logind: switch to sd_bus_track helper

Let logind use the sd_bus_track helper object to track the controllers of
sessions. This does not only remove quite some code but also kills the
unconditional matches for all NameOwnerChanged signals.

The latter is something we should never ever do, as it wakes up the daemon
every time a client connects, which doesn't scale.

1 files changed, 21 insertions, 4 deletions

diff --git a/src/login/logind-session.c b/src/login/logind-session.c
index 9a2da7906e..fc92f7f73b 100644
--- a/src/login/logind-session.c
+++ b/src/login/logind-session.c
@@ -1120,7 +1120,18 @@ static void session_release_controller(Session *s, bool notify) {
                 session_device_free(sd);
 
         s->controller = NULL;
-        manager_drop_busname(s->manager, name);
+        s->track = sd_bus_track_unref(s->track);
+}
+
+static int on_bus_track(sd_bus_track *track, void *userdata) {
+        Session *s = userdata;
+
+        assert(track);
+        assert(s);
+
+        session_drop_controller(s);
+
+        return 0;
 }
 
 int session_set_controller(Session *s, const char *sender, bool force) {
@@ -1139,8 +1150,13 @@ int session_set_controller(Session *s, const char *sender, bool force) {
         if (!name)
                 return -ENOMEM;
 
-        r = manager_watch_busname(s->manager, name);
-        if (r)
+        s->track = sd_bus_track_unref(s->track);
+        r = sd_bus_track_new(s->manager->bus, &s->track, on_bus_track, s);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_track_add_name(s->track, name);
+        if (r < 0)
                 return r;
 
         /* When setting a session controller, we forcibly mute the VT and set
@@ -1153,7 +1169,7 @@ int session_set_controller(Session *s, const char *sender, bool force) {
          * or reset the VT in case it crashed/exited, too. */
         r = session_prepare_vt(s);
         if (r < 0) {
-                manager_drop_busname(s->manager, name);
+                s->track = sd_bus_track_unref(s->track);
                 return r;
         }
 
@@ -1171,6 +1187,7 @@ void session_drop_controller(Session *s) {
         if (!s->controller)
                 return;
 
+        s->track = sd_bus_track_unref(s->track);
         session_release_controller(s, false);
         session_save(s);
         session_restore_vt(s);