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glib/gio/gdbusnameowning.c
Philip Withnall a434bfbb3d gdbusnameowning: Fix race between connection shutdown and NameLost 
As with all D-Bus signal subscriptions, it’s possible for a signal
callback to be invoked in one thread (T1) while another thread (T2) is
unsubscribing from that signal. In this case, T1 is the main thread, and
T2 is the D-Bus connection worker thread which is unsubscribing all
signals as it’s in the process of closing.

Due to this possibility, all `user_data` for signal callbacks needs to
be referenced outside the lifecycle of the code which
subscribes/unsubscribes the signal. In other words, it’s not safe to
subscribe to a signal, store the subscription ID in a struct,
unsubscribe from the signal when freeing the struct, and dereference the
struct in the signal callback. The data passed to the signal callback
has to have its own strong reference.

Instead, it’s safe to subscribe to a signal and add a strong reference
to the struct, store the subscription ID in that struct, and unsubscribe
from the signal when the last external reference to your struct is
dropped. That unsubscription should break the refcount cycle between the
signal connection and the struct, and allow the struct to be completely
freed. Only with that approach is it safe to dereference the struct in
the signal callback, if there’s any possibility that the signal might be
unsubscribed from a separate thread.

The tests need specific additional main loop cycles to completely emit
the NameLost signal callback. Ideally they need refactoring, but this
will do (1000 test cycles passed).

Signed-off-by: Philip Withnall <withnall@endlessm.com>

Fixes: #978
2020-01-20 15:13:52 +00:00

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/* GDBus - GLib D-Bus Library
*
* Copyright (C) 2008-2010 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
*
* Author: David Zeuthen <davidz@redhat.com>
*/
#include "config.h"
#include <stdlib.h>
#include "gdbusutils.h"
#include "gdbusnameowning.h"
#include "gdbuserror.h"
#include "gdbusprivate.h"
#include "gdbusconnection.h"
#include "glibintl.h"
/**
* SECTION:gdbusnameowning
* @title: Owning Bus Names
* @short_description: Simple API for owning bus names
* @include: gio/gio.h
*
* Convenience API for owning bus names.
*
* A simple example for owning a name can be found in
* [gdbus-example-own-name.c](https://git.gnome.org/browse/glib/tree/gio/tests/gdbus-example-own-name.c)
*/
G_LOCK_DEFINE_STATIC (lock);
/* ---------------------------------------------------------------------------------------------------- */
typedef enum
{
PREVIOUS_CALL_NONE = 0,
PREVIOUS_CALL_ACQUIRED,
PREVIOUS_CALL_LOST,
} PreviousCall;
typedef struct
{
volatile gint ref_count;
guint id;
GBusNameOwnerFlags flags;
gchar *name;
GBusAcquiredCallback bus_acquired_handler;
GBusNameAcquiredCallback name_acquired_handler;
GBusNameLostCallback name_lost_handler;
gpointer user_data;
GDestroyNotify user_data_free_func;
GMainContext *main_context;
PreviousCall previous_call;
GDBusConnection *connection;
gulong disconnected_signal_handler_id;
guint name_acquired_subscription_id;
guint name_lost_subscription_id;
volatile gboolean cancelled; /* must hold lock when reading or modifying */
gboolean needs_release;
} Client;
static guint next_global_id = 1;
static GHashTable *map_id_to_client = NULL;
static Client *
client_ref (Client *client)
{
g_atomic_int_inc (&client->ref_count);
return client;
}
static void
client_unref (Client *client)
{
if (g_atomic_int_dec_and_test (&client->ref_count))
{
if (client->connection != NULL)
{
if (client->disconnected_signal_handler_id > 0)
g_signal_handler_disconnect (client->connection, client->disconnected_signal_handler_id);
if (client->name_acquired_subscription_id > 0)
g_dbus_connection_signal_unsubscribe (client->connection, client->name_acquired_subscription_id);
if (client->name_lost_subscription_id > 0)
g_dbus_connection_signal_unsubscribe (client->connection, client->name_lost_subscription_id);
g_object_unref (client->connection);
}
g_main_context_unref (client->main_context);
g_free (client->name);
if (client->user_data_free_func != NULL)
client->user_data_free_func (client->user_data);
g_free (client);
}
}
/* ---------------------------------------------------------------------------------------------------- */
