watch for the Greeter to appear on the bus

1 files changed, 82 insertions, 62 deletions

diff --git a/src/greeter.cpp b/src/greeter.cpp
index d2e34a0..9d331d7 100644
--- a/src/greeter.cpp
+++ b/src/greeter.cpp
@@ -26,21 +26,40 @@ class UnityGreeter::Impl
 {
 public:
 
-    Impl():
+    explicit Impl(GDBusConnection* connection):
+        m_bus(G_DBUS_CONNECTION(g_object_ref(connection))),
         m_cancellable{g_cancellable_new()}
     {
-        g_message("%s getting bus", G_STRLOC);
-        g_bus_get(G_BUS_TYPE_SESSION, m_cancellable, on_bus_ready_static, this);
+g_message("%s %s", G_STRLOC, G_STRFUNC);
+
+        m_watcher_id = g_bus_watch_name_on_connection(
+            m_bus,
+            DBusNames::UnityGreeter::NAME,
+            G_BUS_NAME_WATCHER_FLAGS_AUTO_START,
+            on_greeter_appeared,
+            on_greeter_vanished,
+            this,
+            nullptr);
+
+        m_subscription_id = g_dbus_connection_signal_subscribe(
+            m_bus,
+            DBusNames::UnityGreeter::NAME,
+            DBusNames::Properties::INTERFACE,
+            DBusNames::Properties::PropertiesChanged::NAME,
+            DBusNames::UnityGreeter::PATH,
+            DBusNames::UnityGreeter::INTERFACE,
+            G_DBUS_SIGNAL_FLAGS_NONE,
+            on_properties_changed_signal,
+            this,
+            nullptr);
     }
 
     ~Impl()
     {
         g_cancellable_cancel(m_cancellable);
         g_clear_object(&m_cancellable);
-
-        if (m_subscription_id != 0)
-            g_dbus_connection_signal_unsubscribe (m_bus, m_subscription_id);
-
+        g_bus_unwatch_name(m_watcher_id);
+        g_dbus_connection_signal_unsubscribe(m_bus, m_subscription_id);
         g_clear_object(&m_bus);
     }
 
@@ -51,60 +70,55 @@ public:
 
 private:
 
-    static void on_bus_ready_static(GObject* /*source*/, GAsyncResult* res, gpointer gself)
+    static void on_greeter_appeared(
+        GDBusConnection* /*session_bus*/,
+        const char* /*name*/,
+        const char* name_owner,
+        gpointer gself)
     {
         g_message("%s %s", G_STRLOC, G_STRFUNC);
-        GError* error {};
-        auto bus = g_bus_get_finish (res, &error);
-        if (error != nullptr) {
-            if (!g_error_matches(error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
-                g_warning("UsbSnap: Error getting session bus: %s", error->message);
-            g_clear_error(&error);
-        } else {
-            static_cast<Impl*>(gself)->on_bus_ready(bus);
-        }
-        g_clear_object(&bus);
+        auto self = static_cast<Impl*>(gself);
+
+        self->m_owner = name_owner;
+
+        g_dbus_connection_call(
+            self->m_bus,
+            DBusNames::UnityGreeter::NAME,
+            DBusNames::UnityGreeter::PATH,
+            DBusNames::Properties::INTERFACE,
+            "Get",
+            g_variant_new("(ss)", DBusNames::UnityGreeter::INTERFACE, "IsActive"),
+            G_VARIANT_TYPE("(v)"),
+            G_DBUS_CALL_FLAGS_NONE,
+            -1,
+            self->m_cancellable,
+            on_get_is_active_ready,
+            gself);
     }
 
