[mutter] xprops: Null-terminate property reply values

[Rui Matos <rtcm src gnome org>]

commit a7a376ae1fafb7c9da50d9fe51fc08b0ec13f55e
Author: Sebastian Keller <sebastian-keller gmx de>
Date:   Sun Jan 10 04:15:09 2016 +0100

    xprops: Null-terminate property reply values
    
    Some of the mutter code using these properties expects them to be
    null-terminated whereas xcb does not use null-terminated strings:
    
    http://xcb.freedesktop.org/XcbRationale/
    
    This was in some cases resulting in the WM_CLASS property containing
    garbage data which broke application matching, caused the hot-corner and
    window-switcher to stop working, or was exposed as text in the UI.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=759658

 src/x11/xprops.c |   12 ++++++++++--
 1 files changed, 10 insertions(+), 2 deletions(-)
---
diff --git a/src/x11/xprops.c b/src/x11/xprops.c
index be38824..e3bd931 100644
--- a/src/x11/xprops.c
+++ b/src/x11/xprops.c
@@ -194,6 +194,7 @@ async_get_property_finish (xcb_connection_t          *xcb_conn,
 {
   xcb_get_property_reply_t *reply;
   xcb_generic_error_t *error;
+  int length;
 
   reply = xcb_get_property_reply (xcb_conn, cookie, &error);
   if (error)
@@ -209,8 +210,15 @@ async_get_property_finish (xcb_connection_t          *xcb_conn,
   results->prop = NULL;
 
   if (results->type != None)
-    results->prop = g_memdup (xcb_get_property_value (reply),
-                              xcb_get_property_value_length (reply));
+    {
+      length = xcb_get_property_value_length (reply);
+      /* Leave room for a trailing '\0' since xcb doesn't return null-terminated
+       * strings
+       */
+      results->prop = g_malloc (length + 1);
+      memcpy (results->prop, xcb_get_property_value (reply), length);
+      results->prop[length] = '\0';
+    }
 
   free (reply);
   return (results->prop != NULL);