i915: Fix issues with glDrawBuffer(GL_NONE).

Don't dereference NULL renderbuffer pointer, and make sure the software
fallback sticks.

Fixes https://bugs.freedesktop.org/show_bug.cgi?id=13694 .

1 files changed, 23 insertions, 27 deletions

diff --git a/src/mesa/drivers/dri/intel/intel_buffers.c b/src/mesa/drivers/dri/intel/intel_buffers.c
index 44a55bbed9c..c32d54a2f95 100644
--- a/src/mesa/drivers/dri/intel/intel_buffers.c
+++ b/src/mesa/drivers/dri/intel/intel_buffers.c
@@ -564,7 +564,8 @@ intel_wait_flips(struct intel_context *intel, GLuint batch_flags)
 			     BUFFER_BIT_FRONT_LEFT ? BUFFER_FRONT_LEFT :
 			     BUFFER_BACK_LEFT);
 
-   if (intel_fb->Base.Name == 0 && intel_rb->pf_pending == intel_fb->pf_seq) {
+   if (intel_fb->Base.Name == 0 && intel_rb &&
+       intel_rb->pf_pending == intel_fb->pf_seq) {
       GLint pf_planes = intel_fb->pf_planes;
       BATCH_LOCALS;
 
@@ -863,16 +864,11 @@ intel_draw_buffer(GLcontext * ctx, struct gl_framebuffer *fb)
    /*
     * How many color buffers are we drawing into?
     */
-   if (fb->_NumColorDrawBuffers[0] != 1
-#if 0
-       /* XXX FBO temporary - always use software rendering */
-       || 1
-#endif
-      ) {
+   if (fb->_NumColorDrawBuffers[0] != 1) {
       /* writing to 0 or 2 or 4 color buffers */
       /*_mesa_debug(ctx, "Software rendering\n");*/
       FALLBACK(intel, INTEL_FALLBACK_DRAW_BUFFER, GL_TRUE);
-      front = 1;                /* might not have back color buffer */
+      colorRegion = NULL;
    }
    else {
       /* draw to exactly one color buffer */
@@ -881,30 +877,30 @@ intel_draw_buffer(GLcontext * ctx, struct gl_framebuffer *fb)
       if (fb->_ColorDrawBufferMask[0] == BUFFER_BIT_FRONT_LEFT) {
          front = 1;
       }
-   }
 
-   /*
-    * Get the intel_renderbuffer for the colorbuffer we're drawing into.
-    * And set up cliprects.
-    */
-   if (fb->Name == 0) {
-      /* drawing to window system buffer */
-      if (front) {
-         intelSetFrontClipRects(intel);
-         colorRegion = intel_get_rb_region(fb, BUFFER_FRONT_LEFT);
+      /*
+       * Get the intel_renderbuffer for the colorbuffer we're drawing into.
+       * And set up cliprects.
+       */
+      if (fb->Name == 0) {
+	 /* drawing to window system buffer */
+	 if (front) {
+	    intelSetFrontClipRects(intel);
+	    colorRegion = intel_get_rb_region(fb, BUFFER_FRONT_LEFT);
+	 }
+	 else {
+	    intelSetBackClipRects(intel);
+	    colorRegion = intel_get_rb_region(fb, BUFFER_BACK_LEFT);
+	 }
       }
       else {
-         intelSetBackClipRects(intel);
-         colorRegion = intel_get_rb_region(fb, BUFFER_BACK_LEFT);
+	 /* drawing to user-created FBO */
+	 struct intel_renderbuffer *irb;
+	 intelSetRenderbufferClipRects(intel);
+	 irb = intel_renderbuffer(fb->_ColorDrawBuffers[0][0]);
+	 colorRegion = (irb && irb->region) ? irb->region : NULL;
       }
    }
-   else {
-      /* drawing to user-created FBO */
-      struct intel_renderbuffer *irb;
-      intelSetRenderbufferClipRects(intel);
-      irb = intel_renderbuffer(fb->_ColorDrawBuffers[0][0]);
-      colorRegion = (irb && irb->region) ? irb->region : NULL;
-   }
 
    /* Update culling direction which changes depending on the
     * orientation of the buffer: