logind: modernize Manager object allocation and freeing

Let's propagate errors correctly, and stick to the usual naming and
behaviour of these functions. Or in other words, make this closer to the
matching code in machined.

src/login/logind-core.c

@@ -26,6 +26,8 @@
 #include "user-util.h"
 
 void manager_reset_config(Manager *m) {
+        assert(m);
+
         m->n_autovts = 6;
         m->reserve_vt = 6;
         m->remove_ipc = true;

src/login/logind.c

@@ -30,15 +30,18 @@
 #include "strv.h"
 #include "udev-util.h"
 
-static void manager_free(Manager *m);
+static Manager* manager_unref(Manager *m);
+DEFINE_TRIVIAL_CLEANUP_FUNC(Manager*, manager_unref);
 
-static Manager *manager_new(void) {
-        Manager *m;
+static int manager_new(Manager **ret) {
+        _cleanup_(manager_unrefp) Manager *m = NULL;
         int r;
 
+        assert(ret);
+
         m = new0(Manager, 1);
         if (!m)
-                return NULL;
+                return -ENOMEM;
 
         m->console_active_fd = -1;
         m->reserve_vt_fd = -1;
@@ -56,28 +59,25 @@ static Manager *manager_new(void) {
         m->session_units = hashmap_new(&string_hash_ops);
 
         if (!m->devices || !m->seats || !m->sessions || !m->users || !m->inhibitors || !m->buttons || !m->user_units || !m->session_units)
-                goto fail;
+                return -ENOMEM;
 
         m->udev = udev_new();
         if (!m->udev)
-                goto fail;
+                return -errno;
 
         r = sd_event_default(&m->event);
         if (r < 0)
-                goto fail;
+                return r;
 
-        sd_event_set_watchdog(m->event, true);
+        (void) sd_event_set_watchdog(m->event, true);
 
         manager_reset_config(m);
 
-        return m;
-
-fail:
-        manager_free(m);
-        return NULL;
+        *ret = TAKE_PTR(m);
+        return 0;
 }
 
-static void manager_free(Manager *m) {
+static Manager* manager_unref(Manager *m) {
         Session *session;
         User *u;
         Device *d;
@@ -86,7 +86,7 @@ static void manager_free(Manager *m) {
         Button *b;
 
         if (!m)
-                return;
+                return NULL;
 
         while ((session = hashmap_first(m->sessions)))
                 session_free(session);
@@ -155,7 +155,8 @@ static void manager_free(Manager *m) {
         free(m->scheduled_shutdown_tty);
         free(m->wall_message);
         free(m->action_job);
-        free(m);
+
+        return mfree(m);
 }
 
 static int manager_enumerate_devices(Manager *m) {
@@ -1192,7 +1193,7 @@ static int manager_run(Manager *m) {
 }
 
 int main(int argc, char *argv[]) {
-        Manager *m = NULL;
+        _cleanup_(manager_unrefp) Manager *m = NULL;
         int r;
 
         log_set_target(LOG_TARGET_AUTO);
@@ -1223,13 +1224,13 @@ int main(int argc, char *argv[]) {
         mkdir_label("/run/systemd/users", 0755);
         mkdir_label("/run/systemd/sessions", 0755);
 
-        m = manager_new();
-        if (!m) {
-                r = log_oom();
+        r = manager_new(&m);
+        if (r < 0) {
+                log_error_errno(r, "Failed to allocate manager object: %m");
                 goto finish;
         }
 
-        manager_parse_config_file(m);
+        (void) manager_parse_config_file(m);
 
         r = manager_startup(m);
         if (r < 0) {
@@ -1239,20 +1240,18 @@ int main(int argc, char *argv[]) {
 
         log_debug("systemd-logind running as pid "PID_FMT, getpid_cached());
 
-        sd_notify(false,
-                  "READY=1\n"
-                  "STATUS=Processing requests...");
+        (void) sd_notify(false,
+                         "READY=1\n"
+                         "STATUS=Processing requests...");
 
         r = manager_run(m);
 
         log_debug("systemd-logind stopped as pid "PID_FMT, getpid_cached());
 
+        (void) sd_notify(false,
+                         "STOPPING=1\n"
+                         "STATUS=Shutting down...");
+
 finish:
-        sd_notify(false,
-                  "STOPPING=1\n"
-                  "STATUS=Shutting down...");
-
-        manager_free(m);
-
         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 }