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glib/gio/gdbusnamewatching.c
Matthias Clasen a03cee3b27 Convert remaining examples to links
2014-02-08 17:52:21 -05:00

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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 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
*
* Author: David Zeuthen <davidz@redhat.com>
*/
#include "config.h"
#include <stdlib.h>
#include <string.h>
#include "gdbusutils.h"
#include "gdbusnamewatching.h"
#include "gdbuserror.h"
#include "gdbusprivate.h"
#include "gdbusconnection.h"
#include "glibintl.h"
/**
* SECTION:gdbusnamewatching
* @title: Watching Bus Names
* @short_description: Simple API for watching bus names
* @include: gio/gio.h
*
* Convenience API for watching bus names.
*
* A simple example for watching a name can be found in
* [gdbus-example-watch-name.c](https://git.gnome.org/browse/glib/tree/gio/tests/gdbus-example-watch-name.c)
*/
G_LOCK_DEFINE_STATIC (lock);
/* ---------------------------------------------------------------------------------------------------- */
typedef enum
{
PREVIOUS_CALL_NONE = 0,
PREVIOUS_CALL_APPEARED,
PREVIOUS_CALL_VANISHED,
} PreviousCall;
typedef struct
{
volatile gint ref_count;
guint id;
gchar *name;
GBusNameWatcherFlags flags;
gchar *name_owner;
GBusNameAppearedCallback name_appeared_handler;
GBusNameVanishedCallback name_vanished_handler;
gpointer user_data;
GDestroyNotify user_data_free_func;
GMainContext *main_context;
GDBusConnection *connection;
gulong disconnected_signal_handler_id;
guint name_owner_changed_subscription_id;
PreviousCall previous_call;
gboolean cancelled;
gboolean initialized;
} Client;
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->name_owner_changed_subscription_id > 0)
g_dbus_connection_signal_unsubscribe (client->connection, client->name_owner_changed_subscription_id);
if (client->disconnected_signal_handler_id > 0)
g_signal_handler_disconnect (client->connection, client->disconnected_signal_handler_id);
g_object_unref (client->connection);
}
g_free (client->name);
g_free (client->name_owner);
g_main_context_unref (client->main_context);
if (client->user_data_free_func != NULL)
client->user_data_free_func (client->user_data);
g_free (client);
}
}
/* ---------------------------------------------------------------------------------------------------- */
typedef enum
{
CALL_TYPE_NAME_APPEARED,
CALL_TYPE_NAME_VANISHED
} CallType;
typedef struct
{
Client *client;
/* keep this separate because client->connection may
* be set to NULL after scheduling the call
*/
GDBusConnection *connection;
/* ditto */
gchar *name_owner;
CallType call_type;
} CallHandlerData;
static void
call_handler_data_free (CallHandlerData *data)
{
if (data->connection != NULL)
g_object_unref (data->connection);
g_free (data->name_owner);
client_unref (data->client);
g_free (data);
}
static void
actually_do_call (Client *client, GDBusConnection *connection, const gchar *name_owner, CallType call_type)
{
switch (call_type)
{
case CALL_TYPE_NAME_APPEARED:
if (client->name_appeared_handler != NULL)
{
client->name_appeared_handler (connection,
client->name,
name_owner,
client->user_data);
}
break;
case CALL_TYPE_NAME_VANISHED:
if (client->name_vanished_handler != NULL)
{
client->name_vanished_handler (connection,
client->name,
client->user_data);
}
break;
default:
g_assert_not_reached ();
break;
}
}
static gboolean
call_in_idle_cb (gpointer _data)
{
CallHandlerData *data = _data;
actually_do_call (data->client, data->connection, data->name_owner, data->call_type);
return FALSE;
}
static void
schedule_call_in_idle (Client *client, CallType call_type)
{
CallHandlerData *data;
GSource *idle_source;
data = g_new0 (CallHandlerData, 1);
data->client = client_ref (client);
