gio/gdbusnamewatching.c

   1 /* GDBus - GLib D-Bus Library
   2  *
   3  * Copyright (C) 2008-2010 Red Hat, Inc.
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2.1 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General
  16  * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
  17  *
  18  * Author: David Zeuthen <davidz@redhat.com>
  19  */
  20
  21 #include "config.h"
  22
  23 #include <stdlib.h>
  24 #include <string.h>
  25
  26 #include "gdbusutils.h"
  27 #include "gdbusnamewatching.h"
  28 #include "gdbuserror.h"
  29 #include "gdbusprivate.h"
  30 #include "gdbusconnection.h"
  31
  32 #include "glibintl.h"
  33
  34 /**
  35  * SECTION:gdbusnamewatching
  36  * @title: Watching Bus Names
  37  * @short_description: Simple API for watching bus names
  38  * @include: gio/gio.h
  39  *
  40  * Convenience API for watching bus names.
  41  *
  42  * A simple example for watching a name can be found in
  43  * [gdbus-example-watch-name.c](https://git.gnome.org/browse/glib/tree/gio/tests/gdbus-example-watch-name.c)
  44  */
  45
  46 G_LOCK_DEFINE_STATIC (lock);
  47
  48 /* ---------------------------------------------------------------------------------------------------- */
  49
  50 typedef enum
  51 {
  52   PREVIOUS_CALL_NONE = 0,
  53   PREVIOUS_CALL_APPEARED,
  54   PREVIOUS_CALL_VANISHED,
  55 } PreviousCall;
  56
  57 typedef struct
  58 {
  59   volatile gint             ref_count;
  60   guint                     id;
  61   gchar                    *name;
  62   GBusNameWatcherFlags      flags;
  63   gchar                    *name_owner;
  64   GBusNameAppearedCallback  name_appeared_handler;
  65   GBusNameVanishedCallback  name_vanished_handler;
  66   gpointer                  user_data;
  67   GDestroyNotify            user_data_free_func;
  68   GMainContext             *main_context;
  69
  70   GDBusConnection          *connection;
  71   gulong                    disconnected_signal_handler_id;
  72   guint                     name_owner_changed_subscription_id;
  73
  74   PreviousCall              previous_call;
  75
  76   gboolean                  cancelled;
  77   gboolean                  initialized;
  78 } Client;
  79
  80 /* Must be accessed atomically. */
  81 static volatile guint next_global_id = 1;
  82
  83 /* Must be accessed with @lock held. */
  84 static GHashTable *map_id_to_client = NULL;
  85
  86 static Client *
  87 client_ref (Client *client)
  88 {
  89   g_atomic_int_inc (&client->ref_count);
  90   return client;
  91 }
  92
  93 static void
  94 client_unref (Client *client)
  95 {
  96   if (g_atomic_int_dec_and_test (&client->ref_count))
  97     {
  98       if (client->connection != NULL)
  99         {
 100           if (client->name_owner_changed_subscription_id > 0)
 101             g_dbus_connection_signal_unsubscribe (client->connection, client->name_owner_changed_subscription_id);
 102           if (client->disconnected_signal_handler_id > 0)
 103             g_signal_handler_disconnect (client->connection, client->disconnected_signal_handler_id);
 104           g_object_unref (client->connection);
 105         }
 106       g_free (client->name);
 107       g_free (client->name_owner);
 108       g_main_context_unref (client->main_context);
 109       if (client->user_data_free_func != NULL)
 110         client->user_data_free_func (client->user_data);
 111       g_free (client);
 112     }
 113 }
 114
 115 /* ---------------------------------------------------------------------------------------------------- */
 116
 117 typedef enum
 118 {
 119   CALL_TYPE_NAME_APPEARED,
 120   CALL_TYPE_NAME_VANISHED
 121 } CallType;
 122
 123 typedef struct
 124 {
 125   Client *client;
 126
 127   /* keep this separate because client->connection may
 128    * be set to NULL after scheduling the call
 129    */
 130   GDBusConnection *connection;
