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Diffstat (limited to 'm4/year2038.m4')
| -rw-r--r-- | m4/year2038.m4 | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/m4/year2038.m4 b/m4/year2038.m4 new file mode 100644 index 0000000..2a66163 --- /dev/null +++ b/m4/year2038.m4 @@ -0,0 +1,182 @@ +# This file is part of Autoconf. -*- Autoconf -*- +# Macros that test for specific, unclassified, features. +# +# Copyright (C) 1992-1996, 1998-2017, 2020-2023 Free Software +# Foundation, Inc. + +# This file is part of Autoconf. This program is free +# software; you can redistribute it and/or modify it under the +# terms of the GNU General Public License as published by the +# Free Software Foundation, either version 3 of the License, or +# (at your option) any later version. +# +# This program 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 General Public License for more details. +# +# Under Section 7 of GPL version 3, you are granted additional +# permissions described in the Autoconf Configure Script Exception, +# version 3.0, as published by the Free Software Foundation. +# +# You should have received a copy of the GNU General Public License +# and a copy of the Autoconf Configure Script Exception along with +# this program; see the files COPYINGv3 and COPYING.EXCEPTION +# respectively. If not, see <https://www.gnu.org/licenses/>. + +# Written by David MacKenzie, with help from +# François Pinard, Karl Berry, Richard Pixley, Ian Lance Taylor, +# Roland McGrath, Noah Friedman, david d zuhn, and many others. +# _AC_SYS_YEAR2038_TEST_CODE +# -------------------------- +# C code used to probe for time_t that can represent time points more +# than 2**31 - 1 seconds after the epoch. With the usual Unix epoch, +# these correspond to dates after 2038-01-18 22:14:07 +0000 (Gregorian), +# hence the name. + +AC_DEFUN([_AC_SYS_YEAR2038_TEST_CODE], +[[ + #include <time.h> + /* Check that time_t can represent 2**32 - 1 correctly. */ + #define LARGE_TIME_T \\ + ((time_t) (((time_t) 1 << 30) - 1 + 3 * ((time_t) 1 << 30))) + int verify_time_t_range[(LARGE_TIME_T / 65537 == 65535 + && LARGE_TIME_T % 65537 == 0) + ? 1 : -1]; +]]) + +# _AC_SYS_YEAR2038_OPTIONS +# ------------------------ +# List of known ways to enable support for large time_t. If you change +# this list you probably also need to change the AS_CASE at the end of +# _AC_SYS_YEAR2038_PROBE. +m4_define([_AC_SYS_YEAR2038_OPTIONS], m4_normalize( + ["none needed"] dnl 64-bit and newer 32-bit Unix + ["-D_TIME_BITS=64"] dnl glibc 2.34 with some 32-bit ABIs + ["-D__MINGW_USE_VC2005_COMPAT"] dnl 32-bit MinGW + ["-U_USE_32_BIT_TIME_T -D__MINGW_USE_VC2005_COMPAT"] + dnl 32-bit MinGW (misconfiguration) +)) + +# _AC_SYS_YEAR2038_PROBE +# ---------------------- +# Subroutine of AC_SYS_YEAR2038. Probe for time_t that can represent +# time points more than 2**31 - 1 seconds after the epoch (dates after +# 2038-01-18, see above) and set the cache variable ac_cv_sys_year2038_opts +# to one of the values in the _AC_SYS_YEAR2038_OPTIONS list, or to +# "support not detected" if none of them worked. Then, set compilation +# options and #defines as necessary to enable large time_t support. +# +# Note that we do not test whether mktime, localtime, etc. handle +# large values of time_t correctly, as that would require use of +# AC_TRY_RUN. Note also that some systems only support large time_t +# together with large off_t. +# +# If you change this macro you may also need to change +# _AC_SYS_YEAR2038_OPTIONS. +AC_DEFUN([_AC_SYS_YEAR2038_PROBE], +[AC_CACHE_CHECK([for $CC option for timestamps after 2038], + [ac_cv_sys_year2038_opts], + [ac_save_CPPFLAGS="$CPPFLAGS" + ac_opt_found=no + for ac_opt in _AC_SYS_YEAR2038_OPTIONS; do + AS_IF([test x"$ac_opt" != x"none needed"], + [CPPFLAGS="$ac_save_CPPFLAGS $ac_opt"]) + AC_COMPILE_IFELSE([AC_LANG_PROGRAM([_AC_SYS_YEAR2038_TEST_CODE])], + [ac_cv_sys_year2038_opts="$ac_opt" + ac_opt_found=yes]) + test $ac_opt_found = no || break + done + CPPFLAGS="$ac_save_CPPFLAGS" + test $ac_opt_found = yes || ac_cv_sys_year2038_opts="support not detected"]) + +ac_have_year2038=yes +AS_CASE([$ac_cv_sys_year2038_opts], + ["none needed"], [], + ["support not detected"], + [ac_have_year2038=no], + + ["-D_TIME_BITS=64"], + [AC_DEFINE([_TIME_BITS], [64], + [Number of bits in time_t, on hosts where this is settable.])], + + ["-D__MINGW_USE_VC2005_COMPAT"], + [AC_DEFINE([__MINGW_USE_VC2005_COMPAT], [1], + [Define to 1 on platforms where this makes time_t a 64-bit type.])], + + ["-U_USE_32_BIT_TIME_T"*], + [AC_MSG_FAILURE(m4_text_wrap( + [the 'time_t' type is currently forced to be 32-bit. + It will stop working after mid-January 2038. + Remove _USE_32BIT_TIME_T from the compiler flags.], + [], [], [55]))], + + [AC_MSG_ERROR( + [internal error: bad value for \$ac_cv_sys_year2038_opts])]) +]) + +# _AC_SYS_YEAR2038_ENABLE +# ----------------------- +# Depending on which of the YEAR2038 macros was used, add either an +# --enable-year2038 or a --disable-year2038 to +# the configure script. This is expanded very late and +# therefore there cannot be any code in the AC_ARG_ENABLE. The +# default value for 'enable_year2038' is emitted unconditionally +# because the generated code always looks at this variable. +m4_define([_AC_SYS_YEAR2038_ENABLE], +[m4_divert_text([DEFAULTS], + m4_provide_if([AC_SYS_YEAR2038], + [enable_year2038=yes], + [enable_year2038=no]))]dnl +[AC_ARG_ENABLE([year2038], + m4_provide_if([AC_SYS_YEAR2038], + [AS_HELP_STRING([--disable-year2038], + [don't support timestamps after 2038])], + [AS_HELP_STRING([--enable-year2038], + [support timestamps after 2038])]))]) + +# AC_SYS_YEAR2038 +# --------------- +# Attempt to detect and activate support for large time_t. +# On systems where time_t is not always 64 bits, this probe can be +# skipped by passing the --disable-year2038 option to configure. +AC_DEFUN([AC_SYS_YEAR2038], +[AC_REQUIRE([AC_SYS_LARGEFILE])dnl +AS_IF([test "$enable_year2038,$ac_have_year2038,$cross_compiling" = yes,no,no], + [# If we're not cross compiling and 'touch' works with a large + # timestamp, then we can presume the system supports wider time_t + # *somehow* and we just weren't able to detect it. One common + # case that we deliberately *don't* probe for is a system that + # supports both 32- and 64-bit ABIs but only the 64-bit ABI offers + # wide time_t. (It would be inappropriate for us to override an + # intentional use of -m32.) Error out, demanding use of + # --disable-year2038 if this is intentional. + AS_IF([TZ=UTC0 touch -t 210602070628.15 conftest.time 2>/dev/null], + [AS_CASE([`TZ=UTC0 LC_ALL=C ls -l conftest.time 2>/dev/null`], + [*'Feb 7 2106'* | *'Feb 7 17:10'*], + [AC_MSG_FAILURE(m4_text_wrap( + [this system appears to support timestamps after mid-January 2038, + but no mechanism for enabling wide 'time_t' was detected. + Did you mean to build a 64-bit binary? (E.g., 'CC="${CC} -m64"'.) + To proceed with 32-bit time_t, configure with '--disable-year2038'.], + [], [], [55]))])])])]) + +# AC_SYS_YEAR2038_RECOMMENDED +# --------------------------- +# Same as AC_SYS_YEAR2038, but recommend support for large time_t. +# If we cannot find any way to make time_t capable of representing +# values larger than 2**31 - 1, error out unless --disable-year2038 is given. +AC_DEFUN([AC_SYS_YEAR2038_RECOMMENDED], +[AC_REQUIRE([AC_SYS_YEAR2038])dnl +AS_IF([test "$enable_year2038,$ac_have_year2038" = yes,no], + [AC_MSG_FAILURE(m4_text_wrap( + [could not enable timestamps after mid-January 2038. + This package recommends support for these later timestamps. + However, to proceed with signed 32-bit time_t even though it + will fail then, configure with '--disable-year2038'.], + [], [], [55]))])]) + +AC_DEFUN([UL_YEAR2038_INIT],[ + AS_IF([test "$enable_year2038" != no], + [_AC_SYS_YEAR2038_PROBE]) + AC_CONFIG_COMMANDS_PRE([_AC_SYS_YEAR2038_ENABLE])]) |