Remove unnecessary type violation in tsvectorrecv().

tglsfdc · tglsfdc · commit 5fb9f967c373 · 2025-04-02T16:17:58.000-04:00
compareentry() is declared to work on WordEntryIN structs, but tsvectorrecv() is using it in two places to work on WordEntry structs. This is almost okay, since WordEntry is the first field of WordEntryIN. But on machines with 8-byte pointers, WordEntryIN will have a larger alignment spec than WordEntry, and it's at least theoretically possible that the compiler could generate code that depends on the larger alignment. Given the lack of field reports, this may be just a hypothetical bug that upsets nothing except sanitizer tools. Or it may be real on certain hardware but nobody's tried to use tsvectorrecv() on such hardware. In any case we should fix it, and the fix is trivial: just change compareentry() so that it works on WordEntry without any mention of WordEntryIN. We can also get rid of the quite-useless intermediate function WordEntryCMP. Bug: #18875 Reported-by: Alexander Lakhin <exclusion@gmail.com> Author: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/18875-07a29c49c825a608@postgresql.org Backpatch-through: 13
diff --git a/src/backend/utils/adt/tsvector.c b/src/backend/utils/adt/tsvector.c
@@ -24,7 +24,7 @@
 
 typedef struct
 {
-	WordEntry	entry;			/* must be first! */
+	WordEntry	entry;			/* must be first, see compareentry */
 	WordEntryPos *pos;
 	int			poslen;			/* number of elements in pos */
 } WordEntryIN;
@@ -80,16 +80,19 @@ uniquePos(WordEntryPos *a, int l)
 	return res + 1 - a;
 }
 
-/* Compare two WordEntryIN values for qsort */
+/*
+ * Compare two WordEntry structs for qsort_arg.  This can also be used on
+ * WordEntryIN structs, since those have WordEntry as their first field.
+ */
 static int
 compareentry(const void *va, const void *vb, void *arg)
 {
-	const WordEntryIN *a = (const WordEntryIN *) va;
-	const WordEntryIN *b = (const WordEntryIN *) vb;
+	const WordEntry *a = (const WordEntry *) va;
+	const WordEntry *b = (const WordEntry *) vb;
 	char	   *BufferStr = (char *) arg;
 
-	return tsCompareString(&BufferStr[a->entry.pos], a->entry.len,
-						   &BufferStr[b->entry.pos], b->entry.len,
+	return tsCompareString(&BufferStr[a->pos], a->len,
+						   &BufferStr[b->pos], b->len,
 						   false);
 }
 
@@ -168,12 +171,6 @@ uniqueentry(WordEntryIN *a, int l, char *buf, int *outbuflen)
 	return res + 1 - a;
 }
 
-static int
-WordEntryCMP(WordEntry *a, WordEntry *b, char *buf)
-{
-	return compareentry(a, b, buf);
-}
-
 
 Datum
 tsvectorin(PG_FUNCTION_ARGS)
@@ -512,7 +509,7 @@ tsvectorrecv(PG_FUNCTION_ARGS)
 
 		datalen += lex_len;
 
-		if (i > 0 && WordEntryCMP(&vec->entries[i],
+		if (i > 0 && compareentry(&vec->entries[i],
 								  &vec->entries[i - 1],
 								  STRPTR(vec)) <= 0)
 			needSort = true;
