Import SQLite 3.8.7.4.

third_party/sqlite/src/src/backup.c

 /*
 ** 2009 January 28
 **
 ** 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.
 **
 *************************************************************************
 ** This file contains the implementation of the sqlite3_backup_XXX() 
 ** API functions and the related features.
 */
 #include "sqliteInt.h"
 #include "btreeInt.h"
 
-/* Macro to find the minimum of two numeric values.
-*/
-#ifndef MIN
-# define MIN(x,y) ((x)<(y)?(x):(y))
-#endif
-
 /*
 ** Structure allocated for each backup operation.
 */
 struct sqlite3_backup {
   sqlite3* pDestDb;        /* Destination database handle */
   Btree *pDest;            /* Destination b-tree file */
   u32 iDestSchema;         /* Original schema cookie in destination */
   int bDestLocked;         /* True once a write-transaction is open on pDest */
 
   Pgno iNext;              /* Page number of the next source page to copy */
@@ skipping 52 matching lines @@
 ** error message to pErrorDb.
 */
 static Btree *findBtree(sqlite3 *pErrorDb, sqlite3 *pDb, const char *zDb){
   int i = sqlite3FindDbName(pDb, zDb);
 
   if( i==1 ){
     Parse *pParse;
     int rc = 0;
     pParse = sqlite3StackAllocZero(pErrorDb, sizeof(*pParse));
     if( pParse==0 ){
-      sqlite3Error(pErrorDb, SQLITE_NOMEM, "out of memory");
+      sqlite3ErrorWithMsg(pErrorDb, SQLITE_NOMEM, "out of memory");
       rc = SQLITE_NOMEM;
     }else{
       pParse->db = pDb;
       if( sqlite3OpenTempDatabase(pParse) ){
-        sqlite3Error(pErrorDb, pParse->rc, "%s", pParse->zErrMsg);
+        sqlite3ErrorWithMsg(pErrorDb, pParse->rc, "%s", pParse->zErrMsg);
         rc = SQLITE_ERROR;
       }
       sqlite3DbFree(pErrorDb, pParse->zErrMsg);
+      sqlite3ParserReset(pParse);
       sqlite3StackFree(pErrorDb, pParse);
     }
     if( rc ){
       return 0;
     }
   }
 
   if( i<0 ){
-    sqlite3Error(pErrorDb, SQLITE_ERROR, "unknown database %s", zDb);
+    sqlite3ErrorWithMsg(pErrorDb, SQLITE_ERROR, "unknown database %s", zDb);
     return 0;
   }
 
   return pDb->aDb[i].pBt;
 }
 
 /*
 ** Attempt to set the page size of the destination to match the page size
 ** of the source.
 */
@@ skipping 24 matching lines @@
   ** sqlite3_backup_step(). The user is required to ensure that no
   ** other thread accesses the destination handle for the duration
   ** of the backup operation.  Any attempt to use the destination
   ** database connection while a backup is in progress may cause
   ** a malfunction or a deadlock.
   */
   sqlite3_mutex_enter(pSrcDb->mutex);
   sqlite3_mutex_enter(pDestDb->mutex);
 
   if( pSrcDb==pDestDb ){
-    sqlite3Error(
+    sqlite3ErrorWithMsg(
         pDestDb, SQLITE_ERROR, "source and destination must be distinct"
     );
     p = 0;
   }else {
     /* Allocate space for a new sqlite3_backup object...
     ** EVIDENCE-OF: R-64852-21591 The sqlite3_backup object is created by a
     ** call to sqlite3_backup_init() and is destroyed by a call to
     ** sqlite3_backup_finish(). */
-    p = (sqlite3_backup *)sqlite3_malloc(sizeof(sqlite3_backup));
+    p = (sqlite3_backup *)sqlite3MallocZero(sizeof(sqlite3_backup));
     if( !p ){
-      sqlite3Error(pDestDb, SQLITE_NOMEM, 0);
+      sqlite3Error(pDestDb, SQLITE_NOMEM);
     }
   }
 
   /* If the allocation succeeded, populate the new object. */
   if( p ){
-    memset(p, 0, sizeof(sqlite3_backup));
     p->pSrc = findBtree(pDestDb, pSrcDb, zSrcDb);
     p->pDest = findBtree(pDestDb, pDestDb, zDestDb);
     p->pDestDb = pDestDb;
     p->pSrcDb = pSrcDb;
     p->iNext = 1;
     p->isAttached = 0;
 
     if( 0==p->pSrc || 0==p->pDest || setDestPgsz(p)==SQLITE_NOMEM ){
       /* One (or both) of the named databases did not exist or an OOM
       ** error was hit.  The error has already been written into the
@@ skipping 20 matching lines @@
 */
 static int isFatalError(int rc){
   return (rc!=SQLITE_OK && rc!=SQLITE_BUSY && ALWAYS(rc!=SQLITE_LOCKED));
 }
 
