int sqlite3WalUndo(Wal *pWal, int (*xUndo)(void *, Pgno), object *pUndoCtx);
int sqlite3WalBeginWriteTransaction(Wal *pWal);
int sqlite3WalEndWriteTransaction(Wal *pWal);
int sqlite3WalRead(Wal *pWal, Pgno pgno, int *pInWal, int nOut, u8 *pOut);
Pgno sqlite3WalDbsize(Wal *pWal);
void sqlite3WalEndReadTransaction(Wal *pWal);
int sqlite3WalBeginReadTransaction(Wal *pWal, int );
void sqlite3WalLimit(Wal*, i64);
int sqlite3WalClose(Wal *pWal, int sync_flags, int, u8 );
int sqlite3WalOpen(VirtualFileSystem*, VirtualFile*, string , int, i64, Wal*);