[sql] Import SQLite 3.17.0.

third_party/sqlite/src/src/pager.c

 /*
 ** 2001 September 15
 **
 ** The author disclaims copyright to this source code.  In place of
 ** a legal notice, here is a blessing:
 **
 **    May you do good and not evil.
 **    May you find forgiveness for yourself and forgive others.
 **    May you share freely, never taking more than you give.
 **
@@ skipping 410 matching lines @@
 #endif
 
 /*
 ** The maximum allowed sector size. 64KiB. If the xSectorsize() method 
 ** returns a value larger than this, then MAX_SECTOR_SIZE is used instead.
 ** This could conceivably cause corruption following a power failure on
 ** such a system. This is currently an undocumented limit.
 */
 #define MAX_SECTOR_SIZE 0x10000
 
+
 /*
 ** An instance of the following structure is allocated for each active
 ** savepoint and statement transaction in the system. All such structures
 ** are stored in the Pager.aSavepoint[] array, which is allocated and
 ** resized using sqlite3Realloc().
 **
 ** When a savepoint is created, the PagerSavepoint.iHdrOffset field is
 ** set to 0. If a journal-header is written into the main journal while
 ** the savepoint is active, then iHdrOffset is set to the byte offset 
 ** immediately following the last journal record written into the main
@@ skipping 175 matching lines @@
 **   is always set to SQLITE_FULL, SQLITE_IOERR or one of the SQLITE_IOERR_XXX 
 **   sub-codes.
 */
 struct Pager {
   sqlite3_vfs *pVfs;          /* OS functions to use for IO */
   u8 exclusiveMode;           /* Boolean. True if locking_mode==EXCLUSIVE */
   u8 journalMode;             /* One of the PAGER_JOURNALMODE_* values */
   u8 useJournal;              /* Use a rollback journal on this file */
   u8 noSync;                  /* Do not sync the journal if true */
   u8 fullSync;                /* Do extra syncs of the journal for robustness */
+  u8 extraSync;               /* sync directory after journal delete */
   u8 ckptSyncFlags;           /* SYNC_NORMAL or SYNC_FULL for checkpoint */
   u8 walSyncFlags;            /* SYNC_NORMAL or SYNC_FULL for wal writes */
   u8 syncFlags;               /* SYNC_NORMAL or SYNC_FULL otherwise */
   u8 tempFile;                /* zFilename is a temporary or immutable file */
   u8 noLock;                  /* Do not lock (except in WAL mode) */
   u8 readOnly;                /* True for a read-only database */
   u8 memDb;                   /* True to inhibit all file I/O */
 
   /**************************************************************************
   ** The following block contains those class members that change during
@@ skipping 48 matching lines @@
   i64 journalSizeLimit;       /* Size limit for persistent journal files */
   char *zFilename;            /* Name of the database file */
   char *zJournal;             /* Name of the journal file */
   int (*xBusyHandler)(void*); /* Function to call when busy */
   void *pBusyHandlerArg;      /* Context argument for xBusyHandler */
   int aStat[3];               /* Total cache hits, misses and writes */
 #ifdef SQLITE_TEST
   int nRead;                  /* Database pages read */
 #endif
   void (*xReiniter)(DbPage*); /* Call this routine when reloading pages */
+  int (*xGet)(Pager*,Pgno,DbPage**,int); /* Routine to fetch a patch */
 #ifdef SQLITE_HAS_CODEC
   void *(*xCodec)(void*,void*,Pgno,int); /* Routine for en/decoding data */
   void (*xCodecSizeChng)(void*,int,int); /* Notify of page size changes */
   void (*xCodecFree)(void*);             /* Destructor for the codec */
   void *pCodec;               /* First argument to xCodec... methods */
 #endif
   char *pTmpSpace;            /* Pager.pageSize bytes of space for tmp use */
   PCache *pPCache;            /* Pointer to page cache object */
 #ifndef SQLITE_OMIT_WAL
   Wal *pWal;                  /* Write-ahead log used by "journal_mode=wal" */
@@ skipping 100 matching lines @@
 **
 **   if( isOpen(pPager->jfd) ){ ...
 **
 ** instead of
 **
 **   if( pPager->jfd->pMethods ){ ...
 */
 #define isOpen(pFd) ((pFd)->pMethods!=0)
 
 /*
-** Return true if this pager uses a write-ahead log instead of the usual
-** rollback journal. Otherwise false.
+** Return true if this pager uses a write-ahead log to read page pgno.
+** Return false if the pager reads pgno directly from the database.
 */
+#if !defined(SQLITE_OMIT_WAL) && defined(SQLITE_DIRECT_OVERFLOW_READ)
+int sqlite3PagerUseWal(Pager *pPager, Pgno pgno){
+  u32 iRead = 0;
+  int rc;
+  if( pPager->pWal==0 ) return 0;
+  rc = sqlite3WalFindFrame(pPager->pWal, pgno, &iRead);
+  return rc || iRead;
+}
+#endif
 #ifndef SQLITE_OMIT_WAL
-static int pagerUseWal(Pager *pPager){
-  return (pPager->pWal!=0);
-}
+# define pagerUseWal(x) ((x)->pWal!=0)
 #else
 # define pagerUseWal(x) 0
 # define pagerRollbackWal(x) 0
 # define pagerWalFrames(v,w,x,y) 0
 # define pagerOpenWalIfPresent(z) SQLITE_OK
 # define pagerBeginReadTransaction(z) SQLITE_OK
 #endif
 
 #ifndef NDEBUG 
 /*
@@ skipping 32 matching lines @@
 
   /* Check that MEMDB implies noSync. And an in-memory journal. Since 
   ** this means an in-memory pager performs no IO at all, it cannot encounter 
   ** either SQLITE_IOERR or SQLITE_FULL during rollback or while finalizing 
   ** a journal file. (although the in-memory journal implementation may 
   ** return SQLITE_IOERR_NOMEM while the journal file is being written). It 
   ** is therefore not possible for an in-memory pager to enter the ERROR 
   ** state.
   */
   if( MEMDB ){
+    assert( !isOpen(p->fd) );
     assert( p->noSync );
     assert( p->journalMode==PAGER_JOURNALMODE_OFF 
          || p->journalMode==PAGER_JOURNALMODE_MEMORY 
     );
     assert( p->eState!=PAGER_ERROR && p->eState!=PAGER_OPEN );
     assert( pagerUseWal(p)==0 );
   }
 
   /* If changeCountDone is set, a RESERVED lock or greater must be held
   ** on the file.
@@ skipping 66 matching lines @@
            || p->journalMode==PAGER_JOURNALMODE_WAL 
       );
       break;
 
     case PAGER_ERROR:
       /* There must be at least one outstanding reference to the pager if
       ** in ERROR state. Otherwise the pager should have already dropped
       ** back to OPEN state.
       */
       assert( pPager->errCode!=SQLITE_OK );
-      assert( sqlite3PcacheRefCount(pPager->pPCache)>0 );
+      assert( sqlite3PcacheRefCount(pPager->pPCache)>0 || pPager->tempFile );
       break;
   }
 
   return 1;
 }
 #endif /* ifndef NDEBUG */
 
 #ifdef SQLITE_DEBUG 
 /*
 ** Return a pointer to a human readable string in a static buffer
@@ skipping 38 matching lines @@
         p->journalMode==PAGER_JOURNALMODE_WAL      ? "wal" : "?error?"
       , (int)p->tempFile, (int)p->memDb, (int)p->useJournal
       , p->journalOff, p->journalHdr
       , (int)p->dbSize, (int)p->dbOrigSize, (int)p->dbFileSize
   );
 
   return zRet;
 }
 #endif
 
+/* Forward references to the various page getters */
+static int getPageNormal(Pager*,Pgno,DbPage**,int);
+static int getPageError(Pager*,Pgno,DbPage**,int);
+#if SQLITE_MAX_MMAP_SIZE>0
+static int getPageMMap(Pager*,Pgno,DbPage**,int);
+#endif
+
+/*
+** Set the Pager.xGet method for the appropriate routine used to fetch
+** content from the pager.
+*/
+static void setGetterMethod(Pager *pPager){
+  if( pPager->errCode ){
+    pPager->xGet = getPageError;
+#if SQLITE_MAX_MMAP_SIZE>0
+  }else if( USEFETCH(pPager)
+#ifdef SQLITE_HAS_CODEC
+   && pPager->xCodec==0
+#endif
+  ){
+    pPager->xGet = getPageMMap;
+#endif /* SQLITE_MAX_MMAP_SIZE>0 */
+  }else{
+    pPager->xGet = getPageNormal;
+  }
+}
+
 /*
 ** Return true if it is necessary to write page *pPg into the sub-journal.
 ** A page needs to be written into the sub-journal if there exists one
 ** or more open savepoints for which:
 **
 **   * The page-number is less than or equal to PagerSavepoint.nOrig, and
 **   * The bit corresponding to the page-number is not set in
 **     PagerSavepoint.pInSavepoint.
 */
 static int subjRequiresPage(PgHdr *pPg){
@@ skipping 133 matching lines @@
 
     assert(SQLITE_IOCAP_ATOMIC512==(512>>8));
     assert(SQLITE_IOCAP_ATOMIC64K==(65536>>8));
     if( 0==(dc&(SQLITE_IOCAP_ATOMIC|(szPage>>8)) || nSector>szPage) ){
       return 0;
     }
   }
 
   return JOURNAL_HDR_SZ(pPager) + JOURNAL_PG_SZ(pPager);
 }
+#else
+# define jrnlBufferSize(x) 0
 #endif
 
 /*
 ** If SQLITE_CHECK_PAGES is defined then we do some sanity checking
 ** on the cache using a hash function.  This is used for testing
 ** and debugging only.
 */
 #ifdef SQLITE_CHECK_PAGES
 /*
 ** Return a 32-bit hash of the page data for pPage.
@@ skipping 140 matching lines @@
 ** journal file in bytes is larger than this value, then truncate the
 ** journal file to Pager.journalSizeLimit bytes. The journal file does
 ** not need to be synced following this operation.
 **
 ** If an IO error occurs, abandon processing and return the IO error code.
 ** Otherwise, return SQLITE_OK.
 */
 static int zeroJournalHdr(Pager *pPager, int doTruncate){
   int rc = SQLITE_OK;                               /* Return code */
   assert( isOpen(pPager->jfd) );
+  assert( !sqlite3JournalIsInMemory(pPager->jfd) );
   if( pPager->journalOff ){
     const i64 iLimit = pPager->journalSizeLimit;    /* Local cache of jsl */
 
     IOTRACE(("JZEROHDR %p\n", pPager))
     if( doTruncate || iLimit==0 ){
       rc = sqlite3OsTruncate(pPager->jfd, 0);
     }else{
       static const char zeroHdr[28] = {0};
       rc = sqlite3OsWrite(pPager->jfd, zeroHdr, sizeof(zeroHdr), 0);
     }
@@ skipping 361 matching lines @@
 /*
 ** Free all structures in the Pager.aSavepoint[] array and set both
 ** Pager.aSavepoint and Pager.nSavepoint to zero. Close the sub-journal
 ** if it is open and the pager is not in exclusive mode.
 */
 static void releaseAllSavepoints(Pager *pPager){
   int ii;               /* Iterator for looping through Pager.aSavepoint */
   for(ii=0; ii<pPager->nSavepoint; ii++){
     sqlite3BitvecDestroy(pPager->aSavepoint[ii].pInSavepoint);
   }
-  if( !pPager->exclusiveMode || sqlite3IsMemJournal(pPager->sjfd) ){
+  if( !pPager->exclusiveMode || sqlite3JournalIsInMemory(pPager->sjfd) ){
     sqlite3OsClose(pPager->sjfd);
   }
   sqlite3_free(pPager->aSavepoint);
   pPager->aSavepoint = 0;
   pPager->nSavepoint = 0;
   pPager->nSubRec = 0;
 }
 
 /*
 ** Set the bit number pgno in the PagerSavepoint.pInSavepoint 
@@ skipping 85 matching lines @@
     assert( pPager->errCode || pPager->eState!=PAGER_ERROR );
     pPager->changeCountDone = 0;
     pPager->eState = PAGER_OPEN;
   }
 
   /* If Pager.errCode is set, the contents of the pager cache cannot be
   ** trusted. Now that there are no outstanding references to the pager,
   ** it can safely move back to PAGER_OPEN state. This happens in both
   ** normal and exclusive-locking mode.
   */
+  assert( pPager->errCode==SQLITE_OK || !MEMDB );
   if( pPager->errCode ){
-    assert( !MEMDB );
-    pager_reset(pPager);
-    pPager->changeCountDone = pPager->tempFile;
-    pPager->eState = PAGER_OPEN;
+    if( pPager->tempFile==0 ){
+      pager_reset(pPager);
+      pPager->changeCountDone = 0;
+      pPager->eState = PAGER_OPEN;
+    }else{
+      pPager->eState = (isOpen(pPager->jfd) ? PAGER_OPEN : PAGER_READER);
+    }
+    if( USEFETCH(pPager) ) sqlite3OsUnfetch(pPager->fd, 0, 0);
     pPager->errCode = SQLITE_OK;
-    if( USEFETCH(pPager) ) sqlite3OsUnfetch(pPager->fd, 0, 0);
+    setGetterMethod(pPager);
   }
 
   pPager->journalOff = 0;
   pPager->journalHdr = 0;
   pPager->setMaster = 0;
 }
 
 /*
 ** This function is called whenever an IOERR or FULL error that requires
 ** the pager to transition into the ERROR state may ahve occurred.
@@ skipping 17 matching lines @@
   int rc2 = rc & 0xff;
   assert( rc==SQLITE_OK || !MEMDB );
   assert(
        pPager->errCode==SQLITE_FULL ||
        pPager->errCode==SQLITE_OK ||
        (pPager->errCode & 0xff)==SQLITE_IOERR
   );
   if( rc2==SQLITE_FULL || rc2==SQLITE_IOERR ){
     pPager->errCode = rc;
     pPager->eState = PAGER_ERROR;
+    setGetterMethod(pPager);
   }
   return rc;
 }
 
 static int pager_truncate(Pager *pPager, Pgno nPage);
 
