[gtk+] wayland: Compare serial numbers correctly to avoid overflow problems

[Kristian Høgsberg <krh src gnome org>]

commit 771dbe059248a6f263ec72aa41f1f54f21d94208
Author: Kristian Høgsberg <krh bitplanet net>
Date:   Fri Aug 23 23:08:13 2013 -0700

    wayland: Compare serial numbers correctly to avoid overflow problems
    
    We have to look at the difference between two numbers, which will always
    be well-defined and give the right result, even in case of integer overflow.

 gdk/wayland/gdkdisplay-wayland.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/gdk/wayland/gdkdisplay-wayland.c b/gdk/wayland/gdkdisplay-wayland.c
index db47bfe..e9424b2 100644
--- a/gdk/wayland/gdkdisplay-wayland.c
+++ b/gdk/wayland/gdkdisplay-wayland.c
@@ -678,8 +678,12 @@ void
 _gdk_wayland_display_update_serial (GdkWaylandDisplay *wayland_display,
                                     guint32            serial)
 {
-  if (serial > wayland_display->serial)
+  if (serial - wayland_display->serial < 1000)
     wayland_display->serial = serial;
+  else
+    g_warning (G_STRLOC ": serial number jump bigger than 1000 (%u -> %u",
+               wayland_display->serial, serial);
+
 }
 
 /**