+ struct tm *lt;
+ return ! (lt = localtime (&now)) || mktime (lt) == now;
+}
+
+static int
+mktime_test (time_t now)
+{
+ return (mktime_test1 (now)
+ && mktime_test1 ((time_t) (time_t_max - now))
+ && mktime_test1 ((time_t) (time_t_min + now)));
+}
+
+static int
+irix_6_4_bug ()
+{
+ /* Based on code from Ariel Faigon. */
+ struct tm tm;
+ tm.tm_year = 96;
+ tm.tm_mon = 3;
+ tm.tm_mday = 0;
+ tm.tm_hour = 0;
+ tm.tm_min = 0;
+ tm.tm_sec = 0;
+ tm.tm_isdst = -1;
+ mktime (&tm);
+ return tm.tm_mon == 2 && tm.tm_mday == 31;
+}
+
+static int
+bigtime_test (int j)
+{
+ struct tm tm;
+ time_t now;
+ tm.tm_year = tm.tm_mon = tm.tm_mday = tm.tm_hour = tm.tm_min = tm.tm_sec = j;
+ now = mktime (&tm);
+ if (now != (time_t) -1)
+ {
+ struct tm *lt = localtime (&now);
+ if (! (lt
+ && lt->tm_year == tm.tm_year
+ && lt->tm_mon == tm.tm_mon
+ && lt->tm_mday == tm.tm_mday
+ && lt->tm_hour == tm.tm_hour
+ && lt->tm_min == tm.tm_min
+ && lt->tm_sec == tm.tm_sec
+ && lt->tm_yday == tm.tm_yday
+ && lt->tm_wday == tm.tm_wday
+ && ((lt->tm_isdst < 0 ? -1 : 0 < lt->tm_isdst)
+ == (tm.tm_isdst < 0 ? -1 : 0 < tm.tm_isdst))))
+ return 0;
+ }
+ return 1;
+}
+
+static int
+year_2050_test ()
+{
+ /* The correct answer for 2050-02-01 00:00:00 in Pacific time,
+ ignoring leap seconds. */
+ unsigned long int answer = 2527315200UL;
+
+ struct tm tm;
+ time_t t;
+ tm.tm_year = 2050 - 1900;
+ tm.tm_mon = 2 - 1;
+ tm.tm_mday = 1;
+ tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
+ tm.tm_isdst = -1;
+
+ /* Use the portable POSIX.1 specification "TZ=PST8PDT,M4.1.0,M10.5.0"
+ instead of "TZ=America/Vancouver" in order to detect the bug even
+ on systems that don't support the Olson extension, or don't have the
+ full zoneinfo tables installed. */
+ putenv ("TZ=PST8PDT,M4.1.0,M10.5.0");
+
+ t = mktime (&tm);
+
+ /* Check that the result is either a failure, or close enough
+ to the correct answer that we can assume the discrepancy is
+ due to leap seconds. */
+ return (t == (time_t) -1
+ || (0 < t && answer - 120 <= t && t <= answer + 120));