typedef enum
{
CALL_TYPE_NAME_ACQUIRED,
CALL_TYPE_NAME_LOST
} CallType;
typedef struct
{
Client *client;
/* keep this separate because client->connection may
* be set to NULL after scheduling the call
*/
GDBusConnection *connection;
/* set to TRUE to call acquired */
CallType call_type;
} CallHandlerData;
static void
call_handler_data_free (CallHandlerData *data)
{
if (data->connection != NULL)
g_object_unref (data->connection);
client_unref (data->client);
g_free (data);
}
static void
actually_do_call (Client *client, GDBusConnection *connection, CallType call_type)
{
switch (call_type)
{
case CALL_TYPE_NAME_ACQUIRED:
if (client->name_acquired_handler != NULL)
{
client->name_acquired_handler (connection,
client->name,
client->user_data);
}
break;
case CALL_TYPE_NAME_LOST:
if (client->name_lost_handler != NULL)
{
client->name_lost_handler (connection,
client->name,
client->user_data);
}
break;
default:
g_assert_not_reached ();
break;
}
}
static gboolean
call_in_idle_cb (gpointer _data)
{
CallHandlerData *data = _data;
actually_do_call (data->client, data->connection, data->call_type);
return FALSE;
}
static void
schedule_call_in_idle (Client *client, CallType call_type)
{
CallHandlerData *data;
GSource *idle_source;
data = g_new0 (CallHandlerData, 1);
data->client = client_ref (client);
data->connection = client->connection != NULL ? g_object_ref (client->connection) : NULL;
data->call_type = call_type;
idle_source = g_idle_source_new ();
g_source_set_priority (idle_source, G_PRIORITY_HIGH);
g_source_set_callback (idle_source,
call_in_idle_cb,
data,
(GDestroyNotify) call_handler_data_free);
g_source_set_name (idle_source, "[gio, gdbusnameowning.c] call_in_idle_cb");
g_source_attach (idle_source, client->main_context);
g_source_unref (idle_source);
}
static void
do_call (Client *client, CallType call_type)
{
GMainContext *current_context;
/* only schedule in idle if we're not in the right thread */
current_context = g_main_context_ref_thread_default ();
if (current_context != client->main_context)
schedule_call_in_idle (client, call_type);
else
actually_do_call (client, client->connection, call_type);
g_main_context_unref (current_context);
}
static void
call_acquired_handler (Client *client)
{
G_LOCK (lock);
if (client->previous_call != PREVIOUS_CALL_ACQUIRED)
{
client->previous_call = PREVIOUS_CALL_ACQUIRED;
if (!client->cancelled)
{
G_UNLOCK (lock);
do_call (client, CALL_TYPE_NAME_ACQUIRED);
goto out;
}
}
G_UNLOCK (lock);
out:
;
}
static void
call_lost_handler (Client *client)
{
G_LOCK (lock);
if (client->previous_call != PREVIOUS_CALL_LOST)
{
client->previous_call = PREVIOUS_CALL_LOST;
if (!client->cancelled)
{
G_UNLOCK (lock);
do_call (client, CALL_TYPE_NAME_LOST);
goto out;
}
}
G_UNLOCK (lock);
out:
;
}
/* ---------------------------------------------------------------------------------------------------- */
static void
on_name_lost_or_acquired (GDBusConnection *connection,
const gchar *sender_name,
const gchar *object_path,
const gchar *interface_name,
const gchar *signal_name,
GVariant *parameters,
gpointer user_data)
{
Client *client = user_data;
const gchar *name;
if (g_strcmp0 (object_path, "/org/freedesktop/DBus") != 0 ||
g_strcmp0 (interface_name, "org.freedesktop.DBus") != 0 ||
g_strcmp0 (sender_name, "org.freedesktop.DBus") != 0)
goto out;
if (!g_variant_is_of_type (parameters, G_VARIANT_TYPE ("(s)")))
{
g_warning ("%s signal had unexpected signature %s", signal_name,
g_variant_get_type_string (parameters));
goto out;
}
if (g_strcmp0 (signal_name, "NameLost") == 0)
{
g_variant_get (parameters, "(&s)", &name);
if (g_strcmp0 (name, client->name) == 0)
{
call_lost_handler (client);
}
}
else if (g_strcmp0 (signal_name, "NameAcquired") == 0)
{
g_variant_get (parameters, "(&s)", &name);
if (g_strcmp0 (name, client->name) == 0)
{
call_acquired_handler (client);
}
}
out:
;
}
/* ---------------------------------------------------------------------------------------------------- */
static void
request_name_cb (GObject *source_object,
GAsyncResult *res,
gpointer user_data)
{
Client *client = user_data;
GVariant *result;
guint32 request_name_reply;
gboolean subscribe;
request_name_reply = 0;
result = NULL;
/* don't use client->connection - it may be NULL already */
result = g_dbus_connection_call_finish (G_DBUS_CONNECTION (source_object),
res,
NULL);
if (result != NULL)
{
