1# dup.m4 serial 4
2dnl Copyright (C) 2011-2017 Free Software Foundation, Inc.
3dnl This file is free software; the Free Software Foundation
4dnl gives unlimited permission to copy and/or distribute it,
5dnl with or without modifications, as long as this notice is preserved.
6
7AC_DEFUN([gl_FUNC_DUP],
8[
9  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
10  AC_REQUIRE([gl_MSVC_INVAL])
11  if test $HAVE_MSVC_INVALID_PARAMETER_HANDLER = 1; then
12    REPLACE_DUP=1
13  fi
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], [
17    gl_TEST_FCHDIR
18    if test $HAVE_FCHDIR = 0; then
19      REPLACE_DUP=1
20    fi
21  ])
22  AC_CACHE_CHECK([whether dup works], [gl_cv_func_dup_works],
23    [AC_RUN_IFELSE(
24      [AC_LANG_PROGRAM([[#include <unistd.h>
25                         #include <fcntl.h>
26                         #include <errno.h>]],
27         [[/* On OS/2 kLIBC, dup does not work on a directory fd.  */
28           int fd = open (".", O_RDONLY);
29           return fd < 0 ? 1 : dup (fd) < 0 ? 2 : 0;
30         ]])
31      ],
32      [gl_cv_func_dup_works=yes],
33      [gl_cv_func_dup_works=no],
34      [gl_cv_func_dup_works='guessing yes'])
35    ])
36  case "$gl_cv_func_dup_works" in
37    *yes) ;;
38    *)
39      REPLACE_DUP=1
40      ;;
41  esac
42])
43
44# Prerequisites of lib/dup.c.
45AC_DEFUN([gl_PREREQ_DUP], [:])
46