buffer: convert to try_from

References: wlroots/wlroots#884

include/wlr/types/wlr_buffer.h

@@ -103,7 +103,7 @@ bool wlr_buffer_get_shm(struct wlr_buffer *buffer,
  *
  * The provided struct wl_resource must be a wl_buffer.
  */
-struct wlr_buffer *wlr_buffer_from_resource(struct wl_resource *resource);
+struct wlr_buffer *wlr_buffer_try_from_resource(struct wl_resource *resource);
 
 /**
  * Buffer data pointer access flags.
@@ -160,9 +160,5 @@ struct wlr_client_buffer {
  * buffer, returns NULL.
  */
 struct wlr_client_buffer *wlr_client_buffer_get(struct wlr_buffer *buffer);
-/**
- * Check if a resource is a wl_buffer resource.
- */
-bool wlr_resource_is_buffer(struct wl_resource *resource);
 
 #endif

types/buffer/resource.c

@@ -5,10 +5,6 @@
 #include <wlr/util/log.h>
 #include "types/wlr_buffer.h"
 
-bool wlr_resource_is_buffer(struct wl_resource *resource) {
-	return strcmp(wl_resource_get_class(resource), wl_buffer_interface.name) == 0;
-}
-
 /* struct wlr_buffer_resource_interface */
 static struct wl_array buffer_resource_interfaces = {0};
 
@@ -43,8 +39,10 @@ static const struct wlr_buffer_resource_interface *get_buffer_resource_iface(
 	return NULL;
 }
 
-struct wlr_buffer *wlr_buffer_from_resource(struct wl_resource *resource) {
+struct wlr_buffer *wlr_buffer_try_from_resource(struct wl_resource *resource) {
-	assert(resource && wlr_resource_is_buffer(resource));
+	if (strcmp(wl_resource_get_class(resource), wl_buffer_interface.name) != 0) {
+		return NULL;
+	}
 
 	const struct wlr_buffer_resource_interface *iface =
 			get_buffer_resource_iface(resource);

types/wlr_compositor.c

@@ -61,7 +61,7 @@ static void surface_handle_attach(struct wl_client *client,
 
 	struct wlr_buffer *buffer = NULL;
 	if (buffer_resource != NULL) {
-		buffer = wlr_buffer_from_resource(buffer_resource);
+		buffer = wlr_buffer_try_from_resource(buffer_resource);
 		if (buffer == NULL) {
 			wl_resource_post_error(buffer_resource, 0, "unknown buffer type");
 			return;

types/wlr_screencopy_v1.c

@@ -350,7 +350,7 @@ static void frame_handle_copy(struct wl_client *wl_client,
 		return;
 	}
 
-	struct wlr_buffer *buffer = wlr_buffer_from_resource(buffer_resource);
+	struct wlr_buffer *buffer = wlr_buffer_try_from_resource(buffer_resource);
 	if (buffer == NULL) {
 		wl_resource_post_error(frame->resource,
 			ZWLR_SCREENCOPY_FRAME_V1_ERROR_INVALID_BUFFER,