 131
 132   /* ditto */
 133   gchar *name_owner;
 134
 135   CallType call_type;
 136 } CallHandlerData;
 137
 138 static void
 139 call_handler_data_free (CallHandlerData *data)
 140 {
 141   if (data->connection != NULL)
 142     g_object_unref (data->connection);
 143   g_free (data->name_owner);
 144   client_unref (data->client);
 145   g_free (data);
 146 }
 147
 148 static void
 149 actually_do_call (Client *client, GDBusConnection *connection, const gchar *name_owner, CallType call_type)
 150 {
 151   switch (call_type)
 152     {
 153     case CALL_TYPE_NAME_APPEARED:
 154       if (client->name_appeared_handler != NULL)
 155         {
 156           client->name_appeared_handler (connection,
 157                                          client->name,
 158                                          name_owner,
 159                                          client->user_data);
 160         }
 161       break;
 162
 163     case CALL_TYPE_NAME_VANISHED:
 164       if (client->name_vanished_handler != NULL)
 165         {
 166           client->name_vanished_handler (connection,
 167                                          client->name,
 168                                          client->user_data);
 169         }
 170       break;
 171
 172     default:
 173       g_assert_not_reached ();
 174       break;
 175     }
 176 }
 177
 178 static gboolean
 179 call_in_idle_cb (gpointer _data)
 180 {
 181   CallHandlerData *data = _data;
 182   actually_do_call (data->client, data->connection, data->name_owner, data->call_type);
 183   return FALSE;
 184 }
 185
 186 static void
 187 schedule_call_in_idle (Client *client, CallType call_type)
 188 {
 189   CallHandlerData *data;
 190   GSource *idle_source;
 191
 192   data = g_new0 (CallHandlerData, 1);
 193   data->client = client_ref (client);
 194   data->connection = client->connection != NULL ? g_object_ref (client->connection) : NULL;
 195   data->name_owner = g_strdup (client->name_owner);
 196   data->call_type = call_type;
 197
 198   idle_source = g_idle_source_new ();
 199   g_source_set_priority (idle_source, G_PRIORITY_HIGH);
 200   g_source_set_callback (idle_source,
 201                          call_in_idle_cb,
 202                          data,
 203                          (GDestroyNotify) call_handler_data_free);
 204   g_source_set_name (idle_source, "[gio, gdbusnamewatching.c] call_in_idle_cb");
 205   g_source_attach (idle_source, client->main_context);
 206   g_source_unref (idle_source);
 207 }
 208
 209 static void
 210 do_call (Client *client, CallType call_type)
 211 {
 212   GMainContext *current_context;
 213
 214   /* only schedule in idle if we're not in the right thread */
 215   current_context = g_main_context_ref_thread_default ();
 216   if (current_context != client->main_context)
 217     schedule_call_in_idle (client, call_type);
 218   else
 219     actually_do_call (client, client->connection, client->name_owner, call_type);
 220   g_main_context_unref (current_context);
 221 }
 222
 223 static void
 224 call_appeared_handler (Client *client)
 225 {
 226   if (client->previous_call != PREVIOUS_CALL_APPEARED)
 227     {
 228       client->previous_call = PREVIOUS_CALL_APPEARED;
 229       if (!client->cancelled && client->name_appeared_handler != NULL)
 230         {
 231           do_call (client, CALL_TYPE_NAME_APPEARED);
 232         }
 233     }
 234 }
 235
 236 static void
 237 call_vanished_handler (Client  *client,
 238                        gboolean ignore_cancelled)
 239 {
 240   if (client->previous_call != PREVIOUS_CALL_VANISHED)
 241     {
 242       client->previous_call = PREVIOUS_CALL_VANISHED;
 243       if (((!client->cancelled) || ignore_cancelled) && client->name_vanished_handler != NULL)
 244         {
 245           do_call (client, CALL_TYPE_NAME_VANISHED);
 246         }
 247     }
 248 }
 249