 /*
 ** Parameter zSrcData points to a buffer containing the data for 
 ** page iSrcPg from the source database. Copy this data into the 
 ** destination database.
 */
-static int backupOnePage(sqlite3_backup *p, Pgno iSrcPg, const u8 *zSrcData){
+static int backupOnePage(
+  sqlite3_backup *p,              /* Backup handle */
+  Pgno iSrcPg,                    /* Source database page to backup */
+  const u8 *zSrcData,             /* Source database page data */
+  int bUpdate                     /* True for an update, false otherwise */
+){
   Pager * const pDestPager = sqlite3BtreePager(p->pDest);
   const int nSrcPgsz = sqlite3BtreeGetPageSize(p->pSrc);
   int nDestPgsz = sqlite3BtreeGetPageSize(p->pDest);
   const int nCopy = MIN(nSrcPgsz, nDestPgsz);
   const i64 iEnd = (i64)iSrcPg*(i64)nSrcPgsz;
 #ifdef SQLITE_HAS_CODEC
-  int nSrcReserve = sqlite3BtreeGetReserve(p->pSrc);
+  /* Use BtreeGetReserveNoMutex() for the source b-tree, as although it is
+  ** guaranteed that the shared-mutex is held by this thread, handle
+  ** p->pSrc may not actually be the owner.  */
+  int nSrcReserve = sqlite3BtreeGetReserveNoMutex(p->pSrc);
   int nDestReserve = sqlite3BtreeGetReserve(p->pDest);
 #endif
-
   int rc = SQLITE_OK;
   i64 iOff;
 
+  assert( sqlite3BtreeGetReserveNoMutex(p->pSrc)>=0 );
   assert( p->bDestLocked );
   assert( !isFatalError(p->rc) );
   assert( iSrcPg!=PENDING_BYTE_PAGE(p->pSrc->pBt) );
   assert( zSrcData );
 
   /* Catch the case where the destination is an in-memory database and the
   ** page sizes of the source and destination differ. 
   */
   if( nSrcPgsz!=nDestPgsz && sqlite3PagerIsMemdb(pDestPager) ){
     rc = SQLITE_READONLY;
@@ skipping 36 matching lines @@
 
       /* Copy the data from the source page into the destination page.
       ** Then clear the Btree layer MemPage.isInit flag. Both this module
       ** and the pager code use this trick (clearing the first byte
       ** of the page 'extra' space to invalidate the Btree layers
       ** cached parse of the page). MemPage.isInit is marked 
       ** "MUST BE FIRST" for this purpose.
       */
       memcpy(zOut, zIn, nCopy);
       ((u8 *)sqlite3PagerGetExtra(pDestPg))[0] = 0;
+      if( iOff==0 && bUpdate==0 ){
+        sqlite3Put4byte(&zOut[28], sqlite3BtreeLastPage(p->pSrc));
+      }
     }
     sqlite3PagerUnref(pDestPg);
   }
 
   return rc;
 }
 
 /*
 ** If pFile is currently larger than iSize bytes, then truncate it to
 ** exactly iSize bytes. If pFile is not larger than iSize bytes, then
@@ skipping 84 matching lines @@
   
     /* Now that there is a read-lock on the source database, query the
     ** source pager for the number of pages in the database.
     */
     nSrcPage = (int)sqlite3BtreeLastPage(p->pSrc);
     assert( nSrcPage>=0 );
     for(ii=0; (nPage<0 || ii<nPage) && p->iNext<=(Pgno)nSrcPage && !rc; ii++){
       const Pgno iSrcPg = p->iNext;                 /* Source page number */
       if( iSrcPg!=PENDING_BYTE_PAGE(p->pSrc->pBt) ){
         DbPage *pSrcPg;                             /* Source page object */
-        rc = sqlite3PagerGet(pSrcPager, iSrcPg, &pSrcPg);
+        rc = sqlite3PagerAcquire(pSrcPager, iSrcPg, &pSrcPg,
+                                 PAGER_GET_READONLY);
         if( rc==SQLITE_OK ){
-          rc = backupOnePage(p, iSrcPg, sqlite3PagerGetData(pSrcPg));
+          rc = backupOnePage(p, iSrcPg, sqlite3PagerGetData(pSrcPg), 0);
           sqlite3PagerUnref(pSrcPg);
         }
       }
       p->iNext++;
     }
     if( rc==SQLITE_OK ){
       p->nPagecount = nSrcPage;
       p->nRemaining = nSrcPage+1-p->iNext;
       if( p->iNext>(Pgno)nSrcPage ){
         rc = SQLITE_DONE;
       }else if( !p->isAttached ){
         attachBackupObject(p);
       }
     }
   
