/* GDBus - GLib D-Bus Library

 *

 * Copyright (C) 2008-2010 Red Hat, Inc.

 *

 * This library 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 2.1 of the License, or (at your option) any later version.

 *

 * This library 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 library; if not, see <http://www.gnu.org/licenses/>.

 *

 * Author: David Zeuthen <davidz@redhat.com>

 */

#include "config.h"

#include <stdlib.h>

#include <string.h>

#include "gdbusutils.h"

#include "gdbusnamewatching.h"

#include "gdbuserror.h"

#include "gdbusprivate.h"

#include "gdbusconnection.h"

#include "glibintl.h"

/**

 * SECTION:gdbusnamewatching

 * @title: Watching Bus Names

 * @short_description: Simple API for watching bus names

 * @include: gio/gio.h

 *

 * Convenience API for watching bus names.

 *

 * A simple example for watching a name can be found in

 * [gdbus-example-watch-name.c](https://git.gnome.org/browse/glib/tree/gio/tests/gdbus-example-watch-name.c)

 */

G_LOCK_DEFINE_STATIC (lock);

/* ---------------------------------------------------------------------------------------------------- */

typedef enum

{

  PREVIOUS_CALL_NONE = 0,

  PREVIOUS_CALL_APPEARED,

  PREVIOUS_CALL_VANISHED,

} PreviousCall;

typedef struct

{

  volatile gint             ref_count;

  guint                     id;

  gchar                    *name;

  GBusNameWatcherFlags      flags;

  gchar                    *name_owner;

  GBusNameAppearedCallback  name_appeared_handler;

  GBusNameVanishedCallback  name_vanished_handler;

  gpointer                  user_data;

  GDestroyNotify            user_data_free_func;

  GMainContext             *main_context;

  GDBusConnection          *connection;

  gulong                    disconnected_signal_handler_id;

  guint                     name_owner_changed_subscription_id;

  PreviousCall              previous_call;

  gboolean                  cancelled;

  gboolean                  initialized;

} Client;

/* Must be accessed atomically. */

static volatile guint next_global_id = 1;

/* Must be accessed with @lock held. */

static GHashTable *map_id_to_client = NULL;

static Client *

client_ref (Client *client)

{

  g_atomic_int_inc (&client->ref_count);

  return client;

}

static void

client_unref (Client *client)

{

  if (g_atomic_int_dec_and_test (&client->ref_count))

    {

      if (client->connection != NULL)

        {

          if (client->name_owner_changed_subscription_id > 0)

            g_dbus_connection_signal_unsubscribe (client->connection, client->name_owner_changed_subscription_id);

          if (client->disconnected_signal_handler_id > 0)

            g_signal_handler_disconnect (client->connection, client->disconnected_signal_handler_id);

          g_object_unref (client->connection);

        }

      g_free (client->name);

      g_free (client->name_owner);

      g_main_context_unref (client->main_context);

      if (client->user_data_free_func != NULL)

        client->user_data_free_func (client->user_data);

      g_free (client);

    }

}

/* ---------------------------------------------------------------------------------------------------- */

typedef enum

{

  CALL_TYPE_NAME_APPEARED,

  CALL_TYPE_NAME_VANISHED

} CallType;

typedef struct

{

  Client *client;

  /* keep this separate because client->connection may

   * be set to NULL after scheduling the call

   */

  GDBusConnection *connection;

  /* ditto */

  gchar *name_owner;

  CallType call_type;

} CallHandlerData;

static void

call_handler_data_free (CallHandlerData *data)

{

  if (data->connection != NULL)

    g_object_unref (data->connection);

  g_free (data->name_owner);

  client_unref (data->client);

  g_free (data);

}

static void

actually_do_call (Client *client, GDBusConnection *connection, const gchar *name_owner, CallType call_type)

{

  switch (call_type)

    {

    case CALL_TYPE_NAME_APPEARED:

      if (client->name_appeared_handler != NULL)

        {

          client->name_appeared_handler (connection,

                                         client->name,

                                         name_owner,

                                         client->user_data);

        }

      break;

    case CALL_TYPE_NAME_VANISHED:

      if (client->name_vanished_handler != NULL)

        {

          client->name_vanished_handler (connection,

                                         client->name,

                                         client->user_data);

        }

      break;

    default:

      g_assert_not_reached ();

      break;

    }

}

static gboolean

call_in_idle_cb (gpointer _data)

{

  CallHandlerData *data = _data;

  actually_do_call (data->client, data->connection, data->name_owner, data->call_type);

  return FALSE;

