herdd: implement service startup using posix_spawn

services/herdd/service.c

@@ -11,6 +11,7 @@
 #include <launch.h>
 #include <magenta/log.h>
 #include <rosetta/bootstrap.h>
+#include <spawn.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -174,6 +175,22 @@ int service_start(struct service *svc)
 {
 	log("Starting %s...", svc->s_description);
 
-	log_ok("Started %s.", svc->s_description);
+	pid_t child = 0;
-	return 0;
+	char *const argv[] = {
+		svc->s_name,
+		NULL,
+	};
+
+	int err = posix_spawn(&child, svc->s_exec, NULL, NULL, argv, NULL);
+
+	if (err == 0) {
+		log_ok("Started %s.", svc->s_description);
+	} else {
+		log_fail(
+			"Failed to start %s (%s)",
+			svc->s_description,
+			strerror(errno));
+	}
+
+	return err;
 }