Mesa (master): st/xlib: Add assert to check for null pointer dereference.

[Vinson Lee]

Module: Mesa
Branch: master
Commit: 71e3abc014cf8a1c18dcfd87517546a47ba41b6d
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=71e3abc014cf8a1c18dcfd87517546a47ba41b6d

Author: Vinson Lee <vlee at vmware.com>
Date:   Sat Feb 20 16:23:44 2010 -0800

st/xlib: Add assert to check for null pointer dereference.

---

 src/gallium/state_trackers/glx/xlib/xm_api.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/src/gallium/state_trackers/glx/xlib/xm_api.c b/src/gallium/state_trackers/glx/xlib/xm_api.c
index a274da0..4aac08a 100644
--- a/src/gallium/state_trackers/glx/xlib/xm_api.c
+++ b/src/gallium/state_trackers/glx/xlib/xm_api.c
@@ -1148,6 +1148,7 @@ void XMesaCopySubBuffer( XMesaBuffer b, int x, int y, int width, int height )
    if (!surf_front || !surf_back)
       return;
 
+   assert(pipe);
    pipe->surface_copy(pipe,
                       surf_front, x, y,  /* dest */
                       surf_back, x, y,   /* src */