data->connection = client->connection != NULL ? g_object_ref (client->connection) : NULL;
data->name_owner = g_strdup (client->name_owner);
data->call_type = call_type;
idle_source = g_idle_source_new ();
g_source_set_priority (idle_source, G_PRIORITY_HIGH);
g_source_set_callback (idle_source,
call_in_idle_cb,
data,
(GDestroyNotify) call_handler_data_free);
g_source_attach (idle_source, client->main_context);
g_source_unref (idle_source);
}
static void
do_call (Client *client, CallType call_type)
{
GMainContext *current_context;
/* only schedule in idle if we're not in the right thread */
current_context = g_main_context_ref_thread_default ();
if (current_context != client->main_context)
schedule_call_in_idle (client, call_type);
else
actually_do_call (client, client->connection, client->name_owner, call_type);
g_main_context_unref (current_context);
}
static void
call_appeared_handler (Client *client)
{
if (client->previous_call != PREVIOUS_CALL_APPEARED)
{
client->previous_call = PREVIOUS_CALL_APPEARED;
if (!client->cancelled && client->name_appeared_handler != NULL)
{
do_call (client, CALL_TYPE_NAME_APPEARED);
}
}
}
static void
call_vanished_handler (Client *client,
gboolean ignore_cancelled)
{
if (client->previous_call != PREVIOUS_CALL_VANISHED)
{
client->previous_call = PREVIOUS_CALL_VANISHED;
if (((!client->cancelled) || ignore_cancelled) && client->name_vanished_handler != NULL)
{
do_call (client, CALL_TYPE_NAME_VANISHED);
}
}
}
/* ---------------------------------------------------------------------------------------------------- */
static void
on_connection_disconnected (GDBusConnection *connection,
gboolean remote_peer_vanished,
GError *error,
gpointer user_data)
{
Client *client = user_data;
if (client->name_owner_changed_subscription_id > 0)
g_dbus_connection_signal_unsubscribe (client->connection, client->name_owner_changed_subscription_id);
if (client->disconnected_signal_handler_id > 0)
g_signal_handler_disconnect (client->connection, client->disconnected_signal_handler_id);
g_object_unref (client->connection);
client->disconnected_signal_handler_id = 0;
client->name_owner_changed_subscription_id = 0;
client->connection = NULL;
call_vanished_handler (client, FALSE);
}
/* ---------------------------------------------------------------------------------------------------- */
static void
on_name_owner_changed (GDBusConnection *connection,
const gchar *sender_name,
const gchar *object_path,
const gchar *interface_name,
const gchar *signal_name,
GVariant *parameters,
gpointer user_data)
{
Client *client = user_data;
const gchar *name;
const gchar *old_owner;
const gchar *new_owner;
if (!client->initialized)
goto out;
if (g_strcmp0 (object_path, "/org/freedesktop/DBus") != 0 ||
g_strcmp0 (interface_name, "org.freedesktop.DBus") != 0 ||
g_strcmp0 (sender_name, "org.freedesktop.DBus") != 0)
goto out;
g_variant_get (parameters,
"(&s&s&s)",
&name,
&old_owner,
&new_owner);
/* we only care about a specific name */
if (g_strcmp0 (name, client->name) != 0)
goto out;
if ((old_owner != NULL && strlen (old_owner) > 0) && client->name_owner != NULL)
{
g_free (client->name_owner);
client->name_owner = NULL;
call_vanished_handler (client, FALSE);
}
if (new_owner != NULL && strlen (new_owner) > 0)
{
g_warn_if_fail (client->name_owner == NULL);
g_free (client->name_owner);
client->name_owner = g_strdup (new_owner);
call_appeared_handler (client);
}
out:
;
}
/* ---------------------------------------------------------------------------------------------------- */
static void
get_name_owner_cb (GObject *source_object,
GAsyncResult *res,
gpointer user_data)
{
Client *client = user_data;
GVariant *result;
const char *name_owner;
name_owner = NULL;
result = NULL;
result = g_dbus_connection_call_finish (client->connection,
res,
NULL);
if (result != NULL)
{
