Introduce wlr_client_buffer

Split out the client/resource handling out of wlr_buffer by introducing
wlr_client_buffer. Make wlr_buffer an interface so that compositors can
create their own wlr_buffers (e.g. backed by GBM, like glider [1]).

[1]: c66847dd1c/include/gbm_allocator.h (L7)

include/wlr/types/wlr_buffer.h

@@ -13,14 +13,52 @@
 #include <wayland-server-core.h>
 #include <wlr/render/dmabuf.h>
 
+struct wlr_buffer;
+
+struct wlr_buffer_impl {
+	void (*destroy)(struct wlr_buffer *buffer);
+	bool (*get_dmabuf)(struct wlr_buffer *buffer,
+		struct wlr_dmabuf_attributes *attribs);
+};
+
+struct wlr_buffer {
+	const struct wlr_buffer_impl *impl;
+
+	size_t n_refs;
+};
+
+void wlr_buffer_init(struct wlr_buffer *buffer,
+	const struct wlr_buffer_impl *impl);
+/**
+ * Reference the buffer.
+ */
+struct wlr_buffer *wlr_buffer_ref(struct wlr_buffer *buffer);
+/**
+ * Unreference the buffer. After this call, `buffer` may not be accessed
+ * anymore.
+ */
+void wlr_buffer_unref(struct wlr_buffer *buffer);
+/**
+ * Reads the DMA-BUF attributes of the buffer. If this buffer isn't a DMA-BUF,
+ * returns false.
+ */
+bool wlr_buffer_get_dmabuf(struct wlr_buffer *buffer,
+	struct wlr_dmabuf_attributes *attribs);
+
 /**
  * A client buffer.
  */
-struct wlr_buffer {
+struct wlr_client_buffer {
+	struct wlr_buffer base;
+
 	/**
 	 * The buffer resource, if any. Will be NULL if the client destroys it.
 	 */
 	struct wl_resource *resource;
+	/**
+	 * Whether a release event has been sent to the resource.
+	 */
+	bool resource_released;
 	/**
 	 * The buffer's texture, if any. A buffer will not have a texture if the
 	 * client destroys the buffer before it has been released.
@@ -41,23 +79,13 @@ bool wlr_resource_is_buffer(struct wl_resource *resource);
 /**
  * Get the size of a wl_buffer resource.
  */
-bool wlr_buffer_get_resource_size(struct wl_resource *resource,
+bool wlr_resource_get_buffer_size(struct wl_resource *resource,
 	struct wlr_renderer *renderer, int *width, int *height);
-
 /**
  * Upload a buffer to the GPU and reference it.
  */
-struct wlr_buffer *wlr_buffer_create(struct wlr_renderer *renderer,
-	struct wl_resource *resource);
-/**
- * Reference the buffer.
- */
-struct wlr_buffer *wlr_buffer_ref(struct wlr_buffer *buffer);
-/**
- * Unreference the buffer. After this call, `buffer` may not be accessed
- * anymore.
- */
-void wlr_buffer_unref(struct wlr_buffer *buffer);
+struct wlr_client_buffer *wlr_client_buffer_create(
+	struct wlr_renderer *renderer, struct wl_resource *resource);
 /**
  * Try to update the buffer's content. On success, returns the updated buffer
  * and destroys the provided `buffer`. On error, `buffer` is intact and NULL is
@@ -66,13 +94,8 @@ void wlr_buffer_unref(struct wlr_buffer *buffer);
  * Fails if there's more than one reference to the buffer or if the texture
  * isn't mutable.
  */
-struct wlr_buffer *wlr_buffer_apply_damage(struct wlr_buffer *buffer,
-	struct wl_resource *resource, pixman_region32_t *damage);
-/**
- * Reads the DMA-BUF attributes of the buffer. If this buffer isn't a DMA-BUF,
- * returns false.
- */
-bool wlr_buffer_get_dmabuf(struct wlr_buffer *buffer,
-		struct wlr_dmabuf_attributes *attribs);
+struct wlr_client_buffer *wlr_client_buffer_apply_damage(
+	struct wlr_client_buffer *buffer, struct wl_resource *resource,
+	pixman_region32_t *damage);
 
 #endif

include/wlr/types/wlr_surface.h

@@ -59,7 +59,7 @@ struct wlr_surface {
 	 * have a buffer if it has never committed one, has committed a null buffer,
 	 * or something went wrong with uploading the buffer.
 	 */
-	struct wlr_buffer *buffer;
+	struct wlr_client_buffer *buffer;
 	/**
 	 * The buffer position, in surface-local units.
 	 */

types/wlr_buffer.c

@@ -5,11 +5,46 @@
 #include <wlr/types/wlr_linux_dmabuf_v1.h>
 #include <wlr/util/log.h>
 
