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-rw-r--r--m4/dirfd.m486
1 files changed, 86 insertions, 0 deletions
diff --git a/m4/dirfd.m4 b/m4/dirfd.m4
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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, 2008-2020 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
+])
+])