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 /* 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] 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 static void
 253 on_connection_disconnected (GDBusConnection *connection,
 254                             gboolean         remote_peer_vanished,
 255                             GError          *error,
 256                             gpointer         user_data)
 257 {
 258   Client *client = user_data;
 259
 260   if (client->name_owner_changed_subscription_id > 0)
 261     g_dbus_connection_signal_unsubscribe (client->connection, client->name_owner_changed_subscription_id);
 262   if (client->disconnected_signal_handler_id > 0)
 263     g_signal_handler_disconnect (client->connection, client->disconnected_signal_handler_id);
 264   g_object_unref (client->connection);
 265   client->disconnected_signal_handler_id = 0;
 266   client->name_owner_changed_subscription_id = 0;
 267   client->connection = NULL;
 268
 269   call_vanished_handler (client, FALSE);
 270 }
 271
 272 /* ---------------------------------------------------------------------------------------------------- */
 273
 274 static void
 275 on_name_owner_changed (GDBusConnection *connection,
 276                        const gchar      *sender_name,
 277                        const gchar      *object_path,
 278                        const gchar      *interface_name,
 279                        const gchar      *signal_name,
 280                        GVariant         *parameters,
 281                        gpointer          user_data)
 282 {
 283   Client *client = user_data;
 284   const gchar *name;
 285   const gchar *old_owner;
 286   const gchar *new_owner;
 287
 288   if (!client->initialized)
 289     goto out;
 290
 291   if (g_strcmp0 (object_path, "/org/freedesktop/DBus") != 0 ||
 292       g_strcmp0 (interface_name, "org.freedesktop.DBus") != 0 ||
 293       g_strcmp0 (sender_name, "org.freedesktop.DBus") != 0)
 294     goto out;
 295
 296   g_variant_get (parameters,
 297                  "(&s&s&s)",
 298                  &name,
 299                  &old_owner,
 300                  &new_owner);
 301
 302   /* we only care about a specific name */
 303   if (g_strcmp0 (name, client->name) != 0)
 304     goto out;
 305
 306   if ((old_owner != NULL && strlen (old_owner) > 0) && client->name_owner != NULL)
 307     {
 308       g_free (client->name_owner);
 309       client->name_owner = NULL;
 310       call_vanished_handler (client, FALSE);
 311     }
 312
 313   if (new_owner != NULL && strlen (new_owner) > 0)
 314     {
 315       g_warn_if_fail (client->name_owner == NULL);
 316       g_free (client->name_owner);
 317       client->name_owner = g_strdup (new_owner);
 318       call_appeared_handler (client);
 319     }
 320
 321  out:
 322   ;
 323 }
 324
 325 /* ---------------------------------------------------------------------------------------------------- */
 326
 327 static void
 328 get_name_owner_cb (GObject      *source_object,
 329                    GAsyncResult *res,
 330                    gpointer      user_data)
 331 {
 332   Client *client = user_data;
 333   GVariant *result;
 334   const char *name_owner;
 335
 336   name_owner = NULL;
 337   result = NULL;
 338
 339   result = g_dbus_connection_call_finish (client->connection,
 340                                           res,
 341                                           NULL);
 342   if (result != NULL)
 343     {
 344       g_variant_get (result, "(&s)", &name_owner);
 345     }
 346
 347   if (name_owner != NULL)
 348     {
 349       g_warn_if_fail (client->name_owner == NULL);
 350       client->name_owner = g_strdup (name_owner);
 351       call_appeared_handler (client);
 352     }
 353   else
 354     {
 355       call_vanished_handler (client, FALSE);
 356     }
 357
 358   client->initialized = TRUE;
 359
 360   if (result != NULL)
 361     g_variant_unref (result);
 362   client_unref (client);
 363 }
 364
 365 /* ---------------------------------------------------------------------------------------------------- */
 366
 367 static void
 368 invoke_get_name_owner (Client *client)
 369 {
 370   g_dbus_connection_call (client->connection,
 371                           "org.freedesktop.DBus",  /* bus name */
 372                           "/org/freedesktop/DBus", /* object path */
 373                           "org.freedesktop.DBus",  /* interface name */
 374                           "GetNameOwner",          /* method name */
 375                           g_variant_new ("(s)", client->name),
 376                           G_VARIANT_TYPE ("(s)"),
 377                           G_DBUS_CALL_FLAGS_NONE,
 378                           -1,
 379                           NULL,
 380                           (GAsyncReadyCallback) get_name_owner_cb,
 381                           client_ref (client));
 382 }
 383
 384 /* ---------------------------------------------------------------------------------------------------- */
 385
 386 static void
 387 start_service_by_name_cb (GObject      *source_object,
 388                           GAsyncResult *res,
 389                           gpointer      user_data)
 390 {
 391   Client *client = user_data;
 392   GVariant *result;
 393
 394   result = NULL;
 395
 396   result = g_dbus_connection_call_finish (client->connection,
 397                                           res,
 398                                           NULL);
 399   if (result != NULL)
 400     {
 401       guint32 start_service_result;
 402       g_variant_get (result, "(u)", &start_service_result);
 403
 404       if (start_service_result == 1) /* DBUS_START_REPLY_SUCCESS */
 405         {
 406           invoke_get_name_owner (client);
 407         }
 408       else if (start_service_result == 2) /* DBUS_START_REPLY_ALREADY_RUNNING */
 409         {
 410           invoke_get_name_owner (client);
 411         }
 412       else
 413         {
 414           g_warning ("Unexpected reply %d from StartServiceByName() method", start_service_result);
 415           call_vanished_handler (client, FALSE);
 416           client->initialized = TRUE;
 417         }
 418     }
 419   else
 420     {
 421       /* Errors are not unexpected; the bus will reply e.g.