g_variant_get (result, "(&s)", &name_owner);
}
if (name_owner != NULL)
{
g_warn_if_fail (client->name_owner == NULL);
client->name_owner = g_strdup (name_owner);
call_appeared_handler (client);
}
else
{
call_vanished_handler (client, FALSE);
}
client->initialized = TRUE;
if (result != NULL)
g_variant_unref (result);
client_unref (client);
}
/* ---------------------------------------------------------------------------------------------------- */
static void
invoke_get_name_owner (Client *client)
{
g_dbus_connection_call (client->connection,
"org.freedesktop.DBus", /* bus name */
"/org/freedesktop/DBus", /* object path */
"org.freedesktop.DBus", /* interface name */
"GetNameOwner", /* method name */
g_variant_new ("(s)", client->name),
G_VARIANT_TYPE ("(s)"),
G_DBUS_CALL_FLAGS_NONE,
-1,
NULL,
(GAsyncReadyCallback) get_name_owner_cb,
client_ref (client));
}
/* ---------------------------------------------------------------------------------------------------- */
static void
start_service_by_name_cb (GObject *source_object,
GAsyncResult *res,
gpointer user_data)
{
Client *client = user_data;
GVariant *result;
result = NULL;
result = g_dbus_connection_call_finish (client->connection,
res,
NULL);
if (result != NULL)
{
guint32 start_service_result;
g_variant_get (result, "(u)", &start_service_result);
if (start_service_result == 1) /* DBUS_START_REPLY_SUCCESS */
{
invoke_get_name_owner (client);
}
else if (start_service_result == 2) /* DBUS_START_REPLY_ALREADY_RUNNING */
{
invoke_get_name_owner (client);
}
else
{
g_warning ("Unexpected reply %d from StartServiceByName() method", start_service_result);
call_vanished_handler (client, FALSE);
client->initialized = TRUE;
}
}
else
{
/* Errors are not unexpected; the bus will reply e.g.
*
* org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.Epiphany2
* was not provided by any .service files
*
* This doesn't mean that the name doesn't have an owner, just
* that it's not provided by a .service file. So proceed to
* invoke GetNameOwner().
*/
invoke_get_name_owner (client);
}
if (result != NULL)
g_variant_unref (result);
client_unref (client);
}
/* ---------------------------------------------------------------------------------------------------- */
static void
has_connection (Client *client)
{
/* listen for disconnection */
client->disconnected_signal_handler_id = g_signal_connect (client->connection,
"closed",
G_CALLBACK (on_connection_disconnected),
client);
/* start listening to NameOwnerChanged messages immediately */
client->name_owner_changed_subscription_id = g_dbus_connection_signal_subscribe (client->connection,
"org.freedesktop.DBus", /* name */
"org.freedesktop.DBus", /* if */
"NameOwnerChanged", /* signal */
"/org/freedesktop/DBus", /* path */
client->name,
G_DBUS_SIGNAL_FLAGS_NONE,
on_name_owner_changed,
client,
NULL);
if (client->flags & G_BUS_NAME_WATCHER_FLAGS_AUTO_START)
{
g_dbus_connection_call (client->connection,
"org.freedesktop.DBus", /* bus name */
"/org/freedesktop/DBus", /* object path */
"org.freedesktop.DBus", /* interface name */
"StartServiceByName", /* method name */
g_variant_new ("(su)", client->name, 0),
G_VARIANT_TYPE ("(u)"),
G_DBUS_CALL_FLAGS_NONE,
-1,
NULL,
(GAsyncReadyCallback) start_service_by_name_cb,
client_ref (client));
}
else
{
/* check owner */
invoke_get_name_owner (client);
}
}
static void
connection_get_cb (GObject *source_object,
GAsyncResult *res,
gpointer user_data)
{
Client *client = user_data;
client->connection = g_bus_get_finish (res, NULL);
if (client->connection == NULL)
{
call_vanished_handler (client, FALSE);
goto out;
}
has_connection (client);
out:
client_unref (client);
}
/* ---------------------------------------------------------------------------------------------------- */
/**
* g_bus_watch_name:
* @bus_type: The type of bus to watch a name on.
