125 lines
4.8 KiB
Plaintext
125 lines
4.8 KiB
Plaintext
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# year2038.m4 serial 7
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dnl Copyright (C) 2017-2022 Free Software Foundation, Inc.
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dnl This file is free software; the Free Software Foundation
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dnl gives unlimited permission to copy and/or distribute it,
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dnl with or without modifications, as long as this notice is preserved.
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dnl Attempt to ensure that 'time_t' can go past the year 2038 and that
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dnl the functions 'time', 'stat', etc. work with post-2038 timestamps.
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AC_DEFUN([gl_YEAR2038_EARLY],
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[
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AC_REQUIRE([AC_CANONICAL_HOST])
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case "$host_os" in
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mingw*)
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AC_DEFINE([__MINGW_USE_VC2005_COMPAT], [1],
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[For 64-bit time_t on 32-bit mingw.])
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;;
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esac
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])
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# gl_YEAR2038_TEST_INCLUDES
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# -------------------------
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AC_DEFUN([gl_YEAR2038_TEST_INCLUDES],
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[[
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#include <time.h>
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/* Check that time_t can represent 2**32 - 1 correctly. */
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#define LARGE_TIME_T \\
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((time_t) (((time_t) 1 << 30) - 1 + 3 * ((time_t) 1 << 30)))
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int verify_time_t_range[(LARGE_TIME_T / 65537 == 65535
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&& LARGE_TIME_T % 65537 == 0)
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? 1 : -1];
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]])
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# gl_YEAR2038_BODY(REQUIRE-YEAR2038-SAFE)
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-----------------------------------------
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AC_DEFUN([gl_YEAR2038_BODY],
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[
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AC_ARG_ENABLE([year2038],
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[ --disable-year2038 omit support for timestamps past the year 2038])
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AS_IF([test "$enable_year2038" != no],
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[
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dnl On many systems, time_t is already a 64-bit type.
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dnl On those systems where time_t is still 32-bit, it requires kernel
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dnl and libc support to make it 64-bit. For glibc 2.34 and later on Linux,
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dnl defining _TIME_BITS=64 and _FILE_OFFSET_BITS=64 is needed on x86 and ARM.
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dnl
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dnl On native Windows, the system include files define types __time32_t
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dnl and __time64_t. By default, time_t is an alias of
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dnl - __time32_t on 32-bit mingw,
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dnl - __time64_t on 64-bit mingw and on MSVC (since MSVC 8).
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dnl But when compiling with -D__MINGW_USE_VC2005_COMPAT, time_t is an
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dnl alias of __time64_t.
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dnl And when compiling with -D_USE_32BIT_TIME_T, time_t is an alias of
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dnl __time32_t.
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AC_CACHE_CHECK([for time_t past the year 2038], [gl_cv_type_time_t_y2038],
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[AC_COMPILE_IFELSE(
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[AC_LANG_SOURCE([gl_YEAR2038_TEST_INCLUDES])],
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[gl_cv_type_time_t_y2038=yes], [gl_cv_type_time_t_y2038=no])
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])
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if test "$gl_cv_type_time_t_y2038" = no; then
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AC_CACHE_CHECK([for 64-bit time_t with _TIME_BITS=64],
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[gl_cv_type_time_t_bits_macro],
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[AC_COMPILE_IFELSE(
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[AC_LANG_SOURCE([[#define _TIME_BITS 64
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#define _FILE_OFFSET_BITS 64
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]gl_YEAR2038_TEST_INCLUDES])],
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[gl_cv_type_time_t_bits_macro=yes],
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[gl_cv_type_time_t_bits_macro=no])
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])
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if test "$gl_cv_type_time_t_bits_macro" = yes; then
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AC_DEFINE([_TIME_BITS], [64],
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[Number of bits in a timestamp, on hosts where this is settable.])
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dnl AC_SYS_LARGFILE also defines this; it's OK if we do too.
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AC_DEFINE([_FILE_OFFSET_BITS], [64],
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[Number of bits in a file offset, on hosts where this is settable.])
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gl_cv_type_time_t_y2038=yes
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fi
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fi
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if test $gl_cv_type_time_t_y2038 = no; then
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AC_COMPILE_IFELSE(
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[AC_LANG_SOURCE(
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[[#ifdef _USE_32BIT_TIME_T
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int ok;
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#else
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error fail
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#endif
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]])],
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[AC_MSG_FAILURE(
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[The 'time_t' type stops working after January 2038.
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Remove _USE_32BIT_TIME_T from the compiler flags.])],
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[# If not cross-compiling and $1 says we should check,
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# and 'touch' works with a large timestamp, then evidently wider time_t
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# is desired and supported, so fail and ask the builder to fix the
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# problem. Otherwise, just warn the builder.
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m4_ifval([$1],
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[if test $cross_compiling = no \
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&& TZ=UTC0 touch -t 210602070628.15 conftest.time 2>/dev/null; then
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case `TZ=UTC0 LC_ALL=C ls -l conftest.time 2>/dev/null` in
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*'Feb 7 2106'* | *'Feb 7 17:10'*)
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AC_MSG_FAILURE(
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[The 'time_t' type stops working after January 2038,
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and your system appears to support a wider 'time_t'.
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Try configuring with 'CC="${CC} -m64"'.
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To build with a 32-bit time_t anyway (not recommended),
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configure with '--disable-year2038'.]);;
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esac
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rm -f conftest.time
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fi])
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if test "$gl_warned_about_y2038" != yes; then
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AC_MSG_WARN(
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[The 'time_t' type stops working after January 2038,
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and this package needs a wider 'time_t' type
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if there is any way to access timestamps after that.
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Configure with 'CC="${CC} -m64"' perhaps?])
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gl_warned_about_y2038=yes
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fi
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])
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fi])
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])
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AC_DEFUN([gl_YEAR2038],
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[
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gl_YEAR2038_BODY([require-year2038-safe])
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])
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