output: add wlr_output_state_init()

This changes the semantics of wlr_output_state. Instead of having
fields with uninitialized memory when missing from the committed
bitflag, all fields are always initialized (and maybe NULL/empty),
just like we do in wlr_surface_state. This reduces the chances of
footguns when reading a field, and removes the need to check for
the committed bitfield everywhere.

A new wlr_output_state_init() function takes care of initializing
the Pixman region.

backend/drm/backend.c

@@ -121,22 +121,21 @@ static void handle_session_active(struct wl_listener *listener, void *data) {
 		struct wlr_drm_connector *conn;
 		wl_list_for_each(conn, &drm->connectors, link) {
 			struct wlr_output_mode *mode = NULL;
-			uint32_t committed = WLR_OUTPUT_STATE_ENABLED;
 			if (conn->status != DRM_MODE_DISCONNECTED && conn->output.enabled
 					&& conn->output.current_mode != NULL) {
-				committed |= WLR_OUTPUT_STATE_MODE;
 				mode = conn->output.current_mode;
 			}
-			struct wlr_output_state state = {
+
-				.committed = committed,
+			struct wlr_output_state state;
-				.allow_artifacts = true,
+			wlr_output_state_init(&state);
-				.enabled = mode != NULL,
+			wlr_output_state_set_enabled(&state, mode != NULL);
-				.mode_type = WLR_OUTPUT_STATE_MODE_FIXED,
+			if (mode != NULL) {
-				.mode = mode,
+				wlr_output_state_set_mode(&state, mode);
-			};
+			}
 			if (!drm_connector_commit_state(conn, &state)) {
 				wlr_drm_conn_log(conn, WLR_ERROR, "Failed to restore state after VT switch");
 			}
+			wlr_output_state_finish(&state);
 		}
 	} else {
 		wlr_log(WLR_INFO, "DRM fd paused");

backend/drm/drm.c

@@ -1155,16 +1155,15 @@ static void dealloc_crtc(struct wlr_drm_connector *conn) {
 	wlr_drm_conn_log(conn, WLR_DEBUG, "De-allocating CRTC %" PRIu32,
 		conn->crtc->id);
 
-	struct wlr_output_state state = {
+	struct wlr_output_state state;
-		.committed = WLR_OUTPUT_STATE_ENABLED,
+	wlr_output_state_init(&state);
-		.allow_artifacts = true,
+	wlr_output_state_set_enabled(&state, false);
-		.enabled = false,
-	};
 	if (!drm_connector_commit_state(conn, &state)) {
 		// On GPU unplug, disabling the CRTC can fail with EPERM
 		wlr_drm_conn_log(conn, WLR_ERROR, "Failed to disable CRTC %"PRIu32,
 			conn->crtc->id);
 	}
+	wlr_output_state_finish(&state);
 }
 
 static void realloc_crtcs(struct wlr_drm_backend *drm,

backend/wayland/output.c

@@ -703,12 +703,11 @@ static void xdg_toplevel_handle_configure(void *data,
 		return;
 	}
 
-	struct wlr_output_state state = {
+	struct wlr_output_state state;
-		.committed = WLR_OUTPUT_STATE_MODE,
+	wlr_output_state_init(&state);
-		.mode_type = WLR_OUTPUT_STATE_MODE_CUSTOM,
+	wlr_output_state_set_custom_mode(&state, width, height, 0);
-		.custom_mode = { .width = width, .height = height },
-	};
 	wlr_output_send_request_state(&output->wlr_output, &state);
+	wlr_output_state_finish(&state);
 }
 
 static void xdg_toplevel_handle_close(void *data,

backend/x11/output.c

@@ -623,12 +623,11 @@ void handle_x11_configure_notify(struct wlr_x11_output *output,
 		return;
 	}
 