}

static void

schedule_call_in_idle (Client *client, CallType call_type)

{

  CallHandlerData *data;

  GSource *idle_source;

  data = g_new0 (CallHandlerData, 1);

  data->client = client_ref (client);

  data->connection = client->connection != NULL ? g_object_ref (client->connection) : NULL;

  data->name_owner = g_strdup (client->name_owner);

  data->call_type = call_type;

  idle_source = g_idle_source_new ();

  g_source_set_priority (idle_source, G_PRIORITY_HIGH);

  g_source_set_callback (idle_source,

                         call_in_idle_cb,

                         data,

                         (GDestroyNotify) call_handler_data_free);

  g_source_set_name (idle_source, "[gio, gdbusnamewatching.c] call_in_idle_cb");

  g_source_attach (idle_source, client->main_context);

  g_source_unref (idle_source);

}

static void

do_call (Client *client, CallType call_type)

{

  GMainContext *current_context;

  /* only schedule in idle if we're not in the right thread */

  current_context = g_main_context_ref_thread_default ();

  if (current_context != client->main_context)

    schedule_call_in_idle (client, call_type);

  else

    actually_do_call (client, client->connection, client->name_owner, call_type);

  g_main_context_unref (current_context);

}

static void

call_appeared_handler (Client *client)

{

  if (client->previous_call != PREVIOUS_CALL_APPEARED)

    {

      client->previous_call = PREVIOUS_CALL_APPEARED;

      if (!client->cancelled && client->name_appeared_handler != NULL)

        {

          do_call (client, CALL_TYPE_NAME_APPEARED);

        }

    }

}

static void

call_vanished_handler (Client  *client,

                       gboolean ignore_cancelled)

{

  if (client->previous_call != PREVIOUS_CALL_VANISHED)

    {

      client->previous_call = PREVIOUS_CALL_VANISHED;

      if (((!client->cancelled) || ignore_cancelled) && client->name_vanished_handler != NULL)

        {

          do_call (client, CALL_TYPE_NAME_VANISHED);

        }

    }

}

/* ---------------------------------------------------------------------------------------------------- */

/* Return a reference to the #Client for @watcher_id, or %NULL if it’s been

 * unwatched. This is safe to call from any thread. */

static Client *

dup_client (guint watcher_id)

{

  Client *client;

  G_LOCK (lock);

  g_assert (watcher_id != 0);

  g_assert (map_id_to_client != NULL);

  client = g_hash_table_lookup (map_id_to_client, GUINT_TO_POINTER (watcher_id));

  if (client != NULL)

    client_ref (client);

  G_UNLOCK (lock);

  return client;

}

/* Could be called from any thread, so it could be called after client_unref()

 * has started finalising the #Client. Avoid that by looking up the #Client

 * atomically. */

static void

on_connection_disconnected (GDBusConnection *connection,

                            gboolean         remote_peer_vanished,

                            GError          *error,

                            gpointer         user_data)

{

  guint watcher_id = GPOINTER_TO_UINT (user_data);

  Client *client = NULL;

  client = dup_client (watcher_id);

  if (client == NULL)

    return;

  if (client->name_owner_changed_subscription_id > 0)

    g_dbus_connection_signal_unsubscribe (client->connection, client->name_owner_changed_subscription_id);

  if (client->disconnected_signal_handler_id > 0)

    g_signal_handler_disconnect (client->connection, client->disconnected_signal_handler_id);

  g_object_unref (client->connection);

  client->disconnected_signal_handler_id = 0;

  client->name_owner_changed_subscription_id = 0;

  client->connection = NULL;

  call_vanished_handler (client, FALSE);

  client_unref (client);

}

/* ---------------------------------------------------------------------------------------------------- */

/* Will always be called from the thread which acquired client->main_context. */

static void

on_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)

{

  guint watcher_id = GPOINTER_TO_UINT (user_data);

  Client *client = NULL;

  const gchar *name;

  const gchar *old_owner;

  const gchar *new_owner;

  client = dup_client (watcher_id);

  if (client == NULL)

    return;

  if (!client->initialized)

    goto out;

  if (g_strcmp0 (object_path, "/org/freedesktop/DBus") != 0 ||

      g_strcmp0 (interface_name, "org.freedesktop.DBus") != 0 ||

      g_strcmp0 (sender_name, "org.freedesktop.DBus") != 0)

    goto out;

  g_variant_get (parameters,

                 "(&s&s&s)",

                 &name,

                 &old_owner,

                 &new_owner);

