vdbe.c

SQLite is a software library that implements a self-contained, serverless, zero-configuration, trans

** register P1.  See the Lt opcode for additional information.
*/
case OP_Eq:               /* same as TK_EQ, jump, in1, in3 */
case OP_Ne:               /* same as TK_NE, jump, in1, in3 */
case OP_Lt:               /* same as TK_LT, jump, in1, in3 */
case OP_Le:               /* same as TK_LE, jump, in1, in3 */
case OP_Gt:               /* same as TK_GT, jump, in1, in3 */
case OP_Ge: {             /* same as TK_GE, jump, in1, in3 */
  int flags;
  int res;
  char affinity;
  Mem x1, x3;

  flags = pIn1->flags|pIn3->flags;

  if( flags&MEM_Null ){
    if( (pOp->p5 & SQLITE_NULLEQUAL)!=0 ){
      /*
      ** When SQLITE_NULLEQUAL set and either operand is NULL
      ** then both operands are converted to integers prior to being 
      ** passed down into the normal comparison logic below.  
      ** NULL operands are converted to zero and non-NULL operands
      ** are converted to 1.  Thus, for example, with SQLITE_NULLEQUAL
      ** set,  NULL==NULL is true whereas it would normally NULL.
      ** Similarly,  NULL!=123 is true.
      */
      x1.flags = MEM_Int;
      x1.u.i = (pIn1->flags & MEM_Null)==0;
      pIn1 = &x1;
      x3.flags = MEM_Int;
      x3.u.i = (pIn3->flags & MEM_Null)==0;
      pIn3 = &x3;
    }else{
      /* If the SQLITE_NULLEQUAL bit is clear and either operand is NULL then
      ** the result is always NULL.  The jump is taken if the 
      ** SQLITE_JUMPIFNULL bit is set.
      */
      if( pOp->p5 & SQLITE_STOREP2 ){
        pOut = &p->aMem[pOp->p2];
        MemSetTypeFlag(pOut, MEM_Null);
        REGISTER_TRACE(pOp->p2, pOut);
      }else if( pOp->p5 & SQLITE_JUMPIFNULL ){
        pc = pOp->p2-1;
      }
      break;
    }
  }

  affinity = pOp->p5 & SQLITE_AFF_MASK;
  if( affinity ){
    applyAffinity(pIn1, affinity, encoding);
    applyAffinity(pIn3, affinity, encoding);
  }

  assert( pOp->p4type==P4_COLLSEQ || pOp->p4.pColl==0 );
  ExpandBlob(pIn1);
  ExpandBlob(pIn3);
  res = sqlite3MemCompare(pIn3, pIn1, pOp->p4.pColl);
  switch( pOp->opcode ){
    case OP_Eq:    res = res==0;     break;
    case OP_Ne:    res = res!=0;     break;
    case OP_Lt:    res = res<0;      break;
    case OP_Le:    res = res<=0;     break;
    case OP_Gt:    res = res>0;      break;
    default:       res = res>=0;     break;
  }

  if( pOp->p5 & SQLITE_STOREP2 ){
    pOut = &p->aMem[pOp->p2];
    MemSetTypeFlag(pOut, MEM_Int);
    pOut->u.i = res;
    REGISTER_TRACE(pOp->p2, pOut);
  }else if( res ){
    pc = pOp->p2-1;
  }
  break;
}