-	struct wlr_output_state state = {
+	struct wlr_output_state state;
-		.committed = WLR_OUTPUT_STATE_MODE,
+	wlr_output_state_init(&state);
-		.mode_type = WLR_OUTPUT_STATE_MODE_CUSTOM,
+	wlr_output_state_set_custom_mode(&state, ev->width, ev->height, 0);
-		.custom_mode = { .width = ev->width, .height = ev->height },
-	};
 	wlr_output_send_request_state(&output->wlr_output, &state);
+	wlr_output_state_finish(&state);
 }
 
 bool wlr_output_is_x11(struct wlr_output *wlr_output) {

examples/fullscreen-shell.c

@@ -89,7 +89,8 @@ static void output_handle_frame(struct wl_listener *listener, void *data) {
 	int width, height;
 	wlr_output_effective_resolution(output->wlr_output, &width, &height);
 
-	struct wlr_output_state state = {0};
+	struct wlr_output_state state;
+	wlr_output_state_init(&state);
 	struct wlr_render_pass *pass = wlr_output_begin_render_pass(output->wlr_output, &state, NULL,
 		NULL);
 	if (pass == NULL) {
@@ -166,7 +167,8 @@ static void server_handle_new_output(struct wl_listener *listener, void *data) {
 
 	struct wlr_output_mode *mode = wlr_output_preferred_mode(wlr_output);
 	if (mode != NULL) {
-		struct wlr_output_state state = {0};
+		struct wlr_output_state state;
+		wlr_output_state_init(&state);
 		wlr_output_state_set_mode(&state, mode);
 		wlr_output_commit_state(wlr_output, &state);
 		wlr_output_state_finish(&state);

examples/output-layers.c

@@ -82,7 +82,8 @@ static void output_handle_frame(struct wl_listener *listener, void *data) {
 		};
 	}
 
-	struct wlr_output_state output_state = {0};
+	struct wlr_output_state output_state;
+	wlr_output_state_init(&output_state);
 	wlr_output_state_set_layers(&output_state, layers_arr.data,
 		layers_arr.size / sizeof(struct wlr_output_layer_state));
 
@@ -175,7 +176,8 @@ static void server_handle_new_output(struct wl_listener *listener, void *data) {
 
 	struct wlr_output_mode *mode = wlr_output_preferred_mode(wlr_output);
 	if (mode != NULL) {
-		struct wlr_output_state state = {0};
+		struct wlr_output_state state;
+		wlr_output_state_init(&state);
 		wlr_output_state_set_mode(&state, mode);
 		wlr_output_commit_state(wlr_output, &state);
 		wlr_output_state_finish(&state);

examples/output-layout.c

@@ -114,7 +114,8 @@ static void output_frame_notify(struct wl_listener *listener, void *data) {
 	struct sample_state *sample = output->sample;
 	struct wlr_output *wlr_output = output->output;
 
-	struct wlr_output_state output_state = {0};
+	struct wlr_output_state output_state;
+	wlr_output_state_init(&output_state);
 	struct wlr_render_pass *pass = wlr_output_begin_render_pass(wlr_output, &output_state, NULL, NULL);
 
 	wlr_render_pass_add_rect(pass, &(struct wlr_render_rect_options){
@@ -178,7 +179,8 @@ static void new_output_notify(struct wl_listener *listener, void *data) {
 
 	struct wlr_output_mode *mode = wlr_output_preferred_mode(output);
 	if (mode != NULL) {
-		struct wlr_output_state state = {0};
+		struct wlr_output_state state;
+		wlr_output_state_init(&state);
 		wlr_output_state_set_mode(&state, mode);
 		wlr_output_commit_state(output, &state);
 		wlr_output_state_finish(&state);

examples/pointer.c

@@ -101,7 +101,8 @@ static void output_frame_notify(struct wl_listener *listener, void *data) {
 	struct wlr_renderer *renderer = state->renderer;
 	assert(renderer);
 
