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# fcntl.m4 serial 3
dnl Copyright (C) 2009, 2010 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.
# For now, this module ensures that fcntl()
# - supports F_DUPFD correctly
# - supports or emulates F_DUPFD_CLOEXEC
# - supports F_GETFD
# Still to be ported to mingw:
# - F_SETFD
# - F_GETFL, F_SETFL
# - F_GETOWN, F_SETOWN
# - F_GETLK, F_SETLK, F_SETLKW
AC_DEFUN([gl_FUNC_FCNTL],
[
dnl Persuade glibc to expose F_DUPFD_CLOEXEC.
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
AC_REQUIRE([AC_CANONICAL_HOST])
AC_CHECK_FUNCS_ONCE([fcntl])
if test $ac_cv_func_fcntl = no; then
gl_REPLACE_FCNTL
else
dnl cygwin 1.5.x F_DUPFD has wrong errno, and allows negative target
AC_CACHE_CHECK([whether fcntl handles F_DUPFD correctly],
[gl_cv_func_fcntl_f_dupfd_works],
[AC_RUN_IFELSE([AC_LANG_PROGRAM([[
#include <fcntl.h>
]], [[return fcntl (0, F_DUPFD, -1) != -1;
]])],
[gl_cv_func_fcntl_f_dupfd_works=yes],
[gl_cv_func_fcntl_f_dupfd_works=no],
[# Guess that it works on glibc systems
case $host_os in #((
*-gnu*) gl_cv_func_fcntl_f_dupfd_works="guessing yes";;
*) gl_cv_func_fcntl_f_dupfd_works="guessing no";;
esac])])
case $gl_cv_func_fcntl_f_dupfd_works in
*yes) ;;
*) gl_REPLACE_FCNTL
AC_DEFINE([FCNTL_DUPFD_BUGGY], [1], [Define this to 1 if F_DUPFD
behavior does not match POSIX]) ;;
esac
dnl Many systems lack F_DUPFD_CLOEXEC
AC_CACHE_CHECK([whether fcntl understands F_DUPFD_CLOEXEC],
[gl_cv_func_fcntl_f_dupfd_cloexec],
[AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
#include <fcntl.h>
#ifndef F_DUPFD_CLOEXEC
choke me
#endif
]])],
[AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
#ifdef __linux__
/* The Linux kernel only added F_DUPFD_CLOEXEC in 2.6.24, so we always replace
it to support the semantics on older kernels that failed with EINVAL. */
choke me
#endif
]])],
[gl_cv_func_fcntl_f_dupfd_cloexec=yes],
[gl_cv_func_fcntl_f_dupfd_cloexec="needs runtime check"])],
[gl_cv_func_fcntl_f_dupfd_cloexec=no])])
if test "$gl_cv_func_fcntl_f_dupfd_cloexec" != yes; then
gl_REPLACE_FCNTL
dnl No witness macro needed for this bug.
fi
fi
])
AC_DEFUN([gl_REPLACE_FCNTL],
[
AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
AC_CHECK_FUNCS_ONCE([fcntl])
if test $ac_cv_func_fcntl = no; then
HAVE_FCNTL=0
else
REPLACE_FCNTL=1
fi
AC_LIBOBJ([fcntl])
])
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