/* Opcode: And P1 P2 P3 * *
**
** Take the logical AND of the values in registers P1 and P2 and
** write the result into register P3.
**
** If either P1 or P2 is 0 (false) then the result is 0 even if
** the other input is NULL.  A NULL and true or two NULLs give
** a NULL output.
*/
/* Opcode: Or P1 P2 P3 * *
**
** Take the logical OR of the values in register P1 and P2 and
** store the answer in register P3.
**
** If either P1 or P2 is nonzero (true) then the result is 1 (true)
** even if the other input is NULL.  A NULL and false or two NULLs
** give a NULL output.
*/
case OP_And:              /* same as TK_AND, in1, in2, out3 */
case OP_Or: {             /* same as TK_OR, in1, in2, out3 */
  int v1, v2;    /* 0==FALSE, 1==TRUE, 2==UNKNOWN or NULL */

  if( pIn1->flags & MEM_Null ){
    v1 = 2;
  }else{
    v1 = sqlite3VdbeIntValue(pIn1)!=0;
  }
  if( pIn2->flags & MEM_Null ){
    v2 = 2;
  }else{
    v2 = sqlite3VdbeIntValue(pIn2)!=0;
  }
  if( pOp->opcode==OP_And ){
    static const unsigned char and_logic[] = { 0, 0, 0, 0, 1, 2, 0, 2, 2 };
    v1 = and_logic[v1*3+v2];
  }else{
    static const unsigned char or_logic[] = { 0, 1, 2, 1, 1, 1, 2, 1, 2 };
    v1 = or_logic[v1*3+v2];
  }
  if( v1==2 ){
    MemSetTypeFlag(pOut, MEM_Null);
  }else{
    pOut->u.i = v1;
    MemSetTypeFlag(pOut, MEM_Int);
  }
  break;
}

/* Opcode: Not P1 * * * *
**
** Interpret the value in register P1 as a boolean value.  Replace it
** with its complement.  If the value in register P1 is NULL its value
** is unchanged.
*/
case OP_Not: {                /* same as TK_NOT, in1 */
  if( pIn1->flags & MEM_Null ) break;  /* Do nothing to NULLs */
  sqlite3VdbeMemIntegerify(pIn1);
  pIn1->u.i = !pIn1->u.i;
  assert( pIn1->flags&MEM_Int );
  break;
}

/* Opcode: BitNot P1 * * * *
**
** Interpret the content of register P1 as an integer.  Replace it
** with its ones-complement.  If the value is originally NULL, leave
** it unchanged.
*/
case OP_BitNot: {             /* same as TK_BITNOT, in1 */
  if( pIn1->flags & MEM_Null ) break;  /* Do nothing to NULLs */
  sqlite3VdbeMemIntegerify(pIn1);
  pIn1->u.i = ~pIn1->u.i;
  assert( pIn1->flags&MEM_Int );
  break;
}

/* Opcode: If P1 P2 P3 * *
**
** Jump to P2 if the value in register P1 is true.  The value is
** is considered true if it is numeric and non-zero.  If the value
** in P1 is NULL then take the jump if P3 is true.
*/
/* Opcode: IfNot P1 P2 P3 * *
**
** Jump to P2 if the value in register P1 is False.  The value is
** is considered true if it has a numeric value of zero.  If the value
** in P1 is NULL then take the jump if P3 is true.
*/
case OP_If:                 /* jump, in1 */
case OP_IfNot: {            /* jump, in1 */
  int c;
  if( pIn1->flags & MEM_Null ){
    c = pOp->p3;
  }else{
#ifdef SQLITE_OMIT_FLOATING_POINT
    c = sqlite3VdbeIntValue(pIn1);
#else
    c = sqlite3VdbeRealValue(pIn1)!=0.0;
#endif
    if( pOp->opcode==OP_IfNot ) c = !c;
  }
  if( c ){
    pc = pOp->p2-1;
  }
  break;
}

/* Opcode: IsNull P1 P2 P3 * *
**
** Jump to P2 if the value in register P1 is NULL.  If P3 is greater
** than zero, then check all values reg(P1), reg(P1+1), 
** reg(P1+2), ..., reg(P1+P3-1).
*/
case OP_IsNull: {            /* same as TK_ISNULL, jump, in1 */
  int n = pOp->p3;
  assert( pOp->p3==0 || pOp->p1>0 );
  do{
    if( (pIn1->flags & MEM_Null)!=0 ){
      pc = pOp->p2 - 1;
      break;
    }
    pIn1++;
  }while( --n > 0 );
  break;
}

