Avoid memcpy() with same source and destination address.

hlinnaka · hlinnaka · commit d8f2858b884c · 2014-03-07T13:30:02.000+02:00
The behavior of that is undefined, although unlikely to lead to problems in
practice.

Found by running regression tests with Valgrind.
diff --git a/src/backend/tsearch/dict_ispell.c b/src/backend/tsearch/dict_ispell.c
@@ -127,20 +127,19 @@ dispell_lexize(PG_FUNCTION_ARGS)
 	if (res == NULL)
 		PG_RETURN_POINTER(NULL);
 
-	ptr = cptr = res;
-	while (ptr->lexeme)
+	cptr = res;
+	for (ptr = cptr; ptr->lexeme; ptr++)
 	{
 		if (searchstoplist(&(d->stoplist), ptr->lexeme))
 		{
 			pfree(ptr->lexeme);
 			ptr->lexeme = NULL;
-			ptr++;
 		}
 		else
 		{
-			memcpy(cptr, ptr, sizeof(TSLexeme));
+			if (cptr != ptr)
+				memcpy(cptr, ptr, sizeof(TSLexeme));
 			cptr++;
-			ptr++;
 		}
 	}
 	cptr->lexeme = NULL;
diff --git a/src/backend/utils/adt/tsvector.c b/src/backend/utils/adt/tsvector.c
@@ -125,7 +125,8 @@ uniqueentry(WordEntryIN *a, int l, char *buf, int *outbuflen)
 				buflen += res->poslen * sizeof(WordEntryPos) + sizeof(uint16);
 			}
 			res++;
-			memcpy(res, ptr, sizeof(WordEntryIN));
+			if (res != ptr)
+				memcpy(res, ptr, sizeof(WordEntryIN));
 		}
 		else if (ptr->entry.haspos)
 		{

Original file line number	Diff line number	Diff line change
`@@ -127,20 +127,19 @@ dispell_lexize(PG_FUNCTION_ARGS)`
`127`	`127`	`if (res == NULL)`
`128`	`128`	`PG_RETURN_POINTER(NULL);`
`129`	`129`
`130`		`- ptr = cptr = res;`
`131`		`- while (ptr->lexeme)`
	`130`	`+ cptr = res;`
	`131`	`+ for (ptr = cptr; ptr->lexeme; ptr++)`
`132`	`132`	`{`
`133`	`133`	`if (searchstoplist(&(d->stoplist), ptr->lexeme))`
`134`	`134`	`{`
`135`	`135`	`pfree(ptr->lexeme);`
`136`	`136`	`ptr->lexeme = NULL;`
`137`		`- ptr++;`
`138`	`137`	`}`
`139`	`138`	`else`
`140`	`139`	`{`
`141`		`- memcpy(cptr, ptr, sizeof(TSLexeme));`
	`140`	`+ if (cptr != ptr)`
	`141`	`+ memcpy(cptr, ptr, sizeof(TSLexeme));`
`142`	`142`	`cptr++;`
`143`		`- ptr++;`
`144`	`143`	`}`
`145`	`144`	`}`
`146`	`145`	`cptr->lexeme = NULL;`
Original file line number	Diff line number	Diff line change
`@@ -125,7 +125,8 @@ uniqueentry(WordEntryIN a, int l, char buf, int *outbuflen)`
`125`	`125`	`buflen += res->poslen * sizeof(WordEntryPos) + sizeof(uint16);`
`126`	`126`	`}`
`127`	`127`	`res++;`
`128`		`- memcpy(res, ptr, sizeof(WordEntryIN));`
	`128`	`+ if (res != ptr)`
	`129`	`+ memcpy(res, ptr, sizeof(WordEntryIN));`
`129`	`130`	`}`
`130`	`131`	`else if (ptr->entry.haspos)`
`131`	`132`	`{`