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Overview
Comment:Replace an assert() that a condition may not occur in backup.c with code to handle that condition, which can occur.
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SHA1: 472c74b3452c5a07dfb006010441232b09599ad5
User & Date: dan 2011-08-25 19:28:47
Context
2011-08-25
20:18
Reorder some of the branches in backup.c in order to make the code easier to test. check-in: 2c443d47 user: drh tags: trunk
19:28
Replace an assert() that a condition may not occur in backup.c with code to handle that condition, which can occur. check-in: 472c74b3 user: dan tags: trunk
18:54
Fix harmless compiler warnings in test code. No changes to the core. check-in: 16f83fec user: drh tags: trunk
Changes
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Changes to src/backup.c.

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    ** 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( destMode==PAGER_JOURNALMODE_WAL ){
        /* This call cannot fail. The success of the BtreeUpdateMeta() 
        ** method above indicates that a write transaction has been opened 
        ** and page 1 is already dirty. Therefore this always succeeds.
        */
        TESTONLY(int rc2 =) sqlite3BtreeSetVersion(p->pDest, 2);
        assert( rc2==SQLITE_OK );
      }



      /* 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);
      }
      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
        ){
          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);
        }
      }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.







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    ** 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
    ){


      if( p->pDestDb ){
        sqlite3ResetInternalSchema(p->pDestDb, -1);
      }

      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);
        }
        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
          ){
            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);
          }
        }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.