g_variant_get (result, "(u)", &request_name_reply);
g_variant_unref (result);
}
subscribe = FALSE;
switch (request_name_reply)
{
case 1: /* DBUS_REQUEST_NAME_REPLY_PRIMARY_OWNER */
/* We got the name - now listen for NameLost and NameAcquired */
call_acquired_handler (client);
subscribe = TRUE;
client->needs_release = TRUE;
break;
case 2: /* DBUS_REQUEST_NAME_REPLY_IN_QUEUE */
/* Waiting in line - listen for NameLost and NameAcquired */
call_lost_handler (client);
subscribe = TRUE;
client->needs_release = TRUE;
break;
default:
/* assume we couldn't get the name - explicit fallthrough */
case 3: /* DBUS_REQUEST_NAME_REPLY_EXISTS */
case 4: /* DBUS_REQUEST_NAME_REPLY_ALREADY_OWNER */
/* Some other part of the process is already owning the name */
call_lost_handler (client);
break;
}
if (subscribe)
{
GDBusConnection *connection = NULL;
/* if cancelled, there is no point in subscribing to signals - if not, make sure
* we use a known good Connection object since it may be set to NULL at any point
* after being cancelled
*/
G_LOCK (lock);
if (!client->cancelled)
connection = g_object_ref (client->connection);
G_UNLOCK (lock);
/* Start listening to NameLost and NameAcquired messages. We hold
* references to the Client in the signal closures, since it’s possible
* for a signal to be in-flight after unsubscribing the signal handler.
* This creates a reference count cycle, but that’s explicitly broken by
* disconnecting the signal handlers before calling client_unref() in
* g_bus_unown_name(). */
if (connection != NULL)
{
client->name_lost_subscription_id =
g_dbus_connection_signal_subscribe (connection,
"org.freedesktop.DBus",
"org.freedesktop.DBus",
"NameLost",
"/org/freedesktop/DBus",
client->name,
G_DBUS_SIGNAL_FLAGS_NONE,
on_name_lost_or_acquired,
client_ref (client),
(GDestroyNotify) client_unref);
client->name_acquired_subscription_id =
g_dbus_connection_signal_subscribe (connection,
"org.freedesktop.DBus",
"org.freedesktop.DBus",
"NameAcquired",
"/org/freedesktop/DBus",
client->name,
G_DBUS_SIGNAL_FLAGS_NONE,
on_name_lost_or_acquired,
client_ref (client),
(GDestroyNotify) client_unref);
g_object_unref (connection);
}
}
client_unref (client);
}
/* ---------------------------------------------------------------------------------------------------- */
static void
on_connection_disconnected (GDBusConnection *connection,
gboolean remote_peer_vanished,
GError *error,
gpointer user_data)
{
Client *client = user_data;
if (client->disconnected_signal_handler_id > 0)
g_signal_handler_disconnect (client->connection, client->disconnected_signal_handler_id);
if (client->name_acquired_subscription_id > 0)
g_dbus_connection_signal_unsubscribe (client->connection, client->name_acquired_subscription_id);
if (client->name_lost_subscription_id > 0)
g_dbus_connection_signal_unsubscribe (client->connection, client->name_lost_subscription_id);
g_object_unref (client->connection);
client->disconnected_signal_handler_id = 0;
client->name_acquired_subscription_id = 0;
client->name_lost_subscription_id = 0;
client->connection = NULL;
call_lost_handler (client);
}
/* ---------------------------------------------------------------------------------------------------- */
static void
has_connection (Client *client)
{
/* listen for disconnection */
client->disconnected_signal_handler_id = g_signal_connect (client->connection,
"closed",
G_CALLBACK (on_connection_disconnected),
client);
/* attempt to acquire the name */
g_dbus_connection_call (client->connection,
"org.freedesktop.DBus", /* bus name */
"/org/freedesktop/DBus", /* object path */
"org.freedesktop.DBus", /* interface name */
"RequestName", /* method name */
g_variant_new ("(su)",
client->name,
client->flags),
G_VARIANT_TYPE ("(u)"),
G_DBUS_CALL_FLAGS_NONE,
-1,
NULL,
(GAsyncReadyCallback) request_name_cb,
client_ref (client));
}
static void
connection_get_cb (GObject *source_object,
GAsyncResult *res,
gpointer user_data)
{
Client *client = user_data;
/* must not do anything if already cancelled */
G_LOCK (lock);
if (client->cancelled)
{
G_UNLOCK (lock);
goto out;
}
G_UNLOCK (lock);
client->connection = g_bus_get_finish (res, NULL);
if (client->connection == NULL)
{
call_lost_handler (client);
goto out;
}
/* No need to schedule this in idle as we're already in the thread
* that the user called g_bus_own_name() from. This is because
* g_bus_get() guarantees that.
