Add startup command option to rootston

Allows specifying a command to run at startup.

include/rootston/config.h

@@ -42,6 +42,7 @@ struct roots_config {
 	struct wl_list devices;
 	struct wl_list bindings;
 	char *config_path;
+	char *startup_cmd;
 };
 
 struct roots_config *parse_args(int argc, char *argv[]);

rootston/config.c

@@ -16,12 +16,13 @@
 
 static void usage(const char *name, int ret) {
 	fprintf(stderr,
-		"usage: %s [-C <FILE>]\n"
+		"usage: %s [-C <FILE>] [-E <COMMAND>]\n"
 		"\n"
 		" -C <FILE>      Path to the configuration file\n"
 		"                (default: rootston.ini).\n"
 		"                See `rootston.ini.example` for config\n"
-		"                file documentation.\n", name);
+		"                file documentation.\n"
+		" -E <COMMAND>   Command that will be ran at startup.\n" , name);
 
 	exit(ret);
 }
@@ -273,11 +274,14 @@ struct roots_config *parse_args(int argc, char *argv[]) {
 	wl_list_init(&config->bindings);
 
 	int c;
-	while ((c = getopt(argc, argv, "C:h")) != -1) {
+	while ((c = getopt(argc, argv, "C:E:h")) != -1) {
 		switch (c) {
 		case 'C':
 			config->config_path = strdup(optarg);
 			break;
+		case 'E':
+			config->startup_cmd = strdup(optarg);
+			break;
 		case 'h':
 		case '?':
 			usage(argv[0], c != 'h');

rootston/main.c

@@ -1,6 +1,7 @@
 #define _POSIX_C_SOURCE 200112L
 #include <assert.h>
 #include <stdlib.h>
+#include <unistd.h>
 #include <wayland-server.h>
 #include <wlr/backend.h>
 #include <wlr/render.h>
@@ -42,6 +43,18 @@ int main(int argc, char **argv) {
 	}
 
 	setenv("WAYLAND_DISPLAY", socket, true);
+
+	if (server.config->startup_cmd != NULL) {
+		const char *cmd = server.config->startup_cmd;
+		pid_t pid = fork();
+		if (pid < 0) {
+			wlr_log(L_ERROR, "cannot execute binding command: fork() failed");
+			return 1;
+		} else if (pid == 0) {
+			execl("/bin/sh", "/bin/sh", "-c", cmd, (void *)NULL);
+		}
+	}
+
 	wl_display_run(server.wl_display);
 	wlr_backend_destroy(server.backend);
 	return 0;