 /*
+** The write transaction open on pPager is being committed (bCommit==1)
+** or rolled back (bCommit==0).
+**
+** Return TRUE if and only if all dirty pages should be flushed to disk.
+**
+** Rules:
+**
+**   *  For non-TEMP databases, always sync to disk.  This is necessary
+**      for transactions to be durable.
+**
+**   *  Sync TEMP database only on a COMMIT (not a ROLLBACK) when the backing
+**      file has been created already (via a spill on pagerStress()) and
+**      when the number of dirty pages in memory exceeds 25% of the total
+**      cache size.
+*/
+static int pagerFlushOnCommit(Pager *pPager, int bCommit){
+  if( pPager->tempFile==0 ) return 1;
+  if( !bCommit ) return 0;
+  if( !isOpen(pPager->fd) ) return 0;
+  return (sqlite3PCachePercentDirty(pPager->pPCache)>=25);
+}
+
+/*
 ** This routine ends a transaction. A transaction is usually ended by 
 ** either a COMMIT or a ROLLBACK operation. This routine may be called 
 ** after rollback of a hot-journal, or if an error occurs while opening
 ** the journal file or writing the very first journal-header of a
 ** database transaction.
 ** 
 ** This routine is never called in PAGER_ERROR state. If it is called
 ** in PAGER_NONE or PAGER_SHARED state and the lock held is less
 ** exclusive than a RESERVED lock, it is a no-op.
 **
@@ skipping 61 matching lines @@
   if( pPager->eState<PAGER_WRITER_LOCKED && pPager->eLock<RESERVED_LOCK ){
     return SQLITE_OK;
   }
 
   releaseAllSavepoints(pPager);
   assert( isOpen(pPager->jfd) || pPager->pInJournal==0 );
   if( isOpen(pPager->jfd) ){
     assert( !pagerUseWal(pPager) );
 
     /* Finalize the journal file. */
-    if( sqlite3IsMemJournal(pPager->jfd) ){
-      assert( pPager->journalMode==PAGER_JOURNALMODE_MEMORY );
+    if( sqlite3JournalIsInMemory(pPager->jfd) ){
+      /* assert( pPager->journalMode==PAGER_JOURNALMODE_MEMORY ); */
       sqlite3OsClose(pPager->jfd);
     }else if( pPager->journalMode==PAGER_JOURNALMODE_TRUNCATE ){
       if( pPager->journalOff==0 ){
         rc = SQLITE_OK;
       }else{
         rc = sqlite3OsTruncate(pPager->jfd, 0);
         if( rc==SQLITE_OK && pPager->fullSync ){
           /* Make sure the new file size is written into the inode right away.
           ** Otherwise the journal might resurrect following a power loss and
           ** cause the last transaction to roll back.  See
           ** https://bugzilla.mozilla.org/show_bug.cgi?id=1072773
           */
           rc = sqlite3OsSync(pPager->jfd, pPager->syncFlags);
         }
       }
       pPager->journalOff = 0;
     }else if( pPager->journalMode==PAGER_JOURNALMODE_PERSIST
       || (pPager->exclusiveMode && pPager->journalMode!=PAGER_JOURNALMODE_WAL)
     ){
-      rc = zeroJournalHdr(pPager, hasMaster);
+      rc = zeroJournalHdr(pPager, hasMaster||pPager->tempFile);
       pPager->journalOff = 0;
     }else{
       /* This branch may be executed with Pager.journalMode==MEMORY if
       ** a hot-journal was just rolled back. In this case the journal
       ** file should be closed and deleted. If this connection writes to
-      ** the database file, it will do so using an in-memory journal. 
+      ** the database file, it will do so using an in-memory journal.
       */
-      int bDelete = (!pPager->tempFile && sqlite3JournalExists(pPager->jfd));
+      int bDelete = !pPager->tempFile;
+      assert( sqlite3JournalIsInMemory(pPager->jfd)==0 );
       assert( pPager->journalMode==PAGER_JOURNALMODE_DELETE 
            || pPager->journalMode==PAGER_JOURNALMODE_MEMORY 
            || pPager->journalMode==PAGER_JOURNALMODE_WAL 
       );
       sqlite3OsClose(pPager->jfd);
       if( bDelete ){
-        rc = sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
+        rc = sqlite3OsDelete(pPager->pVfs, pPager->zJournal, pPager->extraSync);
       }
     }
   }
 
 #ifdef SQLITE_CHECK_PAGES
   sqlite3PcacheIterateDirty(pPager->pPCache, pager_set_pagehash);
   if( pPager->dbSize==0 && sqlite3PcacheRefCount(pPager->pPCache)>0 ){
     PgHdr *p = sqlite3PagerLookup(pPager, 1);
     if( p ){
       p->pageHash = 0;
       sqlite3PagerUnrefNotNull(p);
     }
   }
 #endif
 
   sqlite3BitvecDestroy(pPager->pInJournal);
   pPager->pInJournal = 0;
   pPager->nRec = 0;
-  sqlite3PcacheCleanAll(pPager->pPCache);
-  sqlite3PcacheTruncate(pPager->pPCache, pPager->dbSize);
+  if( rc==SQLITE_OK ){
+    if( MEMDB || pagerFlushOnCommit(pPager, bCommit) ){
+      sqlite3PcacheCleanAll(pPager->pPCache);
+    }else{
+      sqlite3PcacheClearWritable(pPager->pPCache);
+    }
+    sqlite3PcacheTruncate(pPager->pPCache, pPager->dbSize);
+  }
 
   if( pagerUseWal(pPager) ){
     /* Drop the WAL write-lock, if any. Also, if the connection was in 
     ** locking_mode=exclusive mode but is no longer, drop the EXCLUSIVE 
     ** lock held on the database file.
     */
     rc2 = sqlite3WalEndWriteTransaction(pPager->pWal);
     assert( rc2==SQLITE_OK );
   }else if( rc==SQLITE_OK && bCommit && pPager->dbFileSize>pPager->dbSize ){
     /* This branch is taken when committing a transaction in rollback-journal
@@ skipping 263 matching lines @@
   ** 2008-04-14:  When attempting to vacuum a corrupt database file, it
   ** is possible to fail a statement on a database that does not yet exist.
   ** Do not attempt to write if database file has never been opened.
   */
   if( pagerUseWal(pPager) ){
     pPg = 0;
   }else{
     pPg = sqlite3PagerLookup(pPager, pgno);
   }
   assert( pPg || !MEMDB );
-  assert( pPager->eState!=PAGER_OPEN || pPg==0 );
+  assert( pPager->eState!=PAGER_OPEN || pPg==0 || pPager->tempFile );
   PAGERTRACE(("PLAYBACK %d page %d hash(%08x) %s\n",
            PAGERID(pPager), pgno, pager_datahash(pPager->pageSize, (u8*)aData),
            (isMainJrnl?"main-journal":"sub-journal")
   ));
   if( isMainJrnl ){
     isSynced = pPager->noSync || (*pOffset <= pPager->journalHdr);
   }else{
     isSynced = (pPg==0 || 0==(pPg->flags & PGHDR_NEED_SYNC));
   }
   if( isOpen(pPager->fd)
    && (pPager->eState>=PAGER_WRITER_DBMOD || pPager->eState==PAGER_OPEN)
    && isSynced
   ){
     i64 ofst = (pgno-1)*(i64)pPager->pageSize;
     testcase( !isSavepnt && pPg!=0 && (pPg->flags&PGHDR_NEED_SYNC)!=0 );
     assert( !pagerUseWal(pPager) );
     rc = sqlite3OsWrite(pPager->fd, (u8 *)aData, pPager->pageSize, ofst);
     if( pgno>pPager->dbFileSize ){
       pPager->dbFileSize = pgno;
     }
     if( pPager->pBackup ){
-      CODEC1(pPager, aData, pgno, 3, rc=SQLITE_NOMEM);
+      CODEC1(pPager, aData, pgno, 3, rc=SQLITE_NOMEM_BKPT);
       sqlite3BackupUpdate(pPager->pBackup, pgno, (u8*)aData);
-      CODEC2(pPager, aData, pgno, 7, rc=SQLITE_NOMEM, aData);
+      CODEC2(pPager, aData, pgno, 7, rc=SQLITE_NOMEM_BKPT, aData);
     }
   }else if( !isMainJrnl && pPg==0 ){
     /* If this is a rollback of a savepoint and data was not written to
     ** the database and the page is not in-memory, there is a potential
     ** problem. When the page is next fetched by the b-tree layer, it 
     ** will be read from the database file, which may or may not be 
     ** current. 
     **
     ** There are a couple of different ways this can happen. All are quite
     ** obscure. When running in synchronous mode, this can only happen 
     ** if the page is on the free-list at the start of the transaction, then
     ** populated, then moved using sqlite3PagerMovepage().
     **
     ** The solution is to add an in-memory page to the cache containing
     ** the data just read from the sub-journal. Mark the page as dirty 
     ** and if the pager requires a journal-sync, then mark the page as 
     ** requiring a journal-sync before it is written.
     */
     assert( isSavepnt );
     assert( (pPager->doNotSpill & SPILLFLAG_ROLLBACK)==0 );
     pPager->doNotSpill |= SPILLFLAG_ROLLBACK;
     rc = sqlite3PagerGet(pPager, pgno, &pPg, 1);
     assert( (pPager->doNotSpill & SPILLFLAG_ROLLBACK)!=0 );
     pPager->doNotSpill &= ~SPILLFLAG_ROLLBACK;
     if( rc!=SQLITE_OK ) return rc;
-    pPg->flags &= ~PGHDR_NEED_READ;
     sqlite3PcacheMakeDirty(pPg);
   }
   if( pPg ){
     /* No page should ever be explicitly rolled back that is in use, except
     ** for page 1 which is held in use in order to keep the lock on the
     ** database active. However such a page may be rolled back as a result
     ** of an internal error resulting in an automatic call to
     ** sqlite3PagerRollback().
     */
     void *pData;
     pData = pPg->pData;
     memcpy(pData, (u8*)aData, pPager->pageSize);
     pPager->xReiniter(pPg);
-    if( isMainJrnl && (!isSavepnt || *pOffset<=pPager->journalHdr) ){
-      /* If the contents of this page were just restored from the main 
-      ** journal file, then its content must be as they were when the 
-      ** transaction was first opened. In this case we can mark the page
-      ** as clean, since there will be no need to write it out to the
-      ** database.
-      **
-      ** There is one exception to this rule. If the page is being rolled
-      ** back as part of a savepoint (or statement) rollback from an 
-      ** unsynced portion of the main journal file, then it is not safe
-      ** to mark the page as clean. This is because marking the page as
-      ** clean will clear the PGHDR_NEED_SYNC flag. Since the page is
-      ** already in the journal file (recorded in Pager.pInJournal) and
-      ** the PGHDR_NEED_SYNC flag is cleared, if the page is written to
-      ** again within this transaction, it will be marked as dirty but
-      ** the PGHDR_NEED_SYNC flag will not be set. It could then potentially
-      ** be written out into the database file before its journal file
-      ** segment is synced. If a crash occurs during or following this,
-      ** database corruption may ensue.
-      */
-      assert( !pagerUseWal(pPager) );
-      sqlite3PcacheMakeClean(pPg);
-    }
+    /* It used to be that sqlite3PcacheMakeClean(pPg) was called here.  But
+    ** that call was dangerous and had no detectable benefit since the cache
+    ** is normally cleaned by sqlite3PcacheCleanAll() after rollback and so
+    ** has been removed. */
     pager_set_pagehash(pPg);
 
     /* If this was page 1, then restore the value of Pager.dbFileVers.
     ** Do this before any decoding. */
     if( pgno==1 ){
       memcpy(&pPager->dbFileVers, &((u8*)pData)[24],sizeof(pPager->dbFileVers));
     }
 
     /* Decode the page just read from disk */
-    CODEC1(pPager, pData, pPg->pgno, 3, rc=SQLITE_NOMEM);
+    CODEC1(pPager, pData, pPg->pgno, 3, rc=SQLITE_NOMEM_BKPT);
     sqlite3PcacheRelease(pPg);
   }
   return rc;
 }
 
 /*
 ** Parameter zMaster is the name of a master journal file. A single journal
 ** file that referred to the master journal file has just been rolled back.
 ** This routine checks if it is possible to delete the master journal file,
 ** and does so if it is.
@@ skipping 45 matching lines @@
   char *zJournal;           /* Pointer to one journal within MJ file */
   char *zMasterPtr;         /* Space to hold MJ filename from a journal file */
   int nMasterPtr;           /* Amount of space allocated to zMasterPtr[] */
 