 250 /* ---------------------------------------------------------------------------------------------------- */
 251
 252 /* Return a reference to the #Client for @watcher_id, or %NULL if it’s been
 253  * unwatched. This is safe to call from any thread. */
 254 static Client *
 255 dup_client (guint watcher_id)
 256 {
 257   Client *client;
 258
 259   G_LOCK (lock);
 260
 261   g_assert (watcher_id != 0);
 262   g_assert (map_id_to_client != NULL);
 263
 264   client = g_hash_table_lookup (map_id_to_client, GUINT_TO_POINTER (watcher_id));
 265
 266   if (client != NULL)
 267     client_ref (client);
 268
 269   G_UNLOCK (lock);
 270
 271   return client;
 272 }
 273
 274 /* Could be called from any thread, so it could be called after client_unref()
 275  * has started finalising the #Client. Avoid that by looking up the #Client
 276  * atomically. */
 277 static void
 278 on_connection_disconnected (GDBusConnection *connection,
 279                             gboolean         remote_peer_vanished,
 280                             GError          *error,
 281                             gpointer         user_data)
 282 {
 283   guint watcher_id = GPOINTER_TO_UINT (user_data);
 284   Client *client = NULL;
 285
 286   client = dup_client (watcher_id);
 287   if (client == NULL)
 288     return;
 289
 290   if (client->name_owner_changed_subscription_id > 0)
 291     g_dbus_connection_signal_unsubscribe (client->connection, client->name_owner_changed_subscription_id);
 292   if (client->disconnected_signal_handler_id > 0)
 293     g_signal_handler_disconnect (client->connection, client->disconnected_signal_handler_id);
 294   g_object_unref (client->connection);
 295   client->disconnected_signal_handler_id = 0;
 296   client->name_owner_changed_subscription_id = 0;
 297   client->connection = NULL;
 298
 299   call_vanished_handler (client, FALSE);
 300
 301   client_unref (client);
 302 }
 303
 304 /* ---------------------------------------------------------------------------------------------------- */
 305
 306 /* Will always be called from the thread which acquired client->main_context. */
 307 static void
 308 on_name_owner_changed (GDBusConnection *connection,
 309                        const gchar      *sender_name,
 310                        const gchar      *object_path,
 311                        const gchar      *interface_name,
 312                        const gchar      *signal_name,
 313                        GVariant         *parameters,
 314                        gpointer          user_data)
 315 {
 316   guint watcher_id = GPOINTER_TO_UINT (user_data);
 317   Client *client = NULL;
 318   const gchar *name;
 319   const gchar *old_owner;
 320   const gchar *new_owner;
 321
 322   client = dup_client (watcher_id);
 323   if (client == NULL)
 324     return;
 325
 326   if (!client->initialized)
 327     goto out;
 328
 329   if (g_strcmp0 (object_path, "/org/freedesktop/DBus") != 0 ||
 330       g_strcmp0 (interface_name, "org.freedesktop.DBus") != 0 ||
 331       g_strcmp0 (sender_name, "org.freedesktop.DBus") != 0)
 332     goto out;
 333
 334   g_variant_get (parameters,
 335                  "(&s&s&s)",
 336                  &name,
 337                  &old_owner,
 338                  &new_owner);
 339
 340   /* we only care about a specific name */
 341   if (g_strcmp0 (name, client->name) != 0)
 342     goto out;
 343
 344   if ((old_owner != NULL && strlen (old_owner) > 0) && client->name_owner != NULL)
 345     {
 346       g_free (client->name_owner);
 347       client->name_owner = NULL;
 348       call_vanished_handler (client, FALSE);
 349     }
 350
 351   if (new_owner != NULL && strlen (new_owner) > 0)
 352     {
 353       g_warn_if_fail (client->name_owner == NULL);
 354       g_free (client->name_owner);
 355       client->name_owner = g_strdup (new_owner);
 356       call_appeared_handler (client);