*
* Also, we need to ensure that the handler is invoked *before*
* we call RequestName(). Otherwise there is a race.
*/
if (client->bus_acquired_handler != NULL)
{
client->bus_acquired_handler (client->connection,
client->name,
client->user_data);
}
has_connection (client);
out:
client_unref (client);
}
/* ---------------------------------------------------------------------------------------------------- */
/**
* g_bus_own_name_on_connection:
* @connection: a #GDBusConnection
* @name: the well-known name to own
* @flags: a set of flags from the #GBusNameOwnerFlags enumeration
* @name_acquired_handler: (nullable): handler to invoke when @name is acquired or %NULL
* @name_lost_handler: (nullable): handler to invoke when @name is lost or %NULL
* @user_data: user data to pass to handlers
* @user_data_free_func: (nullable): function for freeing @user_data or %NULL
*
* Like g_bus_own_name() but takes a #GDBusConnection instead of a
* #GBusType.
*
* Returns: an identifier (never 0) that can be used with
* g_bus_unown_name() to stop owning the name
*
* Since: 2.26
*/
guint
g_bus_own_name_on_connection (GDBusConnection *connection,
const gchar *name,
GBusNameOwnerFlags flags,
GBusNameAcquiredCallback name_acquired_handler,
GBusNameLostCallback name_lost_handler,
gpointer user_data,
GDestroyNotify user_data_free_func)
{
Client *client;
g_return_val_if_fail (G_IS_DBUS_CONNECTION (connection), 0);
g_return_val_if_fail (g_dbus_is_name (name) && !g_dbus_is_unique_name (name), 0);
G_LOCK (lock);
client = g_new0 (Client, 1);
client->ref_count = 1;
client->id = next_global_id++; /* TODO: uh oh, handle overflow */
client->name = g_strdup (name);
client->flags = flags;
client->name_acquired_handler = name_acquired_handler;
client->name_lost_handler = name_lost_handler;
client->user_data = user_data;
client->user_data_free_func = user_data_free_func;
client->main_context = g_main_context_ref_thread_default ();
client->connection = g_object_ref (connection);
if (map_id_to_client == NULL)
{
map_id_to_client = g_hash_table_new (g_direct_hash, g_direct_equal);
}
g_hash_table_insert (map_id_to_client,
GUINT_TO_POINTER (client->id),
client);
G_UNLOCK (lock);
has_connection (client);
return client->id;
}
/**
* g_bus_own_name:
* @bus_type: the type of bus to own a name on
* @name: the well-known name to own
* @flags: a set of flags from the #GBusNameOwnerFlags enumeration
* @bus_acquired_handler: (nullable): handler to invoke when connected to the bus of type @bus_type or %NULL
* @name_acquired_handler: (nullable): handler to invoke when @name is acquired or %NULL
* @name_lost_handler: (nullable): handler to invoke when @name is lost or %NULL
* @user_data: user data to pass to handlers
* @user_data_free_func: (nullable): function for freeing @user_data or %NULL
*
* Starts acquiring @name on the bus specified by @bus_type and calls
* @name_acquired_handler and @name_lost_handler when the name is
* acquired respectively lost. Callbacks will be invoked in the
* [thread-default main context][g-main-context-push-thread-default]
* of the thread you are calling this function from.
