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Overview
Comment:Improved shadow table corruption detection in the matchinfo() function of FTS3.
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SHA3-256: 567be3bb1e8b6477f3bf1c7b4cd6ec066fba69d0dcf8785632e244ce25db639f
User & Date: drh 2019-01-12 00:12:33.531
Context
2019-01-12
00:45
Improved detection of shadow table corruption in the fts5_decode() SQL function. (check-in: b74e5f3f30 user: drh tags: trunk)
00:12
Improved shadow table corruption detection in the matchinfo() function of FTS3. (check-in: 567be3bb1e user: drh tags: trunk)
00:07
Indicate that the database may be corrupt in the fts3corrupt4.test test script. (check-in: 473626d557 user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to ext/fts3/fts3.c.
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** After allocating the Fts3Expr.aMI[] array for each phrase in the 
** expression rooted at pExpr, the cursor iterates through all rows matched
** by pExpr, calling this function for each row. This function increments
** the values in Fts3Expr.aMI[] according to the position-list currently
** found in Fts3Expr.pPhrase->doclist.pList for each of the phrase 
** expression nodes.
*/
static void fts3EvalUpdateCounts(Fts3Expr *pExpr){
  if( pExpr ){
    Fts3Phrase *pPhrase = pExpr->pPhrase;
    if( pPhrase && pPhrase->doclist.pList ){
      int iCol = 0;
      char *p = pPhrase->doclist.pList;

      assert( *p );
      while( 1 ){

        u8 c = 0;
        int iCnt = 0;
        while( 0xFE & (*p | c) ){
          if( (c&0x80)==0 ) iCnt++;
          c = *p++ & 0x80;
        }

        /* aMI[iCol*3 + 1] = Number of occurrences
        ** aMI[iCol*3 + 2] = Number of rows containing at least one instance
        */
        pExpr->aMI[iCol*3 + 1] += iCnt;
        pExpr->aMI[iCol*3 + 2] += (iCnt>0);
        if( *p==0x00 ) break;
        p++;
        p += fts3GetVarint32(p, &iCol);
      }
    }

    fts3EvalUpdateCounts(pExpr->pLeft);
    fts3EvalUpdateCounts(pExpr->pRight);
  }
}

/*
** Expression pExpr must be of type FTSQUERY_PHRASE.
**
** If it is not already allocated and populated, this function allocates and








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** After allocating the Fts3Expr.aMI[] array for each phrase in the 
** expression rooted at pExpr, the cursor iterates through all rows matched
** by pExpr, calling this function for each row. This function increments
** the values in Fts3Expr.aMI[] according to the position-list currently
** found in Fts3Expr.pPhrase->doclist.pList for each of the phrase 
** expression nodes.
*/
static void fts3EvalUpdateCounts(Fts3Expr *pExpr, int nCol){
  if( pExpr ){
    Fts3Phrase *pPhrase = pExpr->pPhrase;
    if( pPhrase && pPhrase->doclist.pList ){
      int iCol = 0;
      char *p = pPhrase->doclist.pList;

      assert( *p );

      do{
        u8 c = 0;
        int iCnt = 0;
        while( 0xFE & (*p | c) ){
          if( (c&0x80)==0 ) iCnt++;
          c = *p++ & 0x80;
        }

        /* aMI[iCol*3 + 1] = Number of occurrences
        ** aMI[iCol*3 + 2] = Number of rows containing at least one instance
        */
        pExpr->aMI[iCol*3 + 1] += iCnt;
        pExpr->aMI[iCol*3 + 2] += (iCnt>0);
        if( *p==0x00 ) break;
        p++;
        p += fts3GetVarint32(p, &iCol);
      }while( iCol<nCol );
    }

    fts3EvalUpdateCounts(pExpr->pLeft, nCol);
    fts3EvalUpdateCounts(pExpr->pRight, nCol);
  }
}

/*
** Expression pExpr must be of type FTSQUERY_PHRASE.
**
** If it is not already allocated and populated, this function allocates and
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        pCsr->iPrevId = pRoot->iDocid;
      }while( pCsr->isEof==0 
           && pRoot->eType==FTSQUERY_NEAR 
           && sqlite3Fts3EvalTestDeferred(pCsr, &rc) 
      );

      if( rc==SQLITE_OK && pCsr->isEof==0 ){
        fts3EvalUpdateCounts(pRoot);
      }
    }

    pCsr->isEof = 0;
    pCsr->iPrevId = iPrevId;

    if( bEof ){








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        pCsr->iPrevId = pRoot->iDocid;
      }while( pCsr->isEof==0 
           && pRoot->eType==FTSQUERY_NEAR 
           && sqlite3Fts3EvalTestDeferred(pCsr, &rc) 
      );

      if( rc==SQLITE_OK && pCsr->isEof==0 ){
        fts3EvalUpdateCounts(pRoot, pTab->nColumn);
      }
    }

    pCsr->isEof = 0;
    pCsr->iPrevId = iPrevId;

    if( bEof ){
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