Mesa (master): intel: Avoid divide by zero for very small linear blits

[Ian Romanick]

Module: Mesa
Branch: master
Commit: d59466279e45a1e9c3f9081f72fedbdf961afbe1
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=d59466279e45a1e9c3f9081f72fedbdf961afbe1

Author: Ian Romanick <ian.d.romanick at intel.com>
Date:   Thu Feb  2 16:32:45 2012 -0700

intel: Avoid divide by zero for very small linear blits

If size is small (such as 1),

   pitch = ROUND_DOWN_TO(MIN2(size, (1 << 15) - 1), 4);

makes pitch = 0.  Then

   height = size / pitch;

causes a division-by-zero exception.  If pitch is zero, set height to
1 and avoid the division.

This fixes piglit's bin/getteximage-formats test and glean's
bufferObject test.

NOTE: This is a candidate for the 8.0 release branch.

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
Reviewed-by: Eric Anholt <eric at anholt.net>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=44971

---

 src/mesa/drivers/dri/intel/intel_blit.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/src/mesa/drivers/dri/intel/intel_blit.c b/src/mesa/drivers/dri/intel/intel_blit.c
index 9eacadd..fd4a86c 100644
--- a/src/mesa/drivers/dri/intel/intel_blit.c
+++ b/src/mesa/drivers/dri/intel/intel_blit.c
@@ -492,7 +492,7 @@ intel_emit_linear_blit(struct intel_context *intel,
     * rounding that down to the nearest DWORD is 1 << 15 - 4
     */
    pitch = ROUND_DOWN_TO(MIN2(size, (1 << 15) - 1), 4);
-   height = size / pitch;
+   height = (pitch == 0) ? 1 : size / pitch;
    ok = intelEmitCopyBlit(intel, 1,
 			  pitch, src_bo, src_offset, I915_TILING_NONE,
 			  pitch, dst_bo, dst_offset, I915_TILING_NONE,