 357     }
 358
 359  out:
 360   client_unref (client);
 361 }
 362
 363 /* ---------------------------------------------------------------------------------------------------- */
 364
 365 static void
 366 get_name_owner_cb (GObject      *source_object,
 367                    GAsyncResult *res,
 368                    gpointer      user_data)
 369 {
 370   Client *client = user_data;
 371   GVariant *result;
 372   const char *name_owner;
 373
 374   name_owner = NULL;
 375   result = NULL;
 376
 377   result = g_dbus_connection_call_finish (client->connection,
 378                                           res,
 379                                           NULL);
 380   if (result != NULL)
 381     {
 382       g_variant_get (result, "(&s)", &name_owner);
 383     }
 384
 385   if (name_owner != NULL)
 386     {
 387       g_warn_if_fail (client->name_owner == NULL);
 388       client->name_owner = g_strdup (name_owner);
 389       call_appeared_handler (client);
 390     }
 391   else
 392     {
 393       call_vanished_handler (client, FALSE);
 394     }
 395
 396   client->initialized = TRUE;
 397
 398   if (result != NULL)
 399     g_variant_unref (result);
 400   client_unref (client);
 401 }
 402
 403 /* ---------------------------------------------------------------------------------------------------- */
 404
 405 static void
 406 invoke_get_name_owner (Client *client)
 407 {
 408   g_dbus_connection_call (client->connection,
 409                           "org.freedesktop.DBus",  /* bus name */
 410                           "/org/freedesktop/DBus", /* object path */
 411                           "org.freedesktop.DBus",  /* interface name */
 412                           "GetNameOwner",          /* method name */
 413                           g_variant_new ("(s)", client->name),
 414                           G_VARIANT_TYPE ("(s)"),
 415                           G_DBUS_CALL_FLAGS_NONE,
 416                           -1,
 417                           NULL,
 418                           (GAsyncReadyCallback) get_name_owner_cb,
 419                           client_ref (client));
 420 }
 421
 422 /* ---------------------------------------------------------------------------------------------------- */
 423
 424 static void
 425 start_service_by_name_cb (GObject      *source_object,
 426                           GAsyncResult *res,
 427                           gpointer      user_data)
 428 {
 429   Client *client = user_data;
 430   GVariant *result;
 431
 432   result = NULL;
 433
 434   result = g_dbus_connection_call_finish (client->connection,
 435                                           res,
 436                                           NULL);
 437   if (result != NULL)
 438     {
 439       guint32 start_service_result;
 440       g_variant_get (result, "(u)", &start_service_result);
 441
 442       if (start_service_result == 1) /* DBUS_START_REPLY_SUCCESS */
 443         {
 444           invoke_get_name_owner (client);
 445         }
 446       else if (start_service_result == 2) /* DBUS_START_REPLY_ALREADY_RUNNING */
 447         {
 448           invoke_get_name_owner (client);
 449         }
 450       else
 451         {
 452           g_warning ("Unexpected reply %d from StartServiceByName() method", start_service_result);
 453           call_vanished_handler (client, FALSE);
 454           client->initialized = TRUE;
 455         }
 456     }
 457   else
 458     {
 459       /* Errors are not unexpected; the bus will reply e.g.
 460        *
 461        *   org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.Epiphany2
 462        *   was not provided by any .service files
 463        *
 464        * This doesn't mean that the name doesn't have an owner, just
 465        * that it's not provided by a .service file. So proceed to
 466        * invoke GetNameOwner().
