xprops: Fix reading Window and XSyncCounter properties

Both Window and XSyncCounter are XIDs which on 64 bit X clients are 8
bytes wide. But the values on the wire are 32 bit so, for these types,
we always copy 4 bytes into results->prop. As such copying them out
with a cast such as *(Window *) means that we are actually reading 8
bytes which depending on whether the higher addressed 4 bytes are zero
means that sometimes this works while others it gives us a bogus
value.

https://bugzilla.gnome.org/show_bug.cgi?id=756074

1 files changed, 2 insertions, 2 deletions

diff --git a/src/x11/xprops.c b/src/x11/xprops.c
index 589d53810..be3882455 100644
--- a/src/x11/xprops.c
+++ b/src/x11/xprops.c
@@ -507,7 +507,7 @@ window_from_results (GetPropertyResults *results,
   if (!validate_or_free_results (results, 32, XA_WINDOW, TRUE))
     return FALSE;
 
-  *window_p = *(Window*) results->prop;
+  *window_p = *(uint32_t *) results->prop;
   g_free (results->prop);
   results->prop = NULL;
 
@@ -523,7 +523,7 @@ counter_from_results (GetPropertyResults *results,
                                  TRUE))
     return FALSE;
 
-  *counter_p = *(XSyncCounter*) results->prop;
+  *counter_p = *(uint32_t *) results->prop;
   g_free (results->prop);
   results->prop = NULL;