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Take care to track ephemeral strings in the VDBE and make copies of ephemeral

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strings that need to be preserved.  Ticket #177. (CVS 769)

FossilOrigin-Name: 562da534bbb605a8ce15824135b012ef2d86bbeb
This commit is contained in:
drh
2002-10-22 15:04:34 +00:00
parent edbbbdf8f7
commit e958bb4aef
3 changed files with 71 additions and 25 deletions
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82
src/vdbe.c
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@ -36,7 +36,7 @@
** 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 1.180 2002/10/19 20:16:38 drh Exp $
** $Id: vdbe.c,v 1.181 2002/10/22 15:04:34 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
@ -152,8 +152,9 @@ typedef struct Mem Mem;
#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_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
@ -798,6 +799,31 @@ static int hardStringify(Vdbe *p, int i){
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
*/
@ -805,7 +831,7 @@ static int hardStringify(Vdbe *p, int 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);
p->aStack[i].flags &= ~(STK_Str|STK_Dyn|STK_Static|STK_Ephem);
}
/*
@ -1577,18 +1603,21 @@ case OP_Dup: {
VERIFY( if( NeedStack(p, p->tos) ) goto no_mem; )
memcpy(&aStack[j], &aStack[i], sizeof(aStack[i])-NBFS);
if( aStack[j].flags & STK_Str ){
if( pOp->p2 || (aStack[j].flags & STK_Static)!=0 ){
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);
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;
aStack[j].flags &= ~(STK_Static|STK_Ephem);
aStack[j].flags |= STK_Dyn;
}
}
break;
@ -1613,8 +1642,11 @@ case OP_Pull: {
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{
@ -1622,6 +1654,7 @@ case OP_Pull: {
}
}
aStack[to] = ts;
assert( (aStack[to].flags & STK_Ephem)==0 );
if( aStack[to].flags & (STK_Dyn|STK_Static) ){
zStack[to] = tz;
}else{
@ -1644,13 +1677,14 @@ case OP_Push: {
if( aStack[to].flags & STK_Dyn ){
sqliteFree(zStack[to]);
}
Deephemeralize(p, from);
aStack[to] = aStack[from];
if( aStack[to].flags & (STK_Dyn|STK_Static) ){
if( aStack[to].flags & (STK_Dyn|STK_Static|STK_Ephem) ){
zStack[to] = zStack[from];
}else{
zStack[to] = aStack[to].z;
}
aStack[from].flags &= ~STK_Dyn;
aStack[from].flags = 0;
p->tos--;
break;
}
@ -2896,7 +2930,7 @@ case OP_IncrKey: {
VERIFY( if( tos<0 ) goto bad_instruction );
if( Stringify(p, tos) ) goto no_mem;
if( aStack[tos].flags & STK_Static ){
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.
@ -3806,7 +3840,7 @@ case OP_Column: {
if( amt==0 ){
aStack[tos].flags = STK_Null;
}else if( zRec ){
aStack[tos].flags = STK_Str | STK_Static;
aStack[tos].flags = STK_Str | STK_Ephem;
aStack[tos].n = amt;
zStack[tos] = &zRec[offset];
}else{
@ -4770,6 +4804,7 @@ case OP_MemStore: {
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;
@ -4791,19 +4826,23 @@ case OP_MemStore: {
}
}
pMem = &p->aMem[i];
if( pMem->s.flags & STK_Dyn ){
flags = pMem->s.flags;
if( flags & STK_Dyn ){
zOld = pMem->z;
}else{
zOld = 0;
}
pMem->s = aStack[tos];
if( pMem->s.flags & (STK_Static|STK_Dyn) ){
if( pOp->p2==0 && (pMem->s.flags & STK_Dyn)!=0 ){
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);
}else{
pMem->z = zStack[tos];
pMem->s.flags |= STK_Dyn;
pMem->s.flags &= ~(STK_Static|STK_Ephem);
}
}else{
pMem->z = pMem->s.z;
@ -4834,7 +4873,7 @@ case OP_MemLoad: {
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_Static;
aStack[tos].flags |= STK_Ephem;
aStack[tos].flags &= ~STK_Dyn;
}
break;
@ -4988,6 +5027,7 @@ case OP_AggSet: {
}else{
zOld = 0;
}
Deephemeralize(p, tos);
pMem->s = aStack[tos];
if( pMem->s.flags & STK_Dyn ){
pMem->z = zStack[tos];
@ -5021,6 +5061,7 @@ case OP_AggGet: {
aStack[tos] = pMem->s;
zStack[tos] = pMem->z;
aStack[tos].flags &= ~STK_Dyn;
aStack[tos].flags |= STK_Ephem;
}
break;
}
@ -5070,7 +5111,7 @@ case OP_AggNext: {
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))==0 ){
(aMem[i].s.flags & (STK_Dyn|STK_Static|STK_Ephem))==0 ){
aMem[i].z = aMem[i].s.z;
}
nErr += ctx.isError;
@ -5185,7 +5226,7 @@ case OP_SetNext: {
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_Static;
aStack[tos].flags = STK_Str | STK_Ephem;
break;
}
@ -5234,8 +5275,13 @@ default: {
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';
}