Make dbus-uuidgen atomic

A Red Hat QA engineer hit in practice a race condition in dbus-uuidgen
where it could leave an empty file.

dbus-uuidgen (_dbus_create_uuid_file_exclusively) formerly created an
empty file in the path to the uuid, then filled it in.  At some point,
the internal libdbus _dbus_string_save_to_file became atomic on Unix
at least (doing the save to temp file, fsync(), rename() dance).

So _dbus_create_uuid_file_exclusively doesn't need to create the file
beforehand anymore.  However, it *does* need the file to be
world-readable, unlike all other consumers of
_dbus_string_save_to_file.  So add a "world_readable" argument.

1 files changed, 1 insertions, 15 deletions

diff --git a/dbus/dbus-internals.c b/dbus/dbus-internals.c
index 2ed56b35..5e864ce3 100644
--- a/dbus/dbus-internals.c
+++ b/dbus/dbus-internals.c
@@ -719,27 +719,13 @@ _dbus_create_uuid_file_exclusively (const DBusString *filename,
       goto error;
     }
   
-  /* FIXME this is racy; we need a save_file_exclusively
-   * function. But in practice this should be fine for now.
-   *
-   * - first be sure we can create the file and it
-   *   doesn't exist by creating it empty with O_EXCL
-   * - then create it by creating a temporary file and
-   *   overwriting atomically with rename()
-   */
-  if (!_dbus_create_file_exclusively (filename, error))
-    goto error;
-
   if (!_dbus_string_append_byte (&encoded, '\n'))
     {
       _DBUS_SET_OOM (error);
       goto error;
     }
   
-  if (!_dbus_string_save_to_file (&encoded, filename, error))
-    goto error;
-
-  if (!_dbus_make_file_world_readable (filename, error))
+  if (!_dbus_string_save_to_file (&encoded, filename, TRUE, error))
     goto error;
 
   _dbus_string_free (&encoded);