2 dnl Copyright (C) 2011-2016 Free Software Foundation, Inc.
3 dnl This file is free software; the Free Software Foundation
4 dnl gives unlimited permission to copy and/or distribute it,
5 dnl with or without modifications, as long as this notice is preserved.
7 AC_DEFUN([gl_FUNC_DUP],
9 AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
10 AC_REQUIRE([gl_MSVC_INVAL])
11 if test $HAVE_MSVC_INVALID_PARAMETER_HANDLER = 1; then
14 dnl Replace dup() for supporting the gnulib-defined fchdir() function,
15 dnl to keep fchdir's bookkeeping up-to-date.
16 m4_ifdef([gl_FUNC_FCHDIR], [
18 if test $HAVE_FCHDIR = 0; then
22 AC_CACHE_CHECK([whether dup works], [gl_cv_func_dup_works],
24 [AC_LANG_PROGRAM([[#include <unistd.h>
27 [[/* On OS/2 kLIBC, dup does not work on a directory fd. */
28 int fd = open (".", O_RDONLY);
29 return fd < 0 ? 1 : dup (fd) < 0 ? 2 : 0;
32 [gl_cv_func_dup_works=yes],
33 [gl_cv_func_dup_works=no],
34 [gl_cv_func_dup_works='guessing yes'])
36 case "$gl_cv_func_dup_works" in
44 # Prerequisites of lib/dup.c.
45 AC_DEFUN([gl_PREREQ_DUP], [:])