 467        */
 468       invoke_get_name_owner (client);
 469     }
 470
 471   if (result != NULL)
 472     g_variant_unref (result);
 473   client_unref (client);
 474 }
 475
 476 /* ---------------------------------------------------------------------------------------------------- */
 477
 478 static void
 479 has_connection (Client *client)
 480 {
 481   /* listen for disconnection */
 482   client->disconnected_signal_handler_id = g_signal_connect (client->connection,
 483                                                              "closed",
 484                                                              G_CALLBACK (on_connection_disconnected),
 485                                                              GUINT_TO_POINTER (client->id));
 486
 487   /* start listening to NameOwnerChanged messages immediately */
 488   client->name_owner_changed_subscription_id = g_dbus_connection_signal_subscribe (client->connection,
 489                                                                                    "org.freedesktop.DBus",  /* name */
 490                                                                                    "org.freedesktop.DBus",  /* if */
 491                                                                                    "NameOwnerChanged",      /* signal */
 492                                                                                    "/org/freedesktop/DBus", /* path */
 493                                                                                    client->name,
 494                                                                                    G_DBUS_SIGNAL_FLAGS_NONE,
 495                                                                                    on_name_owner_changed,
 496                                                                                    GUINT_TO_POINTER (client->id),
 497                                                                                    NULL);
 498
 499   if (client->flags & G_BUS_NAME_WATCHER_FLAGS_AUTO_START)
 500     {
 501       g_dbus_connection_call (client->connection,
 502                               "org.freedesktop.DBus",  /* bus name */
 503                               "/org/freedesktop/DBus", /* object path */
 504                               "org.freedesktop.DBus",  /* interface name */
 505                               "StartServiceByName",    /* method name */
 506                               g_variant_new ("(su)", client->name, 0),
 507                               G_VARIANT_TYPE ("(u)"),
 508                               G_DBUS_CALL_FLAGS_NONE,
 509                               -1,
 510                               NULL,
 511                               (GAsyncReadyCallback) start_service_by_name_cb,
 512                               client_ref (client));
 513     }
 514   else
 515     {
 516       /* check owner */
 517       invoke_get_name_owner (client);
 518     }
 519 }
 520
 521
 522 static void
 523 connection_get_cb (GObject      *source_object,
 524                    GAsyncResult *res,
 525                    gpointer      user_data)
 526 {
 527   Client *client = user_data;
 528
 529   client->connection = g_bus_get_finish (res, NULL);
 530   if (client->connection == NULL)
 531     {
 532       call_vanished_handler (client, FALSE);
 533       goto out;
 534     }
 535
 536   has_connection (client);
 537
 538  out:
 539   client_unref (client);
 540 }
 541
 542 /* ---------------------------------------------------------------------------------------------------- */
 543
 544 /**
 545  * g_bus_watch_name:
 546  * @bus_type: The type of bus to watch a name on.
 547  * @name: The name (well-known or unique) to watch.
 548  * @flags: Flags from the #GBusNameWatcherFlags enumeration.
 549  * @name_appeared_handler: (nullable): Handler to invoke when @name is known to exist or %NULL.
 550  * @name_vanished_handler: (nullable): Handler to invoke when @name is known to not exist or %NULL.
 551  * @user_data: User data to pass to handlers.
 552  * @user_data_free_func: (nullable): Function for freeing @user_data or %NULL.
 553  *
 554  * Starts watching @name on the bus specified by @bus_type and calls
 555  * @name_appeared_handler and @name_vanished_handler when the name is
 556  * known to have a owner respectively known to lose its
 557  * owner. Callbacks will be invoked in the
 558  * [thread-default main context][g-main-context-push-thread-default]
 559  * of the thread you are calling this function from.
 560  *
 561  * You are guaranteed that one of the handlers will be invoked after
 562  * calling this function. When you are done watching the name, just
 563  * call g_bus_unwatch_name() with the watcher id this function
 564  * returns.
 565  *
 566  * If the name vanishes or appears (for example the application owning
 567  * the name could restart), the handlers are also invoked. If the
 568  * #GDBusConnection that is used for watching the name disconnects, then
 569  * @name_vanished_handler is invoked since it is no longer
 570  * possible to access the name.
 571  *
 572  * Another guarantee is that invocations of @name_appeared_handler
 573  * and @name_vanished_handler are guaranteed to alternate; that
 574  * is, if @name_appeared_handler is invoked then you are
 575  * guaranteed that the next time one of the handlers is invoked, it
 576  * will be @name_vanished_handler. The reverse is also true.
 577  *
 578  * This behavior makes it very simple to write applications that want
 579  * to take action when a certain [name exists][gdbus-watching-names].
 580  * Basically, the application should create object proxies in
 581  * @name_appeared_handler and destroy them again (if any) in
 582  * @name_vanished_handler.
 583  *
 584  * Returns: An identifier (never 0) that an be used with
 585  * g_bus_unwatch_name() to stop watching the name.