     /* Update the schema version field in the destination database. This
     ** is to make sure that the schema-version really does change in
     ** the case where the source and destination databases have the
     ** same schema version.
     */
-    if( rc==SQLITE_DONE 
-     && (rc = sqlite3BtreeUpdateMeta(p->pDest,1,p->iDestSchema+1))==SQLITE_OK
-    ){
-      int nDestTruncate;
-  
-      if( p->pDestDb ){
-        sqlite3ResetInternalSchema(p->pDestDb, -1);
+    if( rc==SQLITE_DONE ){
+      if( nSrcPage==0 ){
+        rc = sqlite3BtreeNewDb(p->pDest);
+        nSrcPage = 1;
       }
+      if( rc==SQLITE_OK || rc==SQLITE_DONE ){
+        rc = sqlite3BtreeUpdateMeta(p->pDest,1,p->iDestSchema+1);
+      }
+      if( rc==SQLITE_OK ){
+        if( p->pDestDb ){
+          sqlite3ResetAllSchemasOfConnection(p->pDestDb);
+        }
+        if( destMode==PAGER_JOURNALMODE_WAL ){
+          rc = sqlite3BtreeSetVersion(p->pDest, 2);
+        }
+      }
+      if( rc==SQLITE_OK ){
+        int nDestTruncate;
+        /* Set nDestTruncate to the final number of pages in the destination
+        ** database. The complication here is that the destination page
+        ** size may be different to the source page size. 
+        **
+        ** If the source page size is smaller than the destination page size, 
+        ** round up. In this case the call to sqlite3OsTruncate() below will
+        ** fix the size of the file. However it is important to call
+        ** sqlite3PagerTruncateImage() here so that any pages in the 
+        ** destination file that lie beyond the nDestTruncate page mark are
+        ** journalled by PagerCommitPhaseOne() before they are destroyed
+        ** by the file truncation.
+        */
+        assert( pgszSrc==sqlite3BtreeGetPageSize(p->pSrc) );
+        assert( pgszDest==sqlite3BtreeGetPageSize(p->pDest) );
+        if( pgszSrc<pgszDest ){
+          int ratio = pgszDest/pgszSrc;
+          nDestTruncate = (nSrcPage+ratio-1)/ratio;
+          if( nDestTruncate==(int)PENDING_BYTE_PAGE(p->pDest->pBt) ){
+            nDestTruncate--;
+          }
+        }else{
+          nDestTruncate = nSrcPage * (pgszSrc/pgszDest);
+        }
+        assert( nDestTruncate>0 );
 