/* Opcode: NotNull P1 P2 * * *
**
** Jump to P2 if the value in register P1 is not NULL.  
*/
case OP_NotNull: {            /* same as TK_NOTNULL, jump, in1 */
  if( (pIn1->flags & MEM_Null)==0 ){
    pc = pOp->p2 - 1;
  }
  break;
}

/* Opcode: SetNumColumns * P2 * * *
**
** This opcode sets the number of columns for the cursor opened by the
** following instruction to P2.
**
** An OP_SetNumColumns is only useful if it occurs immediately before 
** one of the following opcodes:
**
**     OpenRead
**     OpenWrite
**     OpenPseudo
**
** If the OP_Column opcode is to be executed on a cursor, then
** this opcode must be present immediately before the opcode that
** opens the cursor.
*/
case OP_SetNumColumns: {
  break;
}

/* Opcode: Column P1 P2 P3 P4 *
**
** Interpret the data that cursor P1 points to as a structure built using
** the MakeRecord instruction.  (See the MakeRecord opcode for additional
** information about the format of the data.)  Extract the P2-th column
** from this record.  If there are less that (P2+1) 
** values in the record, extract a NULL.
**
** The value extracted is stored in register P3.
**
** If the KeyAsData opcode has previously executed on this cursor, then the
** field might be extracted from the key rather than the data.
**
** If the column contains fewer than P2 fields, then extract a NULL.  Or,
** if the P4 argument is a P4_MEM use the value of the P4 argument as
** the result.
*/
case OP_Column: {
  u32 payloadSize;   /* Number of bytes in the record */
  int p1 = pOp->p1;  /* P1 value of the opcode */
  int p2 = pOp->p2;  /* column number to retrieve */
  Cursor *pC = 0;    /* The VDBE cursor */
  char *zRec;        /* Pointer to complete record-data */
  BtCursor *pCrsr;   /* The BTree cursor */
  u32 *aType;        /* aType[i] holds the numeric type of the i-th column */
  u32 *aOffset;      /* aOffset[i] is offset to start of data for i-th column */
  u32 nField;        /* number of fields in the record */
  int len;           /* The length of the serialized data for the column */
  int i;             /* Loop counter */
  char *zData;       /* Part of the record being decoded */
  Mem *pDest;        /* Where to write the extracted value */
  Mem sMem;          /* For storing the record being decoded */

  sMem.flags = 0;
  sMem.db = 0;
  sMem.zMalloc = 0;
  assert( p1<p->nCursor );
  assert( pOp->p3>0 && pOp->p3<=p->nMem );
  pDest = &p->aMem[pOp->p3];
  MemSetTypeFlag(pDest, MEM_Null);

  /* This block sets the variable payloadSize to be the total number of
  ** bytes in the record.
  **
  ** zRec is set to be the complete text of the record if it is available.
  ** The complete record text is always available for pseudo-tables
  ** If the record is stored in a cursor, the complete record text
  ** might be available in the  pC->aRow cache.  Or it might not be.
  ** If the data is unavailable,  zRec is set to NULL.
  **
  ** We also compute the number of columns in the record.  For cursors,
  ** the number of columns is stored in the Cursor.nField element.
  */
  pC = p->apCsr[p1];
  assert( pC!=0 );
#ifndef SQLITE_OMIT_VIRTUALTABLE
  assert( pC->pVtabCursor==0 );
#endif
  if( pC->pCursor!=0 ){
    /* The record is stored in a B-Tree */
    rc = sqlite3VdbeCursorMoveto(pC);
    if( rc ) goto abort_due_to_error;
    zRec = 0;
    pCrsr = pC->pCursor;
    if( pC->nullRow ){
      payloadSize = 0;
    }else if( pC->cacheStatus==p->cacheCtr ){
      payloadSize = pC->payloadSize;
      zRec = (char*)pC->aRow;
    }else if( pC->isIndex ){
      i64 payloadSize64;
      sqlite3BtreeKeySize(pCrsr, &payloadSize64);
      payloadSize = payloadSize64;
    }else{
      sqlite3BtreeDataSize(pCrsr, &payloadSize);
    }
    nField = pC->nField;
  }else{
    assert( pC->pseudoTable );
    /* The record is the sole entry of a pseudo-table */
    payloadSize = pC->nData;
    zRec = pC->pData;
    pC->cacheStatus = CACHE_STALE;
    assert( payloadSize==0 || zRec!=0 );
    nField = pC->nField;
    pCrsr = 0;
  }

