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Overview
Comment:Strengthen the sqlite3VdbeMemAboutToChange() run-time verification mechanism to better detect missed calls to AboutToChange().
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SHA3-256: 793e942205a12eedb7ecc5ad8a27e3e52bbd4e1d50a0d1453d04a83ba728884e
User & Date: drh 2018-06-11 13:10:45
Context
2018-06-11
17:35
Add the OP_SetTabCol and OP_VerifyTabCol opcodes, only when compiling with SQLITE_DEBUG, to do run-time verification of the column cache. check-in: b37614a3 user: drh tags: trunk
13:10
Strengthen the sqlite3VdbeMemAboutToChange() run-time verification mechanism to better detect missed calls to AboutToChange(). check-in: 793e9422 user: drh tags: trunk
01:30
Always initialize the WhereClause.hasOr field that was added by check-in [292724ffc4]. Error detected by OSSFuzz. check-in: 9faf4171 user: drh tags: trunk
Changes
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Changes to src/vdbe.h.

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VdbeOp *sqlite3VdbeTakeOpArray(Vdbe*, int*, int*);
sqlite3_value *sqlite3VdbeGetBoundValue(Vdbe*, int, u8);
void sqlite3VdbeSetVarmask(Vdbe*, int);
#ifndef SQLITE_OMIT_TRACE
  char *sqlite3VdbeExpandSql(Vdbe*, const char*);
#endif
int sqlite3MemCompare(const Mem*, const Mem*, const CollSeq*);


void sqlite3VdbeRecordUnpack(KeyInfo*,int,const void*,UnpackedRecord*);
int sqlite3VdbeRecordCompare(int,const void*,UnpackedRecord*);
int sqlite3VdbeRecordCompareWithSkip(int, const void *, UnpackedRecord *, int);
UnpackedRecord *sqlite3VdbeAllocUnpackedRecord(KeyInfo*);

typedef int (*RecordCompare)(int,const void*,UnpackedRecord*);







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VdbeOp *sqlite3VdbeTakeOpArray(Vdbe*, int*, int*);
sqlite3_value *sqlite3VdbeGetBoundValue(Vdbe*, int, u8);
void sqlite3VdbeSetVarmask(Vdbe*, int);
#ifndef SQLITE_OMIT_TRACE
  char *sqlite3VdbeExpandSql(Vdbe*, const char*);
#endif
int sqlite3MemCompare(const Mem*, const Mem*, const CollSeq*);
int sqlite3BlobCompare(const Mem*, const Mem*);

void sqlite3VdbeRecordUnpack(KeyInfo*,int,const void*,UnpackedRecord*);
int sqlite3VdbeRecordCompare(int,const void*,UnpackedRecord*);
int sqlite3VdbeRecordCompareWithSkip(int, const void *, UnpackedRecord *, int);
UnpackedRecord *sqlite3VdbeAllocUnpackedRecord(KeyInfo*);

typedef int (*RecordCompare)(int,const void*,UnpackedRecord*);

Changes to src/vdbeaux.c.

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}

/*
** Compare two blobs.  Return negative, zero, or positive if the first
** is less than, equal to, or greater than the second, respectively.
** If one blob is a prefix of the other, then the shorter is the lessor.
*/
static SQLITE_NOINLINE int sqlite3BlobCompare(const Mem *pB1, const Mem *pB2){
  int c;
  int n1 = pB1->n;
  int n2 = pB2->n;

  /* It is possible to have a Blob value that has some non-zero content
  ** followed by zero content.  But that only comes up for Blobs formed
  ** by the OP_MakeRecord opcode, and such Blobs never get passed into







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}

/*
** Compare two blobs.  Return negative, zero, or positive if the first
** is less than, equal to, or greater than the second, respectively.
** If one blob is a prefix of the other, then the shorter is the lessor.
*/
SQLITE_NOINLINE int sqlite3BlobCompare(const Mem *pB1, const Mem *pB2){
  int c;
  int n1 = pB1->n;
  int n2 = pB2->n;

  /* It is possible to have a Blob value that has some non-zero content
  ** followed by zero content.  But that only comes up for Blobs formed
  ** by the OP_MakeRecord opcode, and such Blobs never get passed into

Changes to src/vdbemem.c.

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** copies are not misused.
*/
void sqlite3VdbeMemAboutToChange(Vdbe *pVdbe, Mem *pMem){
  int i;
  Mem *pX;
  for(i=0, pX=pVdbe->aMem; i<pVdbe->nMem; i++, pX++){
    if( pX->pScopyFrom==pMem ){














      pX->flags |= MEM_Undefined;
      pX->pScopyFrom = 0;
    }
  }
  pMem->pScopyFrom = 0;
}
#endif /* SQLITE_DEBUG */








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** copies are not misused.
*/
void sqlite3VdbeMemAboutToChange(Vdbe *pVdbe, Mem *pMem){
  int i;
  Mem *pX;
  for(i=0, pX=pVdbe->aMem; i<pVdbe->nMem; i++, pX++){
    if( pX->pScopyFrom==pMem ){
      /* If pX is marked as a shallow copy of pMem, then verify that
      ** no significant changes have been made to pX since the OP_SCopy.
      ** A significant change would indicated a missed call to this
      ** function for pX.  Minor changes, such as adding or removing a
      ** dual type, are allowed, as long as the underlying value is the
      ** same. */
      u16 mFlags = pMem->flags & pX->flags;
      assert( (mFlags&MEM_Int)==0 || pMem->u.i==pX->u.i );
      assert( (mFlags&MEM_Real)==0 || pMem->u.r==pX->u.r );
      assert( (mFlags&MEM_Str)==0  || (pMem->n==pX->n && pMem->z==pX->z) );
      assert( (mFlags&MEM_Blob)==0  || sqlite3BlobCompare(pMem,pX)==0 );
      
      /* pMem is the register that is changing.  But also mark pX as
      ** undefined so that we can quickly detect the shallow-copy error */
      pX->flags = MEM_Undefined;
      pX->pScopyFrom = 0;
    }
  }
  pMem->pScopyFrom = 0;
}
#endif /* SQLITE_DEBUG */