From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 11 Mar 2011 23:18:55 +0000 (-0500)
Subject: Put in some more safeguards against executing a division-by-zero.
X-Git-Tag: REL9_1_ALPHA5~94
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=72330995a52fb7a3fbdc666aebc0402cdcbc9af8;p=postgresql

Put in some more safeguards against executing a division-by-zero.

Add dummy returns before every potential division-by-zero in int8.c,
because apparently further "improvements" in gcc's optimizer have
enabled it to break functions that weren't broken before.

Aurelien Jarno, via Martin Pitt
---

diff --git a/src/backend/utils/adt/int8.c b/src/backend/utils/adt/int8.c
index bbab90c0c1..451916480c 100644
--- a/src/backend/utils/adt/int8.c
+++ b/src/backend/utils/adt/int8.c
@@ -590,9 +590,13 @@ int8div(PG_FUNCTION_ARGS)
 	int64		result;
 
 	if (arg2 == 0)
+	{
 		ereport(ERROR,
 				(errcode(ERRCODE_DIVISION_BY_ZERO),
 				 errmsg("division by zero")));
+		/* ensure compiler realizes we mustn't reach the division (gcc bug) */
+		PG_RETURN_NULL();
+	}
 
 	result = arg1 / arg2;
 
@@ -637,9 +641,14 @@ int8mod(PG_FUNCTION_ARGS)
 	int64		arg2 = PG_GETARG_INT64(1);
 
 	if (arg2 == 0)
+	{
 		ereport(ERROR,
 				(errcode(ERRCODE_DIVISION_BY_ZERO),
 				 errmsg("division by zero")));
+		/* ensure compiler realizes we mustn't reach the division (gcc bug) */
+		PG_RETURN_NULL();
+	}
+
 	/* No overflow is possible */
 
 	PG_RETURN_INT64(arg1 % arg2);
@@ -813,9 +822,13 @@ int84div(PG_FUNCTION_ARGS)
 	int64		result;
 
 	if (arg2 == 0)
+	{
 		ereport(ERROR,
 				(errcode(ERRCODE_DIVISION_BY_ZERO),
 				 errmsg("division by zero")));
+		/* ensure compiler realizes we mustn't reach the division (gcc bug) */
+		PG_RETURN_NULL();
+	}
 
 	result = arg1 / arg2;
 
@@ -997,9 +1010,13 @@ int82div(PG_FUNCTION_ARGS)
 	int64		result;
 
 	if (arg2 == 0)
+	{
 		ereport(ERROR,
 				(errcode(ERRCODE_DIVISION_BY_ZERO),
 				 errmsg("division by zero")));
+		/* ensure compiler realizes we mustn't reach the division (gcc bug) */
+		PG_RETURN_NULL();
+	}
 
 	result = arg1 / arg2;