  /* we only care about a specific name */

  if (g_strcmp0 (name, client->name) != 0)

    goto out;

  if ((old_owner != NULL && strlen (old_owner) > 0) && client->name_owner != NULL)

    {

      g_free (client->name_owner);

      client->name_owner = NULL;

      call_vanished_handler (client, FALSE);

    }

  if (new_owner != NULL && strlen (new_owner) > 0)

    {

      g_warn_if_fail (client->name_owner == NULL);

      g_free (client->name_owner);

      client->name_owner = g_strdup (new_owner);

      call_appeared_handler (client);

    }

 out:

  client_unref (client);

}

/* ---------------------------------------------------------------------------------------------------- */

static void

get_name_owner_cb (GObject      *source_object,

                   GAsyncResult *res,

                   gpointer      user_data)

{

  Client *client = user_data;

  GVariant *result;

  const char *name_owner;

  name_owner = NULL;

  result = NULL;

  result = g_dbus_connection_call_finish (client->connection,

                                          res,

                                          NULL);

  if (result != NULL)

    {

      g_variant_get (result, "(&s)", &name_owner);

    }

  if (name_owner != NULL)

    {

      g_warn_if_fail (client->name_owner == NULL);

      client->name_owner = g_strdup (name_owner);

      call_appeared_handler (client);

    }

  else

    {

      call_vanished_handler (client, FALSE);

    }

  client->initialized = TRUE;

  if (result != NULL)

    g_variant_unref (result);

  client_unref (client);

}

/* ---------------------------------------------------------------------------------------------------- */

static void

invoke_get_name_owner (Client *client)

{

  g_dbus_connection_call (client->connection,

                          "org.freedesktop.DBus",  /* bus name */

                          "/org/freedesktop/DBus", /* object path */

                          "org.freedesktop.DBus",  /* interface name */

                          "GetNameOwner",          /* method name */

                          g_variant_new ("(s)", client->name),

                          G_VARIANT_TYPE ("(s)"),

                          G_DBUS_CALL_FLAGS_NONE,

                          -1,

                          NULL,

                          (GAsyncReadyCallback) get_name_owner_cb,

                          client_ref (client));

}

/* ---------------------------------------------------------------------------------------------------- */

static void

start_service_by_name_cb (GObject      *source_object,

                          GAsyncResult *res,

                          gpointer      user_data)

{

  Client *client = user_data;

  GVariant *result;

  result = NULL;

  result = g_dbus_connection_call_finish (client->connection,

                                          res,

                                          NULL);

  if (result != NULL)

    {

      guint32 start_service_result;

      g_variant_get (result, "(u)", &start_service_result);

      if (start_service_result == 1) /* DBUS_START_REPLY_SUCCESS */

        {

          invoke_get_name_owner (client);

        }

      else if (start_service_result == 2) /* DBUS_START_REPLY_ALREADY_RUNNING */

        {

          invoke_get_name_owner (client);

        }

      else

        {

          g_warning ("Unexpected reply %d from StartServiceByName() method", start_service_result);

          call_vanished_handler (client, FALSE);

          client->initialized = TRUE;

        }

    }

  else

    {

      /* Errors are not unexpected; the bus will reply e.g.

       *

       *   org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.Epiphany2

       *   was not provided by any .service files

       *

       * This doesn't mean that the name doesn't have an owner, just

       * that it's not provided by a .service file. So proceed to

       * invoke GetNameOwner().

       */

      invoke_get_name_owner (client);

    }

  if (result != NULL)

    g_variant_unref (result);

  client_unref (client);

}

/* ---------------------------------------------------------------------------------------------------- */

static void

has_connection (Client *client)

{

  /* listen for disconnection */

  client->disconnected_signal_handler_id = g_signal_connect (client->connection,

                                                             "closed",

                                                             G_CALLBACK (on_connection_disconnected),

                                                             GUINT_TO_POINTER (client->id));

  /* start listening to NameOwnerChanged messages immediately */

  client->name_owner_changed_subscription_id = g_dbus_connection_signal_subscribe (client->connection,

                                                                                   "org.freedesktop.DBus",  /* name */

                                                                                   "org.freedesktop.DBus",  /* if */

                                                                                   "NameOwnerChanged",      /* signal */

                                                                                   "/org/freedesktop/DBus", /* path */

                                                                                   client->name,

                                                                                   G_DBUS_SIGNAL_FLAGS_NONE,

                                                                                   on_name_owner_changed,

                                                                                   GUINT_TO_POINTER (client->id),

                                                                                   NULL);

  if (client->flags & G_BUS_NAME_WATCHER_FLAGS_AUTO_START)

