An example D-Bus server

Here is an example for a D-Bus server: gdbus-example-server.c

An example for exporting a subtree

Here is an example for exporting a subtree: gdbus-example-subtree.c

An example for file descriptor passing

Here is an example for passing UNIX file descriptors: gdbus-unix-fd-client.c

An example for exporting a GObject

Here is an example for exporting a GObject: gdbus-example-export.c

g_bus_get ()

void
g_bus_get (GBusType bus_type,
           GCancellable *cancellable,
           GAsyncReadyCallback callback,
           gpointer user_data);

Asynchronously connects to the message bus specified by bus_type .

When the operation is finished, callback will be invoked. You can then call g_bus_get_finish() to get the result of the operation.

This is an asynchronous failable function. See g_bus_get_sync() for the synchronous version.

Since: 2.26

g_bus_get_finish ()

GDBusConnection *
g_bus_get_finish (GAsyncResult *res,
                  GError **error);

Finishes an operation started with g_bus_get().

The returned object is a singleton, that is, shared with other callers of g_bus_get() and g_bus_get_sync() for bus_type . In the event that you need a private message bus connection, use g_dbus_address_get_for_bus_sync() and g_dbus_connection_new_for_address().

Note that the returned GDBusConnection object will (usually) have the “exit-on-close” property set to TRUE.

Since: 2.26

g_bus_get_sync ()

GDBusConnection *
g_bus_get_sync (GBusType bus_type,
                GCancellable *cancellable,
                GError **error);

Synchronously connects to the message bus specified by bus_type . Note that the returned object may shared with other callers, e.g. if two separate parts of a process calls this function with the same bus_type , they will share the same object.

This is a synchronous failable function. See g_bus_get() and g_bus_get_finish() for the asynchronous version.

The returned object is a singleton, that is, shared with other callers of g_bus_get() and g_bus_get_sync() for bus_type . In the event that you need a private message bus connection, use g_dbus_address_get_for_bus_sync() and g_dbus_connection_new_for_address().

Note that the returned GDBusConnection object will (usually) have the “exit-on-close” property set to TRUE.

Since: 2.26

g_dbus_connection_new ()

void
g_dbus_connection_new (GIOStream *stream,
                       const gchar *guid,
                       GDBusConnectionFlags flags,
                       GDBusAuthObserver *observer,
                       GCancellable *cancellable,
                       GAsyncReadyCallback callback,
                       gpointer user_data);

Asynchronously sets up a D-Bus connection for exchanging D-Bus messages with the end represented by stream .

If stream is a GSocketConnection, then the corresponding GSocket will be put into non-blocking mode.

The D-Bus connection will interact with stream from a worker thread. As a result, the caller should not interact with stream after this method has been called, except by calling g_object_unref() on it.

If observer is not NULL it may be used to control the authentication process.

When the operation is finished, callback will be invoked. You can then call g_dbus_connection_new_finish() to get the result of the operation.

This is an asynchronous failable constructor. See g_dbus_connection_new_sync() for the synchronous version.

Since: 2.26

g_dbus_connection_new_finish ()

GDBusConnection *
g_dbus_connection_new_finish (GAsyncResult *res,
                              GError **error);

Finishes an operation started with g_dbus_connection_new().

Since: 2.26

g_dbus_connection_new_sync ()

GDBusConnection *
g_dbus_connection_new_sync (GIOStream *stream,
                            const gchar *guid,
                            GDBusConnectionFlags flags,
                            GDBusAuthObserver *observer,
                            GCancellable *cancellable,
                            GError **error);

Synchronously sets up a D-Bus connection for exchanging D-Bus messages with the end represented by stream .

If stream is a GSocketConnection, then the corresponding GSocket will be put into non-blocking mode.

The D-Bus connection will interact with stream from a worker thread. As a result, the caller should not interact with stream after this method has been called, except by calling g_object_unref() on it.

If observer is not NULL it may be used to control the authentication process.

This is a synchronous failable constructor. See g_dbus_connection_new() for the asynchronous version.

Since: 2.26

g_dbus_connection_new_for_address ()

void
g_dbus_connection_new_for_address (const gchar *address,
                                   GDBusConnectionFlags flags,
                                   GDBusAuthObserver *observer,
                                   GCancellable *cancellable,
                                   GAsyncReadyCallback callback,
                                   gpointer user_data);

Asynchronously connects and sets up a D-Bus client connection for exchanging D-Bus messages with an endpoint specified by address which must be in the D-Bus address format.

