swaybar: allow identifiers for output and tray

This allows `bar output` and `bar tray_output` to specify an output
identifier. Output names should still work as well.

This parses the output identifier from the xdg_output description,
which wlroots currently sets to `make model serial (name)`. Since this
could change in the future, all identifier comparisons are guarded by
NULL-checks in case the description cannot be parsed to an identifier.

include/swaybar/bar.h

@@ -61,6 +61,7 @@ struct swaybar_output {
 	struct wl_list hotspots; // swaybar_hotspot::link
 
 	char *name;
+	char *identifier;
 	bool focused;
 
 	uint32_t width, height;

swaybar/bar.c

@@ -59,6 +59,7 @@ static void swaybar_output_free(struct swaybar_output *output) {
 	free_workspaces(&output->workspaces);
 	wl_list_remove(&output->link);
 	free(output->name);
+	free(output->identifier);
 	free(output);
 }
 
@@ -166,13 +167,15 @@ bool determine_bar_visibility(struct swaybar *bar, bool moving_layer) {
 	return visible;
 }
 
-static bool bar_uses_output(struct swaybar *bar, const char *name) {
+static bool bar_uses_output(struct swaybar_output *output) {
-	if (bar->config->all_outputs) {
+	if (output->bar->config->all_outputs) {
 		return true;
 	}
+	char *identifier = output->identifier;
 	struct config_output *coutput;
-	wl_list_for_each(coutput, &bar->config->outputs, link) {
+	wl_list_for_each(coutput, &output->bar->config->outputs, link) {
-		if (strcmp(coutput->name, name) == 0) {
+		if (strcmp(coutput->name, output->name) == 0 ||
+				(identifier && strcmp(coutput->name, identifier) == 0)) {
 			return true;
 		}
 	}
@@ -233,7 +236,7 @@ static void xdg_output_handle_done(void *data,
 	struct swaybar *bar = output->bar;
 
 	assert(output->name != NULL);
-	if (!bar_uses_output(bar, output->name)) {
+	if (!bar_uses_output(output)) {
 		swaybar_output_free(output);
 		return;
 	}
@@ -258,7 +261,22 @@ static void xdg_output_handle_name(void *data,
 
 static void xdg_output_handle_description(void *data,
 		struct zxdg_output_v1 *xdg_output, const char *description) {
-	// Who cares
+	// wlroots currently sets the description to `make model serial (name)`
+	// If this changes in the future, this will need to be modified.
+	struct swaybar_output *output = data;
+	free(output->identifier);
+	output->identifier = NULL;
+	char *paren = strrchr(description, '(');
+	if (paren) {
+		size_t length = paren - description;
+		output->identifier = malloc(length);
+		if (!output->identifier) {
+			wlr_log(WLR_ERROR, "Failed to allocate output identifier");
+			return;
+		}
+		strncpy(output->identifier, description, length);
+		output->identifier[length - 1] = '\0';
+	}
 }
 
 struct zxdg_output_v1_listener xdg_output_listener = {

swaybar/tray/tray.c

@@ -101,13 +101,17 @@ void tray_in(int fd, short mask, void *data) {
 }
 
 static int cmp_output(const void *item, const void *cmp_to) {
-	return strcmp(item, cmp_to);
+	const struct swaybar_output *output = cmp_to;
+	if (output->identifier && strcmp(item, output->identifier) == 0) {
+		return 0;
+	}
+	return strcmp(item, output->name);
 }
 
 uint32_t render_tray(cairo_t *cairo, struct swaybar_output *output, double *x) {
 	struct swaybar_config *config = output->bar->config;
 	if (config->tray_outputs) {
-		if (list_seq_find(config->tray_outputs, cmp_output, output->name) == -1) {
+		if (list_seq_find(config->tray_outputs, cmp_output, output) == -1) {
 			return 0;
 		}
 	} // else display on all