# serial 26   -*- Autoconf -*-

dnl Find out how to get the file descriptor associated with an open DIR*.

# Copyright (C) 2001-2006, 2008-2018 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

])

])