    {

      g_dbus_connection_call (client->connection,

                              "org.freedesktop.DBus",  /* bus name */

                              "/org/freedesktop/DBus", /* object path */

                              "org.freedesktop.DBus",  /* interface name */

                              "StartServiceByName",    /* method name */

                              g_variant_new ("(su)", client->name, 0),

                              G_VARIANT_TYPE ("(u)"),

                              G_DBUS_CALL_FLAGS_NONE,

                              -1,

                              NULL,

                              (GAsyncReadyCallback) start_service_by_name_cb,

                              client_ref (client));

    }

  else

    {

      /* check owner */

      invoke_get_name_owner (client);

    }

}

static void

connection_get_cb (GObject      *source_object,

                   GAsyncResult *res,

                   gpointer      user_data)

{

  Client *client = user_data;

  client->connection = g_bus_get_finish (res, NULL);

  if (client->connection == NULL)

    {

      call_vanished_handler (client, FALSE);

      goto out;

    }

  has_connection (client);

 out:

  client_unref (client);

}

/* ---------------------------------------------------------------------------------------------------- */

/**

 * g_bus_watch_name:

 * @bus_type: The type of bus to watch a name on.

 * @name: The name (well-known or unique) to watch.

 * @flags: Flags from the #GBusNameWatcherFlags enumeration.

 * @name_appeared_handler: (nullable): Handler to invoke when @name is known to exist or %NULL.

 * @name_vanished_handler: (nullable): Handler to invoke when @name is known to not exist or %NULL.

 * @user_data: User data to pass to handlers.

 * @user_data_free_func: (nullable): Function for freeing @user_data or %NULL.

 *

 * Starts watching @name on the bus specified by @bus_type and calls

 * @name_appeared_handler and @name_vanished_handler when the name is

 * known to have a owner respectively known to lose its

 * owner. Callbacks will be invoked in the

 * [thread-default main context][g-main-context-push-thread-default]

 * of the thread you are calling this function from.

 *

 * You are guaranteed that one of the handlers will be invoked after

 * calling this function. When you are done watching the name, just

 * call g_bus_unwatch_name() with the watcher id this function

 * returns.

 *

 * If the name vanishes or appears (for example the application owning

 * the name could restart), the handlers are also invoked. If the

 * #GDBusConnection that is used for watching the name disconnects, then

 * @name_vanished_handler is invoked since it is no longer

 * possible to access the name.

 *

 * Another guarantee is that invocations of @name_appeared_handler

 * and @name_vanished_handler are guaranteed to alternate; that

 * is, if @name_appeared_handler is invoked then you are

 * guaranteed that the next time one of the handlers is invoked, it

 * will be @name_vanished_handler. The reverse is also true.

 *

 * This behavior makes it very simple to write applications that want

 * to take action when a certain [name exists][gdbus-watching-names].

 * Basically, the application should create object proxies in

 * @name_appeared_handler and destroy them again (if any) in

 * @name_vanished_handler.

 *

 * Returns: An identifier (never 0) that an be used with

 * g_bus_unwatch_name() to stop watching the name.

 *

 * Since: 2.26

 */

guint

g_bus_watch_name (GBusType                  bus_type,

                  const gchar              *name,

                  GBusNameWatcherFlags      flags,

                  GBusNameAppearedCallback  name_appeared_handler,

                  GBusNameVanishedCallback  name_vanished_handler,

                  gpointer                  user_data,

                  GDestroyNotify            user_data_free_func)

{

  Client *client;

  g_return_val_if_fail (g_dbus_is_name (name), 0);

  G_LOCK (lock);

  client = g_new0 (Client, 1);

  client->ref_count = 1;

  client->id = g_atomic_int_add (&next_global_id, 1); /* TODO: uh oh, handle overflow */

  client->name = g_strdup (name);

  client->flags = flags;

  client->name_appeared_handler = name_appeared_handler;

  client->name_vanished_handler = name_vanished_handler;

  client->user_data = user_data;

  client->user_data_free_func = user_data_free_func;

  client->main_context = g_main_context_ref_thread_default ();

  if (map_id_to_client == NULL)

    {

      map_id_to_client = g_hash_table_new (g_direct_hash, g_direct_equal);

    }

  g_hash_table_insert (map_id_to_client,

                       GUINT_TO_POINTER (client->id),

                       client);

  g_bus_get (bus_type,

             NULL,

             connection_get_cb,

             client_ref (client));

  G_UNLOCK (lock);

  return client->id;

}

/**

 * g_bus_watch_name_on_connection:

 * @connection: A #GDBusConnection.

