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[PATCH v10 1/3] Y2038: provide size of default time_t for target architecture

From: "Albert ARIBAUD (3ADEV)" <albert dot aribaud at 3adev dot fr>
To: libc-alpha at sourceware dot org
Cc: "Albert ARIBAUD (3ADEV)" <albert dot aribaud at 3adev dot fr>
Date: Fri, 12 Oct 2018 23:06:06 +0200
Subject: [PATCH v10 1/3] Y2038: provide size of default time_t for target architecture

To determine whether the default time_t interfaces are 32-bit
and so need conversions, or are 64-bit and so are compatible
with the internal 64-bit type without conversions, a macro
giving the size of the  default time_t is also required.
This macro is called __TIMESIZE.

This macro can then be used instead of __WORDSIZE in msq-pad.h
files, which in turn allows removing the x86 variant of them.

This patch was tested by running 'make check' on branch master
then applying this patch 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/timesize.h: New file.
* sysdeps/unix/sysv/linux/bits/msq-pad.h: Replace __WORDSIZE with __TIMESIZE.
* sysdeps/unix/sysv/linux/hppa/bits/msq-pad.h: Likewise.
* sysdeps/unix/sysv/linux/mips/bits/msq-pad.h: Likewise.
* sysdeps/unix/sysv/linux/powerpc/bits/msq-pad.h: Likewise.
* sysdeps/unix/sysv/linux/sparc/bits/msq-pad.h: Likewise.
* sysdeps/unix/sysv/linux/x86/bits/msq-pad.h: Delete file.
* sysdeps/unix/sysv/linux/x86/bits/timesize.h: New file.
---
 bits/timesize.h                               | 22 +++++++++++++++++++
 sysdeps/unix/sysv/linux/bits/msq-pad.h        |  4 ++--
 sysdeps/unix/sysv/linux/hppa/bits/msq-pad.h   |  4 ++--
 sysdeps/unix/sysv/linux/mips/bits/msq-pad.h   |  6 ++---
 .../unix/sysv/linux/powerpc/bits/msq-pad.h    |  4 ++--
 sysdeps/unix/sysv/linux/sparc/bits/msq-pad.h  |  4 ++--
 .../linux/x86/bits/{msq-pad.h => timesize.h}  | 15 +++++--------
 7 files changed, 39 insertions(+), 20 deletions(-)
 create mode 100644 bits/timesize.h
 rename sysdeps/unix/sysv/linux/x86/bits/{msq-pad.h => timesize.h} (74%)

diff --git a/bits/timesize.h b/bits/timesize.h
new file mode 100644
index 0000000000..cc47ff165f
--- /dev/null
+++ b/bits/timesize.h
@@ -0,0 +1,22 @@
+/* Bit size of the time_t type at glibc build time, general case.
+   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/>.  */
+
+#include <bits/wordsize.h>
+
+/* Size in bits of the 'time_t' type of the default ABI.  */
+#define __TIMESIZE	__WORDSIZE
diff --git a/sysdeps/unix/sysv/linux/bits/msq-pad.h b/sysdeps/unix/sysv/linux/bits/msq-pad.h
index 97dee0beff..53f367dfa2 100644
--- a/sysdeps/unix/sysv/linux/bits/msq-pad.h
+++ b/sysdeps/unix/sysv/linux/bits/msq-pad.h
@@ -20,12 +20,12 @@
 # error "Never use <bits/msq-pad.h> directly; include <sys/msg.h> instead."
 #endif
 
-#include <bits/wordsize.h>
+#include <bits/timesize.h>
 
 /* On most architectures, padding goes after time fields for 32-bit
    systems and is omitted for 64-bit systems.  Some architectures pad
    before time fields instead, or omit padding despite being
    32-bit.  */
 
-#define __MSQ_PAD_AFTER_TIME (__WORDSIZE == 32)
+#define __MSQ_PAD_AFTER_TIME (__TIMESIZE == 32)
 #define __MSQ_PAD_BEFORE_TIME 0
diff --git a/sysdeps/unix/sysv/linux/hppa/bits/msq-pad.h b/sysdeps/unix/sysv/linux/hppa/bits/msq-pad.h
index 10b26b7ea6..05db3fd65b 100644
--- a/sysdeps/unix/sysv/linux/hppa/bits/msq-pad.h
+++ b/sysdeps/unix/sysv/linux/hppa/bits/msq-pad.h
@@ -20,7 +20,7 @@
 # error "Never use <bits/msq-pad.h> directly; include <sys/msg.h> instead."
 #endif
 
