From b63a4f418f5611272f28d0633932ffbf3bbd3015 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 3 Feb 2016 09:15:29 -0500
Subject: [PATCH] pgbench: Install guard against overflow when dividing by -1.
Commit 64f5edca2401f6c2f23564da9dd52e92d08b3a20 fixed the same hazard
on master; this is a backport, but the modulo operator does not exist
in older releases.
Michael Paquier
---
contrib/pgbench/pgbench.c | 30 +++++++++++++++++++++++++++++-
1 file changed, 29 insertions(+), 1 deletion(-)
diff --git a/contrib/pgbench/pgbench.c b/contrib/pgbench/pgbench.c
index 2111f16f358..84b630336fe 100644
--- a/contrib/pgbench/pgbench.c
+++ b/contrib/pgbench/pgbench.c
@@ -56,6 +56,10 @@
#ifndef INT64_MAX
#define INT64_MAX INT64CONST(0x7FFFFFFFFFFFFFFF)
#endif
+#ifndef INT32_MIN
+#define INT32_MIN (-0x7FFFFFFF-1)
+#endif
+
/*
* Multi-platform pthread implementations
@@ -1152,13 +1156,37 @@ top:
snprintf(res, sizeof(res), "%d", ope1 * ope2);
else if (strcmp(argv[3], "/") == 0)
{
+ int operes;
+
if (ope2 == 0)
{
fprintf(stderr, "%s: division by zero\n", argv[0]);
st->ecnt++;
return true;
}
- snprintf(res, sizeof(res), "%d", ope1 / ope2);
+ /*
+ * INT32_MIN / -1 is problematic, since the result can't
+ * be represented on a two's-complement machine. Some
+ * machines produce INT32_MIN, some produce zero, some
+ * throw an exception. We can dodge the problem by
+ * recognizing that division by -1 is the same as
+ * negation.
+ */
+ if (ope2 == -1)
+ {
+ operes = -ope1;
+
+ /* overflow check (needed for INT32_MIN) */
+ if (ope1 == INT32_MIN)
+ {
+ fprintf(stderr, "integer out of range\n");
+ st->ecnt++;
+ return true;
+ }
+ }
+ else
+ operes = ope1 / ope2;
+ snprintf(res, sizeof(res), "%d", operes);
}
else
{
--
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