Tweak the overflow checks in integer division functions to complain if the

machine produces zero (rather than the more usual minimum-possible-integer)
for the only possible overflow case.  This has been seen to occur for at least
some word widths on some hardware, and it's cheap enough to check for
everywhere.  Per Peter's analysis of buildfarm reports.

This could be back-patched, but in the absence of any gripes from the field
I doubt it's worth the trouble.

diff --git a/src/backend/utils/adt/int.c b/src/backend/utils/adt/int.c
index b8d78b783d00a19137e4c0deb20ee7edea5577de..70c5e75db0e01a600ee504368b70bdf4a1974eb2 100644 (file)
--- a/src/backend/utils/adt/int.c
+++ b/src/backend/utils/adt/int.c
@@ -735,9 +735,10 @@ int4div(PG_FUNCTION_ARGS)
        /*
         * Overflow check.      The only possible overflow case is for arg1 = INT_MIN,
         * arg2 = -1, where the correct result is -INT_MIN, which can't be
-        * represented on a two's-complement machine.
+        * represented on a two's-complement machine.  Most machines produce
+        * INT_MIN but it seems some produce zero.
         */
-       if (arg2 == -1 && arg1 < 0 && result < 0)
+       if (arg2 == -1 && arg1 < 0 && result <= 0)
                ereport(ERROR,
                                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                                 errmsg("integer out of range")));
@@ -863,9 +864,10 @@ int2div(PG_FUNCTION_ARGS)
        /*
         * Overflow check.      The only possible overflow case is for arg1 =
         * SHRT_MIN, arg2 = -1, where the correct result is -SHRT_MIN, which can't
-        * be represented on a two's-complement machine.
+        * be represented on a two's-complement machine.  Most machines produce
+        * SHRT_MIN but it seems some produce zero.
         */
-       if (arg2 == -1 && arg1 < 0 && result < 0)
+       if (arg2 == -1 && arg1 < 0 && result <= 0)
                ereport(ERROR,
                                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                                 errmsg("smallint out of range")));
@@ -1041,9 +1043,10 @@ int42div(PG_FUNCTION_ARGS)
        /*
         * Overflow check.      The only possible overflow case is for arg1 = INT_MIN,
         * arg2 = -1, where the correct result is -INT_MIN, which can't be
-        * represented on a two's-complement machine.
+        * represented on a two's-complement machine.  Most machines produce
+        * INT_MIN but it seems some produce zero.
         */
-       if (arg2 == -1 && arg1 < 0 && result < 0)
+       if (arg2 == -1 && arg1 < 0 && result <= 0)
                ereport(ERROR,
                                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                                 errmsg("integer out of range")));

diff --git a/src/backend/utils/adt/int8.c b/src/backend/utils/adt/int8.c
index fa04a29b63d67ac224de413db6d6ba26163d2f3f..b77830f254e481fbadb24a10de76f63892a31f59 100644 (file)
--- a/src/backend/utils/adt/int8.c
+++ b/src/backend/utils/adt/int8.c
@@ -608,9 +608,10 @@ int8div(PG_FUNCTION_ARGS)
        /*
         * Overflow check.      The only possible overflow case is for arg1 =
         * INT64_MIN, arg2 = -1, where the correct result is -INT64_MIN, which
-        * can't be represented on a two's-complement machine.
+        * can't be represented on a two's-complement machine.  Most machines
+        * produce INT64_MIN but it seems some produce zero.
         */
-       if (arg2 == -1 && arg1 < 0 && result < 0)
+       if (arg2 == -1 && arg1 < 0 && result <= 0)
                ereport(ERROR,
                                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                                 errmsg("bigint out of range")));
@@ -830,9 +831,10 @@ int84div(PG_FUNCTION_ARGS)
        /*
         * Overflow check.      The only possible overflow case is for arg1 =
         * INT64_MIN, arg2 = -1, where the correct result is -INT64_MIN, which
-        * can't be represented on a two's-complement machine.
+        * can't be represented on a two's-complement machine.  Most machines
+        * produce INT64_MIN but it seems some produce zero.
         */
-       if (arg2 == -1 && arg1 < 0 && result < 0)
+       if (arg2 == -1 && arg1 < 0 && result <= 0)
                ereport(ERROR,
                                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                                 errmsg("bigint out of range")));
@@ -1008,9 +1010,10 @@ int82div(PG_FUNCTION_ARGS)
        /*
         * Overflow check.      The only possible overflow case is for arg1 =
         * INT64_MIN, arg2 = -1, where the correct result is -INT64_MIN, which
-        * can't be represented on a two's-complement machine.
+        * can't be represented on a two's-complement machine.  Most machines
+        * produce INT64_MIN but it seems some produce zero.
         */
-       if (arg2 == -1 && arg1 < 0 && result < 0)
+       if (arg2 == -1 && arg1 < 0 && result <= 0)
                ereport(ERROR,
                                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                                 errmsg("bigint out of range")));