+void wlr_buffer_init(struct wlr_buffer *buffer,
+		const struct wlr_buffer_impl *impl) {
+	assert(impl->destroy);
+	buffer->impl = impl;
+	buffer->n_refs = 1;
+}
+
+struct wlr_buffer *wlr_buffer_ref(struct wlr_buffer *buffer) {
+	buffer->n_refs++;
+	return buffer;
+}
+
+void wlr_buffer_unref(struct wlr_buffer *buffer) {
+	if (buffer == NULL) {
+		return;
+	}
+
+	assert(buffer->n_refs > 0);
+	buffer->n_refs--;
+	if (buffer->n_refs > 0) {
+		return;
+	}
+
+	buffer->impl->destroy(buffer);
+}
+
+bool wlr_buffer_get_dmabuf(struct wlr_buffer *buffer,
+		struct wlr_dmabuf_attributes *attribs) {
+	if (!buffer->impl->get_dmabuf) {
+		return false;
+	}
+	return buffer->impl->get_dmabuf(buffer, attribs);
+}
+
+
 bool wlr_resource_is_buffer(struct wl_resource *resource) {
 	return strcmp(wl_resource_get_class(resource), wl_buffer_interface.name) == 0;
 }
 
-bool wlr_buffer_get_resource_size(struct wl_resource *resource,
+bool wlr_resource_get_buffer_size(struct wl_resource *resource,
 		struct wlr_renderer *renderer, int *width, int *height) {
 	assert(wlr_resource_is_buffer(resource));
 
@@ -34,10 +69,54 @@ bool wlr_buffer_get_resource_size(struct wl_resource *resource,
 	return true;
 }
 
+static const struct wlr_buffer_impl client_buffer_impl;
 
-static void buffer_resource_handle_destroy(struct wl_listener *listener,
+static struct wlr_client_buffer *client_buffer_from_buffer(
+		struct wlr_buffer *buffer) {
+	assert(buffer->impl == &client_buffer_impl);
+	return (struct wlr_client_buffer *) buffer;
+}
+
+static void client_buffer_destroy(struct wlr_buffer *_buffer) {
+	struct wlr_client_buffer *buffer = client_buffer_from_buffer(_buffer);
+
+	if (!buffer->resource_released && buffer->resource != NULL) {
+		wl_buffer_send_release(buffer->resource);
+	}
+
+	wl_list_remove(&buffer->resource_destroy.link);
+	wlr_texture_destroy(buffer->texture);
+	free(buffer);
+}
+
+static bool client_buffer_get_dmabuf(struct wlr_buffer *_buffer,
+		struct wlr_dmabuf_attributes *attribs) {
+	struct wlr_client_buffer *buffer = client_buffer_from_buffer(_buffer);
+
+	if (buffer->resource == NULL) {
+		return false;
+	}
+
+	struct wl_resource *buffer_resource = buffer->resource;
+	if (!wlr_dmabuf_v1_resource_is_buffer(buffer_resource)) {
+		return false;
+	}
+
+	struct wlr_dmabuf_v1_buffer *dmabuf_buffer =
+		wlr_dmabuf_v1_buffer_from_buffer_resource(buffer_resource);
+	memcpy(attribs, &dmabuf_buffer->attributes,
+		sizeof(struct wlr_dmabuf_attributes));
+	return true;
+}
+
+static const struct wlr_buffer_impl client_buffer_impl = {
+	.destroy = client_buffer_destroy,
+	.get_dmabuf = client_buffer_get_dmabuf,
+};
+
+static void client_buffer_resource_handle_destroy(struct wl_listener *listener,
 		void *data) {
-	struct wlr_buffer *buffer =
+	struct wlr_client_buffer *buffer =
 		wl_container_of(listener, buffer, resource_destroy);
 	wl_list_remove(&buffer->resource_destroy.link);
 	wl_list_init(&buffer->resource_destroy.link);
@@ -51,8 +130,8 @@ static void buffer_resource_handle_destroy(struct wl_listener *listener,
 	// which case we'll read garbage. We decide to accept this risk.
 }
 
-struct wlr_buffer *wlr_buffer_create(struct wlr_renderer *renderer,
-		struct wl_resource *resource) {
+struct wlr_client_buffer *wlr_client_buffer_create(
+		struct wlr_renderer *renderer, struct wl_resource *resource) {
 	assert(wlr_resource_is_buffer(resource));
 
 	struct wlr_texture *texture = NULL;
@@ -100,50 +179,27 @@ struct wlr_buffer *wlr_buffer_create(struct wlr_renderer *renderer,
 		return NULL;
 	}
 
-	struct wlr_buffer *buffer = calloc(1, sizeof(struct wlr_buffer));
+	struct wlr_client_buffer *buffer =
+		calloc(1, sizeof(struct wlr_client_buffer));
 	if (buffer == NULL) {
 		wlr_texture_destroy(texture);
 		wl_resource_post_no_memory(resource);
 		return NULL;
 	}
+	wlr_buffer_init(&buffer->base, &client_buffer_impl);
 	buffer->resource = resource;
 	buffer->texture = texture;
-	buffer->released = released;
-	buffer->n_refs = 1;
+	buffer->resource_released = released;
 
 	wl_resource_add_destroy_listener(resource, &buffer->resource_destroy);
-	buffer->resource_destroy.notify = buffer_resource_handle_destroy;
+	buffer->resource_destroy.notify = client_buffer_resource_handle_destroy;
 
