Mesa (master): glx: Fix use-before-null-check in dri2InvalidateBuffers().

[Eric Anholt]

Module: Mesa
Branch: master
Commit: 164108e3db5ba09d8e0605f88aa17dab83b68742
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=164108e3db5ba09d8e0605f88aa17dab83b68742

Author: Eric Anholt <eric at anholt.net>
Date:   Wed Jun  1 13:39:39 2011 -0700

glx: Fix use-before-null-check in dri2InvalidateBuffers().

The compiler used our dereference here to skip the NULL check below.
Fixes window resize in "jconsole -J-Dsun.java2d.opengl=True" under
OpenJDK 6.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=37766
Reviewed-by: Matt Turner <mattst88 at gmail.com>
Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>

---

 src/glx/dri2_glx.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/src/glx/dri2_glx.c b/src/glx/dri2_glx.c
index b9f6f7f..69b47ae 100644
--- a/src/glx/dri2_glx.c
+++ b/src/glx/dri2_glx.c
@@ -675,9 +675,14 @@ dri2InvalidateBuffers(Display *dpy, XID drawable)
 {
    __GLXDRIdrawable *pdraw =
       dri2GetGlxDrawableFromXDrawableId(dpy, drawable);
-   struct dri2_screen *psc = (struct dri2_screen *) pdraw->psc;
+   struct dri2_screen *psc;
    struct dri2_drawable *pdp = (struct dri2_drawable *) pdraw;
 
+   if (!pdraw)
+      return;
+
+   psc = (struct dri2_screen *) pdraw->psc;
+
 #if __DRI2_FLUSH_VERSION >= 3
    if (pdraw && psc->f && psc->f->base.version >= 3 && psc->f->invalidate)
        psc->f->invalidate(pdp->driDrawable);