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# serial 26 -*- Autoconf -*-
dnl Find out how to get the file descriptor associated with an open DIR*.
# Copyright (C) 2001-2006, 2008-2021 Free Software Foundation, Inc.
# This file is free software; the Free Software Foundation
# gives unlimited permission to copy and/or distribute it,
# with or without modifications, as long as this notice is preserved.
dnl From Jim Meyering
AC_DEFUN([gl_FUNC_DIRFD],
[
AC_REQUIRE([gl_DIRENT_H_DEFAULTS])
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
dnl Persuade glibc <dirent.h> to declare dirfd().
AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
AC_CHECK_FUNCS([dirfd])
AC_CHECK_DECLS([dirfd], , ,
[[#include <sys/types.h>
#include <dirent.h>]])
if test $ac_cv_have_decl_dirfd = no; then
HAVE_DECL_DIRFD=0
fi
AC_CACHE_CHECK([whether dirfd is a macro],
[gl_cv_func_dirfd_macro],
[AC_EGREP_CPP([dirent_header_defines_dirfd], [
#include <sys/types.h>
#include <dirent.h>
#ifdef dirfd
dirent_header_defines_dirfd
#endif],
[gl_cv_func_dirfd_macro=yes],
[gl_cv_func_dirfd_macro=no])])
# Use the replacement if we have no function or macro with that name,
# or if OS/2 kLIBC whose dirfd() does not work.
# Replace only if the system declares dirfd already.
case $ac_cv_func_dirfd,$gl_cv_func_dirfd_macro,$host_os,$ac_cv_have_decl_dirfd in
no,no,*,yes | *,*,os2*,yes)
REPLACE_DIRFD=1
AC_DEFINE([REPLACE_DIRFD], [1],
[Define to 1 if gnulib's dirfd() replacement is used.]);;
esac
])
dnl Prerequisites of lib/dirfd.c.
AC_DEFUN([gl_PREREQ_DIRFD],
[
AC_CACHE_CHECK([how to get the file descriptor associated with an open DIR*],
[gl_cv_sys_dir_fd_member_name],
[
dirfd_save_CFLAGS=$CFLAGS
for ac_expr in d_fd dd_fd; do
CFLAGS="$CFLAGS -DDIR_FD_MEMBER_NAME=$ac_expr"
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
#include <sys/types.h>
#include <dirent.h>]],
[[DIR *dir_p = opendir("."); (void) dir_p->DIR_FD_MEMBER_NAME;]])],
[dir_fd_found=yes]
)
CFLAGS=$dirfd_save_CFLAGS
test "$dir_fd_found" = yes && break
done
test "$dir_fd_found" = yes || ac_expr=no_such_member
gl_cv_sys_dir_fd_member_name=$ac_expr
]
)
if test $gl_cv_sys_dir_fd_member_name != no_such_member; then
AC_DEFINE_UNQUOTED([DIR_FD_MEMBER_NAME],
[$gl_cv_sys_dir_fd_member_name],
[the name of the file descriptor member of DIR])
fi
AH_VERBATIM([DIR_TO_FD],
[#ifdef DIR_FD_MEMBER_NAME
# define DIR_TO_FD(Dir_p) ((Dir_p)->DIR_FD_MEMBER_NAME)
#else
# define DIR_TO_FD(Dir_p) -1
#endif
])
])
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