1# serial 26 -*- Autoconf -*- 2 3dnl Find out how to get the file descriptor associated with an open DIR*. 4 5# Copyright (C) 2001-2006, 2008-2020 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 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles 16 17 dnl Persuade glibc <dirent.h> to declare dirfd(). 18 AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS]) 19 20 AC_CHECK_FUNCS([dirfd]) 21 AC_CHECK_DECLS([dirfd], , , 22 [[#include <sys/types.h> 23 #include <dirent.h>]]) 24 if test $ac_cv_have_decl_dirfd = no; then 25 HAVE_DECL_DIRFD=0 26 fi 27 28 AC_CACHE_CHECK([whether dirfd is a macro], 29 [gl_cv_func_dirfd_macro], 30 [AC_EGREP_CPP([dirent_header_defines_dirfd], [ 31#include <sys/types.h> 32#include <dirent.h> 33#ifdef dirfd 34 dirent_header_defines_dirfd 35#endif], 36 [gl_cv_func_dirfd_macro=yes], 37 [gl_cv_func_dirfd_macro=no])]) 38 39 # Use the replacement if we have no function or macro with that name, 40 # or if OS/2 kLIBC whose dirfd() does not work. 41 # Replace only if the system declares dirfd already. 42 case $ac_cv_func_dirfd,$gl_cv_func_dirfd_macro,$host_os,$ac_cv_have_decl_dirfd in 43 no,no,*,yes | *,*,os2*,yes) 44 REPLACE_DIRFD=1 45 AC_DEFINE([REPLACE_DIRFD], [1], 46 [Define to 1 if gnulib's dirfd() replacement is used.]);; 47 esac 48]) 49 50dnl Prerequisites of lib/dirfd.c. 51AC_DEFUN([gl_PREREQ_DIRFD], 52[ 53 AC_CACHE_CHECK([how to get the file descriptor associated with an open DIR*], 54 [gl_cv_sys_dir_fd_member_name], 55 [ 56 dirfd_save_CFLAGS=$CFLAGS 57 for ac_expr in d_fd dd_fd; do 58 59 CFLAGS="$CFLAGS -DDIR_FD_MEMBER_NAME=$ac_expr" 60 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ 61 #include <sys/types.h> 62 #include <dirent.h>]], 63 [[DIR *dir_p = opendir("."); (void) dir_p->DIR_FD_MEMBER_NAME;]])], 64 [dir_fd_found=yes] 65 ) 66 CFLAGS=$dirfd_save_CFLAGS 67 test "$dir_fd_found" = yes && break 68 done 69 test "$dir_fd_found" = yes || ac_expr=no_such_member 70 71 gl_cv_sys_dir_fd_member_name=$ac_expr 72 ] 73 ) 74 if test $gl_cv_sys_dir_fd_member_name != no_such_member; then 75 AC_DEFINE_UNQUOTED([DIR_FD_MEMBER_NAME], 76 [$gl_cv_sys_dir_fd_member_name], 77 [the name of the file descriptor member of DIR]) 78 fi 79 AH_VERBATIM([DIR_TO_FD], 80 [#ifdef DIR_FD_MEMBER_NAME 81# define DIR_TO_FD(Dir_p) ((Dir_p)->DIR_FD_MEMBER_NAME) 82#else 83# define DIR_TO_FD(Dir_p) -1 84#endif 85]) 86]) 87