This constructor can only be used to initiate client-side connections - use g_dbus_connection_new() if you need to act as the server. In particular, flags cannot contain the G_DBUS_CONNECTION_FLAGS_AUTHENTICATION_SERVER, G_DBUS_CONNECTION_FLAGS_AUTHENTICATION_ALLOW_ANONYMOUS or G_DBUS_CONNECTION_FLAGS_AUTHENTICATION_REQUIRE_SAME_USER flags.

When the operation is finished, callback will be invoked. You can then call g_dbus_connection_new_for_address_finish() to get the result of the operation.

If observer is not NULL it may be used to control the authentication process.

This is an asynchronous failable constructor. See g_dbus_connection_new_for_address_sync() for the synchronous version.

Since: 2.26

g_dbus_connection_new_for_address_finish ()

GDBusConnection *
g_dbus_connection_new_for_address_finish
                               (GAsyncResult *res,
                                GError **error);

Finishes an operation started with g_dbus_connection_new_for_address().

Since: 2.26

g_dbus_connection_new_for_address_sync ()

GDBusConnection *
g_dbus_connection_new_for_address_sync
                               (const gchar *address,
                                GDBusConnectionFlags flags,
                                GDBusAuthObserver *observer,
                                GCancellable *cancellable,
                                GError **error);

Synchronously connects and sets up a D-Bus client connection for exchanging D-Bus messages with an endpoint specified by address which must be in the D-Bus address format.

This constructor can only be used to initiate client-side connections - use g_dbus_connection_new_sync() if you need to act as the server. In particular, flags cannot contain the G_DBUS_CONNECTION_FLAGS_AUTHENTICATION_SERVER, G_DBUS_CONNECTION_FLAGS_AUTHENTICATION_ALLOW_ANONYMOUS or G_DBUS_CONNECTION_FLAGS_AUTHENTICATION_REQUIRE_SAME_USER flags.

This is a synchronous failable constructor. See g_dbus_connection_new_for_address() for the asynchronous version.

If observer is not NULL it may be used to control the authentication process.

Since: 2.26

g_dbus_connection_start_message_processing ()

void
g_dbus_connection_start_message_processing
                               (GDBusConnection *connection);

If connection was created with G_DBUS_CONNECTION_FLAGS_DELAY_MESSAGE_PROCESSING, this method starts processing messages. Does nothing on if connection wasn't created with this flag or if the method has already been called.

Since: 2.26

g_dbus_connection_close ()

void
g_dbus_connection_close (GDBusConnection *connection,
                         GCancellable *cancellable,
                         GAsyncReadyCallback callback,
                         gpointer user_data);

Closes connection . Note that this never causes the process to exit (this might only happen if the other end of a shared message bus connection disconnects, see “exit-on-close”).

Once the connection is closed, operations such as sending a message will return with the error G_IO_ERROR_CLOSED. Closing a connection will not automatically flush the connection so queued messages may be lost. Use g_dbus_connection_flush() if you need such guarantees.

If connection is already closed, this method fails with G_IO_ERROR_CLOSED.

When connection has been closed, the “closed” signal is emitted in the thread-default main context of the thread that connection was constructed in.

This is an asynchronous method. When the operation is finished, callback will be invoked in the thread-default main context of the thread you are calling this method from. You can then call g_dbus_connection_close_finish() to get the result of the operation. See g_dbus_connection_close_sync() for the synchronous version.

Since: 2.26

g_dbus_connection_close_finish ()

gboolean
g_dbus_connection_close_finish (GDBusConnection *connection,
                                GAsyncResult *res,
                                GError **error);

Finishes an operation started with g_dbus_connection_close().

Since: 2.26

g_dbus_connection_close_sync ()

gboolean
g_dbus_connection_close_sync (GDBusConnection *connection,
                              GCancellable *cancellable,
                              GError **error);

Synchronously closes connection . The calling thread is blocked until this is done. See g_dbus_connection_close() for the asynchronous version of this method and more details about what it does.

Since: 2.26

g_dbus_connection_is_closed ()

gboolean
g_dbus_connection_is_closed (GDBusConnection *connection);

Gets whether connection is closed.