 	return buffer;
 }
 
-struct wlr_buffer *wlr_buffer_ref(struct wlr_buffer *buffer) {
-	buffer->n_refs++;
-	return buffer;
-}
-
-void wlr_buffer_unref(struct wlr_buffer *buffer) {
-	if (buffer == NULL) {
-		return;
-	}
-
-	assert(buffer->n_refs > 0);
-	buffer->n_refs--;
-	if (buffer->n_refs > 0) {
-		return;
-	}
-
-	if (!buffer->released && buffer->resource != NULL) {
-		wl_buffer_send_release(buffer->resource);
-	}
-
-	wl_list_remove(&buffer->resource_destroy.link);
-	wlr_texture_destroy(buffer->texture);
-	free(buffer);
-}
-
-struct wlr_buffer *wlr_buffer_apply_damage(struct wlr_buffer *buffer,
-		struct wl_resource *resource, pixman_region32_t *damage) {
+struct wlr_client_buffer *wlr_client_buffer_apply_damage(
+		struct wlr_client_buffer *buffer, struct wl_resource *resource,
+		pixman_region32_t *damage) {
 	assert(wlr_resource_is_buffer(resource));
 
 	if (buffer->n_refs > 1) {
@@ -199,27 +255,9 @@ struct wlr_buffer *wlr_buffer_apply_damage(struct wlr_buffer *buffer,
 
 	wl_list_remove(&buffer->resource_destroy.link);
 	wl_resource_add_destroy_listener(resource, &buffer->resource_destroy);
-	buffer->resource_destroy.notify = buffer_resource_handle_destroy;
+	buffer->resource_destroy.notify = client_buffer_resource_handle_destroy;
 
 	buffer->resource = resource;
 	buffer->released = true;
 	return buffer;
 }
-
-bool wlr_buffer_get_dmabuf(struct wlr_buffer *buffer,
-		struct wlr_dmabuf_attributes *attribs) {
-	if (buffer->resource == NULL) {
-		return false;
-	}
-
-	struct wl_resource *buffer_resource = buffer->resource;
-	if (!wlr_dmabuf_v1_resource_is_buffer(buffer_resource)) {
-		return false;
-	}
-
-	struct wlr_dmabuf_v1_buffer *dmabuf_buffer =
-		wlr_dmabuf_v1_buffer_from_buffer_resource(buffer_resource);
-	memcpy(attribs, &dmabuf_buffer->attributes,
-		sizeof(struct wlr_dmabuf_attributes));
-	return true;
-}

types/wlr_surface.c

@@ -142,7 +142,7 @@ static void surface_state_finalize(struct wlr_surface *surface,
 		struct wlr_surface_state *state) {
 	if ((state->committed & WLR_SURFACE_STATE_BUFFER)) {
 		if (state->buffer_resource != NULL) {
-			wlr_buffer_get_resource_size(state->buffer_resource,
+			wlr_resource_get_buffer_size(state->buffer_resource,
 				surface->renderer, &state->buffer_width, &state->buffer_height);
 		} else {
 			state->buffer_width = state->buffer_height = 0;
@@ -282,27 +282,33 @@ static void surface_apply_damage(struct wlr_surface *surface) {
 	struct wl_resource *resource = surface->current.buffer_resource;
 	if (resource == NULL) {
 		// NULL commit
-		wlr_buffer_unref(surface->buffer);
+		if (surface->buffer != NULL) {
+			wlr_buffer_unref(&surface->buffer->base);
+		}
 		surface->buffer = NULL;
 		return;
 	}
 
 	if (surface->buffer != NULL && surface->buffer->released) {
-		struct wlr_buffer *updated_buffer = wlr_buffer_apply_damage(
-			surface->buffer, resource, &surface->buffer_damage);
+		struct wlr_client_buffer *updated_buffer =
+			wlr_client_buffer_apply_damage(surface->buffer, resource,
+			&surface->buffer_damage);
 		if (updated_buffer != NULL) {
 			surface->buffer = updated_buffer;
 			return;
 		}
 	}
 
-	struct wlr_buffer *buffer = wlr_buffer_create(surface->renderer, resource);
+	struct wlr_client_buffer *buffer =
+		wlr_client_buffer_create(surface->renderer, resource);
 	if (buffer == NULL) {
 		wlr_log(WLR_ERROR, "Failed to upload buffer");
 		return;
 	}
 
-	wlr_buffer_unref(surface->buffer);
+	if (surface->buffer != NULL) {
+		wlr_buffer_unref(&surface->buffer->base);
+	}
 	surface->buffer = buffer;
 }
 
@@ -573,7 +579,9 @@ static void surface_handle_resource_destroy(struct wl_resource *resource) {
 	pixman_region32_fini(&surface->buffer_damage);
 	pixman_region32_fini(&surface->opaque_region);
 	pixman_region32_fini(&surface->input_region);
-	wlr_buffer_unref(surface->buffer);
+	if (surface->buffer != NULL) {
+		wlr_buffer_unref(&surface->buffer->base);
+	}
 	free(surface);
 }