-	struct wlr_output_state output_state = {0};
+	struct wlr_output_state output_state;
+	wlr_output_state_init(&output_state);
 	struct wlr_render_pass *pass = wlr_output_begin_render_pass(wlr_output, &output_state, NULL, NULL);
 	wlr_render_pass_add_rect(pass, &(struct wlr_render_rect_options){
 		.box = { .width = wlr_output->width, .height = wlr_output->height },
@@ -280,7 +281,8 @@ static void new_output_notify(struct wl_listener *listener, void *data) {
 
 	struct wlr_output_mode *mode = wlr_output_preferred_mode(output);
 	if (mode != NULL) {
-		struct wlr_output_state state = {0};
+		struct wlr_output_state state;
+		wlr_output_state_init(&state);
 		wlr_output_state_set_mode(&state, mode);
 		wlr_output_commit_state(output, &state);
 		wlr_output_state_finish(&state);

examples/rotation.c

@@ -59,7 +59,8 @@ static void output_frame_notify(struct wl_listener *listener, void *data) {
 	int32_t width, height;
 	wlr_output_effective_resolution(wlr_output, &width, &height);
 
-	struct wlr_output_state output_state = {0};
+	struct wlr_output_state output_state;
+	wlr_output_state_init(&output_state);
 	struct wlr_render_pass *pass = wlr_output_begin_render_pass(wlr_output, &output_state, NULL, NULL);
 
 	wlr_render_pass_add_rect(pass, &(struct wlr_render_rect_options){
@@ -122,7 +123,8 @@ static void new_output_notify(struct wl_listener *listener, void *data) {
 	sample_output->x_offs = sample_output->y_offs = 0;
 	sample_output->x_vel = sample_output->y_vel = 128;
 
-	struct wlr_output_state state = {0};
+	struct wlr_output_state state;
+	wlr_output_state_init(&state);
 	wlr_output_state_set_transform(&state, sample->transform);
 
 	sample_output->output = output;

examples/scene-graph.c

@@ -83,7 +83,8 @@ static void server_handle_new_output(struct wl_listener *listener, void *data) {
 
 	struct wlr_output_mode *mode = wlr_output_preferred_mode(wlr_output);
 	if (mode != NULL) {
-		struct wlr_output_state state = {0};
+		struct wlr_output_state state;
+		wlr_output_state_init(&state);
 		wlr_output_state_set_mode(&state, mode);
 		wlr_output_commit_state(wlr_output, &state);
 		wlr_output_state_finish(&state);

examples/simple.c

@@ -62,7 +62,8 @@ static void output_frame_notify(struct wl_listener *listener, void *data) {
 		sample->dec = inc;
 	}
 
-	struct wlr_output_state state = {0};
+	struct wlr_output_state state;
+	wlr_output_state_init(&state);
 	struct wlr_render_pass *pass = wlr_output_begin_render_pass(wlr_output, &state, NULL, NULL);
 	wlr_render_pass_add_rect(pass, &(struct wlr_render_rect_options){
 		.box = { .width = wlr_output->width, .height = wlr_output->height },
@@ -107,7 +108,8 @@ static void new_output_notify(struct wl_listener *listener, void *data) {
 
 	struct wlr_output_mode *mode = wlr_output_preferred_mode(output);
 	if (mode != NULL) {
-		struct wlr_output_state state = {0};
+		struct wlr_output_state state;
+		wlr_output_state_init(&state);
 		wlr_output_state_set_mode(&state, mode);
 		wlr_output_commit_state(sample_output->output, &state);
 		wlr_output_state_finish(&state);

examples/tablet.c

@@ -87,7 +87,8 @@ static void output_frame_notify(struct wl_listener *listener, void *data) {
 	int32_t width, height;
 	wlr_output_effective_resolution(wlr_output, &width, &height);
 
-	struct wlr_output_state output_state = {0};
+	struct wlr_output_state output_state;
+	wlr_output_state_init(&output_state);
 	struct wlr_render_pass *pass = wlr_output_begin_render_pass(wlr_output, &output_state, NULL, NULL);
 
 	wlr_render_pass_add_rect(pass, &(struct wlr_render_rect_options){
@@ -285,7 +286,8 @@ static void new_output_notify(struct wl_listener *listener, void *data) {
 
 	struct wlr_output_mode *mode = wlr_output_preferred_mode(output);
 	if (mode != NULL) {
-		struct wlr_output_state state = {0};
+		struct wlr_output_state state;
+		wlr_output_state_init(&state);
 		wlr_output_state_set_mode(&state, mode);
 		wlr_output_commit_state(output, &state);
 		wlr_output_state_finish(&state);

examples/touch.c

@@ -76,7 +76,8 @@ static void output_frame_notify(struct wl_listener *listener, void *data) {
 	int32_t width, height;
 	wlr_output_effective_resolution(wlr_output, &width, &height);
 
