Import upstream version 1.28

[debian/tar] / m4 / fchdir.m4

diff --git a/m4/fchdir.m4 b/m4/fchdir.m4
index fd170d294470c0ae919b02c7c27d092b2a946d4f..9da16b03b4b873222860e8ca558a9d8a27a83289 100644 (file)
--- a/m4/fchdir.m4
+++ b/m4/fchdir.m4
@@ -1,5 +1,5 @@
-# fchdir.m4 serial 4
-dnl Copyright (C) 2006-2007 Free Software Foundation, Inc.
+# fchdir.m4 serial 21
+dnl Copyright (C) 2006-2014 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -7,19 +7,54 @@ dnl with or without modifications, as long as this notice is preserved.
 AC_DEFUN([gl_FUNC_FCHDIR],
 [
   AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
-  AC_CHECK_FUNCS_ONCE([fchdir])
-  if test $ac_cv_func_fchdir = no; then
-    REPLACE_FCHDIR=1
+  AC_REQUIRE([gl_DIRENT_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+
+  AC_CHECK_DECLS_ONCE([fchdir])
+  if test $ac_cv_have_decl_fchdir = no; then
+    HAVE_DECL_FCHDIR=0
+  fi
+
+  AC_REQUIRE([gl_TEST_FCHDIR])
+  if test $HAVE_FCHDIR = 0; then
     AC_LIBOBJ([fchdir])
     gl_PREREQ_FCHDIR
-    AC_DEFINE([FCHDIR_REPLACEMENT], 1,
-      [Define if gnulib's fchdir() replacement is used.])
-    gl_CHECK_NEXT_HEADERS([dirent.h])
-    DIRENT_H='dirent.h'
-  else
-    DIRENT_H=
+    AC_DEFINE([REPLACE_FCHDIR], [1],
+      [Define to 1 if gnulib's fchdir() replacement is used.])
+    dnl We must also replace anything that can manipulate a directory fd,
+    dnl to keep our bookkeeping up-to-date.  We don't have to replace
+    dnl fstatat, since no platform has fstatat but lacks fchdir.
+    AC_CACHE_CHECK([whether open can visit directories],
+      [gl_cv_func_open_directory_works],
+      [AC_RUN_IFELSE([AC_LANG_PROGRAM([[#include <fcntl.h>
+]], [return open(".", O_RDONLY) < 0;])],
+        [gl_cv_func_open_directory_works=yes],
+        [gl_cv_func_open_directory_works=no],
+        [case "$host_os" in
+                   # Guess yes on glibc systems.
+           *-gnu*) gl_cv_func_open_directory_works="guessing yes" ;;
+                   # If we don't know, assume the worst.
+           *)      gl_cv_func_open_directory_works="guessing no" ;;
+         esac
+        ])])
+    case "$gl_cv_func_open_directory_works" in
+      *yes) ;;
+      *)
+        AC_DEFINE([REPLACE_OPEN_DIRECTORY], [1], [Define to 1 if open() should
+work around the inability to open a directory.])
+        ;;
+    esac
+  fi
+])
+
+# Determine whether to use the overrides in lib/fchdir.c.
+AC_DEFUN([gl_TEST_FCHDIR],
+[
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+  AC_CHECK_FUNCS_ONCE([fchdir])
+  if test $ac_cv_func_fchdir = no; then
+    HAVE_FCHDIR=0
   fi
-  AC_SUBST([DIRENT_H])
 ])
 
 # Prerequisites of lib/fchdir.c.