login: make user_new() and user_free() follow coding-style

Few changes to user_new() and user_free():
 - Use _cleanup_(user_freep) in constructor
 - return 'int' from user_new()
 - make user_free() deal with partially initialized objects
 - keep reverse-order in user_free() compared to user_new()
 - make user_free() return NULL
 - make user_free() accept NULL as no-op

1 files changed, 5 insertions, 2 deletions

diff --git a/src/login/logind-user.h b/src/login/logind-user.h
index 722247806b..11d28d2997 100644
--- a/src/login/logind-user.h
+++ b/src/login/logind-user.h
@@ -65,8 +65,11 @@ struct User {
         LIST_FIELDS(User, gc_queue);
 };
 
-User* user_new(Manager *m, uid_t uid, gid_t gid, const char *name);
-void user_free(User *u);
+int user_new(User **out, Manager *m, uid_t uid, gid_t gid, const char *name);
+User *user_free(User *u);
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(User *, user_free);
+
 bool user_check_gc(User *u, bool drop_not_started);
 void user_add_to_gc_queue(User *u);
 int user_start(User *u);