   /* Allocate space for both the pJournal and pMaster file descriptors.
   ** If successful, open the master journal file for reading.
   */
   pMaster = (sqlite3_file *)sqlite3MallocZero(pVfs->szOsFile * 2);
   pJournal = (sqlite3_file *)(((u8 *)pMaster) + pVfs->szOsFile);
   if( !pMaster ){
-    rc = SQLITE_NOMEM;
+    rc = SQLITE_NOMEM_BKPT;
   }else{
     const int flags = (SQLITE_OPEN_READONLY|SQLITE_OPEN_MASTER_JOURNAL);
     rc = sqlite3OsOpen(pVfs, zMaster, pMaster, flags, 0);
   }
   if( rc!=SQLITE_OK ) goto delmaster_out;
 
   /* Load the entire master journal file into space obtained from
   ** sqlite3_malloc() and pointed to by zMasterJournal.   Also obtain
   ** sufficient space (in zMasterPtr) to hold the names of master
   ** journal files extracted from regular rollback-journals.
   */
   rc = sqlite3OsFileSize(pMaster, &nMasterJournal);
   if( rc!=SQLITE_OK ) goto delmaster_out;
   nMasterPtr = pVfs->mxPathname+1;
   zMasterJournal = sqlite3Malloc(nMasterJournal + nMasterPtr + 1);
   if( !zMasterJournal ){
-    rc = SQLITE_NOMEM;
+    rc = SQLITE_NOMEM_BKPT;
     goto delmaster_out;
   }
   zMasterPtr = &zMasterJournal[nMasterJournal+1];
   rc = sqlite3OsRead(pMaster, zMasterJournal, (int)nMasterJournal, 0);
   if( rc!=SQLITE_OK ) goto delmaster_out;
   zMasterJournal[nMasterJournal] = 0;
 
   zJournal = zMasterJournal;
   while( (zJournal-zMasterJournal)<nMasterJournal ){
     int exists;
@@ skipping 227 matching lines @@
   }
 
   /* Read the master journal name from the journal, if it is present.
   ** If a master journal file name is specified, but the file is not
   ** present on disk, then the journal is not hot and does not need to be
   ** played back.
   **
   ** TODO: Technically the following is an error because it assumes that
   ** buffer Pager.pTmpSpace is (mxPathname+1) bytes or larger. i.e. that
   ** (pPager->pageSize >= pPager->pVfs->mxPathname+1). Using os_unix.c,
-  **  mxPathname is 512, which is the same as the minimum allowable value
+  ** mxPathname is 512, which is the same as the minimum allowable value
   ** for pageSize.
   */
   zMaster = pPager->pTmpSpace;
   rc = readMasterJournal(pPager->jfd, zMaster, pPager->pVfs->mxPathname+1);
   if( rc==SQLITE_OK && zMaster[0] ){
     rc = sqlite3OsAccess(pVfs, zMaster, SQLITE_ACCESS_EXISTS, &res);
   }
   zMaster = 0;
   if( rc!=SQLITE_OK || !res ){
     goto end_playback;
@@ skipping 201 matching lines @@
       ** 24..39 of the database are white noise.  But the probability of
       ** white noise equaling 16 bytes of 0xff is vanishingly small so
       ** we should still be ok.
       */
       memset(pPager->dbFileVers, 0xff, sizeof(pPager->dbFileVers));
     }else{
       u8 *dbFileVers = &((u8*)pPg->pData)[24];
       memcpy(&pPager->dbFileVers, dbFileVers, sizeof(pPager->dbFileVers));
     }
   }
-  CODEC1(pPager, pPg->pData, pgno, 3, rc = SQLITE_NOMEM);
+  CODEC1(pPager, pPg->pData, pgno, 3, rc = SQLITE_NOMEM_BKPT);
 
   PAGER_INCR(sqlite3_pager_readdb_count);
   PAGER_INCR(pPager->nRead);
   IOTRACE(("PGIN %p %d\n", pPager, pgno));
   PAGERTRACE(("FETCH %d page %d hash(%08x)\n",
                PAGERID(pPager), pgno, pager_pagehash(pPg)));
 
   return rc;
 }
 
@@ skipping 207 matching lines @@
   Pgno nPage;                     /* Value to return via *pnPage */
 
   /* Query the WAL sub-system for the database size. The WalDbsize()
   ** function returns zero if the WAL is not open (i.e. Pager.pWal==0), or
   ** if the database size is not available. The database size is not
   ** available from the WAL sub-system if the log file is empty or
   ** contains no valid committed transactions.
   */
   assert( pPager->eState==PAGER_OPEN );
   assert( pPager->eLock>=SHARED_LOCK );
+  assert( isOpen(pPager->fd) );
+  assert( pPager->tempFile==0 );
   nPage = sqlite3WalDbsize(pPager->pWal);
 
   /* If the number of pages in the database is not available from the
   ** WAL sub-system, determine the page counte based on the size of
   ** the database file.  If the size of the database file is not an
   ** integer multiple of the page-size, round up the result.
   */
-  if( nPage==0 ){
+  if( nPage==0 && ALWAYS(isOpen(pPager->fd)) ){
     i64 n = 0;                    /* Size of db file in bytes */
-    assert( isOpen(pPager->fd) || pPager->tempFile );
-    if( isOpen(pPager->fd) ){
-      int rc = sqlite3OsFileSize(pPager->fd, &n);
-      if( rc!=SQLITE_OK ){
-        return rc;
-      }
+    int rc = sqlite3OsFileSize(pPager->fd, &n);
+    if( rc!=SQLITE_OK ){
+      return rc;
     }
     nPage = (Pgno)((n+pPager->pageSize-1) / pPager->pageSize);
   }
 
   /* If the current number of pages in the file is greater than the
   ** configured maximum pager number, increase the allowed limit so
   ** that the file can be read.
   */
   if( nPage>pPager->mxPgno ){
     pPager->mxPgno = (Pgno)nPage;
@@ skipping 97 matching lines @@
   int rc = SQLITE_OK;      /* Return code */
   Bitvec *pDone = 0;       /* Bitvec to ensure pages played back only once */
 
   assert( pPager->eState!=PAGER_ERROR );
   assert( pPager->eState>=PAGER_WRITER_LOCKED );
 
   /* Allocate a bitvec to use to store the set of pages rolled back */
   if( pSavepoint ){
     pDone = sqlite3BitvecCreate(pSavepoint->nOrig);
     if( !pDone ){
-      return SQLITE_NOMEM;
+      return SQLITE_NOMEM_BKPT;
     }
   }
 
   /* Set the database size back to the value it was before the savepoint 
   ** being reverted was opened.
   */
   pPager->dbSize = pSavepoint ? pSavepoint->nOrig : pPager->dbOrigSize;
   pPager->changeCountDone = pPager->tempFile;
 
   if( !pSavepoint && pagerUseWal(pPager) ){
@@ skipping 100 matching lines @@
 /*
 ** Invoke SQLITE_FCNTL_MMAP_SIZE based on the current value of szMmap.
 */
 static void pagerFixMaplimit(Pager *pPager){
 #if SQLITE_MAX_MMAP_SIZE>0
   sqlite3_file *fd = pPager->fd;
   if( isOpen(fd) && fd->pMethods->iVersion>=3 ){
     sqlite3_int64 sz;
     sz = pPager->szMmap;
     pPager->bUseFetch = (sz>0);
+    setGetterMethod(pPager);
     sqlite3OsFileControlHint(pPager->fd, SQLITE_FCNTL_MMAP_SIZE, &sz);
   }
 #endif
 }
 
 /*
 ** Change the maximum size of any memory mapping made of the database file.
 */
 void sqlite3PagerSetMmapLimit(Pager *pPager, sqlite3_int64 szMmap){
   pPager->szMmap = szMmap;
   pagerFixMaplimit(pPager);
 }
 
 /*
 ** Free as much memory as possible from the pager.
 */
 void sqlite3PagerShrink(Pager *pPager){
   sqlite3PcacheShrink(pPager->pPCache);
 }
 
 /*
 ** Adjust settings of the pager to those specified in the pgFlags parameter.
 **
 ** The "level" in pgFlags & PAGER_SYNCHRONOUS_MASK sets the robustness
 ** of the database to damage due to OS crashes or power failures by
 ** changing the number of syncs()s when writing the journals.
-** There are three levels:
+** There are four levels:
 **
 **    OFF       sqlite3OsSync() is never called.  This is the default
 **              for temporary and transient files.
 **
 **    NORMAL    The journal is synced once before writes begin on the
 **              database.  This is normally adequate protection, but
 **              it is theoretically possible, though very unlikely,
 **              that an inopertune power failure could leave the journal
 **              in a state which would cause damage to the database
 **              when it is rolled back.
 **
 **    FULL      The journal is synced twice before writes begin on the
 **              database (with some additional information - the nRec field
 **              of the journal header - being written in between the two
 **              syncs).  If we assume that writing a
 **              single disk sector is atomic, then this mode provides
 **              assurance that the journal will not be corrupted to the
 **              point of causing damage to the database during rollback.
 **
+**    EXTRA     This is like FULL except that is also syncs the directory
+**              that contains the rollback journal after the rollback
+**              journal is unlinked.
+**
 ** The above is for a rollback-journal mode.  For WAL mode, OFF continues
 ** to mean that no syncs ever occur.  NORMAL means that the WAL is synced
 ** prior to the start of checkpoint and that the database file is synced
 ** at the conclusion of the checkpoint if the entire content of the WAL
 ** was written back into the database.  But no sync operations occur for
 ** an ordinary commit in NORMAL mode with WAL.  FULL means that the WAL
 ** file is synced following each commit operation, in addition to the
-** syncs associated with NORMAL.
+** syncs associated with NORMAL.  There is no difference between FULL
+** and EXTRA for WAL mode.
 **
 ** Do not confuse synchronous=FULL with SQLITE_SYNC_FULL.  The
 ** SQLITE_SYNC_FULL macro means to use the MacOSX-style full-fsync
 ** using fcntl(F_FULLFSYNC).  SQLITE_SYNC_NORMAL means to do an
 ** ordinary fsync() call.  There is no difference between SQLITE_SYNC_FULL
 ** and SQLITE_SYNC_NORMAL on platforms other than MacOSX.  But the
 ** synchronous=FULL versus synchronous=NORMAL setting determines when
 ** the xSync primitive is called and is relevant to all platforms.
 **
 ** Numeric values associated with these states are OFF==1, NORMAL=2,
 ** and FULL=3.
 */
 #ifndef SQLITE_OMIT_PAGER_PRAGMAS
 void sqlite3PagerSetFlags(
   Pager *pPager,        /* The pager to set safety level for */
   unsigned pgFlags      /* Various flags */
 ){
   unsigned level = pgFlags & PAGER_SYNCHRONOUS_MASK;
-  assert( level>=1 && level<=3 );
-  pPager->noSync =  (level==1 || pPager->tempFile) ?1:0;
-  pPager->fullSync = (level==3 && !pPager->tempFile) ?1:0;
+  if( pPager->tempFile ){
+    pPager->noSync = 1;
+    pPager->fullSync = 0;
+    pPager->extraSync = 0;
+  }else{
+    pPager->noSync =  level==PAGER_SYNCHRONOUS_OFF ?1:0;
+    pPager->fullSync = level>=PAGER_SYNCHRONOUS_FULL ?1:0;
+    pPager->extraSync = level==PAGER_SYNCHRONOUS_EXTRA ?1:0;
+  }
   if( pPager->noSync ){
     pPager->syncFlags = 0;
     pPager->ckptSyncFlags = 0;
   }else if( pgFlags & PAGER_FULLFSYNC ){
     pPager->syncFlags = SQLITE_SYNC_FULL;
     pPager->ckptSyncFlags = SQLITE_SYNC_FULL;
   }else if( pgFlags & PAGER_CKPT_FULLFSYNC ){
     pPager->syncFlags = SQLITE_SYNC_NORMAL;
     pPager->ckptSyncFlags = SQLITE_SYNC_FULL;
   }else{
@@ skipping 141 matching lines @@
    && pageSize && pageSize!=(u32)pPager->pageSize 
   ){
     char *pNew = NULL;             /* New temp space */
     i64 nByte = 0;
 
     if( pPager->eState>PAGER_OPEN && isOpen(pPager->fd) ){
       rc = sqlite3OsFileSize(pPager->fd, &nByte);
     }
     if( rc==SQLITE_OK ){
       pNew = (char *)sqlite3PageMalloc(pageSize);
-      if( !pNew ) rc = SQLITE_NOMEM;
+      if( !pNew ) rc = SQLITE_NOMEM_BKPT;
     }
 
     if( rc==SQLITE_OK ){
       pager_reset(pPager);
       rc = sqlite3PcacheSetPageSize(pPager->pPCache, pageSize);
     }
     if( rc==SQLITE_OK ){
       sqlite3PageFree(pPager->pTmpSpace);
       pPager->pTmpSpace = pNew;
       pPager->dbSize = (Pgno)((nByte+pageSize-1)/pageSize);
@@ skipping 228 matching lines @@
   int rc = SQLITE_OK;
   if( !pPager->noSync ){
     rc = sqlite3OsSync(pPager->jfd, SQLITE_SYNC_NORMAL);
   }
   if( rc==SQLITE_OK ){
     rc = sqlite3OsFileSize(pPager->jfd, &pPager->journalHdr);
   }
   return rc;
 }
 
