SQLite

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.181 2002/10/22 15:04:34 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** The makefile scans this source file and creates the following
** array of string constants which are the names of all VDBE opcodes.

/*
** Allowed values for Stack.flags
*/
#define STK_Null      0x0001   /* Value is NULL */
#define STK_Str       0x0002   /* Value is a string */
#define STK_Int       0x0004   /* Value is an integer */
#define STK_Real      0x0008   /* Value is a real number */
#define STK_Dyn       0x0010   /* Need to call sqliteFree() on zStack[] */
#define STK_Static    0x0020   /* zStack[] points to a static string */
#define STK_Ephem     0x0040   /* zStack[] points to an ephemeral string */

/* The following STK_ value appears only in AggElem.aMem.s.flag fields.
** It indicates that the corresponding AggElem.aMem.z points to a
** aggregate function context that needs to be finalized.
*/
#define STK_AggCtx    0x0040   /* zStack[] points to an agg function context */

    pStack->z[0] = 0;
  }
  *pzStack = pStack->z;
  pStack->n = strlen(*pzStack)+1;
  pStack->flags = STK_Str;
  return 0;
}

/*
** An ephemeral string value (signified by the STK_Ephem flag) contains
** a pointer to a dynamically allocated string where some other entity
** is responsible for deallocating that string.  Because the stack entry
** does not control the string, it might be deleted without the stack
** entry knowing it.
**
** This routine converts an ephemeral string into a dynamically allocated
** string that the stack entry itself controls.  In other words, it
** converts an STK_Ephem string into an STK_Dyn string.
*/
#define Deephemeralize(P,I) \
   if( ((P)->aStack[I].flags&STK_Ephem)!=0 && hardDeephem(P,I) ){ goto no_mem;}
static int hardDeephem(Vdbe *p, int i){
  Stack *pStack = &p->aStack[i];
  char **pzStack = &p->zStack[i];
  char *z;
  assert( (pStack->flags & STK_Ephem)!=0 );
  z = sqliteMalloc( pStack->n );
  if( z==0 ) return 1;
  memcpy(z, *pzStack, pStack->n);
  *pzStack = z;
  return 0;
}

/*
** Release the memory associated with the given stack level
*/
#define Release(P,I)  if((P)->aStack[I].flags&STK_Dyn){ hardRelease(P,I); }
static void hardRelease(Vdbe *p, int i){
  sqliteFree(p->zStack[i]);
  p->zStack[i] = 0;
  p->aStack[i].flags &= ~(STK_Str|STK_Dyn|STK_Static|STK_Ephem);
}

/*
** Convert the given stack entity into a integer if it isn't one
** already.
**
** Any prior string or real representation is invalidated.  

case OP_Dup: {
  int i = p->tos - pOp->p1;
  int j = ++p->tos;
  VERIFY( if( i<0 ) goto not_enough_stack; )
  VERIFY( if( NeedStack(p, p->tos) ) goto no_mem; )
  memcpy(&aStack[j], &aStack[i], sizeof(aStack[i])-NBFS);
  if( aStack[j].flags & STK_Str ){
    int isStatic = (aStack[j].flags & STK_Static)!=0;
    if( pOp->p2 || isStatic ){
      zStack[j] = zStack[i];
      aStack[j].flags &= ~STK_Dyn;
      if( !isStatic ) aStack[j].flags |= STK_Ephem;
    }else if( aStack[i].n<=NBFS ){
      memcpy(aStack[j].z, zStack[i], aStack[j].n);
      zStack[j] = aStack[j].z;
      aStack[j].flags &= ~(STK_Static|STK_Dyn|STK_Ephem);
    }else{
      zStack[j] = sqliteMalloc( aStack[j].n );
      if( zStack[j]==0 ) goto no_mem;
      memcpy(zStack[j], zStack[i], aStack[j].n);
      aStack[j].flags &= ~(STK_Static|STK_Ephem);
      aStack[j].flags |= STK_Dyn;
    }
  }
  break;
}