*
* You are guaranteed that one of the @name_acquired_handler and @name_lost_handler
* callbacks will be invoked after calling this function - there are three
* possible cases:
*
* - @name_lost_handler with a %NULL connection (if a connection to the bus
* can't be made).
*
* - @bus_acquired_handler then @name_lost_handler (if the name can't be
* obtained)
*
* - @bus_acquired_handler then @name_acquired_handler (if the name was
* obtained).
*
* When you are done owning the name, just call g_bus_unown_name()
* with the owner id this function returns.
*
* If the name is acquired or lost (for example another application
* could acquire the name if you allow replacement or the application
* currently owning the name exits), the handlers are also invoked.
* If the #GDBusConnection that is used for attempting to own the name
* closes, then @name_lost_handler is invoked since it is no longer
* possible for other processes to access the process.
*
* You cannot use g_bus_own_name() several times for the same name (unless
* interleaved with calls to g_bus_unown_name()) - only the first call
* will work.
*
* Another guarantee is that invocations of @name_acquired_handler
* and @name_lost_handler are guaranteed to alternate; that
* is, if @name_acquired_handler is invoked then you are
* guaranteed that the next time one of the handlers is invoked, it
* will be @name_lost_handler. The reverse is also true.
*
* If you plan on exporting objects (using e.g.
* g_dbus_connection_register_object()), note that it is generally too late
* to export the objects in @name_acquired_handler. Instead, you can do this
* in @bus_acquired_handler since you are guaranteed that this will run
* before @name is requested from the bus.
*
* This behavior makes it very simple to write applications that wants
* to [own names][gdbus-owning-names] and export objects.
* Simply register objects to be exported in @bus_acquired_handler and
* unregister the objects (if any) in @name_lost_handler.
*
* Returns: an identifier (never 0) that can be used with
* g_bus_unown_name() to stop owning the name.
*
* Since: 2.26
*/
guint
g_bus_own_name (GBusType bus_type,
const gchar *name,
GBusNameOwnerFlags flags,
GBusAcquiredCallback bus_acquired_handler,
GBusNameAcquiredCallback name_acquired_handler,
GBusNameLostCallback name_lost_handler,
gpointer user_data,
GDestroyNotify user_data_free_func)
{
Client *client;
g_return_val_if_fail (g_dbus_is_name (name) && !g_dbus_is_unique_name (name), 0);
G_LOCK (lock);
client = g_new0 (Client, 1);
client->ref_count = 1;
client->id = next_global_id++; /* TODO: uh oh, handle overflow */
client->name = g_strdup (name);
client->flags = flags;
client->bus_acquired_handler = bus_acquired_handler;
client->name_acquired_handler = name_acquired_handler;
client->name_lost_handler = name_lost_handler;
client->user_data = user_data;
client->user_data_free_func = user_data_free_func;
client->main_context = g_main_context_ref_thread_default ();
if (map_id_to_client == NULL)
{
map_id_to_client = g_hash_table_new (g_direct_hash, g_direct_equal);
}
g_hash_table_insert (map_id_to_client,
GUINT_TO_POINTER (client->id),
client);
g_bus_get (bus_type,
NULL,
connection_get_cb,
client_ref (client));
G_UNLOCK (lock);
return client->id;
}
typedef struct {
GClosure *bus_acquired_closure;
GClosure *name_acquired_closure;
GClosure *name_lost_closure;
} OwnNameData;
static OwnNameData *
own_name_data_new (GClosure *bus_acquired_closure,
GClosure *name_acquired_closure,
