1# serial 22   -*- Autoconf -*-
2
3dnl Find out how to get the file descriptor associated with an open DIR*.
4
5# Copyright (C) 2001-2006, 2008-2015 Free Software Foundation, Inc.
6# This file is free software; the Free Software Foundation
7# gives unlimited permission to copy and/or distribute it,
8# with or without modifications, as long as this notice is preserved.
9
10dnl From Jim Meyering
11
12AC_DEFUN([gl_FUNC_DIRFD],
13[
14  AC_REQUIRE([gl_DIRENT_H_DEFAULTS])
15
16  dnl Persuade glibc <dirent.h> to declare dirfd().
17  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
18
19  AC_CHECK_FUNCS([dirfd])
20  AC_CHECK_DECLS([dirfd], , ,
21    [[#include <sys/types.h>
22      #include <dirent.h>]])
23  if test $ac_cv_have_decl_dirfd = no; then
24    HAVE_DECL_DIRFD=0
25  fi
26
27  AC_CACHE_CHECK([whether dirfd is a macro],
28    gl_cv_func_dirfd_macro,
29    [AC_EGREP_CPP([dirent_header_defines_dirfd], [
30#include <sys/types.h>
31#include <dirent.h>
32#ifdef dirfd
33 dirent_header_defines_dirfd
34#endif],
35       gl_cv_func_dirfd_macro=yes,
36       gl_cv_func_dirfd_macro=no)])
37
38  # Use the replacement only if we have no function or macro with that name.
39  if test $ac_cv_func_dirfd = no && test $gl_cv_func_dirfd_macro = no; then
40    if test $ac_cv_have_decl_dirfd = yes; then
41      # If the system declares dirfd already, let's declare rpl_dirfd instead.
42      REPLACE_DIRFD=1
43    fi
44  fi
45])
46
47dnl Prerequisites of lib/dirfd.c.
48AC_DEFUN([gl_PREREQ_DIRFD],
49[
50  AC_CACHE_CHECK([how to get the file descriptor associated with an open DIR*],
51                 [gl_cv_sys_dir_fd_member_name],
52    [
53      dirfd_save_CFLAGS=$CFLAGS
54      for ac_expr in d_fd dd_fd; do
55
56        CFLAGS="$CFLAGS -DDIR_FD_MEMBER_NAME=$ac_expr"
57        AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
58           #include <sys/types.h>
59           #include <dirent.h>]],
60          [[DIR *dir_p = opendir("."); (void) dir_p->DIR_FD_MEMBER_NAME;]])],
61          [dir_fd_found=yes]
62        )
63        CFLAGS=$dirfd_save_CFLAGS
64        test "$dir_fd_found" = yes && break
65      done
66      test "$dir_fd_found" = yes || ac_expr=no_such_member
67
68      gl_cv_sys_dir_fd_member_name=$ac_expr
69    ]
70  )
71  if test $gl_cv_sys_dir_fd_member_name != no_such_member; then
72    AC_DEFINE_UNQUOTED([DIR_FD_MEMBER_NAME],
73      [$gl_cv_sys_dir_fd_member_name],
74      [the name of the file descriptor member of DIR])
75  fi
76  AH_VERBATIM([DIR_TO_FD],
77              [#ifdef DIR_FD_MEMBER_NAME
78# define DIR_TO_FD(Dir_p) ((Dir_p)->DIR_FD_MEMBER_NAME)
79#else
80# define DIR_TO_FD(Dir_p) -1
81#endif
82])
83])
84