1# dup.m4 serial 6
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([AC_CANONICAL_HOST]) dnl for cross-compiles
11  m4_ifdef([gl_MSVC_INVAL], [
12    AC_REQUIRE([gl_MSVC_INVAL])
13    if test $HAVE_MSVC_INVALID_PARAMETER_HANDLER = 1; then
14      REPLACE_DUP=1
15    fi
16  ])
17  dnl Replace dup() for supporting the gnulib-defined fchdir() function,
18  dnl to keep fchdir's bookkeeping up-to-date.
19  m4_ifdef([gl_FUNC_FCHDIR], [
20    gl_TEST_FCHDIR
21    if test $HAVE_FCHDIR = 0; then
22      REPLACE_DUP=1
23    fi
24  ])
25  AC_CACHE_CHECK([whether dup works], [gl_cv_func_dup_works],
26    [AC_RUN_IFELSE(
27      [AC_LANG_PROGRAM([[#include <unistd.h>
28                         #include <fcntl.h>
29                         #include <errno.h>]],
30         [[/* On OS/2 kLIBC, dup does not work on a directory fd.  */
31           int fd = open (".", O_RDONLY);
32           return fd < 0 ? 1 : dup (fd) < 0 ? 2 : 0;
33         ]])
34      ],
35      [gl_cv_func_dup_works=yes],
36      [gl_cv_func_dup_works=no],
37      [case "$host_os" in
38                 # Guess no on native Windows.
39         mingw*) gl_cv_func_dup_works="guessing no" ;;
40         *)      gl_cv_func_dup_works="guessing yes" ;;
41       esac
42      ])
43    ])
44  case "$gl_cv_func_dup_works" in
45    *yes) ;;
46    *)
47      REPLACE_DUP=1
48      ;;
49  esac
50])
51
52# Prerequisites of lib/dup.c.
53AC_DEFUN([gl_PREREQ_DUP], [:])
54