Fix overflow hazards in interval input and output conversions.

DecodeInterval (interval input) was careless about integer-overflow
hazards, allowing bogus results to be obtained for sufficiently
large input values.  Also, since it initially converted the input
to a "struct tm", it was impossible to produce the full range of
representable interval values.

Meanwhile, EncodeInterval (interval output) and a few other
functions could suffer failures if asked to process sufficiently
large interval values, because they also relied on being able to
represent an interval in "struct tm" which is not designed to
handle that.

Fix all this stuff by introducing new struct types that are more
fit for purpose.

While this is clearly a bug fix, it's also an API break for any
code that's calling these functions directly.  So back-patching
doesn't seem wise, especially in view of the lack of field
complaints.

Joe Koshakow, editorialized a bit by me

Discussion: https://postgr.es/m/CAAvxfHff0JLYHwyBrtMx_=6wr=k2Xp+D+-X3vEhHjJYMj+mQcg@mail.gmail.com

1 files changed, 3 insertions, 2 deletions

diff --git a/src/include/utils/timestamp.h b/src/include/utils/timestamp.h
index c1a74f8e2b0..d33421d3809 100644
--- a/src/include/utils/timestamp.h
+++ b/src/include/utils/timestamp.h
@@ -88,8 +88,9 @@ extern int	timestamp2tm(Timestamp dt, int *tzp, struct pg_tm *tm,
 						 fsec_t *fsec, const char **tzn, pg_tz *attimezone);
 extern void dt2time(Timestamp dt, int *hour, int *min, int *sec, fsec_t *fsec);
 
-extern int	interval2tm(Interval span, struct pg_tm *tm, fsec_t *fsec);
-extern int	tm2interval(struct pg_tm *tm, fsec_t fsec, Interval *span);
+extern void interval2itm(Interval span, struct pg_itm *itm);
+extern int	itm2interval(struct pg_itm *itm, Interval *span);
+extern int	itmin2interval(struct pg_itm_in *itm_in, Interval *span);
 
 extern Timestamp SetEpochTimestamp(void);
 extern void GetEpochTime(struct pg_tm *tm);