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