  /* If payloadSize is 0, then just store a NULL */
  if( payloadSize==0 ){
    assert( pDest->flags&MEM_Null );
    goto op_column_out;
  }
  if( payloadSize>db->aLimit[SQLITE_LIMIT_LENGTH] ){
    goto too_big;
  }

  assert( p2<nField );

  /* Read and parse the table header.  Store the results of the parse
  ** into the record header cache fields of the cursor.
  */
  aType = pC->aType;
  if( pC->cacheStatus==p->cacheCtr ){
    aOffset = pC->aOffset;
  }else{
    u8 *zIdx;        /* Index into header */
    u8 *zEndHdr;     /* Pointer to first byte after the header */
    u32 offset;      /* Offset into the data */
    int szHdrSz;     /* Size of the header size field at start of record */
    int avail;       /* Number of bytes of available data */

    assert(aType);
    pC->aOffset = aOffset = &aType[nField];
    pC->payloadSize = payloadSize;
    pC->cacheStatus = p->cacheCtr;

    /* Figure out how many bytes are in the header */
    if( zRec ){
      zData = zRec;
    }else{
      if( pC->isIndex ){
        zData = (char*)sqlite3BtreeKeyFetch(pCrsr, &avail);
      }else{
        zData = (char*)sqlite3BtreeDataFetch(pCrsr, &avail);
      }
      /* If KeyFetch()/DataFetch() managed to get the entire payload,
      ** save the payload in the pC->aRow cache.  That will save us from
      ** having to make additional calls to fetch the content portion of
      ** the record.
      */
      if( avail>=payloadSize ){
        zRec = zData;
        pC->aRow = (u8*)zData;
      }else{
        pC->aRow = 0;
      }
    }
    /* The following assert is true in all cases accept when
    ** the database file has been corrupted externally.
    **    assert( zRec!=0 || avail>=payloadSize || avail>=9 ); */
    szHdrSz = GetVarint((u8*)zData, offset);

    /* The KeyFetch() or DataFetch() above are fast and will get the entire
    ** record header in most cases.  But they will fail to get the complete
    ** record header if the record header does not fit on a single page
    ** in the B-Tree.  When that happens, use sqlite3VdbeMemFromBtree() to
    ** acquire the complete header text.
    */
    if( !zRec && avail<offset ){
      sMem.flags = 0;
      sMem.db = 0;
      rc = sqlite3VdbeMemFromBtree(pCrsr, 0, offset, pC->isIndex, &sMem);
      if( rc!=SQLITE_OK ){
        goto op_column_out;
      }
      zData = sMem.z;
    }
    zEndHdr = (u8 *)&zData[offset];
    zIdx = (u8 *)&zData[szHdrSz];

    /* Scan the header and use it to fill in the aType[] and aOffset[]
    ** arrays.  aType[i] will contain the type integer for the i-th
    ** column and aOffset[i] will contain the offset from the beginning
    ** of the record to the start of the data for the i-th column
    */
    for(i=0; i<nField; i++){
      if( zIdx<zEndHdr ){
        aOffset[i] = offset;
        zIdx += GetVarint(zIdx, aType[i]);
        offset += sqlite3VdbeSerialTypeLen(aType[i]);
      }else{
        /* If i is less that nField, then there are less fields in this
        ** re