| 1 | # year2038.m4 serial 8
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| 2 | dnl Copyright (C) 2017-2022 Free Software Foundation, Inc.
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| 3 | dnl This file is free software; the Free Software Foundation
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| 4 | dnl gives unlimited permission to copy and/or distribute it,
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| 5 | dnl with or without modifications, as long as this notice is preserved.
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| 6 |
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| 7 | dnl Attempt to ensure that 'time_t' can go past the year 2038 and that
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| 8 | dnl the functions 'time', 'stat', etc. work with post-2038 timestamps.
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| 9 |
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| 10 | m4_ifdef([AC_SYS_YEAR2038], [
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| 11 | AC_DEFUN([gl_YEAR2038_EARLY])
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| 12 | AC_DEFUN([gl_YEAR2038], [AC_SYS_YEAR2038])
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| 13 | AC_DEFUN([gl_YEAR2038_BODY], [_AC_SYS_YEAR2038])
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| 14 | ], [
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| 15 |
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| 16 | AC_DEFUN([gl_YEAR2038_EARLY],
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| 17 | [
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| 18 | AC_REQUIRE([AC_CANONICAL_HOST])
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| 19 | case "$host_os" in
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| 20 | mingw*)
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| 21 | AC_DEFINE([__MINGW_USE_VC2005_COMPAT], [1],
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| 22 | [For 64-bit time_t on 32-bit mingw.])
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| 23 | ;;
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| 24 | esac
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| 25 | ])
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| 26 |
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| 27 | # gl_YEAR2038_TEST_INCLUDES
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| 28 | # -------------------------
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| 29 | AC_DEFUN([gl_YEAR2038_TEST_INCLUDES],
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| 30 | [[
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| 31 | #include <time.h>
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| 32 | /* Check that time_t can represent 2**32 - 1 correctly. */
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| 33 | #define LARGE_TIME_T \\
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| 34 | ((time_t) (((time_t) 1 << 30) - 1 + 3 * ((time_t) 1 << 30)))
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| 35 | int verify_time_t_range[(LARGE_TIME_T / 65537 == 65535
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| 36 | && LARGE_TIME_T % 65537 == 0)
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| 37 | ? 1 : -1];
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| 38 | ]])
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| 39 |
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| 40 | # gl_YEAR2038_BODY(REQUIRE-YEAR2038-SAFE)
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| 41 | -----------------------------------------
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| 42 | AC_DEFUN([gl_YEAR2038_BODY],
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| 43 | [
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| 44 | AC_ARG_ENABLE([year2038],
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| 45 | [ --disable-year2038 omit support for timestamps past the year 2038])
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| 46 | AS_IF([test "$enable_year2038" != no],
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| 47 | [
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| 48 | dnl On many systems, time_t is already a 64-bit type.
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| 49 | dnl On those systems where time_t is still 32-bit, it requires kernel
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| 50 | dnl and libc support to make it 64-bit. For glibc 2.34 and later on Linux,
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| 51 | dnl defining _TIME_BITS=64 and _FILE_OFFSET_BITS=64 is needed on x86 and ARM.
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| 52 | dnl
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| 53 | dnl On native Windows, the system include files define types __time32_t
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| 54 | dnl and __time64_t. By default, time_t is an alias of
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| 55 | dnl - __time32_t on 32-bit mingw,
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| 56 | dnl - __time64_t on 64-bit mingw and on MSVC (since MSVC 8).
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| 57 | dnl But when compiling with -D__MINGW_USE_VC2005_COMPAT, time_t is an
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| 58 | dnl alias of __time64_t.
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| 59 | dnl And when compiling with -D_USE_32BIT_TIME_T, time_t is an alias of
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| 60 | dnl __time32_t.