Since: 2.26

g_dbus_connection_flush ()

void
g_dbus_connection_flush (GDBusConnection *connection,
                         GCancellable *cancellable,
                         GAsyncReadyCallback callback,
                         gpointer user_data);

Asynchronously flushes connection , that is, writes all queued outgoing message to the transport and then flushes the transport (using g_output_stream_flush_async()). This is useful in programs that wants to emit a D-Bus signal and then exit immediately. Without flushing the connection, there is no guaranteed that the message has been sent to the networking buffers in the OS kernel.

This is an asynchronous method. When the operation is finished, callback will be invoked in the thread-default main context of the thread you are calling this method from. You can then call g_dbus_connection_flush_finish() to get the result of the operation. See g_dbus_connection_flush_sync() for the synchronous version.

Since: 2.26

g_dbus_connection_flush_finish ()

gboolean
g_dbus_connection_flush_finish (GDBusConnection *connection,
                                GAsyncResult *res,
                                GError **error);

Finishes an operation started with g_dbus_connection_flush().

Since: 2.26

g_dbus_connection_flush_sync ()

gboolean
g_dbus_connection_flush_sync (GDBusConnection *connection,
                              GCancellable *cancellable,
                              GError **error);

Synchronously flushes connection . The calling thread is blocked until this is done. See g_dbus_connection_flush() for the asynchronous version of this method and more details about what it does.

Since: 2.26

g_dbus_connection_get_exit_on_close ()

gboolean
g_dbus_connection_get_exit_on_close (GDBusConnection *connection);

Gets whether the process is terminated when connection is closed by the remote peer. See “exit-on-close” for more details.

Since: 2.26

g_dbus_connection_set_exit_on_close ()

void
g_dbus_connection_set_exit_on_close (GDBusConnection *connection,
                                     gboolean exit_on_close);

Sets whether the process should be terminated when connection is closed by the remote peer. See “exit-on-close” for more details.

Note that this function should be used with care. Most modern UNIX desktops tie the notion of a user session with the session bus, and expect all of a user's applications to quit when their bus connection goes away. If you are setting exit_on_close to FALSE for the shared session bus connection, you should make sure that your application exits when the user session ends.

Since: 2.26

g_dbus_connection_get_stream ()

GIOStream *
g_dbus_connection_get_stream (GDBusConnection *connection);

Gets the underlying stream used for IO.

While the GDBusConnection is active, it will interact with this stream from a worker thread, so it is not safe to interact with the stream directly.

Since: 2.26

g_dbus_connection_get_flags ()

GDBusConnectionFlags
g_dbus_connection_get_flags (GDBusConnection *connection);

Gets the flags used to construct this connection

Since: 2.60

g_dbus_connection_get_guid ()

const gchar *
g_dbus_connection_get_guid (GDBusConnection *connection);

The GUID of the peer performing the role of server when authenticating. See “guid” for more details.

Since: 2.26

g_dbus_connection_get_unique_name ()

const gchar *
g_dbus_connection_get_unique_name (GDBusConnection *connection);

Gets the unique name of connection as assigned by the message bus. This can also be used to figure out if connection is a message bus connection.

Since: 2.26

g_dbus_connection_get_capabilities ()

GDBusCapabilityFlags
g_dbus_connection_get_capabilities (GDBusConnection *connection);

Gets the capabilities negotiated with the remote peer

Since: 2.26

g_dbus_connection_get_peer_credentials ()

GCredentials *
g_dbus_connection_get_peer_credentials
                               (GDBusConnection *connection);

Gets the credentials of the authenticated peer. This will always return NULL unless connection acted as a server (e.g. G_DBUS_CONNECTION_FLAGS_AUTHENTICATION_SERVER was passed) when set up and the client passed credentials as part of the authentication process.

In a message bus setup, the message bus is always the server and each application is a client. So this method will always return NULL for message bus clients.

Since: 2.26

g_dbus_connection_get_last_serial ()

guint32
g_dbus_connection_get_last_serial (GDBusConnection *connection);

Retrieves the last serial number assigned to a GDBusMessage on the current thread. This includes messages sent via both low-level API such as g_dbus_connection_send_message() as well as high-level API such as g_dbus_connection_emit_signal(), g_dbus_connection_call() or g_dbus_proxy_call().