 586  *
 587  * Since: 2.26
 588  */
 589 guint
 590 g_bus_watch_name (GBusType                  bus_type,
 591                   const gchar              *name,
 592                   GBusNameWatcherFlags      flags,
 593                   GBusNameAppearedCallback  name_appeared_handler,
 594                   GBusNameVanishedCallback  name_vanished_handler,
 595                   gpointer                  user_data,
 596                   GDestroyNotify            user_data_free_func)
 597 {
 598   Client *client;
 599
 600   g_return_val_if_fail (g_dbus_is_name (name), 0);
 601
 602   G_LOCK (lock);
 603
 604   client = g_new0 (Client, 1);
 605   client->ref_count = 1;
 606   client->id = g_atomic_int_add (&next_global_id, 1); /* TODO: uh oh, handle overflow */
 607   client->name = g_strdup (name);
 608   client->flags = flags;
 609   client->name_appeared_handler = name_appeared_handler;
 610   client->name_vanished_handler = name_vanished_handler;
 611   client->user_data = user_data;
 612   client->user_data_free_func = user_data_free_func;
 613   client->main_context = g_main_context_ref_thread_default ();
 614
 615   if (map_id_to_client == NULL)
 616     {
 617       map_id_to_client = g_hash_table_new (g_direct_hash, g_direct_equal);
 618     }
 619   g_hash_table_insert (map_id_to_client,
 620                        GUINT_TO_POINTER (client->id),
 621                        client);
 622
 623   g_bus_get (bus_type,
 624              NULL,
 625              connection_get_cb,
 626              client_ref (client));
 627
 628   G_UNLOCK (lock);
 629
 630   return client->id;
 631 }
 632
 633 /**
 634  * g_bus_watch_name_on_connection:
 635  * @connection: A #GDBusConnection.
 636  * @name: The name (well-known or unique) to watch.
 637  * @flags: Flags from the #GBusNameWatcherFlags enumeration.
 638  * @name_appeared_handler: (nullable): Handler to invoke when @name is known to exist or %NULL.
 639  * @name_vanished_handler: (nullable): Handler to invoke when @name is known to not exist or %NULL.
 640  * @user_data: User data to pass to handlers.
 641  * @user_data_free_func: (nullable): Function for freeing @user_data or %NULL.
 642  *
 643  * Like g_bus_watch_name() but takes a #GDBusConnection instead of a
 644  * #GBusType.
 645  *
 646  * Returns: An identifier (never 0) that an be used with
 647  * g_bus_unwatch_name() to stop watching the name.
 648  *
 649  * Since: 2.26
 650  */
 651 guint g_bus_watch_name_on_connection (GDBusConnection          *connection,
 652                                       const gchar              *name,
 653                                       GBusNameWatcherFlags      flags,
 654                                       GBusNameAppearedCallback  name_appeared_handler,
 655                                       GBusNameVanishedCallback  name_vanished_handler,
 656                                       gpointer                  user_data,
 657                                       GDestroyNotify            user_data_free_func)
 658 {
 659   Client *client;
 660
 661   g_return_val_if_fail (G_IS_DBUS_CONNECTION (connection), 0);
 662   g_return_val_if_fail (g_dbus_is_name (name), 0);
 663
 664   G_LOCK (lock);
 665
 666   client = g_new0 (Client, 1);
 667   client->ref_count = 1;
 668   client->id = g_atomic_int_add (&next_global_id, 1); /* TODO: uh oh, handle overflow */
 669   client->name = g_strdup (name);
 670   client->flags = flags;
 671   client->name_appeared_handler = name_appeared_handler;
 672   client->name_vanished_handler = name_vanished_handler;
 673   client->user_data = user_data;
 674   client->user_data_free_func = user_data_free_func;
 675   client->main_context = g_main_context_ref_thread_default ();
 676
 677   if (map_id_to_client == NULL)
