
  nSegment = (iLast >> 8) + 1;
  nFinal = (iLast & 0x000000FF);

**
** If the checksum cannot be verified return SQLITE_ERROR.
*/
int walIndexTryHdr(Wal *pWal, int *pisValid, int *pChanged){
  u32 aCksum[2] = {1, 1};
  u32 aHdr[WALINDEX_HDR_NFIELD+2];

  assert( *pisValid==0 );
  if( pWal->szWIndex==0 ){


    return SQLITE_OK;
  }

  /* Read the header. The caller may or may not have locked the wal-index
  ** file, meaning it is possible that an inconsistent snapshot is read
  ** from the file. If this happens, return SQLITE_ERROR.
  */
  memcpy(aHdr, pWal->pWiData, sizeof(aHdr));

  ** file and try again. If the header checksum verification fails this
  ** time as well, run log recovery.
  */
  if( SQLITE_OK==(rc = walSetLock(pWal, SQLITE_SHM_RECOVER)) ){
    /* This call to walIndexTryHdr() may not return an error code, as the
    ** wal-index is already mapped. It may find that the header is invalid,
    ** but there is no chance of hitting an actual error.  */
    assert( pWal->pWiData );
    rc = walIndexTryHdr(pWal, &isValid, pChanged);
    assert( rc==SQLITE_OK );
    if( isValid==0 ){
      *pChanged = 1;
      rc = walIndexRecover(pWal);
    }
    walSetLock(pWal, SQLITE_SHM_READ);

  assert( rc!=SQLITE_OK || pWal->lockState==SQLITE_SHM_READ );

  if( rc==SQLITE_OK ){
    rc = walIndexReadHdr(pWal, pChanged);
    if( rc!=SQLITE_OK ){
      /* An error occured while attempting log recovery. */
      sqlite3WalCloseSnapshot(pWal);







    }
  }

  walIndexUnmap(pWal);
  return rc;
}

){
  int rc;                         /* Return code */
  u32 iRead = 0;
  u32 *aData; 
  int iFrame = (pWal->hdr.iLastPg & 0xFFFFFF00);

  assert( pWal->lockState==SQLITE_SHM_READ||pWal->lockState==SQLITE_SHM_WRITE );
  rc = walIndexMap(pWal, walMappingSize(pWal->hdr.iLastPg));
  if( rc!=SQLITE_OK ){
    return rc;
  }

  /* Do a linear search of the unindexed block of page-numbers (if any) 
  ** at the end of the wal-index. An alternative to this would be to
  ** build an index in private memory each time a read transaction is

    rc = walSetLock(pWal, SQLITE_SHM_WRITE);

    /* If this connection is not reading the most recent database snapshot,
    ** it is not possible to write to the database. In this case release
    ** the write locks and return SQLITE_BUSY.
    */
    if( rc==SQLITE_OK ){
      rc = walIndexMap(pWal, sizeof(WalIndexHdr));
      if( rc==SQLITE_OK
       && memcmp(&pWal->hdr, pWal->pWiData, sizeof(WalIndexHdr))
      ){
        rc = SQLITE_BUSY;
      }
      walIndexUnmap(pWal);
      if( rc!=SQLITE_OK ){

} {4 10}
do_test wal2-3.5 {
  list [info exists ::sabotage] [info exists ::locked]
} {0 0}
db close
tvfs delete
file delete -force test.db test.db-wal test.db-journal

#-------------------------------------------------------------------------
# Test that a database connection using a VFS that does not support the
# xShmXXX interfaces cannot open a WAL database.
#
do_test wal2-4.1 {
  sqlite3 db test.db
  execsql {
    PRAGMA journal_mode = WAL;
    CREATE TABLE data(x);
    INSERT INTO data VALUES('need xShmOpen to see this');
    PRAGMA wal_checkpoint;
  }
} {wal}
do_test wal2-4.2 {
  db close
  proc ok {args} {return SQLITE_OK}
  testvfs -noshm tvfs ok
  sqlite3 db test.db -vfs tvfs
  catchsql { SELECT * FROM data }
} {1 {unable to open database file}}
do_test wal2-4.3 {
  db close
  proc ok {args} {return SQLITE_OK}
  testvfs tvfs ok
  sqlite3 db test.db -vfs tvfs
  catchsql { SELECT * FROM data }
} {0 {{need xShmOpen to see this}}}
db close
tvfs delete

finish_test