add headless outputs option

include/sway/server.h

@@ -43,7 +43,7 @@ struct sway_server {
 
 struct sway_server server;
 
-bool server_init(struct sway_server *server);
+bool server_init(struct sway_server *server, bool headless);
 void server_fini(struct sway_server *server);
 void server_run(struct sway_server *server);
 

sway/main.c

@@ -250,13 +250,14 @@ static void drop_permissions(bool keep_caps) {
 }
 
 int main(int argc, char **argv) {
-	static int verbose = 0, debug = 0, validate = 0;
+	static int verbose = 0, debug = 0, validate = 0, headless = 0;
 
 	static struct option long_options[] = {
 		{"help", no_argument, NULL, 'h'},
 		{"config", required_argument, NULL, 'c'},
 		{"validate", no_argument, NULL, 'C'},
 		{"debug", no_argument, NULL, 'd'},
+		{"headless", no_argument, NULL, 'H'},
 		{"version", no_argument, NULL, 'v'},
 		{"verbose", no_argument, NULL, 'V'},
 		{"get-socketpath", no_argument, NULL, 'p'},
@@ -272,6 +273,7 @@ int main(int argc, char **argv) {
 		"  -c, --config <config>  Specify a config file.\n"
 		"  -C, --validate         Check the validity of the config file, then exit.\n"
 		"  -d, --debug            Enables full logging, including debug information.\n"
+		"  -H, --headless         Starts sway with the headless backend.\n"
 		"  -v, --version          Show the version number and quit.\n"
 		"  -V, --verbose          Enables more verbose logging.\n"
 		"      --get-socketpath   Gets the IPC socket path and prints it, then exits.\n"
@@ -288,7 +290,7 @@ int main(int argc, char **argv) {
 	int c;
 	while (1) {
 		int option_index = 0;
-		c = getopt_long(argc, argv, "hCdvVc:", long_options, &option_index);
+		c = getopt_long(argc, argv, "hCHdvVc:", long_options, &option_index);
 		if (c == -1) {
 			break;
 		}
@@ -306,6 +308,9 @@ int main(int argc, char **argv) {
 		case 'd': // debug
 			debug = 1;
 			break;
+		case 'H':
+			headless = 1;
+			break;
 		case 'v': // version
 			fprintf(stdout, "sway version " SWAY_VERSION "\n");
 			exit(EXIT_SUCCESS);
@@ -384,7 +389,7 @@ int main(int argc, char **argv) {
 
 	layout_init();
 
-	if (!server_init(&server)) {
+	if (!server_init(&server, headless)) {
 		return 1;
 	}
 

sway/server.c

@@ -5,6 +5,7 @@
 #include <wayland-server.h>
 #include <wlr/backend.h>
 #include <wlr/backend/session.h>
+#include <wlr/backend/headless.h>
 #include <wlr/render/wlr_renderer.h>
 #include <wlr/types/wlr_compositor.h>
 #include <wlr/types/wlr_gamma_control.h>
@@ -38,12 +39,60 @@ static void server_ready(struct wl_listener *listener, void *data) {
 	}
 }
 
-bool server_init(struct sway_server *server) {
+static size_t parse_outputs_env(const char *name) {
+	const char *outputs_str = getenv(name);
+	if (outputs_str == NULL) {
+		return 1;
+	}
+
+	char *end;
+	int outputs = (int)strtol(outputs_str, &end, 10);
+	if (*end || outputs < 0) {
+		wlr_log(L_ERROR, "%s specified with invalid integer, ignoring", name);
+		return 1;
+	}
+
+	return outputs;
+}
+
+static struct wlr_backend *create_headless_backend(struct wl_display *display) {
+	const char *outputs_env = "SWAY_HEADLESS_OUTPUTS";
+	const char *outputs_str = getenv(outputs_env);
+	int outputs = 1;
+
+	if (outputs_str != NULL) {
+		char *end;
+		outputs = (int)strtol(outputs_str, &end, 10);
+		if (*end || outputs < 0) {
+			outputs = 1;
+		}
+	}
+
+	struct wlr_backend *backend = wlr_headless_backend_create(display);
+
+	if (backend == NULL) {
+		return NULL;
+	}
+
+	for (int i = 0; i < outputs; ++i) {
+		wlr_headless_add_output(backend, 1280, 720);
+	}
+
+	return backend;
+}
+
+bool server_init(struct sway_server *server, bool headless) {
 	wlr_log(L_DEBUG, "Initializing Wayland server");
 
 	server->wl_display = wl_display_create();
 	server->wl_event_loop = wl_display_get_event_loop(server->wl_display);
-	server->backend = wlr_backend_autocreate(server->wl_display);
+
+	if (headless) {
+		server->backend = create_headless_backend(server->wl_display);
+	} else {
+		server->backend = wlr_backend_autocreate(server->wl_display);
+	}
+	assert(server->backend);
 
 	struct wlr_renderer *renderer = wlr_backend_get_renderer(server->backend);
 	assert(renderer);