/* Opcode: Pull P1 * *
**

  int to = p->tos;
  int i;
  Stack ts;
  char *tz;
  VERIFY( if( from<0 ) goto not_enough_stack; )
  ts = aStack[from];
  tz = zStack[from];
  Deephemeralize(p, to);
  for(i=from; i<to; i++){
    Deephemeralize(p, i);
    aStack[i] = aStack[i+1];
    assert( (aStack[i].flags & STK_Ephem)==0 );
    if( aStack[i].flags & (STK_Dyn|STK_Static) ){
      zStack[i] = zStack[i+1];
    }else{
      zStack[i] = aStack[i].z;
    }
  }
  aStack[to] = ts;
  assert( (aStack[to].flags & STK_Ephem)==0 );
  if( aStack[to].flags & (STK_Dyn|STK_Static) ){
    zStack[to] = tz;
  }else{
    zStack[to] = aStack[to].z;
  }
  break;
}

  int from = p->tos;
  int to = p->tos - pOp->p1;

  VERIFY( if( to<0 ) goto not_enough_stack; )
  if( aStack[to].flags & STK_Dyn ){
    sqliteFree(zStack[to]);
  }
  Deephemeralize(p, from);
  aStack[to] = aStack[from];
  if( aStack[to].flags & (STK_Dyn|STK_Static|STK_Ephem) ){
    zStack[to] = zStack[from];
  }else{
    zStack[to] = aStack[to].z;
  }
  aStack[from].flags = 0;
  p->tos--;
  break;
}

/* Opcode: ColumnCount P1 * *
**
** Specify the number of column values that will appear in the

** the key itself.
*/
case OP_IncrKey: {
  int tos = p->tos;

  VERIFY( if( tos<0 ) goto bad_instruction );
  if( Stringify(p, tos) ) goto no_mem;
  if( aStack[tos].flags & (STK_Static|STK_Ephem) ){
    /* CANT HAPPEN.  The IncrKey opcode is only applied to keys
    ** generated by MakeKey or MakeIdxKey and the results of those
    ** operands are always dynamic strings.
    */
    goto abort_due_to_error;
  }
  zStack[tos][aStack[tos].n-1]++;

  /* amt and offset now hold the offset to the start of data and the
  ** amount of data.  Go get the data and put it on the stack.
  */
  if( amt==0 ){
    aStack[tos].flags = STK_Null;
  }else if( zRec ){
    aStack[tos].flags = STK_Str | STK_Ephem;
    aStack[tos].n = amt;
    zStack[tos] = &zRec[offset];
  }else{
    if( amt<=NBFS ){
      aStack[tos].flags = STK_Str;
      zStack[tos] = aStack[tos].z;
      aStack[tos].n = amt;

** the original data remains on the stack.
*/
case OP_MemStore: {
  int i = pOp->p1;
  int tos = p->tos;
  char *zOld;
  Mem *pMem;
  int flags;
  VERIFY( if( tos<0 ) goto not_enough_stack; )
  if( i>=p->nMem ){
    int nOld = p->nMem;
    Mem *aMem;
    p->nMem = i + 5;
    aMem = sqliteRealloc(p->aMem, p->nMem*sizeof(p->aMem[0]));
    if( aMem==0 ) goto no_mem;

    }
    p->aMem = aMem;
    if( nOld<p->nMem ){
      memset(&p->aMem[nOld], 0, sizeof(p->aMem[0])*(p->nMem-nOld));
    }
  }
  pMem = &p->aMem[i];
  flags = pMem->s.flags;
  if( flags & STK_Dyn ){
    zOld = pMem->z;
  }else{
    zOld = 0;
  }
  pMem->s = aStack[tos];
  flags = pMem->s.flags;
  if( flags & (STK_Static|STK_Dyn|STK_Ephem) ){
    if( (flags & STK_Static)!=0 || (pOp->p2 && (flags & STK_Dyn)!=0) ){
      pMem->z = zStack[tos];
    }else if( flags & STK_Str ){
      pMem->z = sqliteMalloc( pMem->s.n );
      if( pMem->z==0 ) goto no_mem;
      memcpy(pMem->z, zStack[tos], pMem->s.n);
      pMem->s.flags |= STK_Dyn;
      pMem->s.flags &= ~(STK_Static|STK_Ephem);
    }
  }else{
    pMem->z = pMem->s.z;
  }
  if( zOld ) sqliteFree(zOld);
  if( pOp->p2 ){
    zStack[tos] = 0;

