Catch overflow when rounding intervals in AdjustIntervalForTypmod.

Previously, an interval microseconds field close to INT64_MAX or
INT64_MIN could overflow, producing a result with not even the
correct sign, while being rounded to match a precision specification.

This seems worth fixing, but not worth back-patching, in part
because the ereturn() notation doesn't exist very far back.

Report and patch by Joseph Koshakow (some cosmetic mods by me)

Discussion: https://postgr.es/m/CAAvxfHfpuLgqJYzkUcher466Z1LpmE+5Sm+zc8L6zKCOQ+6TDQ@mail.gmail.com

src/backend/utils/adt/timestamp.c

@@ -1509,17 +1509,23 @@ AdjustIntervalForTypmod(Interval *interval, int32 typmod,
 
 			if (interval->time >= INT64CONST(0))
 			{
-				interval->time = ((interval->time +
-								   IntervalOffsets[precision]) /
-								  IntervalScales[precision]) *
-					IntervalScales[precision];
+				if (pg_add_s64_overflow(interval->time,
+										IntervalOffsets[precision],
+										&interval->time))
+					ereturn(escontext, false,
+							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+							 errmsg("interval out of range")));
+				interval->time -= interval->time % IntervalScales[precision];
 			}
 			else
 			{
-				interval->time = -(((-interval->time +
-									 IntervalOffsets[precision]) /
-									IntervalScales[precision]) *
-								   IntervalScales[precision]);
+				if (pg_sub_s64_overflow(interval->time,
+										IntervalOffsets[precision],
+										&interval->time))
+					ereturn(escontext, false,
+							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+							 errmsg("interval out of range")));
+				interval->time -= interval->time % IntervalScales[precision];
 			}
 		}
 	}

src/test/regress/expected/interval.out

@@ -929,6 +929,14 @@ SELECT interval '1 2:03:04.5678' minute to second(2);
  1 day 02:03:04.57
 (1 row)
 
+SELECT interval '2562047788:00:54.775807' second(2);  -- out of range
+ERROR:  interval out of range
+LINE 1: SELECT interval '2562047788:00:54.775807' second(2);
+                        ^
+SELECT interval '-2562047788:00:54.775807' second(2);  -- out of range
+ERROR:  interval out of range
+LINE 1: SELECT interval '-2562047788:00:54.775807' second(2);
+                        ^
 -- test casting to restricted precision (bug #14479)
 SELECT f1, f1::INTERVAL DAY TO MINUTE AS "minutes",
   (f1 + INTERVAL '1 month')::INTERVAL MONTH::INTERVAL YEAR AS "years"

src/test/regress/sql/interval.sql

@@ -270,6 +270,8 @@ SELECT interval '1 2:03:04.5678' hour to second(2);
 SELECT interval '1 2.3456' minute to second(2);
 SELECT interval '1 2:03.5678' minute to second(2);
 SELECT interval '1 2:03:04.5678' minute to second(2);
+SELECT interval '2562047788:00:54.775807' second(2);  -- out of range
+SELECT interval '-2562047788:00:54.775807' second(2);  -- out of range
 
 -- test casting to restricted precision (bug #14479)
 SELECT f1, f1::INTERVAL DAY TO MINUTE AS "minutes",