logind: rework Seat/Session/User object allocation and freeing a bit

Let's update things a bit to follow current practices:

- User structure initialization rather than zero-initialized allocation

- Always propagate proper errors from allocation functions

- Use _cleanup_ for freeing objects when allocation fails half-way

- Make destructors return NULL

1 files changed, 24 insertions, 14 deletions

diff --git a/src/login/logind-seat.c b/src/login/logind-seat.c
index f24fe96841..398c74d712 100644
--- a/src/login/logind-seat.c
+++ b/src/login/logind-seat.c
@@ -21,33 +21,42 @@
 #include "terminal-util.h"
 #include "util.h"
 
-Seat *seat_new(Manager *m, const char *id) {
-        Seat *s;
+int seat_new(Seat** ret, Manager *m, const char *id) {
+        _cleanup_(seat_freep) Seat *s = NULL;
+        int r;
 
+        assert(ret);
         assert(m);
         assert(id);
 
-        s = new0(Seat, 1);
+        if (!seat_name_is_valid(id))
+                return -EINVAL;
+
+        s = new(Seat, 1);
         if (!s)
-                return NULL;
+                return -ENOMEM;
+
+        *s = (Seat) {
+                .manager = m,
+        };
 
         s->state_file = strappend("/run/systemd/seats/", id);
         if (!s->state_file)
-                return mfree(s);
+                return -ENOMEM;
 
         s->id = basename(s->state_file);
-        s->manager = m;
 
-        if (hashmap_put(m->seats, s->id, s) < 0) {
-                free(s->state_file);
-                return mfree(s);
-        }
+        r = hashmap_put(m->seats, s->id, s);
+        if (r < 0)
+                return r;
 
-        return s;
+        *ret = TAKE_PTR(s);
+        return 0;
 }
 
-void seat_free(Seat *s) {
-        assert(s);
+Seat* seat_free(Seat *s) {
+        if (!s)
+                return NULL;
 
         if (s->in_gc_queue)
                 LIST_REMOVE(gc_queue, s->manager->seat_gc_queue, s);
@@ -64,7 +73,8 @@ void seat_free(Seat *s) {
 
         free(s->positions);
         free(s->state_file);
-        free(s);
+
+        return mfree(s);
 }
 
 int seat_save(Seat *s) {