session: use GDBus object manager to track objects

This changes things to use the object manager to discover the VM instance.
We'll have to add support for other wrappers to use object managers so that
they can be added to the devices list as they are seen.

lib/meson.build

@@ -34,6 +34,7 @@ libmks_private_sources = [
     interface_prefix: 'org.qemu.Display1.',
            namespace: 'MksQemu',
              sources: 'dbus-display1.xml',
+      object_manager: true,
   )
 ]
 

lib/mks-session.c

@@ -91,10 +91,19 @@ struct _MksSession
    */
   GListModel *devices_read_only;
 
-  /* @vm contains our "top-level" proxy object to the Qemu instance. This is
+  /* An object manager client is used to monitor for new objects exported by
-   * where access to other devices begins. It is setup during either GInitable
+   * the Qemu instance. Those objects are then wrapped by MksDevice objects
-   * or GAsyncInitable initialization.
+   * as necessary and exported to consumers via @devices.
    */
+  GDBusObjectManager *object_manager;
+
+  /* A GDBusObjectProxy to the `/org/qemu/Display1/VM` instance. Generally
+   * this used via the `org.qemu.Display1.VM` interface. We track the
+   * top-level object-manager instance so that we can detect easily when
+   * the VM has been removed from the peer. (Which could happen if it is
+   * running on a private D-Bus rather than a socketpair().
+   */
+  MksQemuObject *vm_object;
   MksQemuVM *vm;
 };
 
@@ -161,19 +170,96 @@ mks_session_vm_notify_cb (MksSession *self,
 }
 
 static void
-mks_session_set_vm (MksSession *self,
+mks_session_set_vm (MksSession    *self,
-                    MksQemuVM  *vm)
+                    MksQemuObject *vm_object,
+                    MksQemuVM     *vm)
 {
   g_assert (MKS_IS_SESSION (self));
+  g_assert (MKS_QEMU_IS_OBJECT (vm_object));
   g_assert (MKS_QEMU_IS_VM (vm));
 
+  if (self->vm != NULL)
+    return;
+
+  g_set_object (&self->vm_object, vm_object);
+  g_set_object (&self->vm, vm);
+
   g_signal_connect_object (vm,
                            "notify",
                            G_CALLBACK (mks_session_vm_notify_cb),
                            self,
                            G_CONNECT_SWAPPED);
 
-  self->vm = g_object_ref (vm);
+  g_object_notify_by_pspec (G_OBJECT (self), properties [PROP_NAME]);
+  g_object_notify_by_pspec (G_OBJECT (self), properties [PROP_UUID]);
+}
+
+static void
+mks_session_object_manager_object_added_cb (MksSession         *self,
+                                            MksQemuObject      *object,
+                                            GDBusObjectManager *manager)
+{
+  g_autolist(GDBusInterface) interfaces = NULL;
+
+  g_assert (MKS_IS_SESSION (self));
+  g_assert (MKS_QEMU_IS_OBJECT (object));
+  g_assert (G_IS_DBUS_OBJECT_MANAGER (manager));
+
+  interfaces = g_dbus_object_get_interfaces (G_DBUS_OBJECT (object));
+
+  for (const GList *iter = interfaces; iter; iter = iter->next)
+    {
+      GDBusInterface *iface = iter->data;
+
+      if (MKS_QEMU_IS_VM (iface))
+        mks_session_set_vm (self, object, MKS_QEMU_VM (iface));
+    }
+}
+
+static void
+mks_session_object_manager_object_removed_cb (MksSession         *self,
+                                              MksQemuObject      *object,
+                                              GDBusObjectManager *manager)
+{
+  g_assert (MKS_IS_SESSION (self));
+  g_assert (MKS_QEMU_IS_OBJECT (object));
+  g_assert (G_IS_DBUS_OBJECT_MANAGER (manager));
+
+  if (object == self->vm_object)
+    {
+      g_clear_object (&self->vm);
+      g_clear_object (&self->vm_object);
+      g_list_store_remove_all (self->devices);
+    }
+}
+
+static void
+mks_session_set_object_manager (MksSession         *self,
+                                GDBusObjectManager *object_manager)
+{
+  g_assert (MKS_IS_SESSION (self));
+  g_assert (!object_manager || MKS_QEMU_IS_OBJECT_MANAGER_CLIENT (object_manager));
+  g_assert (self->object_manager == NULL);
+
+  if (g_set_object (&self->object_manager, object_manager))
+    {
+      g_autolist(GDBusObjectProxy) objects = NULL;
+
+      g_signal_connect_object (object_manager,
+                               "object-added",
+                               G_CALLBACK (mks_session_object_manager_object_added_cb),
+                               self,
+                               G_CONNECT_SWAPPED);
+      g_signal_connect_object (object_manager,
+                               "object-removed",
+                               G_CALLBACK (mks_session_object_manager_object_removed_cb),
+                               self,
+                               G_CONNECT_SWAPPED);
+
+      objects = g_dbus_object_manager_get_objects (object_manager);
+      for (const GList *iter = objects; iter; iter = iter->next)
+        mks_session_object_manager_object_added_cb (self, iter->data, object_manager);
+    }
 }
 
 static void
@@ -184,6 +270,10 @@ mks_session_dispose (GObject *object)
   if (self->devices != NULL)
     g_list_store_remove_all (self->devices);
 
