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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 1f2b195ebf
commit 014796aa3f
1 changed files with 29 additions and 1 deletions
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30
contrib/pgbench/pgbench.c
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@ -57,6 +57,10 @@
#ifndef INT64_MAX #ifndef INT64_MAX
#define INT64_MAX INT64CONST(0x7FFFFFFFFFFFFFFF) #define INT64_MAX INT64CONST(0x7FFFFFFFFFFFFFFF)
#endif #endif
#ifndef INT64_MIN
#define INT64_MIN (-INT64CONST(0x7FFFFFFFFFFFFFFF) - 1)
#endif
/* /*
* Multi-platform pthread implementations * Multi-platform pthread implementations
@ -1331,13 +1335,37 @@ top:
snprintf(res, sizeof(res), INT64_FORMAT, ope1 * ope2); snprintf(res, sizeof(res), INT64_FORMAT, ope1 * ope2);
else if (strcmp(argv[3], "/") == 0) else if (strcmp(argv[3], "/") == 0)
{ {
int64 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), INT64_FORMAT, ope1 / ope2); /*
* INT64_MIN / -1 is problematic, since the result can't
* be represented on a two's-complement machine. Some
* machines produce INT64_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 INT64_MIN) */
if (ope1 == INT64_MIN)
{
fprintf(stderr, "bigint out of range\n");
st->ecnt++;
return true;
}
}
else
operes = ope1 / ope2;
snprintf(res, sizeof(res), INT64_FORMAT, operes);
} }
else else
{ {