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# year2038.m4 serial 5
dnl Copyright (C) 2017-2021 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 "$host_os" in
mingw*)
AC_DEFINE([__MINGW_USE_VC2005_COMPAT], [1],
[For 64-bit time_t on 32-bit mingw.])
;;
esac
])
# gl_YEAR2038_TEST_INCLUDES
# -------------------------
AC_DEFUN([gl_YEAR2038_TEST_INCLUDES],
[[
#include <time.h>
/* Check that time_t can represent 2**63 - 1 correctly.
We can't simply define LARGE_TIME_T to be 9223372036854775807,
since some C++ compilers masquerading as C compilers
incorrectly reject 9223372036854775807. */
#define LARGE_TIME_T (((time_t) 1 << 31 << 31) - 1 + ((time_t) 1 << 31 << 31))
int verify_time_t_range[(LARGE_TIME_T % 2147483629 == 721
&& LARGE_TIME_T % 2147483647 == 1)
? 1 : -1];
]])
# gl_YEAR2038_BODY(REQUIRE-64-BIT)
----------------------------------
AC_DEFUN([gl_YEAR2038_BODY],
[
AC_ARG_ENABLE([year2038],
[ --disable-year2038 omit support for timestamps past the year 2038])
AS_IF([test "$enable_year2038" != no],
[
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 2.34 and later on Linux,
dnl defining _TIME_BITS=64 and _FILE_OFFSET_BITS=64 is needed on x86 and ARM.
dnl
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_SOURCE([gl_YEAR2038_TEST_INCLUDES])],
[gl_cv_type_time_t_64=yes], [gl_cv_type_time_t_64=no])
])
if test "$gl_cv_type_time_t_64" = no; then
AC_CACHE_CHECK([for 64-bit time_t with _TIME_BITS=64],
[gl_cv_type_time_t_bits_macro],
[AC_COMPILE_IFELSE(
[AC_LANG_SOURCE([[#define _TIME_BITS 64
#define _FILE_OFFSET_BITS 64
]gl_YEAR2038_TEST_INCLUDES])],
[gl_cv_type_time_t_bits_macro=yes],
[gl_cv_type_time_t_bits_macro=no])
])
if test "$gl_cv_type_time_t_bits_macro" = yes; then
AC_DEFINE([_TIME_BITS], [64],
[Number of bits in a timestamp, on hosts where this is settable.])
dnl AC_SYS_LARGFILE also defines this; it's OK if we do too.
AC_DEFINE([_FILE_OFFSET_BITS], [64],
[Number of bits in a file offset, on hosts where this is settable.])
gl_cv_type_time_t_64=yes
fi
fi
if test $gl_cv_type_time_t_64 = no; then
AC_COMPILE_IFELSE(
[AC_LANG_SOURCE(
[[#ifdef _USE_32BIT_TIME_T
int ok;
#else
error fail
#endif
]])],
[AC_MSG_FAILURE([This package requires a 64-bit 'time_t' type. Remove _USE_32BIT_TIME_T from the compiler flags.])],
[# If not cross-compiling and $1 says we should check,
# and 'touch' works with a large timestamp, then evidently 64-bit time_t
# is desired and supported, so fail and ask the builder to fix the
# problem. Otherwise, just warn the builder.
m4_ifval([$1],
[if test $cross_compiling = no \
&& TZ=UTC0 touch -t 210602070628.16 conftest.time 2>/dev/null; then
rm -f conftest.time
AC_MSG_FAILURE([This package requires a 64-bit 'time_t' type, which your system appears to support. You might try configuring with 'CPPFLAGS="-m64" LDFLAGS="-m64"'. To build with a 32-bit time_t anyway (not recommended), configure with '--disable-year2038'.])
fi])
if test "$gl_warned_about_64_bit_time_t" != yes; then
AC_MSG_WARN([This package requires a 64-bit 'time_t' type if there is any way to access timestamps outside the year range 1901-2038 on your platform. Perhaps you should configure with 'CPPFLAGS="-m64" LDFLAGS="-m64"'?])
gl_warned_about_64_bit_time_t=yes
fi
])
fi])
])
AC_DEFUN([gl_YEAR2038],
[
gl_YEAR2038_BODY([require-64-bit])
])
|