Since: 2.34

g_dbus_connection_call ()

void
g_dbus_connection_call (GDBusConnection *connection,
                        const gchar *bus_name,
                        const gchar *object_path,
                        const gchar *interface_name,
                        const gchar *method_name,
                        GVariant *parameters,
                        const GVariantType *reply_type,
                        GDBusCallFlags flags,
                        gint timeout_msec,
                        GCancellable *cancellable,
                        GAsyncReadyCallback callback,
                        gpointer user_data);

Asynchronously invokes the method_name method on the interface_name D-Bus interface on the remote object at object_path owned by bus_name .

If connection is closed then the operation will fail with G_IO_ERROR_CLOSED. If cancellable is canceled, the operation will fail with G_IO_ERROR_CANCELLED. If parameters contains a value not compatible with the D-Bus protocol, the operation fails with G_IO_ERROR_INVALID_ARGUMENT.

If reply_type is non-NULL then the reply will be checked for having this type and an error will be raised if it does not match. Said another way, if you give a reply_type then any non-NULL return value will be of this type. Unless it’s G_VARIANT_TYPE_UNIT, the reply_type will be a tuple containing one or more values.

If the parameters GVariant is floating, it is consumed. This allows convenient 'inline' use of g_variant_new(), e.g.:

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g_dbus_connection_call (connection,
                        "org.freedesktop.StringThings",
                        "/org/freedesktop/StringThings",
                        "org.freedesktop.StringThings",
                        "TwoStrings",
                        g_variant_new ("(ss)",
                                       "Thing One",
                                       "Thing Two"),
                        NULL,
                        G_DBUS_CALL_FLAGS_NONE,
                        -1,
                        NULL,
                        (GAsyncReadyCallback) two_strings_done,
                        NULL);

This is an asynchronous method. When the operation is finished, callback will be invoked in the thread-default main context of the thread you are calling this method from. You can then call g_dbus_connection_call_finish() to get the result of the operation. See g_dbus_connection_call_sync() for the synchronous version of this function.

If callback is NULL then the D-Bus method call message will be sent with the G_DBUS_MESSAGE_FLAGS_NO_REPLY_EXPECTED flag set.

Since: 2.26

g_dbus_connection_call_finish ()

GVariant *
g_dbus_connection_call_finish (GDBusConnection *connection,
                               GAsyncResult *res,
                               GError **error);

Finishes an operation started with g_dbus_connection_call().

Since: 2.26

g_dbus_connection_call_sync ()

GVariant *
g_dbus_connection_call_sync (GDBusConnection *connection,
                             const gchar *bus_name,
                             const gchar *object_path,
                             const gchar *interface_name,
                             const gchar *method_name,
                             GVariant *parameters,
                             const GVariantType *reply_type,
                             GDBusCallFlags flags,
                             gint timeout_msec,
                             GCancellable *cancellable,
                             GError **error);

Synchronously invokes the method_name method on the interface_name D-Bus interface on the remote object at object_path owned by bus_name .

If connection is closed then the operation will fail with G_IO_ERROR_CLOSED. If cancellable is canceled, the operation will fail with G_IO_ERROR_CANCELLED. If parameters contains a value not compatible with the D-Bus protocol, the operation fails with G_IO_ERROR_INVALID_ARGUMENT.

If reply_type is non-NULL then the reply will be checked for having this type and an error will be raised if it does not match. Said another way, if you give a reply_type then any non-NULL return value will be of this type.

If the parameters GVariant is floating, it is consumed. This allows convenient 'inline' use of g_variant_new(), e.g.:

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g_dbus_connection_call_sync (connection,
                             "org.freedesktop.StringThings",
                             "/org/freedesktop/StringThings",
                             "org.freedesktop.StringThings",
                             "TwoStrings",
                             g_variant_new ("(ss)",
                                            "Thing One",
                                            "Thing Two"),
                             NULL,
                             G_DBUS_CALL_FLAGS_NONE,
                             -1,
                             NULL,
                             &error);

The calling thread is blocked until a reply is received. See g_dbus_connection_call() for the asynchronous version of this method.