 678     map_id_to_client = g_hash_table_new (g_direct_hash, g_direct_equal);
 679
 680   g_hash_table_insert (map_id_to_client,
 681                        GUINT_TO_POINTER (client->id),
 682                        client);
 683
 684   client->connection = g_object_ref (connection);
 685   G_UNLOCK (lock);
 686
 687   has_connection (client);
 688
 689   return client->id;
 690 }
 691
 692 typedef struct {
 693   GClosure *name_appeared_closure;
 694   GClosure *name_vanished_closure;
 695 } WatchNameData;
 696
 697 static WatchNameData *
 698 watch_name_data_new (GClosure *name_appeared_closure,
 699                      GClosure *name_vanished_closure)
 700 {
 701   WatchNameData *data;
 702
 703   data = g_new0 (WatchNameData, 1);
 704
 705   if (name_appeared_closure != NULL)
 706     {
 707       data->name_appeared_closure = g_closure_ref (name_appeared_closure);
 708       g_closure_sink (name_appeared_closure);
 709       if (G_CLOSURE_NEEDS_MARSHAL (name_appeared_closure))
 710         g_closure_set_marshal (name_appeared_closure, g_cclosure_marshal_generic);
 711     }
 712
 713   if (name_vanished_closure != NULL)
 714     {
 715       data->name_vanished_closure = g_closure_ref (name_vanished_closure);
 716       g_closure_sink (name_vanished_closure);
 717       if (G_CLOSURE_NEEDS_MARSHAL (name_vanished_closure))
 718         g_closure_set_marshal (name_vanished_closure, g_cclosure_marshal_generic);
 719     }
 720
 721   return data;
 722 }
 723
 724 static void
 725 watch_with_closures_on_name_appeared (GDBusConnection *connection,
 726                                       const gchar     *name,
 727                                       const gchar     *name_owner,
 728                                       gpointer         user_data)
 729 {
 730   WatchNameData *data = user_data;
 731   GValue params[3] = { G_VALUE_INIT, G_VALUE_INIT, G_VALUE_INIT };
 732
 733   g_value_init (&params[0], G_TYPE_DBUS_CONNECTION);
 734   g_value_set_object (&params[0], connection);
 735
 736   g_value_init (&params[1], G_TYPE_STRING);
 737   g_value_set_string (&params[1], name);
 738
 739   g_value_init (&params[2], G_TYPE_STRING);
 740   g_value_set_string (&params[2], name_owner);
 741
 742   g_closure_invoke (data->name_appeared_closure, NULL, 3, params, NULL);
 743
 744   g_value_unset (params + 0);
 745   g_value_unset (params + 1);
 746   g_value_unset (params + 2);
 747 }
 748
 749 static void
 750 watch_with_closures_on_name_vanished (GDBusConnection *connection,
 751                                       const gchar     *name,
 752                                       gpointer         user_data)
 753 {
 754   WatchNameData *data = user_data;
 755   GValue params[2] = { G_VALUE_INIT, G_VALUE_INIT };
 756
 757   g_value_init (&params[0], G_TYPE_DBUS_CONNECTION);
 758   g_value_set_object (&params[0], connection);
 759
 760   g_value_init (&params[1], G_TYPE_STRING);
 761   g_value_set_string (&params[1], name);
 762
 763   g_closure_invoke (data->name_vanished_closure, NULL, 2, params, NULL);
 764
 765   g_value_unset (params + 0);
 766   g_value_unset (params + 1);
 767 }
 768
 769 static void
 770 bus_watch_name_free_func (gpointer user_data)
 771 {
 772   WatchNameData *data = user_data;
 773
 774   if (data->name_appeared_closure != NULL)
 775     g_closure_unref (data->name_appeared_closure);
 776
 777   if (data->name_vanished_closure != NULL)
 778     g_closure_unref (data->name_vanished_closure);
 779
 780   g_free (data);
 781 }
 782
 783 /**
 784  * g_bus_watch_name_with_closures: (rename-to g_bus_watch_name)
 785  * @bus_type: The type of bus to watch a name on.
 786  * @name: The name (well-known or unique) to watch.
 787  * @flags: Flags from the #GBusNameWatcherFlags enumeration.