+#if SQLITE_MAX_MMAP_SIZE>0
 /*
 ** Obtain a reference to a memory mapped page object for page number pgno. 
 ** The new object will use the pointer pData, obtained from xFetch().
 ** If successful, set *ppPage to point to the new page reference
 ** and return SQLITE_OK. Otherwise, return an SQLite error code and set
 ** *ppPage to zero.
 **
 ** Page references obtained by calling this function should be released
 ** by calling pagerReleaseMapPage().
 */
 static int pagerAcquireMapPage(
   Pager *pPager,                  /* Pager object */
   Pgno pgno,                      /* Page number */
   void *pData,                    /* xFetch()'d data for this page */
   PgHdr **ppPage                  /* OUT: Acquired page object */
 ){
   PgHdr *p;                       /* Memory mapped page to return */
   
   if( pPager->pMmapFreelist ){
     *ppPage = p = pPager->pMmapFreelist;
     pPager->pMmapFreelist = p->pDirty;
     p->pDirty = 0;
-    memset(p->pExtra, 0, pPager->nExtra);
+    assert( pPager->nExtra>=8 );
+    memset(p->pExtra, 0, 8);
   }else{
     *ppPage = p = (PgHdr *)sqlite3MallocZero(sizeof(PgHdr) + pPager->nExtra);
     if( p==0 ){
       sqlite3OsUnfetch(pPager->fd, (i64)(pgno-1) * pPager->pageSize, pData);
-      return SQLITE_NOMEM;
+      return SQLITE_NOMEM_BKPT;
     }
     p->pExtra = (void *)&p[1];
     p->flags = PGHDR_MMAP;
     p->nRef = 1;
     p->pPager = pPager;
   }
 
   assert( p->pExtra==(void *)&p[1] );
   assert( p->pPage==0 );
   assert( p->flags==PGHDR_MMAP );
   assert( p->pPager==pPager );
   assert( p->nRef==1 );
 
   p->pgno = pgno;
   p->pData = pData;
   pPager->nMmapOut++;
 
   return SQLITE_OK;
 }
+#endif
 
 /*
 ** Release a reference to page pPg. pPg must have been returned by an 
 ** earlier call to pagerAcquireMapPage().
 */
 static void pagerReleaseMapPage(PgHdr *pPg){
   Pager *pPager = pPg->pPager;
   pPager->nMmapOut--;
   pPg->pDirty = pPager->pMmapFreelist;
   pPager->pMmapFreelist = pPg;
@@ skipping 22 matching lines @@
 ** transaction is rolled back.  All outstanding pages are invalidated
 ** and their memory is freed.  Any attempt to use a page associated
 ** with this page cache after this function returns will likely
 ** result in a coredump.
 **
 ** This function always succeeds. If a transaction is active an attempt
 ** is made to roll it back. If an error occurs during the rollback 
 ** a hot journal may be left in the filesystem but no error is returned
 ** to the caller.
 */
-int sqlite3PagerClose(Pager *pPager){
+int sqlite3PagerClose(Pager *pPager, sqlite3 *db){
   u8 *pTmp = (u8 *)pPager->pTmpSpace;
 
+  assert( db || pagerUseWal(pPager)==0 );
   assert( assert_pager_state(pPager) );
   disable_simulated_io_errors();
   sqlite3BeginBenignMalloc();
   pagerFreeMapHdrs(pPager);
   /* pPager->errCode = 0; */
   pPager->exclusiveMode = 0;
 #ifndef SQLITE_OMIT_WAL
-  sqlite3WalClose(pPager->pWal, pPager->ckptSyncFlags, pPager->pageSize, pTmp);
+  assert( db || pPager->pWal==0 );
+  sqlite3WalClose(pPager->pWal, db, pPager->ckptSyncFlags, pPager->pageSize,
+      (db && (db->flags & SQLITE_NoCkptOnClose) ? 0 : pTmp)
+  );
   pPager->pWal = 0;
 #endif
   pager_reset(pPager);
   if( MEMDB ){
     pager_unlock(pPager);
   }else{
     /* If it is open, sync the journal file before calling UnlockAndRollback.
     ** If this is not done, then an unsynced portion of the open journal 
     ** file may be played back into the database. If a power failure occurs 
     ** while this is happening, the database could become corrupt.
@@ skipping 221 matching lines @@
 **
 ** If everything is successful, SQLITE_OK is returned. If an IO error 
 ** occurs, an IO error code is returned. Or, if the EXCLUSIVE lock cannot
 ** be obtained, SQLITE_BUSY is returned.
 */
 static int pager_write_pagelist(Pager *pPager, PgHdr *pList){
   int rc = SQLITE_OK;                  /* Return code */
 
   /* This function is only called for rollback pagers in WRITER_DBMOD state. */
   assert( !pagerUseWal(pPager) );
-  assert( pPager->eState==PAGER_WRITER_DBMOD );
+  assert( pPager->tempFile || pPager->eState==PAGER_WRITER_DBMOD );
   assert( pPager->eLock==EXCLUSIVE_LOCK );
+  assert( isOpen(pPager->fd) || pList->pDirty==0 );
 
   /* If the file is a temp-file has not yet been opened, open it now. It
   ** is not possible for rc to be other than SQLITE_OK if this branch
   ** is taken, as pager_wait_on_lock() is a no-op for temp-files.
   */
   if( !isOpen(pPager->fd) ){
     assert( pPager->tempFile && rc==SQLITE_OK );
     rc = pagerOpentemp(pPager, pPager->fd, pPager->vfsFlags);
   }
 
@@ skipping 22 matching lines @@
     ** set (set by sqlite3PagerDontWrite()).
     */
     if( pgno<=pPager->dbSize && 0==(pList->flags&PGHDR_DONT_WRITE) ){
       i64 offset = (pgno-1)*(i64)pPager->pageSize;   /* Offset to write */
       char *pData;                                   /* Data to write */    
 
       assert( (pList->flags&PGHDR_NEED_SYNC)==0 );
       if( pList->pgno==1 ) pager_write_changecounter(pList);
 
       /* Encode the database */
-      CODEC2(pPager, pList->pData, pgno, 6, return SQLITE_NOMEM, pData);
+      CODEC2(pPager, pList->pData, pgno, 6, return SQLITE_NOMEM_BKPT, pData);
 
       /* Write out the page data. */
       rc = sqlite3OsWrite(pPager->fd, pData, pPager->pageSize, offset);
 
       /* If page 1 was just written, update Pager.dbFileVers to match
       ** the value now stored in the database file. If writing this 
       ** page caused the database file to grow, update dbFileSize. 
       */
       if( pgno==1 ){
         memcpy(&pPager->dbFileVers, &pData[24], sizeof(pPager->dbFileVers));
@@ skipping 24 matching lines @@
 ** Ensure that the sub-journal file is open. If it is already open, this 
 ** function is a no-op.
 **
 ** SQLITE_OK is returned if everything goes according to plan. An 
 ** SQLITE_IOERR_XXX error code is returned if a call to sqlite3OsOpen() 
 ** fails.
 */
 static int openSubJournal(Pager *pPager){
   int rc = SQLITE_OK;
   if( !isOpen(pPager->sjfd) ){
+    const int flags =  SQLITE_OPEN_SUBJOURNAL | SQLITE_OPEN_READWRITE 
+      | SQLITE_OPEN_CREATE | SQLITE_OPEN_EXCLUSIVE 
+      | SQLITE_OPEN_DELETEONCLOSE;
+    int nStmtSpill = sqlite3Config.nStmtSpill;
     if( pPager->journalMode==PAGER_JOURNALMODE_MEMORY || pPager->subjInMemory ){
-      sqlite3MemJournalOpen(pPager->sjfd);
-    }else{
-      rc = pagerOpentemp(pPager, pPager->sjfd, SQLITE_OPEN_SUBJOURNAL);
+      nStmtSpill = -1;
     }
+    rc = sqlite3JournalOpen(pPager->pVfs, 0, pPager->sjfd, flags, nStmtSpill);
   }
   return rc;
 }
 
 /*
 ** Append a record of the current state of page pPg to the sub-journal. 
 **
 ** If successful, set the bit corresponding to pPg->pgno in the bitvecs
 ** for all open savepoints before returning.
 **
@@ skipping 17 matching lines @@
     );
     rc = openSubJournal(pPager);
 
     /* If the sub-journal was opened successfully (or was already open),
     ** write the journal record into the file.  */
     if( rc==SQLITE_OK ){
       void *pData = pPg->pData;
       i64 offset = (i64)pPager->nSubRec*(4+pPager->pageSize);
       char *pData2;
   
-      CODEC2(pPager, pData, pPg->pgno, 7, return SQLITE_NOMEM, pData2);
+      CODEC2(pPager, pData, pPg->pgno, 7, return SQLITE_NOMEM_BKPT, pData2);
       PAGERTRACE(("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno));
       rc = write32bits(pPager->sjfd, offset, pPg->pgno);
       if( rc==SQLITE_OK ){
         rc = sqlite3OsWrite(pPager->sjfd, pData2, pPager->pageSize, offset+4);
       }
     }
   }
   if( rc==SQLITE_OK ){
     pPager->nSubRec++;
     assert( pPager->nSavepoint>0 );
@@ skipping 121 matching lines @@
 **
 ** The zFilename argument is the path to the database file to open.
 ** If zFilename is NULL then a randomly-named temporary file is created
 ** and used as the file to be cached. Temporary files are be deleted
 ** automatically when they are closed. If zFilename is ":memory:" then 
 ** all information is held in cache. It is never written to disk. 
 ** This can be used to implement an in-memory database.
 **
 ** The nExtra parameter specifies the number of bytes of space allocated
 ** along with each page reference. This space is available to the user
-** via the sqlite3PagerGetExtra() API.
+** via the sqlite3PagerGetExtra() API.  When a new page is allocated, the
+** first 8 bytes of this space are zeroed but the remainder is uninitialized.
+** (The extra space is used by btree as the MemPage object.)
 **
 ** The flags argument is used to specify properties that affect the
 ** operation of the pager. It should be passed some bitwise combination
 ** of the PAGER_* flags.
 **
 ** The vfsFlags parameter is a bitmask to pass to the flags parameter
 ** of the xOpen() method of the supplied VFS when opening files. 
 **
 ** If the pager object is allocated and the specified file opened 
 ** successfully, SQLITE_OK is returned and *ppPager set to point to
@@ skipping 20 matching lines @@
   int journalFileSize;     /* Bytes to allocate for each journal fd */
   char *zPathname = 0;     /* Full path to database file */
   int nPathname = 0;       /* Number of bytes in zPathname */
   int useJournal = (flags & PAGER_OMIT_JOURNAL)==0; /* False to omit journal */
   int pcacheSize = sqlite3PcacheSize();       /* Bytes to allocate for PCache */
   u32 szPageDflt = SQLITE_DEFAULT_PAGE_SIZE;  /* Default page size */
   const char *zUri = 0;    /* URI args to copy */
   int nUri = 0;            /* Number of bytes of URI args at *zUri */
 
   /* Figure out how much space is required for each journal file-handle
-  ** (there are two of them, the main journal and the sub-journal). This
-  ** is the maximum space required for an in-memory journal file handle 
-  ** and a regular journal file-handle. Note that a "regular journal-handle"
-  ** may be a wrapper capable of caching the first portion of the journal
-  ** file in memory to implement the atomic-write optimization (see 
-  ** source file journal.c).
-  */
-  if( sqlite3JournalSize(pVfs)>sqlite3MemJournalSize() ){
-    journalFileSize = ROUND8(sqlite3JournalSize(pVfs));
-  }else{
-    journalFileSize = ROUND8(sqlite3MemJournalSize());
-  }
+  ** (there are two of them, the main journal and the sub-journal).  */
+  journalFileSize = ROUND8(sqlite3JournalSize(pVfs));
 
   /* Set the output variable to NULL in case an error occurs. */
   *ppPager = 0;
 
 #ifndef SQLITE_OMIT_MEMORYDB
   if( flags & PAGER_MEMORY ){
     memDb = 1;
     if( zFilename && zFilename[0] ){
       zPathname = sqlite3DbStrDup(0, zFilename);
-      if( zPathname==0  ) return SQLITE_NOMEM;
+      if( zPathname==0  ) return SQLITE_NOMEM_BKPT;
       nPathname = sqlite3Strlen30(zPathname);
       zFilename = 0;
     }
   }
 #endif
 
