[Mesa-dev] [PATCH] st/wgl: Clamp wglChoosePixelFormatARB's output nNumFormats to nMaxFormats.

[jfonseca at vmware.com]

From: José Fonseca <jfonseca at vmware.com>

While running https://github.com/nvMcJohn/apitest with apitrace I noticed that Mesa was producing bogus results:

  wglChoosePixelFormatARB(hdc, piAttribIList = {...}, pfAttribFList = &0, nMaxFormats = 1, piFormats = {19, 65576, 37, 198656, 131075, 0, 402653184, 0, 0, 0, 0, -573575710}, nNumFormats = &12) = TRUE

However https://www.opengl.org/registry/specs/ARB/wgl_pixel_format.txt states

    <nNumFormats> returns the number of matching formats. The returned
    value is guaranteed to be no larger than <nMaxFormats>.

Cc: "10.2" <mesa-stable at lists.freedesktop.org>
---
 src/gallium/state_trackers/wgl/stw_ext_pixelformat.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/gallium/state_trackers/wgl/stw_ext_pixelformat.c b/src/gallium/state_trackers/wgl/stw_ext_pixelformat.c
index d303b01..91682d1 100644
--- a/src/gallium/state_trackers/wgl/stw_ext_pixelformat.c
+++ b/src/gallium/state_trackers/wgl/stw_ext_pixelformat.c
@@ -448,9 +448,11 @@ wglChoosePixelFormatARB(
     */
    for (i = 0; i < count; i++) {
       if (scores[i].points > 0) {
-         if (*nNumFormats < nMaxFormats)
-            piFormats[*nNumFormats] = scores[i].index + 1;
+	 piFormats[*nNumFormats] = scores[i].index + 1;
          (*nNumFormats)++;
+	 if (*nNumFormats >= nMaxFormats) {
+	    break;
+	 }
       }
    }
 
-- 
1.9.1