intel: Fix segfaults from trying to use _ColorDrawBuffers in FBO validation.

The _ColorDrawBuffers is a piece of computed state that gets for the
current draw/read buffers at _mesa_update_state time.  However, this
function actually gets used for non-current draw/read buffers when
checking if an FBO is complete from the driver's perspective.  So,
instead of trying to just look at the attachment points that are
currently referenced by glDrawBuffers, look at all attachment points
to see if they're driver-supported formats.  This appears to actually
be more in line with the intent of the spec, too.

Fixes a segfault in my upcoming fbo-clear-formats piglit test, and
hopefully bug #30278

1 files changed, 16 insertions, 4 deletions

diff --git a/src/mesa/drivers/dri/intel/intel_fbo.c b/src/mesa/drivers/dri/intel/intel_fbo.c
index c3f528c2ae5..9d33ad1e83b 100644
--- a/src/mesa/drivers/dri/intel/intel_fbo.c
+++ b/src/mesa/drivers/dri/intel/intel_fbo.c
@@ -587,13 +587,25 @@ intel_validate_framebuffer(struct gl_context *ctx, struct gl_framebuffer *fb)
       }
    }
 
-   for (i = 0; i < ctx->Const.MaxDrawBuffers; i++) {
-      struct gl_renderbuffer *rb = ctx->DrawBuffer->_ColorDrawBuffers[i];
-      struct intel_renderbuffer *irb = intel_renderbuffer(rb);
+   for (i = 0; i < Elements(fb->Attachment); i++) {
+      struct gl_renderbuffer *rb;
+      struct intel_renderbuffer *irb;
 
-      if (rb == NULL)
+      if (fb->Attachment[i].Type == GL_NONE)
 	 continue;
 
+      /* A supported attachment will have a Renderbuffer set either
+       * from being a Renderbuffer or being a texture that got the
+       * intel_wrap_texture() treatment.
+       */
+      rb = fb->Attachment[i].Renderbuffer;
+      if (rb == NULL) {
+	 DBG("attachment without renderbuffer\n");
+	 fb->_Status = GL_FRAMEBUFFER_UNSUPPORTED_EXT;
+	 continue;
+      }
+
+      irb = intel_renderbuffer(rb);
       if (irb == NULL) {
 	 DBG("software rendering renderbuffer\n");
 	 fb->_Status = GL_FRAMEBUFFER_UNSUPPORTED_EXT;