 * @name: The name (well-known or unique) to watch.

 * @flags: Flags from the #GBusNameWatcherFlags enumeration.

 * @name_appeared_handler: (nullable): Handler to invoke when @name is known to exist or %NULL.

 * @name_vanished_handler: (nullable): Handler to invoke when @name is known to not exist or %NULL.

 * @user_data: User data to pass to handlers.

 * @user_data_free_func: (nullable): Function for freeing @user_data or %NULL.

 *

 * Like g_bus_watch_name() but takes a #GDBusConnection instead of a

 * #GBusType.

 *

 * Returns: An identifier (never 0) that an be used with

 * g_bus_unwatch_name() to stop watching the name.

 *

 * Since: 2.26

 */

guint g_bus_watch_name_on_connection (GDBusConnection          *connection,

                                      const gchar              *name,

                                      GBusNameWatcherFlags      flags,

                                      GBusNameAppearedCallback  name_appeared_handler,

                                      GBusNameVanishedCallback  name_vanished_handler,

                                      gpointer                  user_data,

                                      GDestroyNotify            user_data_free_func)

{

  Client *client;

  g_return_val_if_fail (G_IS_DBUS_CONNECTION (connection), 0);

  g_return_val_if_fail (g_dbus_is_name (name), 0);

  G_LOCK (lock);

  client = g_new0 (Client, 1);

  client->ref_count = 1;

  client->id = g_atomic_int_add (&next_global_id, 1); /* TODO: uh oh, handle overflow */

  client->name = g_strdup (name);

  client->flags = flags;

  client->name_appeared_handler = name_appeared_handler;

  client->name_vanished_handler = name_vanished_handler;

  client->user_data = user_data;

  client->user_data_free_func = user_data_free_func;

  client->main_context = g_main_context_ref_thread_default ();

  if (map_id_to_client == NULL)

    map_id_to_client = g_hash_table_new (g_direct_hash, g_direct_equal);

  g_hash_table_insert (map_id_to_client,

                       GUINT_TO_POINTER (client->id),

                       client);

  client->connection = g_object_ref (connection);

  G_UNLOCK (lock);

  has_connection (client);

  return client->id;

}

typedef struct {

  GClosure *name_appeared_closure;

  GClosure *name_vanished_closure;

} WatchNameData;

static WatchNameData *

watch_name_data_new (GClosure *name_appeared_closure,

                     GClosure *name_vanished_closure)

{

  WatchNameData *data;

  data = g_new0 (WatchNameData, 1);

  if (name_appeared_closure != NULL)

    {

      data->name_appeared_closure = g_closure_ref (name_appeared_closure);

      g_closure_sink (name_appeared_closure);

      if (G_CLOSURE_NEEDS_MARSHAL (name_appeared_closure))

        g_closure_set_marshal (name_appeared_closure, g_cclosure_marshal_generic);

    }

  if (name_vanished_closure != NULL)

    {

      data->name_vanished_closure = g_closure_ref (name_vanished_closure);

      g_closure_sink (name_vanished_closure);

      if (G_CLOSURE_NEEDS_MARSHAL (name_vanished_closure))

        g_closure_set_marshal (name_vanished_closure, g_cclosure_marshal_generic);

    }

  return data;

}

static void

watch_with_closures_on_name_appeared (GDBusConnection *connection,

                                      const gchar     *name,

                                      const gchar     *name_owner,

                                      gpointer         user_data)

{

  WatchNameData *data = user_data;

  GValue params[3] = { G_VALUE_INIT, G_VALUE_INIT, G_VALUE_INIT };

  g_value_init (&params[0], G_TYPE_DBUS_CONNECTION);

  g_value_set_object (&params[0], connection);

  g_value_init (&params[1], G_TYPE_STRING);

  g_value_set_string (&params[1], name);

  g_value_init (&params[2], G_TYPE_STRING);

  g_value_set_string (&params[2], name_owner);

  g_closure_invoke (data->name_appeared_closure, NULL, 3, params, NULL);

  g_value_unset (params + 0);

  g_value_unset (params + 1);

  g_value_unset (params + 2);

}

static void

watch_with_closures_on_name_vanished (GDBusConnection *connection,

                                      const gchar     *name,

                                      gpointer         user_data)