 422        *
 423        *   org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.Epiphany2
 424        *   was not provided by any .service files
 425        *
 426        * This doesn't mean that the name doesn't have an owner, just
 427        * that it's not provided by a .service file. So proceed to
 428        * invoke GetNameOwner().
 429        */
 430       invoke_get_name_owner (client);
 431     }
 432
 433   if (result != NULL)
 434     g_variant_unref (result);
 435   client_unref (client);
 436 }
 437
 438 /* ---------------------------------------------------------------------------------------------------- */
 439
 440 static void
 441 has_connection (Client *client)
 442 {
 443   /* listen for disconnection */
 444   client->disconnected_signal_handler_id = g_signal_connect (client->connection,
 445                                                              "closed",
 446                                                              G_CALLBACK (on_connection_disconnected),
 447                                                              client);
 448
 449   /* start listening to NameOwnerChanged messages immediately */
 450   client->name_owner_changed_subscription_id = g_dbus_connection_signal_subscribe (client->connection,
 451                                                                                    "org.freedesktop.DBus",  /* name */
 452                                                                                    "org.freedesktop.DBus",  /* if */
 453                                                                                    "NameOwnerChanged",      /* signal */
 454                                                                                    "/org/freedesktop/DBus", /* path */
 455                                                                                    client->name,
 456                                                                                    G_DBUS_SIGNAL_FLAGS_NONE,
 457                                                                                    on_name_owner_changed,
 458                                                                                    client,
 459                                                                                    NULL);
 460
 461   if (client->flags & G_BUS_NAME_WATCHER_FLAGS_AUTO_START)
 462     {
 463       g_dbus_connection_call (client->connection,
 464                               "org.freedesktop.DBus",  /* bus name */
 465                               "/org/freedesktop/DBus", /* object path */
 466                               "org.freedesktop.DBus",  /* interface name */
 467                               "StartServiceByName",    /* method name */
 468                               g_variant_new ("(su)", client->name, 0),
 469                               G_VARIANT_TYPE ("(u)"),
 470                               G_DBUS_CALL_FLAGS_NONE,
 471                               -1,
 472                               NULL,
 473                               (GAsyncReadyCallback) start_service_by_name_cb,
 474                               client_ref (client));
 475     }
 476   else
 477     {
 478       /* check owner */
 479       invoke_get_name_owner (client);
 480     }
 481 }
 482
 483
 484 static void
 485 connection_get_cb (GObject      *source_object,
 486                    GAsyncResult *res,
 487                    gpointer      user_data)
 488 {
 489   Client *client = user_data;
 490
 491   client->connection = g_bus_get_finish (res, NULL);
 492   if (client->connection == NULL)
 493     {
 494       call_vanished_handler (client, FALSE);
 495       goto out;
 496     }
 497
 498   has_connection (client);
 499
 500  out:
 501   client_unref (client);
 502 }
 503
 504 /* ---------------------------------------------------------------------------------------------------- */
 505
 506 /**
 507  * g_bus_watch_name:
 508  * @bus_type: The type of bus to watch a name on.
 509  * @name: The name (well-known or unique) to watch.
 510  * @flags: Flags from the #GBusNameWatcherFlags enumeration.
 511  * @name_appeared_handler: (nullable): Handler to invoke when @name is known to exist or %NULL.
 512  * @name_vanished_handler: (nullable): Handler to invoke when @name is known to not exist or %NULL.
 513  * @user_data: User data to pass to handlers.
