Fix file-attributes race on GNU hosts

* doc/lispref/files.texi (File Attributes):
Document file-attributes atomicity.
* etc/NEWS: Document the fix.
* src/dired.c (file_attributes): New args DIRNAME and FILENAME,
for diagnostics.  All callers changed.  On platforms like
GNU/Linux that support O_PATH, fix a race condition in
file-attributes and similar functions, so that these functions do
not return nonsense if a directory entry is replaced while getting
its attributes.  On non-GNU platforms, do a better (though not
perfect) job of detecting the race, and return nil if detected.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/kqueue.c b/src/kqueue.c
index a8eb4cb797c..30922ef28b1 100644
--- a/src/kqueue.c
+++ b/src/kqueue.c
@@ -130,7 +130,7 @@ kqueue_compare_dir_list (Lisp_Object watch_object)
     return;
   }
   new_directory_files =
-    directory_files_internal (dir, Qnil, Qnil, Qnil, 1, Qnil);
+    directory_files_internal (dir, Qnil, Qnil, Qnil, true, Qnil);
   new_dl = kqueue_directory_listing (new_directory_files);
 
   /* Parse through the old list.  */
@@ -453,7 +453,7 @@ only when the upper directory of the renamed file is watched.  */)
   if (NILP (Ffile_directory_p (file)))
     watch_object = list4 (watch_descriptor, file, flags, callback);
   else {
-    dir_list = directory_files_internal (file, Qnil, Qnil, Qnil, 1, Qnil);
+    dir_list = directory_files_internal (file, Qnil, Qnil, Qnil, true, Qnil);
     watch_object = list5 (watch_descriptor, file, flags, callback, dir_list);
   }
   watch_list = Fcons (watch_object, watch_list);