-      /* Set nDestTruncate to the final number of pages in the destination
-      ** database. The complication here is that the destination page
-      ** size may be different to the source page size. 
-      **
-      ** If the source page size is smaller than the destination page size, 
-      ** round up. In this case the call to sqlite3OsTruncate() below will
-      ** fix the size of the file. However it is important to call
-      ** sqlite3PagerTruncateImage() here so that any pages in the 
-      ** destination file that lie beyond the nDestTruncate page mark are
-      ** journalled by PagerCommitPhaseOne() before they are destroyed
-      ** by the file truncation.
-      */
-      assert( pgszSrc==sqlite3BtreeGetPageSize(p->pSrc) );
-      assert( pgszDest==sqlite3BtreeGetPageSize(p->pDest) );
-      if( pgszSrc<pgszDest ){
-        int ratio = pgszDest/pgszSrc;
-        nDestTruncate = (nSrcPage+ratio-1)/ratio;
-        if( nDestTruncate==(int)PENDING_BYTE_PAGE(p->pDest->pBt) ){
-          nDestTruncate--;
+        if( pgszSrc<pgszDest ){
+          /* If the source page-size is smaller than the destination page-size,
+          ** two extra things may need to happen:
+          **
+          **   * The destination may need to be truncated, and
+          **
+          **   * Data stored on the pages immediately following the 
+          **     pending-byte page in the source database may need to be
+          **     copied into the destination database.
+          */
+          const i64 iSize = (i64)pgszSrc * (i64)nSrcPage;
+          sqlite3_file * const pFile = sqlite3PagerFile(pDestPager);
+          Pgno iPg;
+          int nDstPage;
+          i64 iOff;
+          i64 iEnd;
+
+          assert( pFile );
+          assert( nDestTruncate==0 
+              || (i64)nDestTruncate*(i64)pgszDest >= iSize || (
+                nDestTruncate==(int)(PENDING_BYTE_PAGE(p->pDest->pBt)-1)
+             && iSize>=PENDING_BYTE && iSize<=PENDING_BYTE+pgszDest
+          ));
+
+          /* This block ensures that all data required to recreate the original
+          ** database has been stored in the journal for pDestPager and the
+          ** journal synced to disk. So at this point we may safely modify
+          ** the database file in any way, knowing that if a power failure
+          ** occurs, the original database will be reconstructed from the 
+          ** journal file.  */
+          sqlite3PagerPagecount(pDestPager, &nDstPage);
+          for(iPg=nDestTruncate; rc==SQLITE_OK && iPg<=(Pgno)nDstPage; iPg++){
+            if( iPg!=PENDING_BYTE_PAGE(p->pDest->pBt) ){
+              DbPage *pPg;
+              rc = sqlite3PagerGet(pDestPager, iPg, &pPg);
+              if( rc==SQLITE_OK ){
+                rc = sqlite3PagerWrite(pPg);
+                sqlite3PagerUnref(pPg);
+              }
+            }
+          }
+          if( rc==SQLITE_OK ){
+            rc = sqlite3PagerCommitPhaseOne(pDestPager, 0, 1);
+          }
+
+          /* Write the extra pages and truncate the database file as required */
+          iEnd = MIN(PENDING_BYTE + pgszDest, iSize);
+          for(
+            iOff=PENDING_BYTE+pgszSrc; 
+            rc==SQLITE_OK && iOff<iEnd; 
+            iOff+=pgszSrc
+          ){
+            PgHdr *pSrcPg = 0;
+            const Pgno iSrcPg = (Pgno)((iOff/pgszSrc)+1);
+            rc = sqlite3PagerGet(pSrcPager, iSrcPg, &pSrcPg);
+            if( rc==SQLITE_OK ){
+              u8 *zData = sqlite3PagerGetData(pSrcPg);
+              rc = sqlite3OsWrite(pFile, zData, pgszSrc, iOff);
+            }
+            sqlite3PagerUnref(pSrcPg);
+          }
+          if( rc==SQLITE_OK ){
+            rc = backupTruncateFile(pFile, iSize);
+          }
+
+          /* Sync the database file to disk. */
+          if( rc==SQLITE_OK ){
+            rc = sqlite3PagerSync(pDestPager, 0);
+          }
+        }else{
+          sqlite3PagerTruncateImage(pDestPager, nDestTruncate);
+          rc = sqlite3PagerCommitPhaseOne(pDestPager, 0, 0);
         }
-      }else{
-        nDestTruncate = nSrcPage * (pgszSrc/pgszDest);
-      }
-      sqlite3PagerTruncateImage(pDestPager, nDestTruncate);
-
-      if( pgszSrc<pgszDest ){
-        /* If the source page-size is smaller than the destination page-size,
-        ** two extra things may need to happen:
-        **
-        **   * The destination may need to be truncated, and
-        **
-        **   * Data stored on the pages immediately following the 
-        **     pending-byte page in the source database may need to be
-        **     copied into the destination database.
-        */
-        const i64 iSize = (i64)pgszSrc * (i64)nSrcPage;
-        sqlite3_file * const pFile = sqlite3PagerFile(pDestPager);
-        i64 iOff;
-        i64 iEnd;
-
-        assert( pFile );
-        assert( (i64)nDestTruncate*(i64)pgszDest >= iSize || (
-              nDestTruncate==(int)(PENDING_BYTE_PAGE(p->pDest->pBt)-1)
-           && iSize>=PENDING_BYTE && iSize<=PENDING_BYTE+pgszDest
-        ));
-
-        /* This call ensures that all data required to recreate the original
-        ** database has been stored in the journal for pDestPager and the
-        ** journal synced to disk. So at this point we may safely modify
-        ** the database file in any way, knowing that if a power failure
-        ** occurs, the original database will be reconstructed from the 
-        ** journal file.  */
-        rc = sqlite3PagerCommitPhaseOne(pDestPager, 0, 1);
-
-        /* Write the extra pages and truncate the database file as required. */
-        iEnd = MIN(PENDING_BYTE + pgszDest, iSize);
-        for(
-          iOff=PENDING_BYTE+pgszSrc; 
-          rc==SQLITE_OK && iOff<iEnd; 
-          iOff+=pgszSrc
+    
+        /* Finish committing the transaction to the destination database. */
+        if( SQLITE_OK==rc
+         && SQLITE_OK==(rc = sqlite3BtreeCommitPhaseTwo(p->pDest, 0))
         ){
-          PgHdr *pSrcPg = 0;
-          const Pgno iSrcPg = (Pgno)((iOff/pgszSrc)+1);
-          rc = sqlite3PagerGet(pSrcPager, iSrcPg, &pSrcPg);
-          if( rc==SQLITE_OK ){
-            u8 *zData = sqlite3PagerGetData(pSrcPg);
-            rc = sqlite3OsWrite(pFile, zData, pgszSrc, iOff);
-          }
-          sqlite3PagerUnref(pSrcPg);
+          rc = SQLITE_DONE;
         }
-        if( rc==SQLITE_OK ){
-          rc = backupTruncateFile(pFile, iSize);
-        }
-
-        /* Sync the database file to disk. */
-        if( rc==SQLITE_OK ){
-          rc = sqlite3PagerSync(pDestPager);
-        }
-      }else{
-        rc = sqlite3PagerCommitPhaseOne(pDestPager, 0, 0);
-      }
-  
-      /* Finish committing the transaction to the destination database. */
-      if( SQLITE_OK==rc
-       && SQLITE_OK==(rc = sqlite3BtreeCommitPhaseTwo(p->pDest, 0))
-      ){
-        rc = SQLITE_DONE;
       }
     }
   
