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Overview
Comment:Always check for cell overflow before returning a slot from the pageFindSlot routine in btree.c.
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SHA1: 9f035c45a4b84203e67b6e1b23cf11691dc43f1e
User & Date: drh 2015-06-02 19:36:29.792
Context
2015-06-04
12:08
Change the name of SrcList.a[].zIndex to the more descriptive SrcList.a[0].zIndexedBy. (check-in: 6a9cf06337 user: drh tags: trunk)
2015-06-02
19:36
Always check for cell overflow before returning a slot from the pageFindSlot routine in btree.c. (check-in: 9f035c45a4 user: drh tags: trunk)
18:09
For FROM-clause subqueries that cannot be flattened, try to push relevant WHERE clause terms of the outer query down into the subquery in order to help the subquery run faster and/or use less memory. Call this the "WHERE-clause push-down optimization". Do not confuse this with the completely different MySQL push-down optimization. (check-in: 6df18e949d user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/btree.c.
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    ** freeblock form a big-endian integer which is the size of the freeblock
    ** in bytes, including the 4-byte header. */
    size = get2byte(&aData[pc+2]);
    if( size>=nByte ){
      int x = size - nByte;
      testcase( x==4 );
      testcase( x==3 );



      if( x<4 ){
        /* EVIDENCE-OF: R-11498-58022 In a well-formed b-tree page, the total
        ** number of bytes in fragments may not exceed 60. */
        if( aData[hdr+7]>=60 ){
          if( pbDefrag ) *pbDefrag = 1;
          return 0;
        }
        /* Remove the slot from the free-list. Update the number of
        ** fragmented bytes within the page. */
        memcpy(&aData[iAddr], &aData[pc], 2);
        aData[hdr+7] += (u8)x;
      }else if( pc < pPg->cellOffset+2*pPg->nCell || size+pc > usableSize ){
        *pRc = SQLITE_CORRUPT_BKPT;
        return 0;
      }else{
        /* The slot remains on the free-list. Reduce its size to account
         ** for the portion used by the new allocation. */
        put2byte(&aData[pc+2], x);
      }
      return &aData[pc + x];
    }








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    ** freeblock form a big-endian integer which is the size of the freeblock
    ** in bytes, including the 4-byte header. */
    size = get2byte(&aData[pc+2]);
    if( size>=nByte ){
      int x = size - nByte;
      testcase( x==4 );
      testcase( x==3 );
      if( pc < pPg->cellOffset+2*pPg->nCell || size+pc > usableSize ){
        *pRc = SQLITE_CORRUPT_BKPT;
        return 0;
      }else if( x<4 ){
        /* EVIDENCE-OF: R-11498-58022 In a well-formed b-tree page, the total
        ** number of bytes in fragments may not exceed 60. */
        if( aData[hdr+7]>=60 ){
          if( pbDefrag ) *pbDefrag = 1;
          return 0;
        }
        /* Remove the slot from the free-list. Update the number of
        ** fragmented bytes within the page. */
        memcpy(&aData[iAddr], &aData[pc], 2);
        aData[hdr+7] += (u8)x;



      }else{
        /* The slot remains on the free-list. Reduce its size to account
         ** for the portion used by the new allocation. */
        put2byte(&aData[pc+2], x);
      }
      return &aData[pc + x];
    }
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Changes to test/fuzzdata3.db.

cannot compute difference between binary files