   /* Compute and store the full pathname in an allocated buffer pointed
   ** to by zPathname, length nPathname. Or, if this is a temporary file,
   ** leave both nPathname and zPathname set to 0.
   */
   if( zFilename && zFilename[0] ){
     const char *z;
     nPathname = pVfs->mxPathname+1;
     zPathname = sqlite3DbMallocRaw(0, nPathname*2);
     if( zPathname==0 ){
-      return SQLITE_NOMEM;
+      return SQLITE_NOMEM_BKPT;
     }
     zPathname[0] = 0; /* Make sure initialized even if FullPathname() fails */
     rc = sqlite3OsFullPathname(pVfs, zFilename, nPathname, zPathname);
     nPathname = sqlite3Strlen30(zPathname);
     z = zUri = &zFilename[sqlite3Strlen30(zFilename)+1];
     while( *z ){
       z += sqlite3Strlen30(z)+1;
       z += sqlite3Strlen30(z)+1;
     }
     nUri = (int)(&z[1] - zUri);
@@ skipping 32 matching lines @@
     journalFileSize * 2 +          /* The two journal files */ 
     nPathname + 1 + nUri +         /* zFilename */
     nPathname + 8 + 2              /* zJournal */
 #ifndef SQLITE_OMIT_WAL
     + nPathname + 4 + 2            /* zWal */
 #endif
   );
   assert( EIGHT_BYTE_ALIGNMENT(SQLITE_INT_TO_PTR(journalFileSize)) );
   if( !pPtr ){
     sqlite3DbFree(0, zPathname);
-    return SQLITE_NOMEM;
+    return SQLITE_NOMEM_BKPT;
   }
   pPager =              (Pager*)(pPtr);
   pPager->pPCache =    (PCache*)(pPtr += ROUND8(sizeof(*pPager)));
   pPager->fd =   (sqlite3_file*)(pPtr += ROUND8(pcacheSize));
   pPager->sjfd = (sqlite3_file*)(pPtr += ROUND8(pVfs->szOsFile));
   pPager->jfd =  (sqlite3_file*)(pPtr += journalFileSize);
   pPager->zFilename =    (char*)(pPtr += journalFileSize);
   assert( EIGHT_BYTE_ALIGNMENT(pPager->jfd) );
 
   /* Fill in the Pager.zFilename and Pager.zJournal buffers, if required. */
@@ skipping 88 matching lines @@
   ** Pager.pageSize and to allocate the Pager.pTmpSpace buffer.
   */
   if( rc==SQLITE_OK ){
     assert( pPager->memDb==0 );
     rc = sqlite3PagerSetPagesize(pPager, &szPageDflt, -1);
     testcase( rc!=SQLITE_OK );
   }
 
   /* Initialize the PCache object. */
   if( rc==SQLITE_OK ){
-    assert( nExtra<1000 );
     nExtra = ROUND8(nExtra);
+    assert( nExtra>=8 && nExtra<1000 );
     rc = sqlite3PcacheOpen(szPageDflt, nExtra, !memDb,
                        !memDb?pagerStress:0, (void *)pPager, pPager->pPCache);
   }
 
   /* If an error occurred above, free the  Pager structure and close the file.
   */
   if( rc!=SQLITE_OK ){
     sqlite3OsClose(pPager->fd);
     sqlite3PageFree(pPager->pTmpSpace);
     sqlite3_free(pPager);
@@ skipping 18 matching lines @@
           || tempFile==PAGER_LOCKINGMODE_EXCLUSIVE );
   assert( PAGER_LOCKINGMODE_EXCLUSIVE==1 );
   pPager->exclusiveMode = (u8)tempFile; 
   pPager->changeCountDone = pPager->tempFile;
   pPager->memDb = (u8)memDb;
   pPager->readOnly = (u8)readOnly;
   assert( useJournal || pPager->tempFile );
   pPager->noSync = pPager->tempFile;
   if( pPager->noSync ){
     assert( pPager->fullSync==0 );
+    assert( pPager->extraSync==0 );
     assert( pPager->syncFlags==0 );
     assert( pPager->walSyncFlags==0 );
     assert( pPager->ckptSyncFlags==0 );
   }else{
     pPager->fullSync = 1;
+    pPager->extraSync = 0;
     pPager->syncFlags = SQLITE_SYNC_NORMAL;
     pPager->walSyncFlags = SQLITE_SYNC_NORMAL | WAL_SYNC_TRANSACTIONS;
     pPager->ckptSyncFlags = SQLITE_SYNC_NORMAL;
   }
   /* pPager->pFirst = 0; */
   /* pPager->pFirstSynced = 0; */
   /* pPager->pLast = 0; */
   pPager->nExtra = (u16)nExtra;
   pPager->journalSizeLimit = SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT;
   assert( isOpen(pPager->fd) || tempFile );
   setSectorSize(pPager);
   if( !useJournal ){
     pPager->journalMode = PAGER_JOURNALMODE_OFF;
   }else if( memDb ){
     pPager->journalMode = PAGER_JOURNALMODE_MEMORY;
   }
   /* pPager->xBusyHandler = 0; */
   /* pPager->pBusyHandlerArg = 0; */
   pPager->xReiniter = xReinit;
+  setGetterMethod(pPager);
   /* memset(pPager->aHash, 0, sizeof(pPager->aHash)); */
   /* pPager->szMmap = SQLITE_DEFAULT_MMAP_SIZE // will be set by btree.c */
 
   *ppPager = pPager;
   return SQLITE_OK;
 }
 
 
 /* Verify that the database file has not be deleted or renamed out from
 ** under the pager.  Return SQLITE_OK if the database is still were it ought
@@ skipping 77 matching lines @@
     ** call above, but then delete the journal and drop the lock before
     ** we get to the following sqlite3OsCheckReservedLock() call.  If that
     ** is the case, this routine might think there is a hot journal when
     ** in fact there is none.  This results in a false-positive which will
     ** be dealt with by the playback routine.  Ticket #3883.
     */
     rc = sqlite3OsCheckReservedLock(pPager->fd, &locked);
     if( rc==SQLITE_OK && !locked ){
       Pgno nPage;                 /* Number of pages in database file */
 
+      assert( pPager->tempFile==0 );
       rc = pagerPagecount(pPager, &nPage);
       if( rc==SQLITE_OK ){
         /* If the database is zero pages in size, that means that either (1) the
         ** journal is a remnant from a prior database with the same name where
         ** the database file but not the journal was deleted, or (2) the initial
         ** transaction that populates a new database is being rolled back.
         ** In either case, the journal file can be deleted.  However, take care
         ** not to delete the journal file if it is already open due to
         ** journal_mode=PERSIST.
         */
@@ skipping 72 matching lines @@
 ** If everything is successful, SQLITE_OK is returned. If an IO error 
 ** occurs while locking the database, checking for a hot-journal file or 
 ** rolling back a journal file, the IO error code is returned.
 */
 int sqlite3PagerSharedLock(Pager *pPager){
   int rc = SQLITE_OK;                /* Return code */
 
   /* This routine is only called from b-tree and only when there are no
   ** outstanding pages. This implies that the pager state should either
   ** be OPEN or READER. READER is only possible if the pager is or was in 
-  ** exclusive access mode.
-  */
+  ** exclusive access mode.  */
   assert( sqlite3PcacheRefCount(pPager->pPCache)==0 );
   assert( assert_pager_state(pPager) );
   assert( pPager->eState==PAGER_OPEN || pPager->eState==PAGER_READER );
-  if( NEVER(MEMDB && pPager->errCode) ){ return pPager->errCode; }
+  assert( pPager->errCode==SQLITE_OK );
 
   if( !pagerUseWal(pPager) && pPager->eState==PAGER_OPEN ){
     int bHotJournal = 1;          /* True if there exists a hot journal-file */
 
     assert( !MEMDB );
+    assert( pPager->tempFile==0 || pPager->eLock==EXCLUSIVE_LOCK );
 
     rc = pager_wait_on_lock(pPager, SHARED_LOCK);
     if( rc!=SQLITE_OK ){
       assert( pPager->eLock==NO_LOCK || pPager->eLock==UNKNOWN_LOCK );
       goto failed;
     }
 
     /* If a journal file exists, and there is no RESERVED lock on the
     ** database file, then it either needs to be played back or deleted.
     */
@@ skipping 65 matching lines @@
       ** playing back the hot-journal so that we don't end up with
       ** an inconsistent cache.  Sync the hot journal before playing
       ** it back since the process that crashed and left the hot journal
       ** probably did not sync it and we are required to always sync
       ** the journal before playing it back.
       */
       if( isOpen(pPager->jfd) ){
         assert( rc==SQLITE_OK );
         rc = pagerSyncHotJournal(pPager);
         if( rc==SQLITE_OK ){
-          rc = pager_playback(pPager, 1);
+          rc = pager_playback(pPager, !pPager->tempFile);
           pPager->eState = PAGER_OPEN;
         }
       }else if( !pPager->exclusiveMode ){
         pagerUnlockDb(pPager, SHARED_LOCK);
       }
 
       if( rc!=SQLITE_OK ){
         /* This branch is taken if an error occurs while trying to open
         ** or roll back a hot-journal while holding an EXCLUSIVE lock. The
         ** pager_unlock() routine will be called before returning to unlock
@@ skipping 75 matching lines @@
 #ifndef SQLITE_OMIT_WAL
     assert( pPager->pWal==0 || rc==SQLITE_OK );
 #endif
   }
 
   if( pagerUseWal(pPager) ){
     assert( rc==SQLITE_OK );
     rc = pagerBeginReadTransaction(pPager);
   }
 
-  if( pPager->eState==PAGER_OPEN && rc==SQLITE_OK ){
+  if( pPager->tempFile==0 && pPager->eState==PAGER_OPEN && rc==SQLITE_OK ){
     rc = pagerPagecount(pPager, &pPager->dbSize);
   }
 
  failed:
   if( rc!=SQLITE_OK ){
     assert( !MEMDB );
     pager_unlock(pPager);
     assert( pPager->eState==PAGER_OPEN );
   }else{
     pPager->eState = PAGER_READER;
@@ skipping 10 matching lines @@
 ** the rollback journal, the unlock is not performed and there is
 ** nothing to rollback, so this routine is a no-op.
 */ 
 static void pagerUnlockIfUnused(Pager *pPager){
   if( pPager->nMmapOut==0 && (sqlite3PcacheRefCount(pPager->pPCache)==0) ){
     pagerUnlockAndRollback(pPager);
   }
 }
 
 /*
-** Acquire a reference to page number pgno in pager pPager (a page
-** reference has type DbPage*). If the requested reference is 
+** The page getter methods each try to acquire a reference to a
+** page with page number pgno. If the requested reference is 
 ** successfully obtained, it is copied to *ppPage and SQLITE_OK returned.
 **
+** There are different implementations of the getter method depending
+** on the current state of the pager.
+**
+**     getPageNormal()         --  The normal getter
+**     getPageError()          --  Used if the pager is in an error state
+**     getPageMmap()           --  Used if memory-mapped I/O is enabled
+**
 ** If the requested page is already in the cache, it is returned. 
 ** Otherwise, a new page object is allocated and populated with data
 ** read from the database file. In some cases, the pcache module may
 ** choose not to allocate a new page object and may reuse an existing
 ** object with no outstanding references.
 **
 ** The extra data appended to a page is always initialized to zeros the 
 ** first time a page is loaded into memory. If the page requested is 
 ** already in the cache when this function is called, then the extra
 ** data is left as it was when the page object was last used.
 **
-** If the database image is smaller than the requested page or if a 
-** non-zero value is passed as the noContent parameter and the 
+** If the database image is smaller than the requested page or if 
+** the flags parameter contains the PAGER_GET_NOCONTENT bit and the 
 ** requested page is not already stored in the cache, then no 
 ** actual disk read occurs. In this case the memory image of the 
 ** page is initialized to all zeros. 
 **
-** If noContent is true, it means that we do not care about the contents
-** of the page. This occurs in two scenarios:
+** If PAGER_GET_NOCONTENT is true, it means that we do not care about
+** the contents of the page. This occurs in two scenarios:
 **
 **   a) When reading a free-list leaf page from the database, and
 **
 **   b) When a savepoint is being rolled back and we need to load
 **      a new page into the cache to be filled with the data read
 **      from the savepoint journal.
 **
-** If noContent is true, then the data returned is zeroed instead of
-** being read from the database. Additionally, the bits corresponding
+** If PAGER_GET_NOCONTENT is true, then the data returned is zeroed instead
+** of being read from the database. Additionally, the bits corresponding
 ** to pgno in Pager.pInJournal (bitvec of pages already written to the
 ** journal file) and the PagerSavepoint.pInSavepoint bitvecs of any open
 ** savepoints are set. This means if the page is made writable at any
 ** point in the future, using a call to sqlite3PagerWrite(), its contents
 ** will not be journaled. This saves IO.
 **
 ** The acquisition might fail for several reasons.  In all cases,
 ** an appropriate error code is returned and *ppPage is set to NULL.
 **
 ** See also sqlite3PagerLookup().  Both this routine and Lookup() attempt
 ** to find a page in the in-memory cache first.  If the page is not already
 ** in memory, this routine goes to disk to read it in whereas Lookup()
 ** just returns 0.  This routine acquires a read-lock the first time it
 ** has to go to disk, and could also playback an old journal if necessary.
 ** Since Lookup() never goes to disk, it never has to deal with locks
 ** or journal files.
 */
-int sqlite3PagerGet(
+static int getPageNormal(
   Pager *pPager,      /* The pager open on the database file */
   Pgno pgno,          /* Page number to fetch */
   DbPage **ppPage,    /* Write a pointer to the page here */
   int flags           /* PAGER_GET_XXX flags */
 ){
   int rc = SQLITE_OK;
-  PgHdr *pPg = 0;
-  u32 iFrame = 0;                 /* Frame to read from WAL file */
-  const int noContent = (flags & PAGER_GET_NOCONTENT);
+  PgHdr *pPg;
+  u8 noContent;                   /* True if PAGER_GET_NOCONTENT is set */
+  sqlite3_pcache_page *pBase;
 
