buffer: make wlr_client_buffer_apply_damage return a bool

We always return the same wlr_client_buffer as the one passed in,
so no need to return anything.

include/wlr/types/wlr_buffer.h

@@ -178,15 +178,12 @@ struct wlr_client_buffer *wlr_client_buffer_get(struct wlr_buffer *buffer);
  */
 bool wlr_resource_is_buffer(struct wl_resource *resource);
 /**
- * Try to update the buffer's content. On success, returns the updated buffer
+ * Try to update the buffer's content.
- * and destroys the provided `buffer`. On error, `buffer` is intact and NULL is
- * returned.
  *
  * Fails if there's more than one reference to the buffer or if the texture
  * isn't mutable.
  */
-struct wlr_client_buffer *wlr_client_buffer_apply_damage(
+bool wlr_client_buffer_apply_damage(struct wlr_client_buffer *client_buffer,
-	struct wlr_client_buffer *buffer, struct wlr_buffer *next,
+	struct wlr_buffer *next, pixman_region32_t *damage);
-	pixman_region32_t *damage);
 
 #endif

types/wlr_buffer.c

@@ -271,36 +271,35 @@ struct wlr_client_buffer *wlr_client_buffer_create(struct wlr_buffer *buffer,
 	return client_buffer;
 }
 
-struct wlr_client_buffer *wlr_client_buffer_apply_damage(
+bool wlr_client_buffer_apply_damage(struct wlr_client_buffer *client_buffer,
-		struct wlr_client_buffer *client_buffer, struct wlr_buffer *next,
+		struct wlr_buffer *next, pixman_region32_t *damage) {
-		pixman_region32_t *damage) {
 	if (client_buffer->base.n_locks > 1) {
 		// Someone else still has a reference to the buffer
-		return NULL;
+		return false;
 	}
 
 	if ((uint32_t)next->width != client_buffer->texture->width ||
 			(uint32_t)next->height != client_buffer->texture->height) {
-		return NULL;
+		return false;
 	}
 
 	if (client_buffer->shm_source_format == DRM_FORMAT_INVALID) {
 		// Uploading only damaged regions only works for wl_shm buffers and
 		// mutable textures (created from wl_shm buffer)
-		return NULL;
+		return false;
 	}
 
 	void *data;
 	uint32_t format;
 	size_t stride;
 	if (!buffer_begin_data_ptr_access(next, &data, &format, &stride)) {
-		return NULL;
+		return false;
 	}
 
 	if (format != client_buffer->shm_source_format) {
 		// Uploading to textures can't change the format
 		buffer_end_data_ptr_access(next);
-		return NULL;
+		return false;
 	}
 
 	int n;
@@ -311,13 +310,13 @@ struct wlr_client_buffer *wlr_client_buffer_apply_damage(
 				r->x2 - r->x1, r->y2 - r->y1, r->x1, r->y1,
 				r->x1, r->y1, data)) {
 			buffer_end_data_ptr_access(next);
-			return NULL;
+			return false;
 		}
 	}
 
 	buffer_end_data_ptr_access(next);
 
-	return client_buffer;
+	return true;
 }
 
 static const struct wlr_buffer_impl shm_client_buffer_impl;

types/wlr_surface.c

@@ -364,13 +364,10 @@ static void surface_apply_damage(struct wlr_surface *surface) {
 	}
 
 	if (surface->buffer != NULL) {
-		struct wlr_client_buffer *updated_buffer =
+		if (wlr_client_buffer_apply_damage(surface->buffer,
-			wlr_client_buffer_apply_damage(surface->buffer,
+				surface->current.buffer, &surface->buffer_damage)) {
-			surface->current.buffer, &surface->buffer_damage);
-		if (updated_buffer != NULL) {
 			wlr_buffer_unlock(surface->current.buffer);
 			surface->current.buffer = NULL;
-			surface->buffer = updated_buffer;
 			return;
 		}
 	}