Y2038: Add 64-bit time for all architectures

glibc support for 64-bit time_t on 32-bit architectures
will involve:

- Using 64-bit times inside glibc, with conversions
  to and from 32-bit times taking place as necessary
  for interfaces using such times.

- Adding 64-bit-time support in the glibc public API.
  This support should be dynamic, i.e. glibc should
  provide both 32-bit and 64-bit implementations and
   let user code choose at compile time whether to use
   the 32-bit or 64-bit interfaces.

This requires a glibc-internal name for a type for times
that are always 64-bit.

Based on __TIMESIZE, a new macro is defined, __TIME64_T_TYPE,
 which is always the right __*_T_TYPE to hold a 64-bit-time.
__TIME64_T_TYPE equals __TIME_T_TYPE if __TIMESIZE equals 64
and equals __SQUAD_T_TYPE otherwise.

__time64_t can then replace uses of internal_time_t.

This patch was tested by running 'make check' on branch
master then applying this patch and its predecessor and
running 'make check' again, and checking that both 'make
check' yield identical results. This was done on
x86_64-linux-gnu and i686-linux-gnu.

	* bits/time64.h: New file.
	* include/time.h: Replace internal_time_t with __time64_t.
	* posix/bits/types (__time64_t): Add.
	* stdlib/Makefile: Add bits/time64.h to includes.
	* time/tzfile.c: Replace internal_time_t with __time64_t.

1 files changed, 36 insertions, 0 deletions

diff --git a/bits/time64.h b/bits/time64.h
new file mode 100644
index 0000000000..c8a9c7db5f
--- /dev/null
+++ b/bits/time64.h
@@ -0,0 +1,36 @@
+/* bits/time64.h -- underlying types for __time64_t.  Generic version.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library 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.
+
+   The GNU C Library 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 the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _BITS_TYPES_H
+# error "Never include <bits/time64.h> directly; use <sys/types.h> instead."
+#endif
+
+#ifndef	_BITS_TIME64_H
+#define	_BITS_TIME64_H	1
+
+/* Define __TIME64_T_TYPE so that it is always a 64-bit type.  */
+
+#if __TIMESIZE == 64
+/* If we already have 64-bit time type then use it.  */
+# define __TIME64_T_TYPE		__TIME_T_TYPE
+#else
+/* Define a 64-bit time type alongsize the 32-bit one.  */
+# define __TIME64_T_TYPE		__SQUAD_TYPE
+#endif
+
+#endif /* bits/time64.h */