commands/create_output: Add name argument

Allow specifying a name to be set for the newly created output, which
avoids the need for traversing the output list to find out what was
created. This is particularly useful for reusing configuration.

sway/commands/create_output.c

@@ -5,27 +5,26 @@
 #if WLR_HAS_X11_BACKEND
 #include <wlr/backend/x11.h>
 #endif
+#include <wlr/types/wlr_output.h>
 #include "sway/commands.h"
+#include "sway/output.h"
 #include "sway/server.h"
 #include "log.h"
 
 static void create_output(struct wlr_backend *backend, void *data) {
-	bool *done = data;
-	if (*done) {
+	struct wlr_output **result = data;
+	if (*result) {
 		return;
 	}
 
 	if (wlr_backend_is_wl(backend)) {
-		wlr_wl_output_create(backend);
-		*done = true;
+		*result = wlr_wl_output_create(backend);
 	} else if (wlr_backend_is_headless(backend)) {
-		wlr_headless_add_output(backend, 1920, 1080);
-		*done = true;
+		*result = wlr_headless_add_output(backend, 1920, 1080);
 	}
 #if WLR_HAS_X11_BACKEND
 	else if (wlr_backend_is_x11(backend)) {
-		wlr_x11_output_create(backend);
-		*done = true;
+		*result = wlr_x11_output_create(backend);
 	}
 #endif
 }
@@ -37,13 +36,24 @@ struct cmd_results *cmd_create_output(int argc, char **argv) {
 	sway_assert(wlr_backend_is_multi(server.backend),
 			"Expected a multi backend");
 
-	bool done = false;
-	wlr_multi_for_each_backend(server.backend, create_output, &done);
+	struct cmd_results *error = NULL;
+	if ((error = checkarg(argc, "create_output", EXPECTED_AT_MOST, 1))) {
+		return error;
+	}
+	if (argc > 0 && all_output_by_name_or_id(argv[0])) {
+		return cmd_results_new(CMD_INVALID, "Output name already in use");
+	}
+	struct wlr_output *result = NULL;
+	wlr_multi_for_each_backend(server.backend, create_output, &result);
 
-	if (!done) {
+	if (!result) {
 		return cmd_results_new(CMD_INVALID,
 			"Can only create outputs for Wayland, X11 or headless backends");
 	}
 
+	if (argc > 0) {
+		wlr_output_set_name(result, argv[0]);
+	}
+
 	return cmd_results_new(CMD_SUCCESS, NULL);
 }