-	struct wlr_output_state output_state = {0};
+	struct wlr_output_state output_state;
+	wlr_output_state_init(&output_state);
 	struct wlr_render_pass *pass = wlr_output_begin_render_pass(wlr_output, &output_state, NULL, NULL);
 	wlr_render_pass_add_rect(pass, &(struct wlr_render_rect_options){
 		.box = { .width = width, .height = height },
@@ -184,7 +185,8 @@ static void new_output_notify(struct wl_listener *listener, void *data) {
 
 	struct wlr_output_mode *mode = wlr_output_preferred_mode(output);
 	if (mode != NULL) {
-		struct wlr_output_state state = {0};
+		struct wlr_output_state state;
+		wlr_output_state_init(&state);
 		wlr_output_state_set_mode(&state, mode);
 		wlr_output_commit_state(output, &state);
 		wlr_output_state_finish(&state);

include/wlr/types/wlr_output.h

@@ -88,10 +88,8 @@ struct wlr_output_state {
 	uint32_t render_format;
 	enum wl_output_subpixel subpixel;
 
-	// only valid if WLR_OUTPUT_STATE_BUFFER
 	struct wlr_buffer *buffer;
 
-	// only valid if WLR_OUTPUT_STATE_MODE
 	enum wlr_output_state_mode_type mode_type;
 	struct wlr_output_mode *mode;
 	struct {
@@ -99,11 +97,9 @@ struct wlr_output_state {
 		int32_t refresh; // mHz, may be zero
 	} custom_mode;
 
-	// only valid if WLR_OUTPUT_STATE_GAMMA_LUT
 	uint16_t *gamma_lut;
 	size_t gamma_lut_size;
 
-	// only valid if WLR_OUTPUT_STATE_LAYERS
 	struct wlr_output_layer_state *layers;
 	size_t layers_len;
 };
@@ -567,6 +563,10 @@ bool wlr_output_cursor_move(struct wlr_output_cursor *cursor,
 	double x, double y);
 void wlr_output_cursor_destroy(struct wlr_output_cursor *cursor);
 
+/**
+ * Initialize an output state.
+ */
+void wlr_output_state_init(struct wlr_output_state *state);
 /**
  * Releases all resources associated with an output state.
  */

tinywl/tinywl.c

@@ -603,7 +603,8 @@ static void server_new_output(struct wl_listener *listener, void *data) {
 	 * would let the user configure it. */
 	struct wlr_output_mode *mode = wlr_output_preferred_mode(wlr_output);
 	if (mode != NULL) {
-		struct wlr_output_state state = {0};
+		struct wlr_output_state state;
+		wlr_output_state_init(&state);
 		wlr_output_state_set_mode(&state, mode);
 		wlr_output_state_set_enabled(&state, true);
 		if (!wlr_output_commit_state(wlr_output, &state)) {

types/output/output.c

@@ -319,15 +319,10 @@ static void handle_display_destroy(struct wl_listener *listener, void *data) {
 	wlr_output_destroy_global(output);
 }
 
-static void output_state_init(struct wlr_output_state *state) {
-	memset(state, 0, sizeof(*state));
-	pixman_region32_init(&state->damage);
-}
-
 static void output_state_move(struct wlr_output_state *dst,
 		struct wlr_output_state *src) {
 	*dst = *src;
-	output_state_init(src);
+	wlr_output_state_init(src);
 }
 
 void wlr_output_init(struct wlr_output *output, struct wlr_backend *backend,
@@ -359,7 +354,7 @@ void wlr_output_init(struct wlr_output *output, struct wlr_backend *backend,
 	wl_signal_init(&output->events.description);
 	wl_signal_init(&output->events.request_state);
 	wl_signal_init(&output->events.destroy);
-	output_state_init(&output->pending);
+	wlr_output_state_init(&output->pending);
 
 	output->software_cursor_locks = env_parse_bool("WLR_NO_HARDWARE_CURSORS");
 	if (output->software_cursor_locks) {

types/output/state.c

@@ -3,20 +3,19 @@
 #include <wlr/util/log.h>
 #include "types/wlr_output.h"
 
