From 4ecbdc8220d02aecdde6174d77ebb6d2e23edefd Mon Sep 17 00:00:00 2001 From: Bruno Haible Date: Sat, 13 May 2017 03:04:54 +0200 Subject: [PATCH] year2038: New module. * m4/year2038.m4: New file. * modules/year2038: New file. * doc/year2038.texi: New file. * doc/gnulib.texi: Include it. --- ChangeLog | 8 ++++++ doc/gnulib.texi | 3 +++ doc/year2038.texi | 10 ++++++++ m4/year2038.m4 | 63 +++++++++++++++++++++++++++++++++++++++++++++++ modules/year2038 | 28 +++++++++++++++++++++ 5 files changed, 112 insertions(+) create mode 100644 doc/year2038.texi create mode 100644 m4/year2038.m4 create mode 100644 modules/year2038 diff --git a/ChangeLog b/ChangeLog index 11775f9a8e..5629553223 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,11 @@ +2017-05-13 Bruno Haible + + year2038: New module. + * m4/year2038.m4: New file. + * modules/year2038: New file. + * doc/year2038.texi: New file. + * doc/gnulib.texi: Include it. + 2017-05-13 Bruno Haible largefile: Simplify. diff --git a/doc/gnulib.texi b/doc/gnulib.texi index 9a255531a3..5cadf468ea 100644 --- a/doc/gnulib.texi +++ b/doc/gnulib.texi @@ -6325,6 +6325,7 @@ to POSIX that it can be treated like any other Unix-like platform. * Libtool and Windows:: * Large File Support:: * Precise file timestamps on Windows:: +* Avoiding the year 2038 problem:: * Windows sockets:: * Native Windows Support without MSVC Support:: @end menu @@ -6335,6 +6336,8 @@ to POSIX that it can be treated like any other Unix-like platform. @include windows-stat-timespec.texi +@include year2038.texi + @include windows-sockets.texi @include windows-without-msvc.texi diff --git a/doc/year2038.texi b/doc/year2038.texi new file mode 100644 index 0000000000..de85bc6d28 --- /dev/null +++ b/doc/year2038.texi @@ -0,0 +1,10 @@ +@node Avoiding the year 2038 problem +@section Avoiding the year 2038 problem + +The ``year 2038 problem'' denotes unpredictable behaviour of programs +that will likely occur in the year 2038, for programs that use a 32-bit +@samp{time_t} type. See @url{https://en.wikipedia.org/wiki/Year_2038_problem} +for details. + +The gnulib module @samp{year2038} attempts to avoid this problem, by +ensuring that @code{time_t} is a 64-bit type. diff --git a/m4/year2038.m4 b/m4/year2038.m4 new file mode 100644 index 0000000000..6e21f631dd --- /dev/null +++ b/m4/year2038.m4 @@ -0,0 +1,63 @@ +# year2038.m4 serial 1 +dnl Copyright (C) 2017 Free Software Foundation, Inc. +dnl This file is free software; the Free Software Foundation +dnl gives unlimited permission to copy and/or distribute it, +dnl with or without modifications, as long as this notice is preserved. + +dnl Attempt to ensure that 'time_t' is a 64-bit type +dnl and that the functions time(), stat(), etc. return 64-bit times. + +AC_DEFUN([gl_YEAR2038_EARLY], +[ + AC_REQUIRE([AC_CANONICAL_HOST]) + case "$host_os" in + mingw*) + AC_DEFINE([__MINGW_USE_VC2005_COMPAT], [1], + [For 64-bit time_t on 32-bit mingw.]) + ;; + esac +]) + +AC_DEFUN([gl_YEAR2038], +[ + AC_REQUIRE([AC_CANONICAL_HOST]) + case "$host_os" in + mingw*) + dnl On native Windows, the system include files define types __time32_t + dnl and __time64_t. By default, time_t is an alias of + dnl - __time32_t on 32-bit mingw, + dnl - __time64_t on 64-bit mingw and on MSVC (since MSVC 8). + dnl But when compiling with -D__MINGW_USE_VC2005_COMPAT, time_t is an + dnl alias of __time64_t. + dnl And when compiling with -D_USE_32BIT_TIME_T, time_t is an alias of + dnl __time32_t. + AC_CACHE_CHECK([for 64-bit time_t], [gl_cv_type_time_t_64], + [AC_COMPILE_IFELSE( + [AC_LANG_PROGRAM( + [[#include + int verify_time_t_size[sizeof (time_t) >= 8 ? 1 : -1]; + ]], + [[]])], + [gl_cv_type_time_t_64=yes], [gl_cv_type_time_t_64=no]) + ]) + if test $gl_cv_type_time_t_64 = no; then + dnl Just bail out if 'time_t' is not 64-bit, and let the user fix the + dnl problem. + AC_EGREP_CPP([booboo], [ + #ifdef _USE_32BIT_TIME_T + booboo + #endif + ], + [AC_MSG_FAILURE([This package requires a 64-bit 'time_t' type. Remove _USE_32BIT_TIME_T from the compiler flags.])], + [AC_MSG_FAILURE([This package requires a 64-bit 'time_t' type. Your system include files surely provide a way to make 'time_t' an alias of '__time64_t'.])]) + fi + ;; + *) + dnl On many systems, time_t is already a 64-bit type. + dnl On those systems where time_t is still 32-bit, it requires kernel + dnl and libc support to make it 64-bit. For glibc on Linux/x86, this + dnl is work in progress; see + dnl . + ;; + esac +]) diff --git a/modules/year2038 b/modules/year2038 new file mode 100644 index 0000000000..af145b8a02 --- /dev/null +++ b/modules/year2038 @@ -0,0 +1,28 @@ +Description: +Attempt to ensure that 'time_t' is a 64-bit type. + +Comment: +This module should not be used as a dependency from a test module, +otherwise when this module occurs as a tests-related module, it will +have side effects on the compilation of the main modules in lib/. + +Files: +m4/year2038.m4 + +Depends-on: + +configure.ac-early: +AC_REQUIRE([gl_YEAR2038_EARLY]) + +configure.ac: +AC_REQUIRE([gl_YEAR2038]) + +Makefile.am: + +Include: + +License: +LGPLv2+ + +Maintainer: +all -- 2.39.5