1 files changed, 34 insertions, 1 deletions
diff --git a/lib/mktime-internal.h b/lib/mktime-internal.h
index 4287acf4ac..0c9e204050 100644
--- a/lib/mktime-internal.h
+++ b/lib/mktime-internal.h
@@ -1,4 +1,37 @@
+/* mktime variant that also uses an offset guess
+
+   Copyright 2016 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this program; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
 #include <time.h>
+
+/* mktime_offset_t is a signed type wide enough to hold a UTC offset
+   in seconds, and used as part of the type of the offset-guess
+   argument to mktime_internal.  Use time_t on platforms where time_t
+   is signed, to be compatible with platforms like BeOS that export
+   this implementation detail of mktime.  On platforms where time_t is
+   unsigned, GNU and POSIX code can assume 'int' is at least 32 bits
+   which is wide enough for a UTC offset.  */
+
+#if TIME_T_IS_SIGNED
+typedef time_t mktime_offset_t;
+#else
+typedef int mktime_offset_t;
+#endif
+
 time_t mktime_internal (struct tm *,
                         struct tm * (*) (time_t const *, struct tm *),
-                        time_t *);
+                        mktime_offset_t *);