* @name: The name (well-known or unique) to watch.
* @flags: Flags from the #GBusNameWatcherFlags enumeration.
* @name_appeared_handler: (allow-none): Handler to invoke when @name is known to exist or %NULL.
* @name_vanished_handler: (allow-none): Handler to invoke when @name is known to not exist or %NULL.
* @user_data: User data to pass to handlers.
* @user_data_free_func: (allow-none): Function for freeing @user_data or %NULL.
*
* Starts watching @name on the bus specified by @bus_type and calls
* @name_appeared_handler and @name_vanished_handler when the name is
* known to have a owner respectively known to lose its
* owner. Callbacks will be invoked in the
* [thread-default main context][g-main-context-push-thread-default]
* of the thread you are calling this function from.
*
* You are guaranteed that one of the handlers will be invoked after
* calling this function. When you are done watching the name, just
* call g_bus_unwatch_name() with the watcher id this function
* returns.
*
* If the name vanishes or appears (for example the application owning
* the name could restart), the handlers are also invoked. If the
* #GDBusConnection that is used for watching the name disconnects, then
* @name_vanished_handler is invoked since it is no longer
* possible to access the name.
*
* Another guarantee is that invocations of @name_appeared_handler
* and @name_vanished_handler are guaranteed to alternate; that
* is, if @name_appeared_handler is invoked then you are
* guaranteed that the next time one of the handlers is invoked, it
* will be @name_vanished_handler. The reverse is also true.
*
* This behavior makes it very simple to write applications that want
* to take action when a certain [name exists][gdbus-watching-names].
* Basically, the application should create object proxies in
* @name_appeared_handler and destroy them again (if any) in
* @name_vanished_handler.
*
* Returns: An identifier (never 0) that an be used with
* g_bus_unwatch_name() to stop watching the name.
*
* Since: 2.26
*/
guint
g_bus_watch_name (GBusType bus_type,
const gchar *name,
GBusNameWatcherFlags flags,
GBusNameAppearedCallback name_appeared_handler,
GBusNameVanishedCallback name_vanished_handler,
gpointer user_data,
GDestroyNotify user_data_free_func)
{
Client *client;
g_return_val_if_fail (g_dbus_is_name (name), 0);
G_LOCK (lock);
client = g_new0 (Client, 1);
client->ref_count = 1;
client->id = next_global_id++; /* TODO: uh oh, handle overflow */
client->name = g_strdup (name);
client->flags = flags;
client->name_appeared_handler = name_appeared_handler;
client->name_vanished_handler = name_vanished_handler;
client->user_data = user_data;
client->user_data_free_func = user_data_free_func;
client->main_context = g_main_context_ref_thread_default ();
if (map_id_to_client == NULL)
{
map_id_to_client = g_hash_table_new (g_direct_hash, g_direct_equal);
}
g_hash_table_insert (map_id_to_client,
GUINT_TO_POINTER (client->id),
client);
g_bus_get (bus_type,
NULL,
connection_get_cb,
client_ref (client));
G_UNLOCK (lock);
return client->id;
}
/**
* g_bus_watch_name_on_connection:
* @connection: A #GDBusConnection.
* @name: The name (well-known or unique) to watch.
* @flags: Flags from the #GBusNameWatcherFlags enumeration.
* @name_appeared_handler: (allow-none): Handler to invoke when @name is known to exist or %NULL.
* @name_vanished_handler: (allow-none): Handler to invoke when @name is known to not exist or %NULL.
* @user_data: User data to pass to handlers.
* @user_data_free_func: (allow-none): Function for freeing @user_data or %NULL.