-  /* It is acceptable to use a read-only (mmap) page for any page except
-  ** page 1 if there is no write-transaction open or the ACQUIRE_READONLY
-  ** flag was specified by the caller. And so long as the db is not a 
-  ** temporary or in-memory database.  */
-  const int bMmapOk = (pgno>1 && USEFETCH(pPager)
-   && (pPager->eState==PAGER_READER || (flags & PAGER_GET_READONLY))
-#ifdef SQLITE_HAS_CODEC
-   && pPager->xCodec==0
-#endif
-  );
-
-  /* Optimization note:  Adding the "pgno<=1" term before "pgno==0" here
-  ** allows the compiler optimizer to reuse the results of the "pgno>1"
-  ** test in the previous statement, and avoid testing pgno==0 in the
-  ** common case where pgno is large. */
-  if( pgno<=1 && pgno==0 ){
-    return SQLITE_CORRUPT_BKPT;
-  }
+  assert( pPager->errCode==SQLITE_OK );
   assert( pPager->eState>=PAGER_READER );
   assert( assert_pager_state(pPager) );
-  assert( noContent==0 || bMmapOk==0 );
-
   assert( pPager->hasHeldSharedLock==1 );
 
-  /* If the pager is in the error state, return an error immediately. 
-  ** Otherwise, request the page from the PCache layer. */
-  if( pPager->errCode!=SQLITE_OK ){
-    rc = pPager->errCode;
-  }else{
-    if( bMmapOk && pagerUseWal(pPager) ){
-      rc = sqlite3WalFindFrame(pPager->pWal, pgno, &iFrame);
-      if( rc!=SQLITE_OK ) goto pager_acquire_err;
-    }
-
-    if( bMmapOk && iFrame==0 ){
-      void *pData = 0;
-
-      rc = sqlite3OsFetch(pPager->fd, 
-          (i64)(pgno-1) * pPager->pageSize, pPager->pageSize, &pData
-      );
-
-      if( rc==SQLITE_OK && pData ){
-        if( pPager->eState>PAGER_READER ){
-          pPg = sqlite3PagerLookup(pPager, pgno);
-        }
-        if( pPg==0 ){
-          rc = pagerAcquireMapPage(pPager, pgno, pData, &pPg);
-        }else{
-          sqlite3OsUnfetch(pPager->fd, (i64)(pgno-1)*pPager->pageSize, pData);
-        }
-        if( pPg ){
-          assert( rc==SQLITE_OK );
-          *ppPage = pPg;
-          return SQLITE_OK;
-        }
-      }
-      if( rc!=SQLITE_OK ){
-        goto pager_acquire_err;
-      }
-    }
-
-    {
-      sqlite3_pcache_page *pBase;
-      pBase = sqlite3PcacheFetch(pPager->pPCache, pgno, 3);
-      if( pBase==0 ){
-        rc = sqlite3PcacheFetchStress(pPager->pPCache, pgno, &pBase);
-        if( rc!=SQLITE_OK ) goto pager_acquire_err;
-        if( pBase==0 ){
-          pPg = *ppPage = 0;
-          rc = SQLITE_NOMEM;
-          goto pager_acquire_err;
-        }
-      }
-      pPg = *ppPage = sqlite3PcacheFetchFinish(pPager->pPCache, pgno, pBase);
-      assert( pPg!=0 );
+  if( pgno==0 ) return SQLITE_CORRUPT_BKPT;
+  pBase = sqlite3PcacheFetch(pPager->pPCache, pgno, 3);
+  if( pBase==0 ){
+    pPg = 0;
+    rc = sqlite3PcacheFetchStress(pPager->pPCache, pgno, &pBase);
+    if( rc!=SQLITE_OK ) goto pager_acquire_err;
+    if( pBase==0 ){
+      rc = SQLITE_NOMEM_BKPT;
+      goto pager_acquire_err;
     }
   }
-
-  if( rc!=SQLITE_OK ){
-    /* Either the call to sqlite3PcacheFetch() returned an error or the
-    ** pager was already in the error-state when this function was called.
-    ** Set pPg to 0 and jump to the exception handler.  */
-    pPg = 0;
-    goto pager_acquire_err;
-  }
+  pPg = *ppPage = sqlite3PcacheFetchFinish(pPager->pPCache, pgno, pBase);
   assert( pPg==(*ppPage) );
   assert( pPg->pgno==pgno );
   assert( pPg->pPager==pPager || pPg->pPager==0 );
 
+  noContent = (flags & PAGER_GET_NOCONTENT)!=0;
   if( pPg->pPager && !noContent ){
     /* In this case the pcache already contains an initialized copy of
     ** the page. Return without further ado.  */
     assert( pgno<=PAGER_MAX_PGNO && pgno!=PAGER_MJ_PGNO(pPager) );
     pPager->aStat[PAGER_STAT_HIT]++;
     return SQLITE_OK;
 
   }else{
     /* The pager cache has created a new page. Its content needs to 
-    ** be initialized.  */
-
-    pPg->pPager = pPager;
-
-    /* The maximum page number is 2^31. Return SQLITE_CORRUPT if a page
-    ** number greater than this, or the unused locking-page, is requested. */
+    ** be initialized. But first some error checks:
+    **
+    ** (1) The maximum page number is 2^31
+    ** (2) Never try to fetch the locking page
+    */
     if( pgno>PAGER_MAX_PGNO || pgno==PAGER_MJ_PGNO(pPager) ){
       rc = SQLITE_CORRUPT_BKPT;
       goto pager_acquire_err;
     }
 
-    if( MEMDB || pPager->dbSize<pgno || noContent || !isOpen(pPager->fd) ){
+    pPg->pPager = pPager;
+
+    assert( !isOpen(pPager->fd) || !MEMDB );
+    if( !isOpen(pPager->fd) || pPager->dbSize<pgno || noContent ){
       if( pgno>pPager->mxPgno ){
         rc = SQLITE_FULL;
         goto pager_acquire_err;
       }
       if( noContent ){
         /* Failure to set the bits in the InJournal bit-vectors is benign.
         ** It merely means that we might do some extra work to journal a 
         ** page that does not need to be journaled.  Nevertheless, be sure 
         ** to test the case where a malloc error occurs while trying to set 
         ** a bit in a bit vector.
         */
         sqlite3BeginBenignMalloc();
         if( pgno<=pPager->dbOrigSize ){
           TESTONLY( rc = ) sqlite3BitvecSet(pPager->pInJournal, pgno);
           testcase( rc==SQLITE_NOMEM );
         }
         TESTONLY( rc = ) addToSavepointBitvecs(pPager, pgno);
         testcase( rc==SQLITE_NOMEM );
         sqlite3EndBenignMalloc();
       }
       memset(pPg->pData, 0, pPager->pageSize);
       IOTRACE(("ZERO %p %d\n", pPager, pgno));
     }else{
-      if( pagerUseWal(pPager) && bMmapOk==0 ){
+      u32 iFrame = 0;                 /* Frame to read from WAL file */
+      if( pagerUseWal(pPager) ){
         rc = sqlite3WalFindFrame(pPager->pWal, pgno, &iFrame);
         if( rc!=SQLITE_OK ) goto pager_acquire_err;
       }
       assert( pPg->pPager==pPager );
       pPager->aStat[PAGER_STAT_MISS]++;
       rc = readDbPage(pPg, iFrame);
       if( rc!=SQLITE_OK ){
         goto pager_acquire_err;
       }
     }
     pager_set_pagehash(pPg);
   }
-
   return SQLITE_OK;
 
 pager_acquire_err:
   assert( rc!=SQLITE_OK );
   if( pPg ){
     sqlite3PcacheDrop(pPg);
   }
   pagerUnlockIfUnused(pPager);
-
   *ppPage = 0;
   return rc;
 }
 
+#if SQLITE_MAX_MMAP_SIZE>0
+/* The page getter for when memory-mapped I/O is enabled */
+static int getPageMMap(
+  Pager *pPager,      /* The pager open on the database file */
+  Pgno pgno,          /* Page number to fetch */
+  DbPage **ppPage,    /* Write a pointer to the page here */
+  int flags           /* PAGER_GET_XXX flags */
+){
+  int rc = SQLITE_OK;
+  PgHdr *pPg = 0;
+  u32 iFrame = 0;                 /* Frame to read from WAL file */
+
+  /* It is acceptable to use a read-only (mmap) page for any page except
+  ** page 1 if there is no write-transaction open or the ACQUIRE_READONLY
+  ** flag was specified by the caller. And so long as the db is not a 
+  ** temporary or in-memory database.  */
+  const int bMmapOk = (pgno>1
+   && (pPager->eState==PAGER_READER || (flags & PAGER_GET_READONLY))
+  );
+
+  assert( USEFETCH(pPager) );
+#ifdef SQLITE_HAS_CODEC
+  assert( pPager->xCodec==0 );
+#endif
+
+  /* Optimization note:  Adding the "pgno<=1" term before "pgno==0" here
+  ** allows the compiler optimizer to reuse the results of the "pgno>1"
+  ** test in the previous statement, and avoid testing pgno==0 in the
+  ** common case where pgno is large. */
+  if( pgno<=1 && pgno==0 ){
+    return SQLITE_CORRUPT_BKPT;
+  }
+  assert( pPager->eState>=PAGER_READER );
+  assert( assert_pager_state(pPager) );
+  assert( pPager->hasHeldSharedLock==1 );
+  assert( pPager->errCode==SQLITE_OK );
+
+  if( bMmapOk && pagerUseWal(pPager) ){
+    rc = sqlite3WalFindFrame(pPager->pWal, pgno, &iFrame);
+    if( rc!=SQLITE_OK ){
+      *ppPage = 0;
+      return rc;
+    }
+  }
+  if( bMmapOk && iFrame==0 ){
+    void *pData = 0;
+    rc = sqlite3OsFetch(pPager->fd, 
+        (i64)(pgno-1) * pPager->pageSize, pPager->pageSize, &pData
+    );
+    if( rc==SQLITE_OK && pData ){
+      if( pPager->eState>PAGER_READER || pPager->tempFile ){
+        pPg = sqlite3PagerLookup(pPager, pgno);
+      }
+      if( pPg==0 ){
+        rc = pagerAcquireMapPage(pPager, pgno, pData, &pPg);
+     }else{
+        sqlite3OsUnfetch(pPager->fd, (i64)(pgno-1)*pPager->pageSize, pData);
+      }
+      if( pPg ){
+        assert( rc==SQLITE_OK );
+        *ppPage = pPg;
+        return SQLITE_OK;
+      }
+    }
+    if( rc!=SQLITE_OK ){
+      *ppPage = 0;
+      return rc;
+    }
+  }
+  return getPageNormal(pPager, pgno, ppPage, flags);
+}
+#endif /* SQLITE_MAX_MMAP_SIZE>0 */
+
+/* The page getter method for when the pager is an error state */
+static int getPageError(
+  Pager *pPager,      /* The pager open on the database file */
+  Pgno pgno,          /* Page number to fetch */
+  DbPage **ppPage,    /* Write a pointer to the page here */
+  int flags           /* PAGER_GET_XXX flags */
+){
+  UNUSED_PARAMETER(pgno);
+  UNUSED_PARAMETER(flags);
+  assert( pPager->errCode!=SQLITE_OK );
+  *ppPage = 0;
+  return pPager->errCode;
+}
+
+
+/* Dispatch all page fetch requests to the appropriate getter method.
+*/
+int sqlite3PagerGet(
+  Pager *pPager,      /* The pager open on the database file */
+  Pgno pgno,          /* Page number to fetch */
+  DbPage **ppPage,    /* Write a pointer to the page here */
+  int flags           /* PAGER_GET_XXX flags */
+){
+  return pPager->xGet(pPager, pgno, ppPage, flags);
+}
+
 /*
 ** Acquire a page if it is already in the in-memory cache.  Do
 ** not read the page from disk.  Return a pointer to the page,
 ** or 0 if the page is not in cache. 
 **
 ** See also sqlite3PagerGet().  The difference between this routine
 ** and sqlite3PagerGet() is that _get() will go to the disk and read
 ** in the page if the page is not already in cache.  This routine
 ** returns NULL if the page is not in cache or if a disk I/O error 
 ** has ever happened.
@@ skipping 63 matching lines @@
   assert( pPager->pInJournal==0 );
   
   /* If already in the error state, this function is a no-op.  But on
   ** the other hand, this routine is never called if we are already in
   ** an error state. */
   if( NEVER(pPager->errCode) ) return pPager->errCode;
 
   if( !pagerUseWal(pPager) && pPager->journalMode!=PAGER_JOURNALMODE_OFF ){
     pPager->pInJournal = sqlite3BitvecCreate(pPager->dbSize);
     if( pPager->pInJournal==0 ){
-      return SQLITE_NOMEM;
+      return SQLITE_NOMEM_BKPT;
     }
   
     /* Open the journal file if it is not already open. */
     if( !isOpen(pPager->jfd) ){
       if( pPager->journalMode==PAGER_JOURNALMODE_MEMORY ){
         sqlite3MemJournalOpen(pPager->jfd);
       }else{
-        const int flags =                   /* VFS flags to open journal file */
-          SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|
-          (pPager->tempFile ? 
-            (SQLITE_OPEN_DELETEONCLOSE|SQLITE_OPEN_TEMP_JOURNAL):
-            (SQLITE_OPEN_MAIN_JOURNAL)
-          );
+        int flags = SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE;
+        int nSpill;
 