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| 61 | AC_CACHE_CHECK([for time_t past the year 2038], [gl_cv_type_time_t_y2038],
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| 62 | [AC_COMPILE_IFELSE(
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| 63 | [AC_LANG_SOURCE([gl_YEAR2038_TEST_INCLUDES])],
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| 64 | [gl_cv_type_time_t_y2038=yes], [gl_cv_type_time_t_y2038=no])
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| 65 | ])
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| 66 | if test "$gl_cv_type_time_t_y2038" = no; then
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| 67 | AC_CACHE_CHECK([for 64-bit time_t with _TIME_BITS=64],
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| 68 | [gl_cv_type_time_t_bits_macro],
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| 69 | [AC_COMPILE_IFELSE(
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| 70 | [AC_LANG_SOURCE([[#define _TIME_BITS 64
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| 71 | #define _FILE_OFFSET_BITS 64
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| 72 | ]gl_YEAR2038_TEST_INCLUDES])],
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| 73 | [gl_cv_type_time_t_bits_macro=yes],
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| 74 | [gl_cv_type_time_t_bits_macro=no])
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| 75 | ])
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| 76 | if test "$gl_cv_type_time_t_bits_macro" = yes; then
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| 77 | AC_DEFINE([_TIME_BITS], [64],
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| 78 | [Number of bits in a timestamp, on hosts where this is settable.])
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| 79 | dnl AC_SYS_LARGFILE also defines this; it's OK if we do too.
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| 80 | AC_DEFINE([_FILE_OFFSET_BITS], [64],
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| 81 | [Number of bits in a file offset, on hosts where this is settable.])
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| 82 | gl_cv_type_time_t_y2038=yes
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| 83 | fi
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| 84 | fi
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| 85 | if test $gl_cv_type_time_t_y2038 = no; then
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| 86 | AC_COMPILE_IFELSE(
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| 87 | [AC_LANG_SOURCE(
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| 88 | [[#ifdef _USE_32BIT_TIME_T
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| 89 | int ok;
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| 90 | #else
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| 91 | error fail
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| 92 | #endif
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| 93 | ]])],
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| 94 | [AC_MSG_FAILURE(
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| 95 | [The 'time_t' type stops working after January 2038.
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| 96 | Remove _USE_32BIT_TIME_T from the compiler flags.])],
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| 97 | [# If not cross-compiling and $1 says we should check,
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| 98 | # and 'touch' works with a large timestamp, then evidently wider time_t
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| 99 | # is desired and supported, so fail and ask the builder to fix the
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| 100 | # problem. Otherwise, just warn the builder.
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| 101 | m4_ifval([$1],
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| 102 | [if test $cross_compiling = no \
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| 103 | && TZ=UTC0 touch -t 210602070628.15 conftest.time 2>/dev/null; then
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| 104 | case `TZ=UTC0 LC_ALL=C ls -l conftest.time 2>/dev/null` in
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| 105 | *'Feb 7 2106'* | *'Feb 7 17:10'*)
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| 106 | AC_MSG_FAILURE(
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| 107 | [The 'time_t' type stops working after January 2038,
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| 108 | and your system appears to support a wider 'time_t'.
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| 109 | Try configuring with 'CC="${CC} -m64"'.
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| 110 | To build with a 32-bit time_t anyway (not recommended),
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| 111 | configure with '--disable-year2038'.]);;
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| 112 | esac
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| 113 | rm -f conftest.time
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| 114 | fi])
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| 115 | if test "$gl_warned_about_y2038" != yes; then
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| 116 | AC_MSG_WARN(
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| 117 | [The 'time_t' type stops working after January 2038,
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| 118 | and this package needs a wider 'time_t' type
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| 119 | if there is any way to access timestamps after that.
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| 120 | Configure with 'CC="${CC} -m64"' perhaps?])
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| 121 | gl_warned_about_y2038=yes
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| 122 | fi
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| 123 | ])
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| 124 | fi])
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| 125 | ])
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| 126 |
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| 127 | AC_DEFUN([gl_YEAR2038],
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| 128 | [
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| 129 | gl_YEAR2038_BODY([require-year2038-safe])
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| 130 | ])
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| 131 |
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| 132 | ]) # m4_ifndef AC_SYS_YEAR2038
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