gl-renderer, pixman: disconnect the client on unhandled buffer type.

Introduce a helper function to disconnect the client on unhandled
buffer types, and use it in the gl and pixman renderers. The function
is modeled after linux_dmabuf_buffer_send_server_error.

Also print the egl error state in the gl renderer, in case the
unrecognized buffer error happens when querying an egl buffer.

https://gitlab.freedesktop.org/wayland/weston/issues/148

libweston/compositor.c

@@ -7103,3 +7103,38 @@ weston_compositor_load_xwayland(struct weston_compositor *compositor)
 		return -1;
 	return 0;
 }
+
+/** Resolve an internal compositor error by disconnecting the client.
+ *
+ * This function is used in cases when the wl_buffer turns out
+ * unusable and there is no fallback path.
+ *
+ * It is possible the fault is caused by a compositor bug, the underlying
+ * graphics stack bug or normal behaviour, or perhaps a client mistake.
+ * In any case, the options are to either composite garbage or nothing,
+ * or disconnect the client. This is a helper function for the latter.
+ *
+ * The error is sent as an INVALID_OBJECT error on the client's wl_display.
+ *
+ * \param buffer The weston buffer that is unusable.
+ * \param msg A custom error message attached to the protocol error.
+ */
+WL_EXPORT void
+weston_buffer_send_server_error(struct weston_buffer *buffer,
+				      const char *msg)
+{
+	struct wl_client *client;
+	struct wl_resource *display_resource;
+	uint32_t id;
+
+	assert(buffer->resource);
+	id = wl_resource_get_id(buffer->resource);
+	client = wl_resource_get_client(buffer->resource);
+	display_resource = wl_client_get_object(client, 1);
+
+	assert(display_resource);
+	wl_resource_post_error(display_resource,
+			       WL_DISPLAY_ERROR_INVALID_OBJECT,
+			       "server error with "
+			       "wl_buffer@%u: %s", id, msg);
+}

libweston/compositor.h

@@ -2345,6 +2345,10 @@ weston_debug_compositor_create(struct weston_compositor *compositor);
 void
 weston_debug_compositor_destroy(struct weston_compositor *compositor);
 
+void
+weston_buffer_send_server_error(struct weston_buffer *buffer,
+				      const char *msg);
+
 #ifdef  __cplusplus
 }
 #endif

libweston/gl-renderer.c

@@ -2377,10 +2377,16 @@ gl_renderer_attach(struct weston_surface *es, struct weston_buffer *buffer)
 		gl_renderer_attach_dmabuf(es, buffer, dmabuf);
 	else {
 		weston_log("unhandled buffer type!\n");
+		if (gr->has_bind_display) {
+		  weston_log("eglQueryWaylandBufferWL failed\n");
+		  gl_renderer_print_egl_error_state();
+		}
 		weston_buffer_reference(&gs->buffer_ref, NULL);
 		gs->buffer_type = BUFFER_TYPE_NULL;
 		gs->y_inverted = 1;
 		es->is_opaque = false;
+                weston_buffer_send_server_error(buffer,
+			"disconnecting due to unhandled buffer type");
 	}
 }
 

libweston/pixman-renderer.c

@@ -661,8 +661,11 @@ pixman_renderer_attach(struct weston_surface *es, struct weston_buffer *buffer)
 		es->is_opaque = true;
 		break;
 	default:
-		weston_log("Unsupported SHM buffer format\n");
+		weston_log("Unsupported SHM buffer format 0x%x\n",
+			wl_shm_buffer_get_format(shm_buffer));
 		weston_buffer_reference(&ps->buffer_ref, NULL);
+                weston_buffer_send_server_error(buffer,
+			"disconnecting due to unhandled buffer type");
 		return;
 	break;
 	}