Imported Upstream version 1.4

[debian/gzip] / m4 / dirfd.m4

diff --git a/m4/dirfd.m4 b/m4/dirfd.m4
new file mode 100644 (file)
index 0000000..7fefa2e
--- /dev/null
+++ b/m4/dirfd.m4
@@ -0,0 +1,83 @@
+# serial 17   -*- Autoconf -*-
+
+dnl Find out how to get the file descriptor associated with an open DIR*.
+
+# Copyright (C) 2001-2006, 2008-2010 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])
+  gl_REPLACE_DIRENT_H
+
+  dnl Persuade glibc <dirent.h> to declare dirfd().
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+
+  dnl Work around a bug of AC_EGREP_CPP in autoconf-2.57.
+  AC_REQUIRE([AC_PROG_CPP])
+  AC_REQUIRE([AC_PROG_EGREP])
+
+  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 only if we have no function, macro,
+  # or declaration with that name.
+  if test $ac_cv_func_dirfd,$ac_cv_have_decl_dirfd,$gl_cv_func_dirfd_macro \
+      = no,no,no; then
+    AC_REPLACE_FUNCS([dirfd])
+    AC_CACHE_CHECK(
+              [how to get the file descriptor associated with an open DIR*],
+                   gl_cv_sys_dir_fd_member_name,
+      [
+        dirfd_save_CFLAGS=$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
+])
+  fi
+])