 514  * @user_data_free_func: (nullable): Function for freeing @user_data or %NULL.
 515  *
 516  * Starts watching @name on the bus specified by @bus_type and calls
 517  * @name_appeared_handler and @name_vanished_handler when the name is
 518  * known to have a owner respectively known to lose its
 519  * owner. Callbacks will be invoked in the
 520  * [thread-default main context][g-main-context-push-thread-default]
 521  * of the thread you are calling this function from.
 522  *
 523  * You are guaranteed that one of the handlers will be invoked after
 524  * calling this function. When you are done watching the name, just
 525  * call g_bus_unwatch_name() with the watcher id this function
 526  * returns.
 527  *
 528  * If the name vanishes or appears (for example the application owning
 529  * the name could restart), the handlers are also invoked. If the
 530  * #GDBusConnection that is used for watching the name disconnects, then
 531  * @name_vanished_handler is invoked since it is no longer
 532  * possible to access the name.
 533  *
 534  * Another guarantee is that invocations of @name_appeared_handler
 535  * and @name_vanished_handler are guaranteed to alternate; that
 536  * is, if @name_appeared_handler is invoked then you are
 537  * guaranteed that the next time one of the handlers is invoked, it
 538  * will be @name_vanished_handler. The reverse is also true.
 539  *
 540  * This behavior makes it very simple to write applications that want
 541  * to take action when a certain [name exists][gdbus-watching-names].
 542  * Basically, the application should create object proxies in
 543  * @name_appeared_handler and destroy them again (if any) in
 544  * @name_vanished_handler.
 545  *
 546  * Returns: An identifier (never 0) that an be used with
 547  * g_bus_unwatch_name() to stop watching the name.
 548  *
 549  * Since: 2.26
 550  */
 551 guint
 552 g_bus_watch_name (GBusType                  bus_type,
 553                   const gchar              *name,
 554                   GBusNameWatcherFlags      flags,
 555                   GBusNameAppearedCallback  name_appeared_handler,
 556                   GBusNameVanishedCallback  name_vanished_handler,
 557                   gpointer                  user_data,
 558                   GDestroyNotify            user_data_free_func)
 559 {
 560   Client *client;
 561
 562   g_return_val_if_fail (g_dbus_is_name (name), 0);
 563
 564   G_LOCK (lock);
 565
 566   client = g_new0 (Client, 1);
 567   client->ref_count = 1;
 568   client->id = g_atomic_int_add (&next_global_id, 1); /* TODO: uh oh, handle overflow */
 569   client->name = g_strdup (name);
 570   client->flags = flags;
 571   client->name_appeared_handler = name_appeared_handler;
 572   client->name_vanished_handler = name_vanished_handler;
 573   client->user_data = user_data;
 574   client->user_data_free_func = user_data_free_func;
 575   client->main_context = g_main_context_ref_thread_default ();
 576
 577   if (map_id_to_client == NULL)
 578     {
 579       map_id_to_client = g_hash_table_new (g_direct_hash, g_direct_equal);
 580     }
 581   g_hash_table_insert (map_id_to_client,
 582                        GUINT_TO_POINTER (client->id),
 583                        client);
 584
 585   g_bus_get (bus_type,
 586              NULL,
 587              connection_get_cb,
 588              client_ref (client));
 589
 590   G_UNLOCK (lock);
 591
 592   return client->id;
 593 }
 594
 595 /**
 596  * g_bus_watch_name_on_connection:
 597  * @connection: A #GDBusConnection.
 598  * @name: The name (well-known or unique) to watch.
 599  * @flags: Flags from the #GBusNameWatcherFlags enumeration.
 600  * @name_appeared_handler: (nullable): Handler to invoke when @name is known to exist or %NULL.
 601  * @name_vanished_handler: (nullable): Handler to invoke when @name is known to not exist or %NULL.
 602  * @user_data: User data to pass to handlers.
 603  * @user_data_free_func: (nullable): Function for freeing @user_data or %NULL.
 604  *
 605  * Like g_bus_watch_name() but takes a #GDBusConnection instead of a
 606  * #GBusType.
 607  *
 608  * Returns: An identifier (never 0) that an be used with
 609  * g_bus_unwatch_name() to stop watching the name.
