Mesa (10.2): draw: (trivial) fix clamping of viewport index

[Carl Worth]

Module: Mesa
Branch: 10.2
Commit: 6ae4aff3035dd93cd589310674cecb541780e609
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=6ae4aff3035dd93cd589310674cecb541780e609

Author: Roland Scheidegger <sroland at vmware.com>
Date:   Mon Jun 23 22:06:15 2014 +0200

draw: (trivial) fix clamping of viewport index

The old logic would let all negative values go through unclamped, with
potentially disastrous results (probably trying to fetch viewport values
from random memory locations). GL has undefined rendering for vp indices
outside valid range but that's a bit too undefined...
(The logic is now the same as in llvmpipe.)

CC: "10.1 10.2" <mesa-stable at lists.freedesktop.org>

Reviewed-by: Jose Fonseca <jfonseca at vmware.com>
Reviewed-by: Ilia Mirkin <imirkin at alum.mit.edu>
Tested-by: Ilia Mirkin <imirkin at alum.mit.edu>
(cherry picked from commit 604e54de78aa00430b1d61d030656e387866e840)

---

 src/gallium/auxiliary/draw/draw_private.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/gallium/auxiliary/draw/draw_private.h b/src/gallium/auxiliary/draw/draw_private.h
index 783c3ef..d8dc2ab 100644
--- a/src/gallium/auxiliary/draw/draw_private.h
+++ b/src/gallium/auxiliary/draw/draw_private.h
@@ -493,7 +493,7 @@ draw_stats_clipper_primitives(struct draw_context *draw,
 static INLINE unsigned
 draw_clamp_viewport_idx(int idx)
 {
-   return ((PIPE_MAX_VIEWPORTS > idx || idx < 0) ? idx : 0);
+   return ((PIPE_MAX_VIEWPORTS > idx && idx >= 0) ? idx : 0);
 }
 
 /**