 788  * @name_appeared_closure: (nullable): #GClosure to invoke when @name is known
 789  * to exist or %NULL.
 790  * @name_vanished_closure: (nullable): #GClosure to invoke when @name is known
 791  * to not exist or %NULL.
 792  *
 793  * Version of g_bus_watch_name() using closures instead of callbacks for
 794  * easier binding in other languages.
 795  *
 796  * Returns: An identifier (never 0) that an be used with
 797  * g_bus_unwatch_name() to stop watching the name.
 798  *
 799  * Since: 2.26
 800  */
 801 guint
 802 g_bus_watch_name_with_closures (GBusType                 bus_type,
 803                                 const gchar             *name,
 804                                 GBusNameWatcherFlags     flags,
 805                                 GClosure                *name_appeared_closure,
 806                                 GClosure                *name_vanished_closure)
 807 {
 808   return g_bus_watch_name (bus_type,
 809           name,
 810           flags,
 811           name_appeared_closure != NULL ? watch_with_closures_on_name_appeared : NULL,
 812           name_vanished_closure != NULL ? watch_with_closures_on_name_vanished : NULL,
 813           watch_name_data_new (name_appeared_closure, name_vanished_closure),
 814           bus_watch_name_free_func);
 815 }
 816
 817 /**
 818  * g_bus_watch_name_on_connection_with_closures: (rename-to g_bus_watch_name_on_connection)
 819  * @connection: A #GDBusConnection.
 820  * @name: The name (well-known or unique) to watch.
 821  * @flags: Flags from the #GBusNameWatcherFlags enumeration.
 822  * @name_appeared_closure: (nullable): #GClosure to invoke when @name is known
 823  * to exist or %NULL.
 824  * @name_vanished_closure: (nullable): #GClosure to invoke when @name is known
 825  * to not exist or %NULL.
 826  *
 827  * Version of g_bus_watch_name_on_connection() using closures instead of callbacks for
 828  * easier binding in other languages.
 829  *
 830  * Returns: An identifier (never 0) that an be used with
 831  * g_bus_unwatch_name() to stop watching the name.
 832  *
 833  * Since: 2.26
 834  */
 835 guint g_bus_watch_name_on_connection_with_closures (
 836                                       GDBusConnection          *connection,
 837                                       const gchar              *name,
 838                                       GBusNameWatcherFlags      flags,
 839                                       GClosure                 *name_appeared_closure,
 840                                       GClosure                 *name_vanished_closure)
 841 {
 842   return g_bus_watch_name_on_connection (connection,
 843           name,
 844           flags,
 845           name_appeared_closure != NULL ? watch_with_closures_on_name_appeared : NULL,
 846           name_vanished_closure != NULL ? watch_with_closures_on_name_vanished : NULL,
 847           watch_name_data_new (name_appeared_closure, name_vanished_closure),
 848           bus_watch_name_free_func);
 849 }
 850
 851 /**
 852  * g_bus_unwatch_name:
 853  * @watcher_id: An identifier obtained from g_bus_watch_name()
 854  *
 855  * Stops watching a name.
 856  *
 857  * Since: 2.26
 858  */
 859 void
 860 g_bus_unwatch_name (guint watcher_id)
 861 {
 862   Client *client;
 863
 864   g_return_if_fail (watcher_id > 0);
 865
 866   client = NULL;
 867
 868   G_LOCK (lock);
 869   if (watcher_id == 0 ||
 870       map_id_to_client == NULL ||
 871       (client = g_hash_table_lookup (map_id_to_client, GUINT_TO_POINTER (watcher_id))) == NULL)
 872     {
 873       g_warning ("Invalid id %d passed to g_bus_unwatch_name()", watcher_id);
 874       goto out;
 875     }
 876
 877   client->cancelled = TRUE;
 878   g_warn_if_fail (g_hash_table_remove (map_id_to_client, GUINT_TO_POINTER (watcher_id)));
 879
 880  out:
 881   G_UNLOCK (lock);
 882
 883   /* do callback without holding lock */
 884   if (client != NULL)
 885     {
 886       client_unref (client);
 887     }
 888 }