-#include <bits/wordsize.h>
+#include <bits/timesize.h>
 
 #define __MSQ_PAD_AFTER_TIME 0
-#define __MSQ_PAD_BEFORE_TIME (__WORDSIZE == 32)
+#define __MSQ_PAD_BEFORE_TIME (__TIMESIZE == 32)
diff --git a/sysdeps/unix/sysv/linux/mips/bits/msq-pad.h b/sysdeps/unix/sysv/linux/mips/bits/msq-pad.h
index 1ddfb0d271..530babe3f9 100644
--- a/sysdeps/unix/sysv/linux/mips/bits/msq-pad.h
+++ b/sysdeps/unix/sysv/linux/mips/bits/msq-pad.h
@@ -20,12 +20,12 @@
 # error "Never use <bits/msq-pad.h> directly; include <sys/msg.h> instead."
 #endif
 
-#include <bits/wordsize.h>
+#include <bits/timesize.h>
 
 #ifdef __MIPSEL__
-# define __MSQ_PAD_AFTER_TIME (__WORDSIZE == 32)
+# define __MSQ_PAD_AFTER_TIME (__TIMESIZE == 32)
 # define __MSQ_PAD_BEFORE_TIME 0
 #else
 # define __MSQ_PAD_AFTER_TIME 0
-# define __MSQ_PAD_BEFORE_TIME (__WORDSIZE == 32)
+# define __MSQ_PAD_BEFORE_TIME (__TIMESIZE == 32)
 #endif
diff --git a/sysdeps/unix/sysv/linux/powerpc/bits/msq-pad.h b/sysdeps/unix/sysv/linux/powerpc/bits/msq-pad.h
index 9680176abb..d19dfd5126 100644
--- a/sysdeps/unix/sysv/linux/powerpc/bits/msq-pad.h
+++ b/sysdeps/unix/sysv/linux/powerpc/bits/msq-pad.h
@@ -20,7 +20,7 @@
 # error "Never use <bits/msq-pad.h> directly; include <sys/msg.h> instead."
 #endif
 
-#include <bits/wordsize.h>
+#include <bits/timesize.h>
 
 #define __MSQ_PAD_AFTER_TIME 0
-#define __MSQ_PAD_BEFORE_TIME (__WORDSIZE == 32)
+#define __MSQ_PAD_BEFORE_TIME (__TIMESIZE == 32)
diff --git a/sysdeps/unix/sysv/linux/sparc/bits/msq-pad.h b/sysdeps/unix/sysv/linux/sparc/bits/msq-pad.h
index 3dfeb07a48..72324e8428 100644
--- a/sysdeps/unix/sysv/linux/sparc/bits/msq-pad.h
+++ b/sysdeps/unix/sysv/linux/sparc/bits/msq-pad.h
@@ -20,7 +20,7 @@
 # error "Never use <bits/msq-pad.h> directly; include <sys/msg.h> instead."
 #endif
 
-#include <bits/wordsize.h>
+#include <bits/timesize.h>
 
 #define __MSQ_PAD_AFTER_TIME 0
-#define __MSQ_PAD_BEFORE_TIME (__WORDSIZE == 32)
+#define __MSQ_PAD_BEFORE_TIME (__TIMESIZE == 32)
diff --git a/sysdeps/unix/sysv/linux/x86/bits/msq-pad.h b/sysdeps/unix/sysv/linux/x86/bits/timesize.h
similarity index 74%
rename from sysdeps/unix/sysv/linux/x86/bits/msq-pad.h
rename to sysdeps/unix/sysv/linux/x86/bits/timesize.h
index 5d46956c77..8b88ab84b0 100644
--- a/sysdeps/unix/sysv/linux/x86/bits/msq-pad.h
+++ b/sysdeps/unix/sysv/linux/x86/bits/timesize.h
@@ -1,4 +1,4 @@
-/* Define where padding goes in struct msqid_ds.  x86 version.
+/* Bit size of the time_t type at glibc build time, x86-64 and x32 case.
    Copyright (C) 2018 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
@@ -16,13 +16,10 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#ifndef _SYS_MSG_H
-# error "Never use <bits/msq-pad.h> directly; include <sys/msg.h> instead."
-#endif
-
-#ifdef __x86_64__
-# define __MSQ_PAD_AFTER_TIME 0
+#if defined __x86_64__ && defined __ILP32__
+/* For x32, time is 64-bit even though word size is 32-bit.  */
+# define __TIMESIZE	64
 #else
-# define __MSQ_PAD_AFTER_TIME 1
+/* For others, time size is word size.  */
+# define __TIMESIZE	__WORDSIZE
 #endif
-#define __MSQ_PAD_BEFORE_TIME 0
-- 
2.17.1

Follow-Ups:
- [PATCH v10 2/3] Y2038: Add 64-bit time for all architectures
  - From: Albert ARIBAUD (3ADEV)
- [PATCH v10 3/3] Y2038: make __tz_convert compatible with 64-bit-time
  - From: Albert ARIBAUD (3ADEV)
- Re: [PATCH v10 1/3] Y2038: provide size of default time_t for target architecture
  - From: Joseph Myers

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