     /* If bCloseTrans is true, then this function opened a read transaction
     ** on the source database. Close the read transaction here. There is
     ** no need to check the return values of the btree methods here, as
     ** "committing" a read-only transaction cannot fail.
     */
     if( bCloseTrans ){
       TESTONLY( int rc2 );
@@ skipping 13 matching lines @@
   sqlite3BtreeLeave(p->pSrc);
   sqlite3_mutex_leave(p->pSrcDb->mutex);
   return rc;
 }
 
 /*
 ** Release all resources associated with an sqlite3_backup* handle.
 */
 int sqlite3_backup_finish(sqlite3_backup *p){
   sqlite3_backup **pp;                 /* Ptr to head of pagers backup list */
-  sqlite3_mutex *mutex;                /* Mutex to protect source database */
+  sqlite3 *pSrcDb;                     /* Source database connection */
   int rc;                              /* Value to return */
 
   /* Enter the mutexes */
   if( p==0 ) return SQLITE_OK;
-  sqlite3_mutex_enter(p->pSrcDb->mutex);
+  pSrcDb = p->pSrcDb;
+  sqlite3_mutex_enter(pSrcDb->mutex);
   sqlite3BtreeEnter(p->pSrc);
-  mutex = p->pSrcDb->mutex;
   if( p->pDestDb ){
     sqlite3_mutex_enter(p->pDestDb->mutex);
   }
 
   /* Detach this backup from the source pager. */
   if( p->pDestDb ){
     p->pSrc->nBackup--;
   }
   if( p->isAttached ){
     pp = sqlite3PagerBackupPtr(sqlite3BtreePager(p->pSrc));
     while( *pp!=p ){
       pp = &(*pp)->pNext;
     }
     *pp = p->pNext;
   }
 
   /* If a transaction is still open on the Btree, roll it back. */
-  sqlite3BtreeRollback(p->pDest);
+  sqlite3BtreeRollback(p->pDest, SQLITE_OK, 0);
 
   /* Set the error code of the destination database handle. */
   rc = (p->rc==SQLITE_DONE) ? SQLITE_OK : p->rc;
-  sqlite3Error(p->pDestDb, rc, 0);
+  if( p->pDestDb ){
+    sqlite3Error(p->pDestDb, rc);
 