+        if( pPager->tempFile ){
+          flags |= (SQLITE_OPEN_DELETEONCLOSE|SQLITE_OPEN_TEMP_JOURNAL);
+          nSpill = sqlite3Config.nStmtSpill;
+        }else{
+          flags |= SQLITE_OPEN_MAIN_JOURNAL;
+          nSpill = jrnlBufferSize(pPager);
+        }
+          
         /* Verify that the database still has the same name as it did when
         ** it was originally opened. */
         rc = databaseIsUnmoved(pPager);
         if( rc==SQLITE_OK ){
-#ifdef SQLITE_ENABLE_ATOMIC_WRITE
-          rc = sqlite3JournalOpen(
-              pVfs, pPager->zJournal, pPager->jfd, flags, jrnlBufferSize(pPager)
+          rc = sqlite3JournalOpen (
+              pVfs, pPager->zJournal, pPager->jfd, flags, nSpill
           );
-#else
-          rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, flags, 0);
-#endif
         }
       }
       assert( rc!=SQLITE_OK || isOpen(pPager->jfd) );
     }
   
   
     /* Write the first journal header to the journal file and open 
     ** the sub-journal if necessary.
     */
     if( rc==SQLITE_OK ){
@@ skipping 109 matching lines @@
   u32 cksum;
   char *pData2;
   i64 iOff = pPager->journalOff;
 
   /* We should never write to the journal file the page that
   ** contains the database locks.  The following assert verifies
   ** that we do not. */
   assert( pPg->pgno!=PAGER_MJ_PGNO(pPager) );
 
   assert( pPager->journalHdr<=pPager->journalOff );
-  CODEC2(pPager, pPg->pData, pPg->pgno, 7, return SQLITE_NOMEM, pData2);
+  CODEC2(pPager, pPg->pData, pPg->pgno, 7, return SQLITE_NOMEM_BKPT, pData2);
   cksum = pager_cksum(pPager, (u8*)pData2);
 
   /* Even if an IO or diskfull error occurs while journalling the
   ** page in the block above, set the need-sync flag for the page.
   ** Otherwise, when the transaction is rolled back, the logic in
   ** playback_one_page() will think that the page needs to be restored
   ** in the database file. And if an IO error occurs while doing so,
   ** then corruption may follow.
   */
   pPg->flags |= PGHDR_NEED_SYNC;
@@ skipping 214 matching lines @@
 ** must have been written to the journal file before returning.
 **
 ** If an error occurs, SQLITE_NOMEM or an IO error code is returned
 ** as appropriate. Otherwise, SQLITE_OK.
 */
 int sqlite3PagerWrite(PgHdr *pPg){
   Pager *pPager = pPg->pPager;
   assert( (pPg->flags & PGHDR_MMAP)==0 );
   assert( pPager->eState>=PAGER_WRITER_LOCKED );
   assert( assert_pager_state(pPager) );
-  if( pPager->errCode ){
-    return pPager->errCode;
-  }else if( (pPg->flags & PGHDR_WRITEABLE)!=0 && pPager->dbSize>=pPg->pgno ){
+  if( (pPg->flags & PGHDR_WRITEABLE)!=0 && pPager->dbSize>=pPg->pgno ){
     if( pPager->nSavepoint ) return subjournalPageIfRequired(pPg);
     return SQLITE_OK;
+  }else if( pPager->errCode ){
+    return pPager->errCode;
   }else if( pPager->sectorSize > (u32)pPager->pageSize ){
+    assert( pPager->tempFile==0 );
     return pagerWriteLargeSector(pPg);
   }else{
     return pager_write(pPg);
   }
 }
 
 /*
 ** Return TRUE if the page given in the argument was previously passed
 ** to sqlite3PagerWrite().  In other words, return TRUE if it is ok
 ** to change the content of the page.
@@ skipping 10 matching lines @@
 ** that page might be marked as dirty.  This happens, for example, when
 ** the page has been added as a leaf of the freelist and so its
 ** content no longer matters.
 **
 ** The overlying software layer calls this routine when all of the data
 ** on the given page is unused. The pager marks the page as clean so
 ** that it does not get written to disk.
 **
 ** Tests show that this optimization can quadruple the speed of large 
 ** DELETE operations.
+**
+** This optimization cannot be used with a temp-file, as the page may
+** have been dirty at the start of the transaction. In that case, if
+** memory pressure forces page pPg out of the cache, the data does need 
+** to be written out to disk so that it may be read back in if the 
+** current transaction is rolled back.
 */
 void sqlite3PagerDontWrite(PgHdr *pPg){
   Pager *pPager = pPg->pPager;
-  if( (pPg->flags&PGHDR_DIRTY) && pPager->nSavepoint==0 ){
+  if( !pPager->tempFile && (pPg->flags&PGHDR_DIRTY) && pPager->nSavepoint==0 ){
     PAGERTRACE(("DONT_WRITE page %d of %d\n", pPg->pgno, PAGERID(pPager)));
     IOTRACE(("CLEAN %p %d\n", pPager, pPg->pgno))
     pPg->flags |= PGHDR_DONT_WRITE;
     pPg->flags &= ~PGHDR_WRITEABLE;
+    testcase( pPg->flags & PGHDR_NEED_SYNC );
     pager_set_pagehash(pPg);
   }
 }
 
 /*
 ** This routine is called to increment the value of the database file 
 ** change-counter, stored as a 4-byte big-endian integer starting at 
 ** byte offset 24 of the pager file.  The secondary change counter at
 ** 92 is also updated, as is the SQLite version number at offset 96.
 **
@@ skipping 58 matching lines @@
     }
 
     if( rc==SQLITE_OK ){
       /* Actually do the update of the change counter */
       pager_write_changecounter(pPgHdr);
 
       /* If running in direct mode, write the contents of page 1 to the file. */
       if( DIRECT_MODE ){
         const void *zBuf;
         assert( pPager->dbFileSize>0 );
-        CODEC2(pPager, pPgHdr->pData, 1, 6, rc=SQLITE_NOMEM, zBuf);
+        CODEC2(pPager, pPgHdr->pData, 1, 6, rc=SQLITE_NOMEM_BKPT, zBuf);
         if( rc==SQLITE_OK ){
           rc = sqlite3OsWrite(pPager->fd, zBuf, pPager->pageSize, 0);
           pPager->aStat[PAGER_STAT_WRITE]++;
         }
         if( rc==SQLITE_OK ){
           /* Update the pager's copy of the change-counter. Otherwise, the
           ** next time a read transaction is opened the cache will be
           ** flushed (as the change-counter values will not match).  */
           const void *pCopy = (const void *)&((const char *)zBuf)[24];
           memcpy(&pPager->dbFileVers, pCopy, sizeof(pPager->dbFileVers));
@@ skipping 95 matching lines @@
   assert( pPager->eState==PAGER_WRITER_LOCKED
        || pPager->eState==PAGER_WRITER_CACHEMOD
        || pPager->eState==PAGER_WRITER_DBMOD
        || pPager->eState==PAGER_ERROR
   );
   assert( assert_pager_state(pPager) );
 
   /* If a prior error occurred, report that error again. */
   if( NEVER(pPager->errCode) ) return pPager->errCode;
 
+  /* Provide the ability to easily simulate an I/O error during testing */
+  if( sqlite3FaultSim(400) ) return SQLITE_IOERR;
+
   PAGERTRACE(("DATABASE SYNC: File=%s zMaster=%s nSize=%d\n", 
       pPager->zFilename, zMaster, pPager->dbSize));
 
   /* If no database changes have been made, return early. */
   if( pPager->eState<PAGER_WRITER_CACHEMOD ) return SQLITE_OK;
 
-  if( MEMDB ){
+  assert( MEMDB==0 || pPager->tempFile );
+  assert( isOpen(pPager->fd) || pPager->tempFile );
+  if( 0==pagerFlushOnCommit(pPager, 1) ){
     /* If this is an in-memory db, or no pages have been written to, or this
     ** function has already been called, it is mostly a no-op.  However, any
-    ** backup in progress needs to be restarted.
-    */
+    ** backup in progress needs to be restarted.  */
     sqlite3BackupRestart(pPager->pBackup);
   }else{
     if( pagerUseWal(pPager) ){
       PgHdr *pList = sqlite3PcacheDirtyList(pPager->pPCache);
       PgHdr *pPageOne = 0;
       if( pList==0 ){
         /* Must have at least one page for the WAL commit flag.
         ** Ticket [2d1a5c67dfc2363e44f29d9bbd57f] 2011-05-18 */
         rc = sqlite3PagerGet(pPager, 1, &pPageOne, 0);
         pList = pPageOne;
@@ skipping 218 matching lines @@
   }else if( !isOpen(pPager->jfd) || pPager->eState==PAGER_WRITER_LOCKED ){
     int eState = pPager->eState;
     rc = pager_end_transaction(pPager, 0, 0);
     if( !MEMDB && eState>PAGER_WRITER_LOCKED ){
       /* This can happen using journal_mode=off. Move the pager to the error 
       ** state to indicate that the contents of the cache may not be trusted.
       ** Any active readers will get SQLITE_ABORT.
       */
       pPager->errCode = SQLITE_ABORT;
       pPager->eState = PAGER_ERROR;
+      setGetterMethod(pPager);
       return rc;
     }
   }else{
     rc = pager_playback(pPager, 0);
   }
 
   assert( pPager->eState==PAGER_READER || rc!=SQLITE_OK );
   assert( rc==SQLITE_OK || rc==SQLITE_FULL || rc==SQLITE_CORRUPT
           || rc==SQLITE_NOMEM || (rc&0xFF)==SQLITE_IOERR 
           || rc==SQLITE_CANTOPEN
@@ skipping 80 matching lines @@
   assert( SQLITE_DBSTATUS_CACHE_HIT+2==SQLITE_DBSTATUS_CACHE_WRITE );
   assert( PAGER_STAT_HIT==0 && PAGER_STAT_MISS==1 && PAGER_STAT_WRITE==2 );
 
   *pnVal += pPager->aStat[eStat - SQLITE_DBSTATUS_CACHE_HIT];
   if( reset ){
     pPager->aStat[eStat - SQLITE_DBSTATUS_CACHE_HIT] = 0;
   }
 }
 
 /*
-** Return true if this is an in-memory pager.
+** Return true if this is an in-memory or temp-file backed pager.
 */
 int sqlite3PagerIsMemdb(Pager *pPager){
-  return MEMDB;
+  return pPager->tempFile;
 }
 
 /*
 ** Check that there are at least nSavepoint savepoints open. If there are
 ** currently less than nSavepoints open, then open one or more savepoints
 ** to make up the difference. If the number of savepoints is already
 ** equal to nSavepoint, then this function is a no-op.
 **
 ** If a memory allocation fails, SQLITE_NOMEM is returned. If an error 
 ** occurs while opening the sub-journal file, then an IO error code is
@@ skipping 10 matching lines @@
   assert( nSavepoint>nCurrent && pPager->useJournal );
 
   /* Grow the Pager.aSavepoint array using realloc(). Return SQLITE_NOMEM
   ** if the allocation fails. Otherwise, zero the new portion in case a 
   ** malloc failure occurs while populating it in the for(...) loop below.
   */
   aNew = (PagerSavepoint *)sqlite3Realloc(
       pPager->aSavepoint, sizeof(PagerSavepoint)*nSavepoint
   );
   if( !aNew ){
-    return SQLITE_NOMEM;
+    return SQLITE_NOMEM_BKPT;
   }
   memset(&aNew[nCurrent], 0, (nSavepoint-nCurrent) * sizeof(PagerSavepoint));
   pPager->aSavepoint = aNew;
 
   /* Populate the PagerSavepoint structures just allocated. */
   for(ii=nCurrent; ii<nSavepoint; ii++){
     aNew[ii].nOrig = pPager->dbSize;
     if( isOpen(pPager->jfd) && pPager->journalOff>0 ){
       aNew[ii].iOffset = pPager->journalOff;
     }else{
       aNew[ii].iOffset = JOURNAL_HDR_SZ(pPager);
     }
     aNew[ii].iSubRec = pPager->nSubRec;
     aNew[ii].pInSavepoint = sqlite3BitvecCreate(pPager->dbSize);
     if( !aNew[ii].pInSavepoint ){
-      return SQLITE_NOMEM;
+      return SQLITE_NOMEM_BKPT;
     }
     if( pagerUseWal(pPager) ){
       sqlite3WalSavepoint(pPager->pWal, aNew[ii].aWalData);
     }
     pPager->nSavepoint = ii+1;
   }
   assert( pPager->nSavepoint==nSavepoint );
   assertTruncateConstraint(pPager);
   return rc;
 }
@@ skipping 33 matching lines @@
 **
 ** In any case, all savepoints with an index greater than iSavepoint 
 ** are destroyed. If this is a release operation (op==SAVEPOINT_RELEASE),
 ** then savepoint iSavepoint is also destroyed.
 **
 ** This function may return SQLITE_NOMEM if a memory allocation fails,
 ** or an IO error code if an IO error occurs while rolling back a 
 ** savepoint. If no errors occur, SQLITE_OK is returned.
 */ 
 int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint){
-  int rc = pPager->errCode;       /* Return code */
+  int rc = pPager->errCode;
+  
+#ifdef SQLITE_ENABLE_ZIPVFS
+  if( op==SAVEPOINT_RELEASE ) rc = SQLITE_OK;
+#endif
 
   assert( op==SAVEPOINT_RELEASE || op==SAVEPOINT_ROLLBACK );
   assert( iSavepoint>=0 || op==SAVEPOINT_ROLLBACK );
 
   if( rc==SQLITE_OK && iSavepoint<pPager->nSavepoint ){
     int ii;            /* Iterator variable */
     int nNew;          /* Number of remaining savepoints after this op. */
 