+void wlr_output_state_init(struct wlr_output_state *state) {
+	*state = (struct wlr_output_state){0};
+	pixman_region32_init(&state->damage);
+}
+
 void wlr_output_state_finish(struct wlr_output_state *state) {
-	if (state->committed & WLR_OUTPUT_STATE_BUFFER) {
+	wlr_buffer_unlock(state->buffer);
-		wlr_buffer_unlock(state->buffer);
+	// struct wlr_buffer is ref'counted, so the pointer may remain valid after
-		// struct wlr_buffer is ref'counted, so the pointer may remain valid after
+	// wlr_buffer_unlock(). Reset the field to NULL to ensure nobody mistakenly
-		// wlr_buffer_unlock(). Reset the field to NULL to ensure nobody mistakenly
+	// reads it after output_state_finish().
-		// reads it after output_state_finish().
+	state->buffer = NULL;
-		state->buffer = NULL;
+	pixman_region32_fini(&state->damage);
-	}
+	free(state->gamma_lut);
-	if (state->committed & WLR_OUTPUT_STATE_DAMAGE) {
-		pixman_region32_fini(&state->damage);
-	}
-	if (state->committed & WLR_OUTPUT_STATE_GAMMA_LUT) {
-		free(state->gamma_lut);
-	}
 }
 
 void wlr_output_state_set_enabled(struct wlr_output_state *state,
@@ -75,23 +74,14 @@ void wlr_output_state_set_subpixel(struct wlr_output_state *state,
 
 void wlr_output_state_set_buffer(struct wlr_output_state *state,
 		struct wlr_buffer *buffer) {
-	if (state->committed & WLR_OUTPUT_STATE_BUFFER) {
-		wlr_buffer_unlock(state->buffer);
-	}
-
 	state->committed |= WLR_OUTPUT_STATE_BUFFER;
+	wlr_buffer_unlock(state->buffer);
 	state->buffer = wlr_buffer_lock(buffer);
 }
 
 void wlr_output_state_set_damage(struct wlr_output_state *state,
 		const pixman_region32_t *damage) {
-	if (state->committed & WLR_OUTPUT_STATE_DAMAGE) {
-		pixman_region32_fini(&state->damage);
-	}
-
 	state->committed |= WLR_OUTPUT_STATE_DAMAGE;
-
-	pixman_region32_init(&state->damage);
 	pixman_region32_copy(&state->damage, damage);
 }
 
@@ -99,11 +89,7 @@ bool wlr_output_state_set_gamma_lut(struct wlr_output_state *state,
 		size_t ramp_size, const uint16_t *r, const uint16_t *g, const uint16_t *b) {
 	uint16_t *gamma_lut = NULL;
 	if (ramp_size > 0) {
-		if (state->committed & WLR_OUTPUT_STATE_GAMMA_LUT) {
+		gamma_lut = realloc(state->gamma_lut, 3 * ramp_size * sizeof(uint16_t));
-			gamma_lut = realloc(state->gamma_lut, 3 * ramp_size * sizeof(uint16_t));
-		} else {
-			gamma_lut = malloc(3 * ramp_size * sizeof(uint16_t));
-		}
 		if (gamma_lut == NULL) {
 			wlr_log_errno(WLR_ERROR, "Allocation failed");
 			return false;
@@ -112,9 +98,7 @@ bool wlr_output_state_set_gamma_lut(struct wlr_output_state *state,
 		memcpy(gamma_lut + ramp_size, g, ramp_size * sizeof(uint16_t));
 		memcpy(gamma_lut + 2 * ramp_size, b, ramp_size * sizeof(uint16_t));
 	} else {
-		if (state->committed & WLR_OUTPUT_STATE_GAMMA_LUT) {
+		free(state->gamma_lut);
-			free(state->gamma_lut);
-		}
 	}
 