GClosure *name_lost_closure)
{
OwnNameData *data;
data = g_new0 (OwnNameData, 1);
if (bus_acquired_closure != NULL)
{
data->bus_acquired_closure = g_closure_ref (bus_acquired_closure);
g_closure_sink (bus_acquired_closure);
if (G_CLOSURE_NEEDS_MARSHAL (bus_acquired_closure))
g_closure_set_marshal (bus_acquired_closure, g_cclosure_marshal_generic);
}
if (name_acquired_closure != NULL)
{
data->name_acquired_closure = g_closure_ref (name_acquired_closure);
g_closure_sink (name_acquired_closure);
if (G_CLOSURE_NEEDS_MARSHAL (name_acquired_closure))
g_closure_set_marshal (name_acquired_closure, g_cclosure_marshal_generic);
}
if (name_lost_closure != NULL)
{
data->name_lost_closure = g_closure_ref (name_lost_closure);
g_closure_sink (name_lost_closure);
if (G_CLOSURE_NEEDS_MARSHAL (name_lost_closure))
g_closure_set_marshal (name_lost_closure, g_cclosure_marshal_generic);
}
return data;
}
static void
own_with_closures_on_bus_acquired (GDBusConnection *connection,
const gchar *name,
gpointer user_data)
{
OwnNameData *data = user_data;
GValue params[2] = { G_VALUE_INIT, G_VALUE_INIT };
g_value_init (&params[0], G_TYPE_DBUS_CONNECTION);
g_value_set_object (&params[0], connection);
g_value_init (&params[1], G_TYPE_STRING);
g_value_set_string (&params[1], name);
g_closure_invoke (data->bus_acquired_closure, NULL, 2, params, NULL);
g_value_unset (params + 0);
g_value_unset (params + 1);
}
static void
own_with_closures_on_name_acquired (GDBusConnection *connection,
const gchar *name,
gpointer user_data)
{
OwnNameData *data = user_data;
GValue params[2] = { G_VALUE_INIT, G_VALUE_INIT };
g_value_init (&params[0], G_TYPE_DBUS_CONNECTION);
g_value_set_object (&params[0], connection);
g_value_init (&params[1], G_TYPE_STRING);
g_value_set_string (&params[1], name);
g_closure_invoke (data->name_acquired_closure, NULL, 2, params, NULL);
g_value_unset (params + 0);
g_value_unset (params + 1);
}
static void
own_with_closures_on_name_lost (GDBusConnection *connection,
const gchar *name,
gpointer user_data)
{
OwnNameData *data = user_data;
GValue params[2] = { G_VALUE_INIT, G_VALUE_INIT };
g_value_init (&params[0], G_TYPE_DBUS_CONNECTION);
g_value_set_object (&params[0], connection);
g_value_init (&params[1], G_TYPE_STRING);
g_value_set_string (&params[1], name);
g_closure_invoke (data->name_lost_closure, NULL, 2, params, NULL);
g_value_unset (params + 0);
g_value_unset (params + 1);
}
static void
bus_own_name_free_func (gpointer user_data)
{
OwnNameData *data = user_data;
if (data->bus_acquired_closure != NULL)
g_closure_unref (data->bus_acquired_closure);
if (data->name_acquired_closure != NULL)
g_closure_unref (data->name_acquired_closure);
if (data->name_lost_closure != NULL)
g_closure_unref (data->name_lost_closure);
g_free (data);
}
/**
* g_bus_own_name_with_closures: (rename-to g_bus_own_name)
* @bus_type: the type of bus to own a name on
* @name: the well-known name to own
* @flags: a set of flags from the #GBusNameOwnerFlags enumeration
* @bus_acquired_closure: (nullable): #GClosure to invoke when connected to
* the bus of type @bus_type or %NULL
* @name_acquired_closure: (nullable): #GClosure to invoke when @name is
* acquired or %NULL
* @name_lost_closure: (nullable): #GClosure to invoke when @name is lost or
* %NULL
*
* Version of g_bus_own_name() using closures instead of callbacks for
* easier binding in other languages.
*
* Returns: an identifier (never 0) that can be used with
* g_bus_unown_name() to stop owning the name.