{

  WatchNameData *data = user_data;

  GValue params[2] = { G_VALUE_INIT, G_VALUE_INIT };

  g_value_init (&params[0], G_TYPE_DBUS_CONNECTION);

  g_value_set_object (&params[0], connection);

  g_value_init (&params[1], G_TYPE_STRING);

  g_value_set_string (&params[1], name);

  g_closure_invoke (data->name_vanished_closure, NULL, 2, params, NULL);

  g_value_unset (params + 0);

  g_value_unset (params + 1);

}

static void

bus_watch_name_free_func (gpointer user_data)

{

  WatchNameData *data = user_data;

  if (data->name_appeared_closure != NULL)

    g_closure_unref (data->name_appeared_closure);

  if (data->name_vanished_closure != NULL)

    g_closure_unref (data->name_vanished_closure);

  g_free (data);

}

/**

 * g_bus_watch_name_with_closures: (rename-to g_bus_watch_name)

 * @bus_type: The type of bus to watch a name on.

 * @name: The name (well-known or unique) to watch.

 * @flags: Flags from the #GBusNameWatcherFlags enumeration.

 * @name_appeared_closure: (nullable): #GClosure to invoke when @name is known

 * to exist or %NULL.

 * @name_vanished_closure: (nullable): #GClosure to invoke when @name is known

 * to not exist or %NULL.

 *

 * Version of g_bus_watch_name() using closures instead of callbacks for

 * easier binding in other languages.

 *

 * Returns: An identifier (never 0) that an be used with

 * g_bus_unwatch_name() to stop watching the name.

 *

 * Since: 2.26

 */

guint

g_bus_watch_name_with_closures (GBusType                 bus_type,

                                const gchar             *name,

                                GBusNameWatcherFlags     flags,

                                GClosure                *name_appeared_closure,

                                GClosure                *name_vanished_closure)

{

  return g_bus_watch_name (bus_type,

          name,

          flags,

          name_appeared_closure != NULL ? watch_with_closures_on_name_appeared : NULL,

          name_vanished_closure != NULL ? watch_with_closures_on_name_vanished : NULL,

          watch_name_data_new (name_appeared_closure, name_vanished_closure),

          bus_watch_name_free_func);

}

/**

 * g_bus_watch_name_on_connection_with_closures: (rename-to g_bus_watch_name_on_connection)

 * @connection: A #GDBusConnection.

 * @name: The name (well-known or unique) to watch.

 * @flags: Flags from the #GBusNameWatcherFlags enumeration.

 * @name_appeared_closure: (nullable): #GClosure to invoke when @name is known

 * to exist or %NULL.

 * @name_vanished_closure: (nullable): #GClosure to invoke when @name is known

 * to not exist or %NULL.

 *

 * Version of g_bus_watch_name_on_connection() using closures instead of callbacks for

 * easier binding in other languages.

 *

 * Returns: An identifier (never 0) that an be used with

 * g_bus_unwatch_name() to stop watching the name.

 *

 * Since: 2.26

 */

guint g_bus_watch_name_on_connection_with_closures (

                                      GDBusConnection          *connection,

                                      const gchar              *name,

                                      GBusNameWatcherFlags      flags,

                                      GClosure                 *name_appeared_closure,

                                      GClosure                 *name_vanished_closure)

{

  return g_bus_watch_name_on_connection (connection,

          name,

          flags,

          name_appeared_closure != NULL ? watch_with_closures_on_name_appeared : NULL,

          name_vanished_closure != NULL ? watch_with_closures_on_name_vanished : NULL,

          watch_name_data_new (name_appeared_closure, name_vanished_closure),

          bus_watch_name_free_func);

}

/**

 * g_bus_unwatch_name:

 * @watcher_id: An identifier obtained from g_bus_watch_name()

 *

 * Stops watching a name.

 *

 * Since: 2.26

 */

void

g_bus_unwatch_name (guint watcher_id)

{

  Client *client;

  g_return_if_fail (watcher_id > 0);

  client = NULL;

  G_LOCK (lock);

  if (watcher_id == 0 ||

      map_id_to_client == NULL ||

      (client = g_hash_table_lookup (map_id_to_client, GUINT_TO_POINTER (watcher_id))) == NULL)

    {

      g_warning ("Invalid id %d passed to g_bus_unwatch_name()", watcher_id);

      goto out;

    }

  client->cancelled = TRUE;

  g_warn_if_fail (g_hash_table_remove (map_id_to_client, GUINT_TO_POINTER (watcher_id)));

 out: