systemd-verify: a simple tool for offline unit verification

This tool will warn about misspelt directives, unknown sections, and
non-executable commands. It will also catch the common mistake of
using Accept=yes with a non-template unit and vice versa.

https://bugs.freedesktop.org/show_bug.cgi?id=56607

src/core/socket.c

@@ -180,9 +180,8 @@ static int socket_arm_timer(Socket *s) {
                         socket_dispatch_timer, s);
 }
 
-static int socket_instantiate_service(Socket *s) {
-        _cleanup_free_ char *prefix = NULL;
-        _cleanup_free_ char *name = NULL;
+int socket_instantiate_service(Socket *s) {
+        _cleanup_free_ char *prefix = NULL, *name = NULL;
         int r;
         Unit *u;
 
@@ -193,11 +192,9 @@ static int socket_instantiate_service(Socket *s) {
          * here. For Accept=no this is mostly a NOP since the service
          * is figured out at load time anyway. */
 
-        if (UNIT_DEREF(s->service))
+        if (UNIT_DEREF(s->service) || !s->accept)
                 return 0;
 
-        assert(s->accept);
-
         prefix = unit_name_to_prefix(UNIT(s)->id);
         if (!prefix)
                 return -ENOMEM;