*
* Since: 2.26
*/
guint
g_bus_own_name_with_closures (GBusType bus_type,
const gchar *name,
GBusNameOwnerFlags flags,
GClosure *bus_acquired_closure,
GClosure *name_acquired_closure,
GClosure *name_lost_closure)
{
return g_bus_own_name (bus_type,
name,
flags,
bus_acquired_closure != NULL ? own_with_closures_on_bus_acquired : NULL,
name_acquired_closure != NULL ? own_with_closures_on_name_acquired : NULL,
name_lost_closure != NULL ? own_with_closures_on_name_lost : NULL,
own_name_data_new (bus_acquired_closure,
name_acquired_closure,
name_lost_closure),
bus_own_name_free_func);
}
/**
* g_bus_own_name_on_connection_with_closures: (rename-to g_bus_own_name_on_connection)
* @connection: a #GDBusConnection
* @name: the well-known name to own
* @flags: a set of flags from the #GBusNameOwnerFlags enumeration
* @name_acquired_closure: (nullable): #GClosure to invoke when @name is
* acquired or %NULL
* @name_lost_closure: (nullable): #GClosure to invoke when @name is lost
* or %NULL
*
* Version of g_bus_own_name_on_connection() using closures instead of
* callbacks for easier binding in other languages.
*
* Returns: an identifier (never 0) that can be used with
* g_bus_unown_name() to stop owning the name.
*
* Since: 2.26
*/
guint
g_bus_own_name_on_connection_with_closures (GDBusConnection *connection,
const gchar *name,
GBusNameOwnerFlags flags,
GClosure *name_acquired_closure,
GClosure *name_lost_closure)
{
return g_bus_own_name_on_connection (connection,
name,
flags,
name_acquired_closure != NULL ? own_with_closures_on_name_acquired : NULL,
name_lost_closure != NULL ? own_with_closures_on_name_lost : NULL,
own_name_data_new (NULL,
name_acquired_closure,
name_lost_closure),
bus_own_name_free_func);
}
/**
* g_bus_unown_name:
* @owner_id: an identifier obtained from g_bus_own_name()
*
* Stops owning a name.
*
* Since: 2.26
*/
void
g_bus_unown_name (guint owner_id)
{
Client *client;
g_return_if_fail (owner_id > 0);
client = NULL;
G_LOCK (lock);
if (owner_id == 0 || map_id_to_client == NULL ||
(client = g_hash_table_lookup (map_id_to_client, GUINT_TO_POINTER (owner_id))) == NULL)
{
g_warning ("Invalid id %d passed to g_bus_unown_name()", owner_id);
goto out;
}
client->cancelled = TRUE;
g_warn_if_fail (g_hash_table_remove (map_id_to_client, GUINT_TO_POINTER (owner_id)));
out:
G_UNLOCK (lock);
/* do callback without holding lock */
if (client != NULL)
{
/* Release the name if needed */
if (client->needs_release &&
client->connection != NULL &&
!g_dbus_connection_is_closed (client->connection))
{
GVariant *result;
GError *error;
guint32 release_name_reply;
/* TODO: it kinda sucks having to do a sync call to release the name - but if
* we don't, then a subsequent grab of the name will make the bus daemon return
* IN_QUEUE which will trigger name_lost().
*
* I believe this is a bug in the bus daemon.
*/
error = NULL;
result = g_dbus_connection_call_sync (client->connection,
"org.freedesktop.DBus", /* bus name */
"/org/freedesktop/DBus", /* object path */
"org.freedesktop.DBus", /* interface name */
"ReleaseName", /* method name */
g_variant_new ("(s)", client->name),
G_VARIANT_TYPE ("(u)"),
G_DBUS_CALL_FLAGS_NONE,
-1,
NULL,
&error);
if (result == NULL)
{
g_warning ("Error releasing name %s: %s", client->name, error->message);
g_error_free (error);
}
else
{
g_variant_get (result, "(u)", &release_name_reply);
if (release_name_reply != 1 /* DBUS_RELEASE_NAME_REPLY_RELEASED */)
{
g_warning ("Unexpected reply %d when releasing name %s", release_name_reply, client->name);
}
g_variant_unref (result);
}
}
if (client->disconnected_signal_handler_id > 0)
g_signal_handler_disconnect (client->connection, client->disconnected_signal_handler_id);
if (client->name_acquired_subscription_id > 0)
g_dbus_connection_signal_unsubscribe (client->connection, client->name_acquired_subscription_id);
if (client->name_lost_subscription_id > 0)
g_dbus_connection_signal_unsubscribe (client->connection, client->name_lost_subscription_id);
client->disconnected_signal_handler_id = 0;
client->name_acquired_subscription_id = 0;
client->name_lost_subscription_id = 0;
if (client->connection != NULL)
{
g_object_unref (client->connection);
client->connection = NULL;
}
client_unref (client);
}
}
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