Y2038: add function __gmtime64

Tested with 'make check' on x86_64-linux-gnu and i686-linux.gnu.

	* include/time.h
	(__gmtime64): Add.
	* time/gmtime.c
	(__gmtime64): Add.
	[__TIMESIZE != 64] (__gmtime): Turn into a wrapper.

3 files changed, 29 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index 4724c84e08..fe1b8fcec6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,12 @@
 2018-12-18  Albert ARIBAUD <albert.aribaud@3adev.fr>
 
 	* include/time.h
+	(__gmtime64): Add.
+	* time/gmtime.c
+	(__gmtime64): Add.
+	[__TIMESIZE != 64] (__gmtime): Turn into a wrapper.
+
+	* include/time.h
 	(__localtime64_r): Add.
 	* time/localtime.c
 	(__localtime64_r): Add.
diff --git a/include/time.h b/include/time.h
index 876b8a2b5f..c5881acf9f 100644
--- a/include/time.h
+++ b/include/time.h
@@ -79,6 +79,13 @@ extern struct tm *__gmtime_r (const time_t *__restrict __timer,
 			      struct tm *__restrict __tp);
 libc_hidden_proto (__gmtime_r)
 
+#if __TIMESIZE == 64
+# define __gmtime64 gmtime
+#else
+extern struct tm *__gmtime64 (const __time64_t *__timer);
+libc_hidden_proto (__gmtime64)
+#endif
+
 /* Compute the `struct tm' representation of T,
    offset OFFSET seconds east of UTC,
    and store year, yday, mon, mday, wday, hour, min, sec into *TP.
diff --git a/time/gmtime.c b/time/gmtime.c
index bda09bc021..ee901c3ba1 100644
--- a/time/gmtime.c
+++ b/time/gmtime.c
@@ -28,10 +28,24 @@ __gmtime_r (const time_t *t, struct tm *tp)
 libc_hidden_def (__gmtime_r)
 weak_alias (__gmtime_r, gmtime_r)
 
+/* Return the `struct tm' representation of *T in UTC.  */
+struct tm *
+__gmtime64 (const __time64_t *t)
+{
+  return __tz_convert (*t, 0, &_tmbuf);
+}
+
+/* Provide a 32-bit variant if needed.  */
+
+#if __TIMESIZE != 64
+
+libc_hidden_def (__gmtime64)
 
-/* Return the `struct tm' representation of *T in UTC.	*/
 struct tm *
 gmtime (const time_t *t)
 {
-  return __tz_convert (*t, 0, &_tmbuf);
+  __time64_t t64 = *t;
+  return __gmtime64 (&t64);
 }
+
+#endif