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# dup.m4 serial 8
dnl Copyright (C) 2011-2023 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.
AC_DEFUN([gl_FUNC_DUP],
[
AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
m4_ifdef([gl_MSVC_INVAL], [
AC_REQUIRE([gl_MSVC_INVAL])
if test $HAVE_MSVC_INVALID_PARAMETER_HANDLER = 1; then
REPLACE_DUP=1
fi
])
dnl Replace dup() for supporting the gnulib-defined fchdir() function,
dnl to keep fchdir's bookkeeping up-to-date.
m4_ifdef([gl_FUNC_FCHDIR], [
gl_TEST_FCHDIR
if test $HAVE_FCHDIR = 0; then
REPLACE_DUP=1
fi
])
AC_CACHE_CHECK([whether dup works], [gl_cv_func_dup_works],
[AC_RUN_IFELSE(
[AC_LANG_PROGRAM([[#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
]GL_MDA_DEFINES],
[[/* On OS/2 kLIBC, dup does not work on a directory fd. */
int fd = open (".", O_RDONLY);
return fd < 0 ? 1 : dup (fd) < 0 ? 2 : 0;
]])
],
[gl_cv_func_dup_works=yes],
[gl_cv_func_dup_works=no],
[case "$host_os" in
# Guess no on native Windows.
mingw* | windows*) gl_cv_func_dup_works="guessing no" ;;
*) gl_cv_func_dup_works="guessing yes" ;;
esac
])
])
case "$gl_cv_func_dup_works" in
*yes) ;;
*)
REPLACE_DUP=1
;;
esac
])
# Prerequisites of lib/dup.c.
AC_DEFUN([gl_PREREQ_DUP], [:])
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