-    void on_bus_ready(GDBusConnection* bus)
+    static void on_greeter_vanished(
+        GDBusConnection* /*session_bus*/,
+        const char* /*name*/,
+        gpointer gself)
     {
-        g_message("%s bus is ready", G_STRLOC);
-
-        m_bus = G_DBUS_CONNECTION(g_object_ref(G_OBJECT(bus)));
-
-        g_dbus_connection_call(m_bus,
-                               DBusNames::UnityGreeter::NAME,
-                               DBusNames::UnityGreeter::PATH,
-                               DBusNames::Properties::INTERFACE,
-                               "Get",
-                               g_variant_new("(ss)", DBusNames::UnityGreeter::INTERFACE, "IsActive"),
-                               G_VARIANT_TYPE("(v)"),
-                               G_DBUS_CALL_FLAGS_NONE,
-                               -1,
-                               m_cancellable,
-                               on_get_is_active_ready,
-                               this);
-
-        m_subscription_id = g_dbus_connection_signal_subscribe(m_bus,
-                                                               DBusNames::UnityGreeter::NAME,
-                                                               DBusNames::Properties::INTERFACE,
-                                                               DBusNames::Properties::PropertiesChanged::NAME,
-                                                               DBusNames::UnityGreeter::PATH,
-                                                               DBusNames::UnityGreeter::INTERFACE,
-                                                               G_DBUS_SIGNAL_FLAGS_NONE,
-                                                               on_properties_changed_signal,
-                                                               this,
-                                                               nullptr);
+        g_message("%s %s", G_STRLOC, G_STRFUNC);
+        auto self = static_cast<Impl*>(gself);
+
+        self->m_owner.clear();
+        self->m_is_active.set(false);
     }
 
-    static void on_get_is_active_ready(GObject* source, GAsyncResult* res, gpointer gself)
+    static void on_get_is_active_ready(
+        GObject* source,
+        GAsyncResult* res, 
+        gpointer gself)
     {
         g_message("%s", G_STRLOC);
         GError* error {};
         auto v = g_dbus_connection_call_finish(G_DBUS_CONNECTION(source), res, &error);
         if (error != nullptr) {
             if (!g_error_matches(error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
-                g_warning("UsbSnap: Error getting session bus: %s", error->message);
+                g_warning("Greeter: Error getting IsActive property: %s", error->message);
             g_clear_error(&error);
         } else {
             g_message("%s v is %s", G_STRLOC, g_variant_print(v, true));
@@ -116,22 +130,24 @@ private:
         g_clear_pointer(&v, g_variant_unref);
     }
 
-    static void on_properties_changed_signal(GDBusConnection* /*connection*/,
-                                             const gchar* /*sender_name*/,
-                                             const gchar* object_path,
-                                             const gchar* interface_name,
-                                             const gchar* signal_name,
-                                             GVariant* parameters,
-                                             gpointer gself)
+    static void on_properties_changed_signal(
+        GDBusConnection* /*connection*/,
+        const gchar* sender_name,
+        const gchar* object_path,
+        const gchar* interface_name,
+        const gchar* signal_name,
+        GVariant* parameters,
+        gpointer gself)
     {
-        g_message("%s", G_STRLOC);
+        auto self = static_cast<Impl*>(gself);
 
+        g_return_if_fail(!g_strcmp0(sender_name, self->m_owner.c_str()));
         g_return_if_fail(!g_strcmp0(object_path, DBusNames::UnityGreeter::PATH));
         g_return_if_fail(!g_strcmp0(interface_name, DBusNames::Properties::INTERFACE));
         g_return_if_fail(!g_strcmp0(signal_name, DBusNames::Properties::PropertiesChanged::NAME));
         g_return_if_fail(g_variant_is_of_type(parameters, G_VARIANT_TYPE(DBusNames::Properties::PropertiesChanged::ARGS_VARIANT_TYPE)));
 
-        auto v = g_variant_get_child_value (parameters, 1);
+        auto v = g_variant_get_child_value(parameters, 1);
         if (v != nullptr)
             g_message("%s v is %s", G_STRLOC, g_variant_print(v, true));
 
@@ -139,15 +155,19 @@ private:
         if (g_variant_lookup(v, "IsActive", "b", &is_active))
         {
             g_message("%s is_active changed to %d", G_STRLOC, int(is_active));
-            static_cast<Impl*>(gself)->m_is_active.set(is_active);
+            self->m_is_active.set(is_active);
         }
         g_clear_pointer(&v, g_variant_unref);
+
     }
 
-    core::Property<bool> m_is_active;
-    GCancellable* m_cancellable {};
+    core::Property<bool> m_is_active {false};
+
     GDBusConnection* m_bus {};
+    GCancellable* m_cancellable {};
+    guint m_watcher_id {};
     unsigned int m_subscription_id {};
+    std::string m_owner;
 };
 
 /***
@@ -158,8 +178,8 @@ Greeter::Greeter() =default;
 
 Greeter::~Greeter() =default;
 
-UnityGreeter::UnityGreeter():
-    impl{new Impl{}}
+UnityGreeter::UnityGreeter(GDBusConnection* connection):
+    impl{new Impl{connection}}
 {
 }