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pgbench: Install guard against overflow when dividing by -1.

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Commit 64f5edca2401f6c2f23564da9dd52e92d08b3a20 fixed the same hazard
on master; this is a backport, but the modulo operator does not exist
in older releases.

Michael Paquier
This commit is contained in:
Robert Haas 2016-02-03 09:15:29 -05:00
parent d9ce5d201d
commit b63a4f418f
1 changed files with 29 additions and 1 deletions
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30
contrib/pgbench/pgbench.c
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@ -56,6 +56,10 @@
#ifndef INT64_MAX #ifndef INT64_MAX
#define INT64_MAX INT64CONST(0x7FFFFFFFFFFFFFFF) #define INT64_MAX INT64CONST(0x7FFFFFFFFFFFFFFF)
#endif #endif
#ifndef INT32_MIN
#define INT32_MIN (-0x7FFFFFFF-1)
#endif
/* /*
* Multi-platform pthread implementations * Multi-platform pthread implementations
@ -1152,13 +1156,37 @@ top:
snprintf(res, sizeof(res), "%d", ope1 * ope2); snprintf(res, sizeof(res), "%d", ope1 * ope2);
else if (strcmp(argv[3], "/") == 0) else if (strcmp(argv[3], "/") == 0)
{ {
int operes;
if (ope2 == 0) if (ope2 == 0)
{ {
fprintf(stderr, "%s: division by zero\n", argv[0]); fprintf(stderr, "%s: division by zero\n", argv[0]);
st->ecnt++; st->ecnt++;
return true; 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 else
{ {