time-util: refuse formatting/parsing times that we can't store

usec_t is always 64bit, which means it can cover quite a number of
years. However, 4 digit year display and glibc limitations around time_t
limit what we can actually parse and format. Let's make this explicit,
so that we never end up formatting dates we can#t parse and vice versa.

Note that this is really just about formatting/parsing. Internal
calculations with times outside of the formattable range are not
affected.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/basic/calendarspec.c b/src/basic/calendarspec.c
index 35dfb6a3db..3fa1c51ace 100644
--- a/src/basic/calendarspec.c
+++ b/src/basic/calendarspec.c
@@ -1228,6 +1228,9 @@ int calendar_spec_next_usec(const CalendarSpec *spec, usec_t usec, usec_t *next)
         assert(spec);
         assert(next);
 
+        if (usec > USEC_TIMESTAMP_FORMATTABLE_MAX)
+                return -EINVAL;
+
         usec++;
         t = (time_t) (usec / USEC_PER_SEC);
         assert_se(localtime_or_gmtime_r(&t, &tm, spec->utc));