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-rw-r--r--plugins/media-keys/bus-watch-namespace.c347
1 files changed, 347 insertions, 0 deletions
diff --git a/plugins/media-keys/bus-watch-namespace.c b/plugins/media-keys/bus-watch-namespace.c
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+++ b/plugins/media-keys/bus-watch-namespace.c
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+/*
+ * Copyright 2013 Canonical Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Lars Uebernickel <lars.uebernickel@canonical.com>
+ */
+
+#include <gio/gio.h>
+#include <string.h>
+#include "bus-watch-namespace.h"
+
+typedef struct
+{
+ guint id;
+ gchar *name_space;
+ GBusNameAppearedCallback appeared_handler;
+ GBusNameVanishedCallback vanished_handler;
+ gpointer user_data;
+ GDestroyNotify user_data_destroy;
+
+ GDBusConnection *connection;
+ GCancellable *cancellable;
+ GHashTable *names;
+ guint subscription_id;
+} NamespaceWatcher;
+
+typedef struct
+{
+ NamespaceWatcher *watcher;
+ gchar *name;
+} GetNameOwnerData;
+
+static guint namespace_watcher_next_id;
+static GHashTable *namespace_watcher_watchers;
+
+static void
+namespace_watcher_stop (gpointer data)
+{
+ NamespaceWatcher *watcher = data;
+
+ g_cancellable_cancel (watcher->cancellable);
+ g_object_unref (watcher->cancellable);
+
+ if (watcher->subscription_id)
+ g_dbus_connection_signal_unsubscribe (watcher->connection, watcher->subscription_id);
+
+ if (watcher->vanished_handler)
+ {
+ GHashTableIter it;
+ const gchar *name;
+
+ g_hash_table_iter_init (&it, watcher->names);
+ while (g_hash_table_iter_next (&it, (gpointer *) &name, NULL))
+ watcher->vanished_handler (watcher->connection, name, watcher->user_data);
+ }
+
+ if (watcher->user_data_destroy)
+ watcher->user_data_destroy (watcher->user_data);
+
+ if (watcher->connection)
+ {
+ g_signal_handlers_disconnect_by_func (watcher->connection, namespace_watcher_stop, watcher);
+ g_object_unref (watcher->connection);
+ }
+
+ g_hash_table_unref (watcher->names);
+
+ g_hash_table_remove (namespace_watcher_watchers, GUINT_TO_POINTER (watcher->id));
+ if (g_hash_table_size (namespace_watcher_watchers) == 0)
+ g_clear_pointer (&namespace_watcher_watchers, g_hash_table_destroy);
+
+ g_free (watcher);
+}
+
+static void
+namespace_watcher_name_appeared (NamespaceWatcher *watcher,
+ const gchar *name,
+ const gchar *owner)
+{
+ /* There's a race between NameOwnerChanged signals arriving and the
+ * ListNames/GetNameOwner sequence returning, so this function might
+ * be called more than once for the same name. To ensure that
+ * appeared_handler is only called once for each name, it is only
+ * called when inserting the name into watcher->names (each name is
+ * only inserted once there).
+ */
+ if (g_hash_table_contains (watcher->names, name))
+ return;
+
+ g_hash_table_add (watcher->names, g_strdup (name));
+
+ if (watcher->appeared_handler)
+ watcher->appeared_handler (watcher->connection, name, owner, watcher->user_data);
+}
+
+static void
+namespace_watcher_name_vanished (NamespaceWatcher *watcher,
+ const gchar *name)
+{
+ if (g_hash_table_remove (watcher->names, name) && watcher->vanished_handler)
+ watcher->vanished_handler (watcher->connection, name, watcher->user_data);
+}
+
+static gboolean
+dbus_name_has_namespace (const gchar *name,
+ const gchar *name_space)
+{
+ gint len_name;
+ gint len_namespace;
+
+ len_name = strlen (name);
+ len_namespace = strlen (name_space);
+
+ if (len_name < len_namespace)
+ return FALSE;
+
+ if (memcmp (name_space, name, len_namespace) != 0)
+ return FALSE;
+
+ return len_namespace == len_name || name[len_namespace] == '.';
+}
+
+static void
+name_owner_changed (GDBusConnection *connection,
+ const gchar *sender_name,
+ const gchar *object_path,
+ const gchar *interface_name,
+ const gchar *signal_name,
+ GVariant *parameters,
+ gpointer user_data)
+{
+ NamespaceWatcher *watcher = user_data;
+ const gchar *name;
+ const gchar *old_owner;
+ const gchar *new_owner;
+
+ g_variant_get (parameters, "(&s&s&s)", &name, &old_owner, &new_owner);
+
+ if (old_owner[0] != '\0')
+ namespace_watcher_name_vanished (watcher, name);
+
+ if (new_owner[0] != '\0')
+ namespace_watcher_name_appeared (watcher, name, new_owner);
+}
+
+static void
+got_name_owner (GObject *object,
+ GAsyncResult *result,
+ gpointer user_data)
+{
+ GetNameOwnerData *data = user_data;
+ GError *error = NULL;
+ GVariant *reply;
+ const gchar *owner;
+
+ reply = g_dbus_connection_call_finish (G_DBUS_CONNECTION (object), result, &error);
+
+ if (g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
+ {
+ g_error_free (error);
+ goto out;
+ }
+
+ if (reply == NULL)
+ {