  int tos = ++p->tos;
  int i = pOp->p1;
  VERIFY( if( NeedStack(p, tos) ) goto no_mem; )
  VERIFY( if( i<0 || i>=p->nMem ) goto bad_instruction; )
  memcpy(&aStack[tos], &p->aMem[i].s, sizeof(aStack[tos])-NBFS);;
  if( aStack[tos].flags & STK_Str ){
    zStack[tos] = p->aMem[i].z;
    aStack[tos].flags |= STK_Ephem;
    aStack[tos].flags &= ~STK_Dyn;
  }
  break;
}

/* Opcode: MemIncr P1 P2 *
**

    Mem *pMem = &pFocus->aMem[i];
    char *zOld;
    if( pMem->s.flags & STK_Dyn ){
      zOld = pMem->z;
    }else{
      zOld = 0;
    }
    Deephemeralize(p, tos);
    pMem->s = aStack[tos];
    if( pMem->s.flags & STK_Dyn ){
      pMem->z = zStack[tos];
      zStack[tos] = 0;
      aStack[tos].flags = 0;
    }else if( pMem->s.flags & (STK_Static|STK_AggCtx) ){
      pMem->z = zStack[tos];

  VERIFY( if( NeedStack(p, tos) ) goto no_mem; )
  if( pFocus==0 ) goto no_mem;
  if( VERIFY( i>=0 && ) i<p->agg.nMem ){
    Mem *pMem = &pFocus->aMem[i];
    aStack[tos] = pMem->s;
    zStack[tos] = pMem->z;
    aStack[tos].flags &= ~STK_Dyn;
    aStack[tos].flags |= STK_Ephem;
  }
  break;
}

/* Opcode: AggNext * P2 *
**
** Make the next aggregate value the current aggregate.  The prior

      (*p->agg.apFunc[i]->xFinalize)(&ctx);
      if( freeCtx ){
        sqliteFree( aMem[i].z );
      }
      aMem[i].s = ctx.s;
      aMem[i].z = ctx.z;
      if( (aMem[i].s.flags & STK_Str) &&
              (aMem[i].s.flags & (STK_Dyn|STK_Static|STK_Ephem))==0 ){
        aMem[i].z = aMem[i].s.z;
      }
      nErr += ctx.isError;
    }
  }
  break;
}

      pc = pOp->p2 - 1;
    }
  }
  tos = ++p->tos;
  VERIFY( if( NeedStack(p, p->tos) ) goto no_mem; )
  zStack[tos] = sqliteHashKey(pSet->prev);
  aStack[tos].n = sqliteHashKeysize(pSet->prev);
  aStack[tos].flags = STK_Str | STK_Ephem;
  break;
}

/* An other opcode is illegal...
*/
default: {
  sprintf(zBuf,"%d",pOp->opcode);

          fprintf(p->trace, " r:%g", aStack[i].r);
        }else if( aStack[i].flags & STK_Str ){
          int j, k;
          char zBuf[100];
          zBuf[0] = ' ';
          if( aStack[i].flags & STK_Dyn ){
            zBuf[1] = 'z';
            assert( (aStack[i].flags & (STK_Static|STK_Ephem))==0 );
          }else if( aStack[i].flags & STK_Static ){
            zBuf[1] = 't';
            assert( (aStack[i].flags & (STK_Dyn|STK_Ephem))==0 );
          }else if( aStack[i].flags & STK_Ephem ){
            zBuf[1] = 'e';
            assert( (aStack[i].flags & (STK_Static|STK_Dyn))==0 );
          }else{
            zBuf[1] = 's';
          }
          zBuf[2] = '[';
          k = 3;
          for(j=0; j<20 && j<aStack[i].n; j++){
            int c = zStack[i][j];