SQLite

** omits changes made by other database connections.  The
** [PRAGMA data_version] command provides a mechanism to detect changes to
** a single attached database that occur due to other database connections,
** but omits changes implemented by the database connection on which it is
** called.  This file control is the only mechanism to detect changes that
** happen either internally or externally and that are associated with
** a particular attached database.
**
** <li>[[SQLITE_FCNTL_CKPT_DONE]]
** The [SQLITE_FCNTL_CKPT_DONE] opcode is invoked from within a checkpoint
** in wal mode after the client has finished copying pages from the wal
** file to the database file, but before the *-shm file is updated to
** record the fact that the pages have been checkpointed.
** </ul>
*/
#define SQLITE_FCNTL_LOCKSTATE               1
#define SQLITE_FCNTL_GET_LOCKPROXYFILE       2
#define SQLITE_FCNTL_SET_LOCKPROXYFILE       3
#define SQLITE_FCNTL_LAST_ERRNO              4
#define SQLITE_FCNTL_SIZE_HINT               5

#define SQLITE_FCNTL_PDB                    30
#define SQLITE_FCNTL_BEGIN_ATOMIC_WRITE     31
#define SQLITE_FCNTL_COMMIT_ATOMIC_WRITE    32
#define SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE  33
#define SQLITE_FCNTL_LOCK_TIMEOUT           34
#define SQLITE_FCNTL_DATA_VERSION           35
#define SQLITE_FCNTL_SIZE_LIMIT             36
#define SQLITE_FCNTL_CKPT_DONE              37

/* deprecated names */
#define SQLITE_GET_LOCKPROXYFILE      SQLITE_FCNTL_GET_LOCKPROXYFILE
#define SQLITE_SET_LOCKPROXYFILE      SQLITE_FCNTL_SET_LOCKPROXYFILE
#define SQLITE_LAST_ERRNO             SQLITE_FCNTL_LAST_ERRNO

          i64 szDb = pWal->hdr.nPage*(i64)szPage;
          testcase( IS_BIG_INT(szDb) );
          rc = sqlite3OsTruncate(pWal->pDbFd, szDb);
          if( rc==SQLITE_OK ){
            rc = sqlite3OsSync(pWal->pDbFd, CKPT_SYNC_FLAGS(sync_flags));
          }
        }
        if( rc==SQLITE_OK ){
          rc = sqlite3OsFileControl(pWal->pDbFd, SQLITE_FCNTL_CKPT_DONE, 0);
          if( rc==SQLITE_NOTFOUND ) rc = SQLITE_OK;
        }
        if( rc==SQLITE_OK ){
          pInfo->nBackfill = mxSafeFrame;
        }
      }

      /* Release the reader lock held while backfilling */
      walUnlockExclusive(pWal, WAL_READ_LOCK(0), 1);