+ if (!g_error_matches (error, G_DBUS_ERROR, G_DBUS_ERROR_NAME_HAS_NO_OWNER))
+ g_warning ("bus_watch_namespace: error calling org.freedesktop.DBus.GetNameOwner: %s", error->message);
+ g_error_free (error);
+ goto out;
+ }
+
+ g_variant_get (reply, "(&s)", &owner);
+ namespace_watcher_name_appeared (data->watcher, data->name, owner);
+
+ g_variant_unref (reply);
+
+out:
+ g_free (data->name);
+ g_free (data);
+}
+
+static void
+names_listed (GObject *object,
+ GAsyncResult *result,
+ gpointer user_data)
+{
+ NamespaceWatcher *watcher;
+ GError *error = NULL;
+ GVariant *reply;
+ GVariantIter *iter;
+ const gchar *name;
+
+ reply = g_dbus_connection_call_finish (G_DBUS_CONNECTION (object), result, &error);
+
+ if (g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
+ {
+ g_error_free (error);
+ return;
+ }
+
+ watcher = user_data;
+
+ if (reply == NULL)
+ {
+ g_warning ("bus_watch_namespace: error calling org.freedesktop.DBus.ListNames: %s", error->message);
+ g_error_free (error);
+ return;
+ }
+
+ g_variant_get (reply, "(as)", &iter);
+ while (g_variant_iter_next (iter, "&s", &name))
+ {
+ if (dbus_name_has_namespace (name, watcher->name_space))
+ {
+ GetNameOwnerData *data = g_new (GetNameOwnerData, 1);
+ data->watcher = watcher;
+ data->name = g_strdup (name);
+ g_dbus_connection_call (watcher->connection, "org.freedesktop.DBus", "/",
+ "org.freedesktop.DBus", "GetNameOwner",
+ g_variant_new ("(s)", name), G_VARIANT_TYPE ("(s)"),
+ G_DBUS_CALL_FLAGS_NONE, -1, watcher->cancellable,
+ got_name_owner, data);
+ }
+ }
+
+ g_variant_iter_free (iter);
+ g_variant_unref (reply);
+}
+
+static void
+connection_closed (GDBusConnection *connection,
+ gboolean remote_peer_vanished,
+ GError *error,
+ gpointer user_data)
+{
+ NamespaceWatcher *watcher = user_data;
+
+ namespace_watcher_stop (watcher);
+}
+
+static void
+got_bus (GObject *object,
+ GAsyncResult *result,
+ gpointer user_data)
+{
+ GDBusConnection *connection;
+ NamespaceWatcher *watcher;
+ GError *error = NULL;
+
+ connection = g_bus_get_finish (result, &error);
+
+ if (g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
+ {
+ g_error_free (error);
+ return;
+ }
+
+ watcher = user_data;
+
+ if (connection == NULL)
+ {
+ namespace_watcher_stop (watcher);
+ return;
+ }
+
+ watcher->connection = connection;
+ g_signal_connect (watcher->connection, "closed", G_CALLBACK (connection_closed), watcher);
+
+ watcher->subscription_id =
+ g_dbus_connection_signal_subscribe (watcher->connection, "org.freedesktop.DBus",
+ "org.freedesktop.DBus", "NameOwnerChanged", "/org/freedesktop/DBus",
+ watcher->name_space, G_DBUS_SIGNAL_FLAGS_MATCH_ARG0_NAMESPACE,
+ name_owner_changed, watcher, NULL);
+
+ g_dbus_connection_call (watcher->connection, "org.freedesktop.DBus", "/",
+ "org.freedesktop.DBus", "ListNames", NULL, G_VARIANT_TYPE ("(as)"),
+ G_DBUS_CALL_FLAGS_NONE, -1, watcher->cancellable,
+ names_listed, watcher);
+}
+
+guint
+bus_watch_namespace (GBusType bus_type,
+ const gchar *name_space,
+ GBusNameAppearedCallback appeared_handler,
+ GBusNameVanishedCallback vanished_handler,
+ gpointer user_data,
+ GDestroyNotify user_data_destroy)
+{
+ NamespaceWatcher *watcher;
+
+ /* same rules for interfaces and well-known names */
+ g_return_val_if_fail (name_space != NULL && g_dbus_is_interface_name (name_space), 0);
+ g_return_val_if_fail (appeared_handler || vanished_handler, 0);
+
+ watcher = g_new0 (NamespaceWatcher, 1);
+ watcher->id = namespace_watcher_next_id++;
+ watcher->name_space = g_strdup (name_space);
+ watcher->appeared_handler = appeared_handler;
+ watcher->vanished_handler = vanished_handler;
+ watcher->user_data = user_data;
+ watcher->user_data_destroy = user_data_destroy;
+ watcher->cancellable = g_cancellable_new ();;
+ watcher->names = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, NULL);
+
+ if (namespace_watcher_watchers == NULL)
+ namespace_watcher_watchers = g_hash_table_new (g_direct_hash, g_direct_equal);
+ g_hash_table_insert (namespace_watcher_watchers, GUINT_TO_POINTER (watcher->id), watcher);
+
+ g_bus_get (bus_type, watcher->cancellable, got_bus, watcher);
+
+ return watcher->id;
+}
+
+void
+bus_unwatch_namespace (guint id)
+{
+ /* namespace_watcher_stop() might have already removed the watcher
+ * with @id in the case of a connection error. Thus, this function
+ * doesn't warn when @id is absent from the hash table.
+ */
+
+ if (namespace_watcher_watchers)
+ {
+ NamespaceWatcher *watcher;
+
+ watcher = g_hash_table_lookup (namespace_watcher_watchers, GUINT_TO_POINTER (id));
+ if (watcher)
+ {
+ /* make sure vanished() is not called as a result of this function */
+ g_hash_table_remove_all (watcher->names);
+
+ namespace_watcher_stop (watcher);
+ }
+ }
+}