 610  *
 611  * Since: 2.26
 612  */
 613 guint g_bus_watch_name_on_connection (GDBusConnection          *connection,
 614                                       const gchar              *name,
 615                                       GBusNameWatcherFlags      flags,
 616                                       GBusNameAppearedCallback  name_appeared_handler,
 617                                       GBusNameVanishedCallback  name_vanished_handler,
 618                                       gpointer                  user_data,
 619                                       GDestroyNotify            user_data_free_func)
 620 {
 621   Client *client;
 622
 623   g_return_val_if_fail (G_IS_DBUS_CONNECTION (connection), 0);
 624   g_return_val_if_fail (g_dbus_is_name (name), 0);
 625
 626   G_LOCK (lock);
 627
 628   client = g_new0 (Client, 1);
 629   client->ref_count = 1;
 630   client->id = g_atomic_int_add (&next_global_id, 1); /* TODO: uh oh, handle overflow */
 631   client->name = g_strdup (name);
 632   client->flags = flags;
 633   client->name_appeared_handler = name_appeared_handler;
 634   client->name_vanished_handler = name_vanished_handler;
 635   client->user_data = user_data;
 636   client->user_data_free_func = user_data_free_func;
 637   client->main_context = g_main_context_ref_thread_default ();
 638
 639   if (map_id_to_client == NULL)
 640     map_id_to_client = g_hash_table_new (g_direct_hash, g_direct_equal);
 641
 642   g_hash_table_insert (map_id_to_client,
 643                        GUINT_TO_POINTER (client->id),
 644                        client);
 645
 646   client->connection = g_object_ref (connection);
 647   G_UNLOCK (lock);
 648
 649   has_connection (client);
 650
 651   return client->id;
 652 }
 653
 654 typedef struct {
 655   GClosure *name_appeared_closure;
 656   GClosure *name_vanished_closure;
 657 } WatchNameData;
 658
 659 static WatchNameData *
 660 watch_name_data_new (GClosure *name_appeared_closure,
 661                      GClosure *name_vanished_closure)
 662 {
 663   WatchNameData *data;
 664
 665   data = g_new0 (WatchNameData, 1);
 666
 667   if (name_appeared_closure != NULL)
 668     {
 669       data->name_appeared_closure = g_closure_ref (name_appeared_closure);
 670       g_closure_sink (name_appeared_closure);
 671       if (G_CLOSURE_NEEDS_MARSHAL (name_appeared_closure))
 672         g_closure_set_marshal (name_appeared_closure, g_cclosure_marshal_generic);
 673     }
 674
 675   if (name_vanished_closure != NULL)
 676     {
 677       data->name_vanished_closure = g_closure_ref (name_vanished_closure);
 678       g_closure_sink (name_vanished_closure);
 679       if (G_CLOSURE_NEEDS_MARSHAL (name_vanished_closure))
 680         g_closure_set_marshal (name_vanished_closure, g_cclosure_marshal_generic);
 681     }
 682
 683   return data;
 684 }
 685
 686 static void
 687 watch_with_closures_on_name_appeared (GDBusConnection *connection,
 688                                       const gchar     *name,
 689                                       const gchar     *name_owner,
 690                                       gpointer         user_data)
 691 {
 692   WatchNameData *data = user_data;
 693   GValue params[3] = { G_VALUE_INIT, G_VALUE_INIT, G_VALUE_INIT };
 694
 695   g_value_init (&params[0], G_TYPE_DBUS_CONNECTION);
 696   g_value_set_object (&params[0], connection);
 697
 698   g_value_init (&params[1], G_TYPE_STRING);
 699   g_value_set_string (&params[1], name);
 700
 701   g_value_init (&params[2], G_TYPE_STRING);
 702   g_value_set_string (&params[2], name_owner);
 703
 704   g_closure_invoke (data->name_appeared_closure, NULL, 3, params, NULL);
 705
 706   g_value_unset (params + 0);
 707   g_value_unset (params + 1);
 708   g_value_unset (params + 2);
 709 }
 710
 711 static void
 712 watch_with_closures_on_name_vanished (GDBusConnection *connection,
 713                                       const gchar     *name,
 714                                       gpointer         user_data)
 715 {
 716   WatchNameData *data = user_data;
 717   GValue params[2] = { G_VALUE_INIT, G_VALUE_INIT };
 718
 719   g_value_init (&params[0], G_TYPE_DBUS_CONNECTION);
 720   g_value_set_object (&params[0], connection);
 721
 722   g_value_init (&params[1], G_TYPE_STRING);
 723   g_value_set_string (&params[1], name);
 724
 725   g_closure_invoke (data->name_vanished_closure, NULL, 2, params, NULL);
 726
 727   g_value_unset (params + 0);
 728   g_value_unset (params + 1);
 729 }
 730
 731 static void
 732 bus_watch_name_free_func (gpointer user_data)
 733 {
 734   WatchNameData *data = user_data;
 735
 736   if (data->name_appeared_closure != NULL)
 737     g_closure_unref (data->name_appeared_closure);
 738
 739   if (data->name_vanished_closure != NULL)
 740     g_closure_unref (data->name_vanished_closure);
 741
 742   g_free (data);
 743 }
 744
 745 /**
 746  * g_bus_watch_name_with_closures: (rename-to g_bus_watch_name)
 747  * @bus_type: The type of bus to watch a name on.