-  /* Exit the mutexes and free the backup context structure. */
-  if( p->pDestDb ){
-    sqlite3_mutex_leave(p->pDestDb->mutex);
+    /* Exit the mutexes and free the backup context structure. */
+    sqlite3LeaveMutexAndCloseZombie(p->pDestDb);
   }
   sqlite3BtreeLeave(p->pSrc);
   if( p->pDestDb ){
     /* EVIDENCE-OF: R-64852-21591 The sqlite3_backup object is created by a
     ** call to sqlite3_backup_init() and is destroyed by a call to
     ** sqlite3_backup_finish(). */
     sqlite3_free(p);
   }
-  sqlite3_mutex_leave(mutex);
+  sqlite3LeaveMutexAndCloseZombie(pSrcDb);
   return rc;
 }
 
 /*
 ** Return the number of pages still to be backed up as of the most recent
 ** call to sqlite3_backup_step().
 */
 int sqlite3_backup_remaining(sqlite3_backup *p){
   return p->nRemaining;
 }
@@ skipping 23 matching lines @@
   for(p=pBackup; p; p=p->pNext){
     assert( sqlite3_mutex_held(p->pSrc->pBt->mutex) );
     if( !isFatalError(p->rc) && iPage<p->iNext ){
       /* The backup process p has already copied page iPage. But now it
       ** has been modified by a transaction on the source pager. Copy
       ** the new data into the backup.
       */
       int rc;
       assert( p->pDestDb );
       sqlite3_mutex_enter(p->pDestDb->mutex);
-      rc = backupOnePage(p, iPage, aData);
+      rc = backupOnePage(p, iPage, aData, 1);
       sqlite3_mutex_leave(p->pDestDb->mutex);
       assert( rc!=SQLITE_BUSY && rc!=SQLITE_LOCKED );
       if( rc!=SQLITE_OK ){
         p->rc = rc;
       }
     }
   }
 }
 
 /*
@@ skipping 19 matching lines @@
 /*
 ** Copy the complete content of pBtFrom into pBtTo.  A transaction
 ** must be active for both files.
 **
 ** The size of file pTo may be reduced by this operation. If anything 
 ** goes wrong, the transaction on pTo is rolled back. If successful, the 
 ** transaction is committed before returning.
 */
 int sqlite3BtreeCopyFile(Btree *pTo, Btree *pFrom){
   int rc;
+  sqlite3_file *pFd;              /* File descriptor for database pTo */
   sqlite3_backup b;
   sqlite3BtreeEnter(pTo);
   sqlite3BtreeEnter(pFrom);
 
+  assert( sqlite3BtreeIsInTrans(pTo) );
+  pFd = sqlite3PagerFile(sqlite3BtreePager(pTo));
+  if( pFd->pMethods ){
+    i64 nByte = sqlite3BtreeGetPageSize(pFrom)*(i64)sqlite3BtreeLastPage(pFrom);
+    rc = sqlite3OsFileControl(pFd, SQLITE_FCNTL_OVERWRITE, &nByte);
+    if( rc==SQLITE_NOTFOUND ) rc = SQLITE_OK;
+    if( rc ) goto copy_finished;
+  }
+
   /* Set up an sqlite3_backup object. sqlite3_backup.pDestDb must be set
   ** to 0. This is used by the implementations of sqlite3_backup_step()
   ** and sqlite3_backup_finish() to detect that they are being called
   ** from this function, not directly by the user.
   */
   memset(&b, 0, sizeof(b));
   b.pSrcDb = pFrom->db;
   b.pSrc = pFrom;
   b.pDest = pTo;
   b.iNext = 1;
 
   /* 0x7FFFFFFF is the hard limit for the number of pages in a database
   ** file. By passing this as the number of pages to copy to
   ** sqlite3_backup_step(), we can guarantee that the copy finishes 
   ** within a single call (unless an error occurs). The assert() statement
   ** checks this assumption - (p->rc) should be set to either SQLITE_DONE 
   ** or an error code.
   */
   sqlite3_backup_step(&b, 0x7FFFFFFF);
   assert( b.rc!=SQLITE_OK );
   rc = sqlite3_backup_finish(&b);
   if( rc==SQLITE_OK ){
-    pTo->pBt->pageSizeFixed = 0;
+    pTo->pBt->btsFlags &= ~BTS_PAGESIZE_FIXED;
+  }else{
+    sqlite3PagerClearCache(sqlite3BtreePager(b.pDest));
   }
 
+  assert( sqlite3BtreeIsInTrans(pTo)==0 );
+copy_finished:
   sqlite3BtreeLeave(pFrom);
   sqlite3BtreeLeave(pTo);
   return rc;
 }
 #endif /* SQLITE_OMIT_VACUUM */