*
* Like g_bus_watch_name() but takes a #GDBusConnection instead of a
* #GBusType.
*
* Returns: An identifier (never 0) that an be used with
* g_bus_unwatch_name() to stop watching the name.
*
* Since: 2.26
*/
guint g_bus_watch_name_on_connection (GDBusConnection *connection,
const gchar *name,
GBusNameWatcherFlags flags,
GBusNameAppearedCallback name_appeared_handler,
GBusNameVanishedCallback name_vanished_handler,
gpointer user_data,
GDestroyNotify user_data_free_func)
{
Client *client;
g_return_val_if_fail (G_IS_DBUS_CONNECTION (connection), 0);
g_return_val_if_fail (g_dbus_is_name (name), 0);
G_LOCK (lock);
client = g_new0 (Client, 1);
client->ref_count = 1;
client->id = next_global_id++; /* TODO: uh oh, handle overflow */
client->name = g_strdup (name);
client->flags = flags;
client->name_appeared_handler = name_appeared_handler;
client->name_vanished_handler = name_vanished_handler;
client->user_data = user_data;
client->user_data_free_func = user_data_free_func;
client->main_context = g_main_context_ref_thread_default ();
if (map_id_to_client == NULL)
map_id_to_client = g_hash_table_new (g_direct_hash, g_direct_equal);
g_hash_table_insert (map_id_to_client,
GUINT_TO_POINTER (client->id),
client);
client->connection = g_object_ref (connection);
G_UNLOCK (lock);
has_connection (client);
return client->id;
}
typedef struct {
GClosure *name_appeared_closure;
GClosure *name_vanished_closure;
} WatchNameData;
static WatchNameData *
watch_name_data_new (GClosure *name_appeared_closure,
GClosure *name_vanished_closure)
{
WatchNameData *data;
data = g_new0 (WatchNameData, 1);
if (name_appeared_closure != NULL)
{
data->name_appeared_closure = g_closure_ref (name_appeared_closure);
g_closure_sink (name_appeared_closure);
if (G_CLOSURE_NEEDS_MARSHAL (name_appeared_closure))
g_closure_set_marshal (name_appeared_closure, g_cclosure_marshal_generic);
}
if (name_vanished_closure != NULL)
{
data->name_vanished_closure = g_closure_ref (name_vanished_closure);
g_closure_sink (name_vanished_closure);
if (G_CLOSURE_NEEDS_MARSHAL (name_vanished_closure))
g_closure_set_marshal (name_vanished_closure, g_cclosure_marshal_generic);
}
return data;
}
static void
watch_with_closures_on_name_appeared (GDBusConnection *connection,
const gchar *name,
const gchar *name_owner,
gpointer user_data)
{
WatchNameData *data = user_data;
GValue params[3] = { G_VALUE_INIT, G_VALUE_INIT, G_VALUE_INIT };
g_value_init (&params[0], G_TYPE_DBUS_CONNECTION);
g_value_set_object (&params[0], connection);
g_value_init (&params[1], G_TYPE_STRING);
g_value_set_string (&params[1], name);
g_value_init (&params[2], G_TYPE_STRING);
g_value_set_string (&params[2], name_owner);
g_closure_invoke (data->name_appeared_closure, NULL, 3, params, NULL);
g_value_unset (params + 0);
g_value_unset (params + 1);
g_value_unset (params + 2);
}
static void
watch_with_closures_on_name_vanished (GDBusConnection *connection,
const gchar *name,
gpointer user_data)
{
WatchNameData *data = user_data;
GValue params[2] = { G_VALUE_INIT, G_VALUE_INIT };
g_value_init (&params[0], G_TYPE_DBUS_CONNECTION);
g_value_set_object (&params[0], connection);
g_value_init (&params[1], G_TYPE_STRING);
g_value_set_string (&params[1], name);
g_closure_invoke (data->name_vanished_closure, NULL, 2, params, NULL);
g_value_unset (params + 0);
g_value_unset (params + 1);
}
static void
bus_watch_name_free_func (gpointer user_data)
{
WatchNameData *data = user_data;
if (data->name_appeared_closure != NULL)
g_closure_unref (data->name_appeared_closure);
if (data->name_vanished_closure != NULL)
g_closure_unref (data->name_vanished_closure);
g_free (data);
}
/**
* g_bus_watch_name_with_closures:
* @bus_type: The type of bus to watch a name on.
