file-has-acl: use acl_extended_file_nofollow if available

* lib/acl-internal.h (HAVE_ACL_EXTENDED_FILE): New macro.
(acl_extended_file): New macro.
* lib/file-has-acl.c (file_has_acl): Use acl_extended_file_nofollow.
* m4/acl.m4 (gl_FUNC_ACL): Check for acl_extended_file_nofollow.
This addresses http://bugzilla.redhat.com/692823.

diff --git a/ChangeLog b/ChangeLog
index 606b9fe..4b9955c 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2011-07-22  Kamil Dudka  <kdudka@redhat.com>
+
+       file-has-acl: use acl_extended_file_nofollow if available
+       * lib/acl-internal.h (HAVE_ACL_EXTENDED_FILE): New macro.
+       (acl_extended_file): New macro.
+       * lib/file-has-acl.c (file_has_acl): Use acl_extended_file_nofollow.
+       * m4/acl.m4 (gl_FUNC_ACL): Check for acl_extended_file_nofollow.
+
 2011-07-21  Bruno Haible  <bruno@clisp.org>
 
        Declare system functions in a way that works with C++.

diff --git a/lib/acl-internal.h b/lib/acl-internal.h
index b3160a7..b509666 100644 (file)
--- a/lib/acl-internal.h
+++ b/lib/acl-internal.h
@@ -133,6 +133,12 @@ rpl_acl_set_fd (int fd, acl_t acl)
 #  endif
 
 /* Linux-specific */
+#  ifndef HAVE_ACL_EXTENDED_FILE_NOFOLLOW
+#   define HAVE_ACL_EXTENDED_FILE_NOFOLLOW false
+#   define acl_extended_file_nofollow(name) (-1)
+#  endif
+
+/* Linux-specific */
 #  ifndef HAVE_ACL_FROM_MODE
 #   define HAVE_ACL_FROM_MODE false
 #   define acl_from_mode(mode) (NULL)

diff --git a/lib/file-has-acl.c b/lib/file-has-acl.c
index 3d4d5c1..2ee6ba2 100644 (file)
--- a/lib/file-has-acl.c
+++ b/lib/file-has-acl.c
@@ -366,12 +366,20 @@ file_has_acl (char const *name, struct stat const *sb)
       /* Linux, FreeBSD, MacOS X, IRIX, Tru64 */
       int ret;
 
-      if (HAVE_ACL_EXTENDED_FILE) /* Linux */
+      if (HAVE_ACL_EXTENDED_FILE || HAVE_ACL_EXTENDED_FILE_NOFOLLOW) /* Linux */
         {
+#  if HAVE_ACL_EXTENDED_FILE_NOFOLLOW
+          /* acl_extended_file_nofollow() uses lgetxattr() in order to prevent
+             unnecessary mounts, but it returns the same result as we already
+             know that NAME is not a symbolic link at this point (modulo the
+             TOCTTOU race condition).  */
+          ret = acl_extended_file_nofollow (name);
+#  else
           /* On Linux, acl_extended_file is an optimized function: It only
              makes two calls to getxattr(), one for ACL_TYPE_ACCESS, one for
              ACL_TYPE_DEFAULT.  */
           ret = acl_extended_file (name);
+#  endif
         }
       else /* FreeBSD, MacOS X, IRIX, Tru64 */
         {

diff --git a/m4/acl.m4 b/m4/acl.m4
index d6a448a..ecf0384 100644 (file)
--- a/m4/acl.m4
+++ b/m4/acl.m4
@@ -33,7 +33,7 @@ AC_DEFUN([gl_FUNC_ACL],
            AC_CHECK_FUNCS(
              [acl_get_file acl_get_fd acl_set_file acl_set_fd \
               acl_free acl_from_mode acl_from_text \
-              acl_delete_def_file acl_extended_file \
+              acl_delete_def_file acl_extended_file acl_extended_file_nofollow \
               acl_delete_fd_np acl_delete_file_np \
               acl_copy_ext_native acl_create_entry_np \
               acl_to_short_text acl_free_text])