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Use memmove() instead of memcpy() when moving between memory regions that

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might overlap.  Ticket #2334. (CVS 3905)

FossilOrigin-Name: 678d672b73cc7b7f563c15daee3831cb5bbd890e
This commit is contained in:
drh
2007-05-03 13:02:26 +00:00
parent cdf1c4d21f
commit f68d7d17a1
3 changed files with 26 additions and 12 deletions
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22
src/select.c
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@@ -12,7 +12,7 @@
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.338 2007/04/16 17:07:55 drh Exp $
** $Id: select.c,v 1.339 2007/05/03 13:02:27 drh Exp $
*/
#include "sqliteInt.h"
@@ -1909,8 +1909,8 @@ static int multiSelect(
KeyInfo *pKeyInfo; /* Collating sequence for the result set */
Select *pLoop; /* For looping through SELECT statements */
int nKeyCol; /* Number of entries in pKeyInfo->aCol[] */
CollSeq **apColl;
CollSeq **aCopy;
CollSeq **apColl; /* For looping through pKeyInfo->aColl[] */
CollSeq **aCopy; /* A copy of pKeyInfo->aColl[] */
assert( p->pRightmost==p );
nKeyCol = nCol + (pOrderBy ? pOrderBy->nExpr : 0);
@@ -1951,9 +1951,23 @@ static int multiSelect(
int addr;
u8 *pSortOrder;
/* Reuse the same pKeyInfo for the ORDER BY as was used above for
** the compound select statements. Except we have to change out the
** pKeyInfo->aColl[] values. Some of the aColl[] values will be
** reused when constructing the pKeyInfo for the ORDER BY, so make
** a copy. Sufficient space to hold both the nCol entries for
** the compound select and the nOrderbyExpr entries for the ORDER BY
** was allocated above. But we need to move the compound select
** entries out of the way before constructing the ORDER BY entries.
** Move the compound select entries into aCopy[] where they can be
** accessed and reused when constructing the ORDER BY entries.
** Because nCol might be greater than or less than nOrderByExpr
** we have to use memmove() when doing the copy.
*/
aCopy = &pKeyInfo->aColl[nOrderByExpr];
pSortOrder = pKeyInfo->aSortOrder = (u8*)&aCopy[nCol];
memcpy(aCopy, pKeyInfo->aColl, nCol*sizeof(CollSeq*));
memmove(aCopy, pKeyInfo->aColl, nCol*sizeof(CollSeq*));
apColl = pKeyInfo->aColl;
for(i=0; i<nOrderByExpr; i++, pOTerm++, apColl++, pSortOrder++){
Expr *pExpr = pOTerm->pExpr;