* @name: The name (well-known or unique) to watch.
* @flags: Flags from the #GBusNameWatcherFlags enumeration.
* @name_appeared_closure: (allow-none): #GClosure to invoke when @name is known
* to exist or %NULL.
* @name_vanished_closure: (allow-none): #GClosure to invoke when @name is known
* to not exist or %NULL.
*
* Version of g_bus_watch_name() using closures instead of callbacks for
* easier binding in other languages.
*
* Returns: An identifier (never 0) that an be used with
* g_bus_unwatch_name() to stop watching the name.
*
* Rename to: g_bus_watch_name
*
* Since: 2.26
*/
guint
g_bus_watch_name_with_closures (GBusType bus_type,
const gchar *name,
GBusNameWatcherFlags flags,
GClosure *name_appeared_closure,
GClosure *name_vanished_closure)
{
return g_bus_watch_name (bus_type,
name,
flags,
name_appeared_closure != NULL ? watch_with_closures_on_name_appeared : NULL,
name_vanished_closure != NULL ? watch_with_closures_on_name_vanished : NULL,
watch_name_data_new (name_appeared_closure, name_vanished_closure),
bus_watch_name_free_func);
}
/**
* g_bus_watch_name_on_connection_with_closures:
* @connection: A #GDBusConnection.
* @name: The name (well-known or unique) to watch.
* @flags: Flags from the #GBusNameWatcherFlags enumeration.
* @name_appeared_closure: (allow-none): #GClosure to invoke when @name is known
* to exist or %NULL.
* @name_vanished_closure: (allow-none): #GClosure to invoke when @name is known
* to not exist or %NULL.
*
* Version of g_bus_watch_name_on_connection() using closures instead of callbacks for
* easier binding in other languages.
*
* Returns: An identifier (never 0) that an be used with
* g_bus_unwatch_name() to stop watching the name.
*
* Rename to: g_bus_watch_name_on_connection
*
* Since: 2.26
*/
guint g_bus_watch_name_on_connection_with_closures (
GDBusConnection *connection,
const gchar *name,
GBusNameWatcherFlags flags,
GClosure *name_appeared_closure,
GClosure *name_vanished_closure)
{
return g_bus_watch_name_on_connection (connection,
name,
flags,
name_appeared_closure != NULL ? watch_with_closures_on_name_appeared : NULL,
name_vanished_closure != NULL ? watch_with_closures_on_name_vanished : NULL,
watch_name_data_new (name_appeared_closure, name_vanished_closure),
bus_watch_name_free_func);
}
/**
* g_bus_unwatch_name:
* @watcher_id: An identifier obtained from g_bus_watch_name()
*
* Stops watching a name.
*
* Since: 2.26
*/
void
g_bus_unwatch_name (guint watcher_id)
{
Client *client;
g_return_if_fail (watcher_id > 0);
client = NULL;
G_LOCK (lock);
if (watcher_id == 0 ||
map_id_to_client == NULL ||
(client = g_hash_table_lookup (map_id_to_client, GUINT_TO_POINTER (watcher_id))) == NULL)
{
g_warning ("Invalid id %d passed to g_bus_unwatch_name()", watcher_id);
goto out;
}
client->cancelled = TRUE;
g_warn_if_fail (g_hash_table_remove (map_id_to_client, GUINT_TO_POINTER (watcher_id)));
out:
G_UNLOCK (lock);
/* do callback without holding lock */
if (client != NULL)
{
client_unref (client);
}
}
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