     /* Figure out how many savepoints will still be active after this
     ** operation. Store this value in nNew. Then free resources associated 
     ** with any savepoints that are destroyed by this operation.
     */
     nNew = iSavepoint + (( op==SAVEPOINT_RELEASE ) ? 0 : 1);
     for(ii=nNew; ii<pPager->nSavepoint; ii++){
       sqlite3BitvecDestroy(pPager->aSavepoint[ii].pInSavepoint);
     }
     pPager->nSavepoint = nNew;
 
     /* If this is a release of the outermost savepoint, truncate 
     ** the sub-journal to zero bytes in size. */
     if( op==SAVEPOINT_RELEASE ){
       if( nNew==0 && isOpen(pPager->sjfd) ){
         /* Only truncate if it is an in-memory sub-journal. */
-        if( sqlite3IsMemJournal(pPager->sjfd) ){
+        if( sqlite3JournalIsInMemory(pPager->sjfd) ){
           rc = sqlite3OsTruncate(pPager->sjfd, 0);
           assert( rc==SQLITE_OK );
         }
         pPager->nSubRec = 0;
       }
     }
     /* Else this is a rollback operation, playback the specified savepoint.
     ** If this is a temp-file, it is possible that the journal file has
     ** not yet been opened. In this case there have been no changes to
     ** the database file, so the playback operation can be skipped.
     */
     else if( pagerUseWal(pPager) || isOpen(pPager->jfd) ){
       PagerSavepoint *pSavepoint = (nNew==0)?0:&pPager->aSavepoint[nNew-1];
       rc = pagerPlaybackSavepoint(pPager, pSavepoint);
       assert(rc!=SQLITE_DONE);
     }
+    
+#ifdef SQLITE_ENABLE_ZIPVFS
+    /* If the cache has been modified but the savepoint cannot be rolled 
+    ** back journal_mode=off, put the pager in the error state. This way,
+    ** if the VFS used by this pager includes ZipVFS, the entire transaction
+    ** can be rolled back at the ZipVFS level.  */
+    else if( 
+        pPager->journalMode==PAGER_JOURNALMODE_OFF 
+     && pPager->eState>=PAGER_WRITER_CACHEMOD
+    ){
+      pPager->errCode = SQLITE_ABORT;
+      pPager->eState = PAGER_ERROR;
+      setGetterMethod(pPager);
+    }
+#endif
   }
 
   return rc;
 }
 
 /*
 ** Return the full pathname of the database file.
 **
 ** Except, if the pager is in-memory only, then return an empty string if
 ** nullIfMemDb is true.  This routine is called with nullIfMemDb==1 when
@@ skipping 34 matching lines @@
 #endif
 }
 
 /*
 ** Return the full pathname of the journal file.
 */
 const char *sqlite3PagerJournalname(Pager *pPager){
   return pPager->zJournal;
 }
 
-/*
-** Return true if fsync() calls are disabled for this pager.  Return FALSE
-** if fsync()s are executed normally.
-*/
-int sqlite3PagerNosync(Pager *pPager){
-  return pPager->noSync;
-}
-
 #ifdef SQLITE_HAS_CODEC
 /*
 ** Set or retrieve the codec for this pager
 */
 void sqlite3PagerSetCodec(
   Pager *pPager,
   void *(*xCodec)(void*,void*,Pgno,int),
   void (*xCodecSizeChng)(void*,int,int),
   void (*xCodecFree)(void*),
   void *pCodec
 ){
   if( pPager->xCodecFree ) pPager->xCodecFree(pPager->pCodec);
   pPager->xCodec = pPager->memDb ? 0 : xCodec;
   pPager->xCodecSizeChng = xCodecSizeChng;
   pPager->xCodecFree = xCodecFree;
   pPager->pCodec = pCodec;
+  setGetterMethod(pPager);
   pagerReportSize(pPager);
 }
 void *sqlite3PagerGetCodec(Pager *pPager){
   return pPager->pCodec;
 }
 
 /*
 ** This function is called by the wal module when writing page content
 ** into the log file.
 **
@@ skipping 48 matching lines @@
 
   assert( pPg->nRef>0 );
   assert( pPager->eState==PAGER_WRITER_CACHEMOD
        || pPager->eState==PAGER_WRITER_DBMOD
   );
   assert( assert_pager_state(pPager) );
 
   /* In order to be able to rollback, an in-memory database must journal
   ** the page we are moving from.
   */
-  if( MEMDB ){
+  assert( pPager->tempFile || !MEMDB );
+  if( pPager->tempFile ){
     rc = sqlite3PagerWrite(pPg);
     if( rc ) return rc;
   }
 
   /* If the page being moved is dirty and has not been saved by the latest
   ** savepoint, then save the current contents of the page into the 
   ** sub-journal now. This is required to handle the following scenario:
   **
   **   BEGIN;
   **     <journal page X, then modify it in memory>
@@ skipping 36 matching lines @@
   /* If the cache contains a page with page-number pgno, remove it
   ** from its hash chain. Also, if the PGHDR_NEED_SYNC flag was set for 
   ** page pgno before the 'move' operation, it needs to be retained 
   ** for the page moved there.
   */
   pPg->flags &= ~PGHDR_NEED_SYNC;
   pPgOld = sqlite3PagerLookup(pPager, pgno);
   assert( !pPgOld || pPgOld->nRef==1 );
   if( pPgOld ){
     pPg->flags |= (pPgOld->flags&PGHDR_NEED_SYNC);
-    if( MEMDB ){
+    if( pPager->tempFile ){
       /* Do not discard pages from an in-memory database since we might
       ** need to rollback later.  Just move the page out of the way. */
       sqlite3PcacheMove(pPgOld, pPager->dbSize+1);
     }else{
       sqlite3PcacheDrop(pPgOld);
     }
   }
 
   origPgno = pPg->pgno;
   sqlite3PcacheMove(pPg, pgno);
   sqlite3PcacheMakeDirty(pPg);
 
   /* For an in-memory database, make sure the original page continues
   ** to exist, in case the transaction needs to roll back.  Use pPgOld
   ** as the original page since it has already been allocated.
   */
-  if( MEMDB ){
-    assert( pPgOld );
+  if( pPager->tempFile && pPgOld ){
     sqlite3PcacheMove(pPgOld, origPgno);
     sqlite3PagerUnrefNotNull(pPgOld);
   }
 
   if( needSyncPgno ){
     /* If needSyncPgno is non-zero, then the journal file needs to be 
     ** sync()ed before any data is written to database file page needSyncPgno.
     ** Currently, no such page exists in the page-cache and the 
     ** "is journaled" bitvec flag has been set. This needs to be remedied by
     ** loading the page into the pager-cache and setting the PGHDR_NEED_SYNC
@@ skipping 231 matching lines @@
 */
 sqlite3_backup **sqlite3PagerBackupPtr(Pager *pPager){
   return &pPager->pBackup;
 }
 
 #ifndef SQLITE_OMIT_VACUUM
 /*
 ** Unless this is an in-memory or temporary database, clear the pager cache.
 */
 void sqlite3PagerClearCache(Pager *pPager){
-  if( !MEMDB && pPager->tempFile==0 ) pager_reset(pPager);
+  assert( MEMDB==0 || pPager->tempFile );
+  if( pPager->tempFile==0 ) pager_reset(pPager);
 }
 #endif
 
+
 #ifndef SQLITE_OMIT_WAL
 /*
 ** This function is called when the user invokes "PRAGMA wal_checkpoint",
 ** "PRAGMA wal_blocking_checkpoint" or calls the sqlite3_wal_checkpoint()
 ** or wal_blocking_checkpoint() API functions.
 **
 ** Parameter eMode is one of SQLITE_CHECKPOINT_PASSIVE, FULL or RESTART.
 */
-int sqlite3PagerCheckpoint(Pager *pPager, int eMode, int *pnLog, int *pnCkpt){
+int sqlite3PagerCheckpoint(
+  Pager *pPager,                  /* Checkpoint on this pager */
+  sqlite3 *db,                    /* Db handle used to check for interrupts */
+  int eMode,                      /* Type of checkpoint */
+  int *pnLog,                     /* OUT: Final number of frames in log */
+  int *pnCkpt                     /* OUT: Final number of checkpointed frames */
+){
   int rc = SQLITE_OK;
   if( pPager->pWal ){
-    rc = sqlite3WalCheckpoint(pPager->pWal, eMode,
+    rc = sqlite3WalCheckpoint(pPager->pWal, db, eMode,
         (eMode==SQLITE_CHECKPOINT_PASSIVE ? 0 : pPager->xBusyHandler),
         pPager->pBusyHandlerArg,
         pPager->ckptSyncFlags, pPager->pageSize, (u8 *)pPager->pTmpSpace,
         pnLog, pnCkpt
     );
   }
   return rc;
 }
 
 int sqlite3PagerWalCallback(Pager *pPager){
   return sqlite3WalCallback(pPager->pWal);
 }
 
 /*
 ** Return true if the underlying VFS for the given pager supports the
 ** primitives necessary for write-ahead logging.
 */
 int sqlite3PagerWalSupported(Pager *pPager){
   const sqlite3_io_methods *pMethods = pPager->fd->pMethods;
+  if( pPager->noLock ) return 0;
   return pPager->exclusiveMode || (pMethods->iVersion>=2 && pMethods->xShmMap);
 }
 
 /*
 ** Attempt to take an exclusive lock on the database file. If a PENDING lock
 ** is obtained instead, immediately release it.
 */
 static int pagerExclusiveLock(Pager *pPager){
   int rc;                         /* Return code */
 
@@ skipping 91 matching lines @@
 
 /*
 ** This function is called to close the connection to the log file prior
 ** to switching from WAL to rollback mode.
 **
 ** Before closing the log file, this function attempts to take an 
 ** EXCLUSIVE lock on the database file. If this cannot be obtained, an
 ** error (SQLITE_BUSY) is returned and the log connection is not closed.
 ** If successful, the EXCLUSIVE lock is not released before returning.
 */
-int sqlite3PagerCloseWal(Pager *pPager){
+int sqlite3PagerCloseWal(Pager *pPager, sqlite3 *db){
   int rc = SQLITE_OK;
 
   assert( pPager->journalMode==PAGER_JOURNALMODE_WAL );
 
   /* If the log file is not already open, but does exist in the file-system,
   ** it may need to be checkpointed before the connection can switch to
   ** rollback mode. Open it now so this can happen.
   */
   if( !pPager->pWal ){
     int logexists = 0;
     rc = pagerLockDb(pPager, SHARED_LOCK);
     if( rc==SQLITE_OK ){
       rc = sqlite3OsAccess(
           pPager->pVfs, pPager->zWal, SQLITE_ACCESS_EXISTS, &logexists
       );
     }
     if( rc==SQLITE_OK && logexists ){
       rc = pagerOpenWal(pPager);
     }
   }
     
   /* Checkpoint and close the log. Because an EXCLUSIVE lock is held on
   ** the database file, the log and log-summary files will be deleted.
   */
   if( rc==SQLITE_OK && pPager->pWal ){
     rc = pagerExclusiveLock(pPager);
     if( rc==SQLITE_OK ){
-      rc = sqlite3WalClose(pPager->pWal, pPager->ckptSyncFlags,
+      rc = sqlite3WalClose(pPager->pWal, db, pPager->ckptSyncFlags,
                            pPager->pageSize, (u8*)pPager->pTmpSpace);
       pPager->pWal = 0;
       pagerFixMaplimit(pPager);
+      if( rc && !pPager->exclusiveMode ) pagerUnlockDb(pPager, SHARED_LOCK);
     }
   }
   return rc;
 }
 
 #ifdef SQLITE_ENABLE_SNAPSHOT
 /*
 ** If this is a WAL database, obtain a snapshot handle for the snapshot
 ** currently open. Otherwise, return an error.
 */
@@ skipping 12 matching lines @@
 */
 int sqlite3PagerSnapshotOpen(Pager *pPager, sqlite3_snapshot *pSnapshot){
   int rc = SQLITE_OK;
   if( pPager->pWal ){
     sqlite3WalSnapshotOpen(pPager->pWal, pSnapshot);
   }else{
     rc = SQLITE_ERROR;
   }
   return rc;
 }
+
+/*
+** If this is a WAL database, call sqlite3WalSnapshotRecover(). If this 
+** is not a WAL database, return an error.
+*/
+int sqlite3PagerSnapshotRecover(Pager *pPager){
+  int rc;
+  if( pPager->pWal ){
+    rc = sqlite3WalSnapshotRecover(pPager->pWal);
+  }else{
+    rc = SQLITE_ERROR;
+  }
+  return rc;
+}
 #endif /* SQLITE_ENABLE_SNAPSHOT */
 #endif /* !SQLITE_OMIT_WAL */
 
 #ifdef SQLITE_ENABLE_ZIPVFS
 /*
 ** A read-lock must be held on the pager when this function is called. If
 ** the pager is in WAL mode and the WAL file currently contains one or more
 ** frames, return the size in bytes of the page images stored within the
 ** WAL frames. Otherwise, if this is not a WAL database or the WAL file
 ** is empty, return 0.
 */
 int sqlite3PagerWalFramesize(Pager *pPager){
   assert( pPager->eState>=PAGER_READER );
   return sqlite3WalFramesize(pPager->pWal);
 }
 #endif
 
-
 #endif /* SQLITE_OMIT_DISKIO */