 	state->committed |= WLR_OUTPUT_STATE_GAMMA_LUT;
@@ -136,6 +120,10 @@ bool wlr_output_state_copy(struct wlr_output_state *dst,
 	copy.committed &= ~(WLR_OUTPUT_STATE_BUFFER |
 		WLR_OUTPUT_STATE_DAMAGE |
 		WLR_OUTPUT_STATE_GAMMA_LUT);
+	copy.buffer = NULL;
+	pixman_region32_init(&copy.damage);
+	copy.gamma_lut = NULL;
+	copy.gamma_lut_size = 0;
 
 	if (src->committed & WLR_OUTPUT_STATE_BUFFER) {
 		wlr_output_state_set_buffer(&copy, src->buffer);
@@ -146,21 +134,18 @@ bool wlr_output_state_copy(struct wlr_output_state *dst,
 	}
 
 	if (src->committed & WLR_OUTPUT_STATE_GAMMA_LUT) {
-		size_t gamma_buffer_size = 3 * src->gamma_lut_size * sizeof(uint16_t);
+		const uint16_t *r = src->gamma_lut;
-		copy.gamma_lut = malloc(gamma_buffer_size);
+		const uint16_t *g = src->gamma_lut + src->gamma_lut_size;
-		if (!copy.gamma_lut) {
+		const uint16_t *b = src->gamma_lut + 2 * src->gamma_lut_size;
-			wlr_log_errno(WLR_ERROR, "Allocation failed");
+		if (!wlr_output_state_set_gamma_lut(&copy, src->gamma_lut_size, r, g, b)) {
 			goto err;
 		}
-
-		copy.committed |= WLR_OUTPUT_STATE_GAMMA_LUT;
-		memcpy(copy.gamma_lut, src->gamma_lut, gamma_buffer_size);
-		copy.gamma_lut_size = src->gamma_lut_size;
 	}
 
 	wlr_output_state_finish(dst);
 	*dst = copy;
 	return true;
+
 err:
 	wlr_output_state_finish(&copy);
 	return false;

types/output/swapchain.c

@@ -65,8 +65,9 @@ static bool test_swapchain(struct wlr_output *output,
 
 bool wlr_output_configure_primary_swapchain(struct wlr_output *output,
 		const struct wlr_output_state *state, struct wlr_swapchain **swapchain_ptr) {
-	const struct wlr_output_state empty_state = {0};
+	struct wlr_output_state empty_state;
 	if (state == NULL) {
+		wlr_output_state_init(&empty_state);
 		state = &empty_state;
 	}
 

types/scene/wlr_scene.c

@@ -1534,7 +1534,8 @@ static bool scene_buffer_can_consider_direct_scanout(struct wlr_scene_buffer *bu
 
 static bool scene_buffer_try_direct_scanout(struct wlr_scene_buffer *buffer,
 		struct wlr_scene_output *scene_output, struct wlr_output_state *state) {
-	struct wlr_output_state pending = {0};
+	struct wlr_output_state pending;
+	wlr_output_state_init(&pending);
 	if (!wlr_output_state_copy(&pending, state)) {
 		return false;
 	}
@@ -1564,19 +1565,23 @@ bool wlr_scene_output_commit(struct wlr_scene_output *scene_output) {
 		return true;
 	}
 
-	struct wlr_output_state state = {0};
+	bool ok = false;
+	struct wlr_output_state state;
+	wlr_output_state_init(&state);
 	if (!wlr_scene_output_build_state(scene_output, &state)) {
-		return false;
+		goto out;
 	}
 
-	bool success = wlr_output_commit_state(scene_output->output, &state);
+	ok = wlr_output_commit_state(scene_output->output, &state);
-	wlr_output_state_finish(&state);
+	if (!ok) {
-
+		goto out;
-	if (success) {
-		wlr_damage_ring_rotate(&scene_output->damage_ring);
 	}
 
-	return success;
+	wlr_damage_ring_rotate(&scene_output->damage_ring);
+
+out:
+	wlr_output_state_finish(&state);
+	return ok;
 }
 
 bool wlr_scene_output_build_state(struct wlr_scene_output *scene_output,