 748  * @name: The name (well-known or unique) to watch.
 749  * @flags: Flags from the #GBusNameWatcherFlags enumeration.
 750  * @name_appeared_closure: (nullable): #GClosure to invoke when @name is known
 751  * to exist or %NULL.
 752  * @name_vanished_closure: (nullable): #GClosure to invoke when @name is known
 753  * to not exist or %NULL.
 754  *
 755  * Version of g_bus_watch_name() using closures instead of callbacks for
 756  * easier binding in other languages.
 757  *
 758  * Returns: An identifier (never 0) that an be used with
 759  * g_bus_unwatch_name() to stop watching the name.
 760  *
 761  * Since: 2.26
 762  */
 763 guint
 764 g_bus_watch_name_with_closures (GBusType                 bus_type,
 765                                 const gchar             *name,
 766                                 GBusNameWatcherFlags     flags,
 767                                 GClosure                *name_appeared_closure,
 768                                 GClosure                *name_vanished_closure)
 769 {
 770   return g_bus_watch_name (bus_type,
 771           name,
 772           flags,
 773           name_appeared_closure != NULL ? watch_with_closures_on_name_appeared : NULL,
 774           name_vanished_closure != NULL ? watch_with_closures_on_name_vanished : NULL,
 775           watch_name_data_new (name_appeared_closure, name_vanished_closure),
 776           bus_watch_name_free_func);
 777 }
 778
 779 /**
 780  * g_bus_watch_name_on_connection_with_closures: (rename-to g_bus_watch_name_on_connection)
 781  * @connection: A #GDBusConnection.
 782  * @name: The name (well-known or unique) to watch.
 783  * @flags: Flags from the #GBusNameWatcherFlags enumeration.
 784  * @name_appeared_closure: (nullable): #GClosure to invoke when @name is known
 785  * to exist or %NULL.
 786  * @name_vanished_closure: (nullable): #GClosure to invoke when @name is known
 787  * to not exist or %NULL.
 788  *
 789  * Version of g_bus_watch_name_on_connection() using closures instead of callbacks for
 790  * easier binding in other languages.
 791  *
 792  * Returns: An identifier (never 0) that an be used with
 793  * g_bus_unwatch_name() to stop watching the name.
 794  *
 795  * Since: 2.26
 796  */
 797 guint g_bus_watch_name_on_connection_with_closures (
 798                                       GDBusConnection          *connection,
 799                                       const gchar              *name,
 800                                       GBusNameWatcherFlags      flags,
 801                                       GClosure                 *name_appeared_closure,
 802                                       GClosure                 *name_vanished_closure)
 803 {
 804   return g_bus_watch_name_on_connection (connection,
 805           name,
 806           flags,
 807           name_appeared_closure != NULL ? watch_with_closures_on_name_appeared : NULL,
 808           name_vanished_closure != NULL ? watch_with_closures_on_name_vanished : NULL,
 809           watch_name_data_new (name_appeared_closure, name_vanished_closure),
 810           bus_watch_name_free_func);
 811 }
 812
 813 /**
 814  * g_bus_unwatch_name:
 815  * @watcher_id: An identifier obtained from g_bus_watch_name()
 816  *
 817  * Stops watching a name.
 818  *
 819  * Since: 2.26
 820  */
 821 void
 822 g_bus_unwatch_name (guint watcher_id)
 823 {
 824   Client *client;
 825
 826   g_return_if_fail (watcher_id > 0);
 827
 828   client = NULL;
 829
 830   G_LOCK (lock);
 831   if (watcher_id == 0 ||
 832       map_id_to_client == NULL ||
 833       (client = g_hash_table_lookup (map_id_to_client, GUINT_TO_POINTER (watcher_id))) == NULL)
 834     {
 835       g_warning ("Invalid id %d passed to g_bus_unwatch_name()", watcher_id);
 836       goto out;
 837     }
 838
 839   client->cancelled = TRUE;
 840   g_warn_if_fail (g_hash_table_remove (map_id_to_client, GUINT_TO_POINTER (watcher_id)));
 841
 842  out:
 843   G_UNLOCK (lock);
 844
 845   /* do callback without holding lock */
 846   if (client != NULL)
 847     {
 848       client_unref (client);
 849     }
 850 }