+  g_clear_object (&self->object_manager);
+  g_clear_object (&self->vm);
+  g_clear_object (&self->vm_object);
+
   G_OBJECT_CLASS (mks_session_parent_class)->dispose (object);
 }
 
@@ -192,7 +282,6 @@ mks_session_finalize (GObject *object)
 {
   MksSession *self = (MksSession *)object;
 
-  g_clear_object (&self->vm);
   g_clear_object (&self->devices);
   g_clear_object (&self->devices_read_only);
   g_clear_object (&self->connection);
@@ -320,7 +409,8 @@ mks_session_initable_init (GInitable     *initable,
                            GError       **error)
 {
   MksSession *self = (MksSession *)initable;
-  g_autoptr(MksQemuVM) vm = NULL;
+  g_autoptr(GDBusObjectManager) object_manager = NULL;
+  g_autolist(GDBusObjectProxy) objects = NULL;
 
   g_assert (MKS_IS_SESSION (self));
   g_assert (!cancellable || G_IS_CANCELLABLE (cancellable));
@@ -334,17 +424,17 @@ mks_session_initable_init (GInitable     *initable,
       return FALSE;
     }
 
-  vm = mks_qemu_vm_proxy_new_sync (self->connection,
+  object_manager =
-                                   G_DBUS_PROXY_FLAGS_NONE,
+    mks_qemu_object_manager_client_new_sync (self->connection,
-                                   "org.qemu",
+                                             G_DBUS_OBJECT_MANAGER_CLIENT_FLAGS_DO_NOT_AUTO_START,
-                                   "/org/qemu/Display1/VM",
+                                             "org.qemu",
-                                   cancellable,
+                                             "/org/qemu/Display1",
-                                   error);
+                                             cancellable,
+                                             error);
 
-  if (vm != NULL)
+  mks_session_set_object_manager (self, object_manager);
-    mks_session_set_vm (self, vm);
 
-  return vm != NULL;
+  return object_manager != NULL;
 }
 
 static void
@@ -352,7 +442,7 @@ mks_session_async_initable_vm_cb (GObject      *object,
                                   GAsyncResult *result,
                                   gpointer      user_data)
 {
-  g_autoptr(MksQemuVM) vm = NULL;
+  g_autoptr(GDBusObjectManager) object_manager = NULL;
   g_autoptr(GError) error = NULL;
   g_autoptr(GTask) task = user_data;
   MksSession *self;
@@ -361,15 +451,14 @@ mks_session_async_initable_vm_cb (GObject      *object,
   g_assert (G_IS_TASK (task));
 
   self = g_task_get_source_object (task);
-  vm = mks_qemu_vm_proxy_new_finish (result, &error);
+  object_manager = mks_qemu_object_manager_client_new_finish (result, &error);
 
   g_assert (MKS_IS_SESSION (self));
-  g_assert (!vm || MKS_QEMU_IS_VM (vm));
+  g_assert (!object_manager || MKS_QEMU_IS_OBJECT_MANAGER_CLIENT (object_manager));
 
-  if (vm != NULL)
+  mks_session_set_object_manager (self, object_manager);
-    mks_session_set_vm (self, vm);
 
-  if (error)
+  if (error != NULL)
     g_task_return_error (task, g_steal_pointer (&error));
   else
     g_task_return_boolean (task, TRUE);
@@ -398,13 +487,13 @@ mks_session_async_initable_init_async (GAsyncInitable      *async_initable,
                              G_IO_ERROR_NOT_CONNECTED,
                              "Not connected");
   else
-    mks_qemu_vm_proxy_new (self->connection,
+    mks_qemu_object_manager_client_new (self->connection,
-                           G_DBUS_PROXY_FLAGS_NONE,
+                                        G_DBUS_OBJECT_MANAGER_CLIENT_FLAGS_DO_NOT_AUTO_START,
-                           "org.qemu",
+                                        "org.qemu",
-                           "/org/qemu/Display1/VM",
+                                        "/org/qemu/Display1/VM",
-                           cancellable,
+                                        cancellable,
-                           mks_session_async_initable_vm_cb,
+                                        mks_session_async_initable_vm_cb,
-                           g_steal_pointer (&task));
+                                        g_steal_pointer (&task));
 }
 
 static gboolean