Since: 2.26

g_dbus_connection_call_with_unix_fd_list ()

void
g_dbus_connection_call_with_unix_fd_list
                               (GDBusConnection *connection,
                                const gchar *bus_name,
                                const gchar *object_path,
                                const gchar *interface_name,
                                const gchar *method_name,
                                GVariant *parameters,
                                const GVariantType *reply_type,
                                GDBusCallFlags flags,
                                gint timeout_msec,
                                GUnixFDList *fd_list,
                                GCancellable *cancellable,
                                GAsyncReadyCallback callback,
                                gpointer user_data);

Like g_dbus_connection_call() but also takes a GUnixFDList object.

The file descriptors normally correspond to G_VARIANT_TYPE_HANDLE values in the body of the message. For example, if a message contains two file descriptors, fd_list would have length 2, and g_variant_new_handle (0) and g_variant_new_handle (1) would appear somewhere in the body of the message (not necessarily in that order!) to represent the file descriptors at indexes 0 and 1 respectively.

When designing D-Bus APIs that are intended to be interoperable, please note that non-GDBus implementations of D-Bus can usually only access file descriptors if they are referenced in this way by a value of type G_VARIANT_TYPE_HANDLE in the body of the message.

This method is only available on UNIX.

Since: 2.30

g_dbus_connection_call_with_unix_fd_list_finish ()

GVariant *
g_dbus_connection_call_with_unix_fd_list_finish
                               (GDBusConnection *connection,
                                GUnixFDList **out_fd_list,
                                GAsyncResult *res,
                                GError **error);

Finishes an operation started with g_dbus_connection_call_with_unix_fd_list().

The file descriptors normally correspond to G_VARIANT_TYPE_HANDLE values in the body of the message. For example, if g_variant_get_handle() returns 5, that is intended to be a reference to the file descriptor that can be accessed by g_unix_fd_list_get (*out_fd_list, 5, ...).

When designing D-Bus APIs that are intended to be interoperable, please note that non-GDBus implementations of D-Bus can usually only access file descriptors if they are referenced in this way by a value of type G_VARIANT_TYPE_HANDLE in the body of the message.

Since: 2.30

g_dbus_connection_call_with_unix_fd_list_sync ()

GVariant *
g_dbus_connection_call_with_unix_fd_list_sync
                               (GDBusConnection *connection,
                                const gchar *bus_name,
                                const gchar *object_path,
                                const gchar *interface_name,
                                const gchar *method_name,
                                GVariant *parameters,
                                const GVariantType *reply_type,
                                GDBusCallFlags flags,
                                gint timeout_msec,
                                GUnixFDList *fd_list,
                                GUnixFDList **out_fd_list,
                                GCancellable *cancellable,
                                GError **error);

Like g_dbus_connection_call_sync() but also takes and returns GUnixFDList objects. See g_dbus_connection_call_with_unix_fd_list() and g_dbus_connection_call_with_unix_fd_list_finish() for more details.

This method is only available on UNIX.

Since: 2.30

g_dbus_connection_emit_signal ()

gboolean
g_dbus_connection_emit_signal (GDBusConnection *connection,
                               const gchar *destination_bus_name,
                               const gchar *object_path,
                               const gchar *interface_name,
                               const gchar *signal_name,
                               GVariant *parameters,
                               GError **error);

Emits a signal.

If the parameters GVariant is floating, it is consumed.

This can only fail if parameters is not compatible with the D-Bus protocol (G_IO_ERROR_INVALID_ARGUMENT), or if connection has been closed (G_IO_ERROR_CLOSED).

Since: 2.26

GDBusSignalCallback ()

void
(*GDBusSignalCallback) (GDBusConnection *connection,
                        const gchar *sender_name,
                        const gchar *object_path,
                        const gchar *interface_name,
                        const gchar *signal_name,
                        GVariant *parameters,
                        gpointer user_data);

Signature for callback function used in g_dbus_connection_signal_subscribe().

Since: 2.26

g_dbus_connection_signal_subscribe ()

guint
g_dbus_connection_signal_subscribe (GDBusConnection *connection,
                                    const gchar *sender,
                                    const gchar *interface_name,
                                    const gchar *member,
                                    const gchar *object_path,
                                    const gchar *arg0,
                                    GDBusSignalFlags flags,
                                    GDBusSignalCallback callback,
                                    gpointer user_data,
                                    GDestroyNotify user_data_free_func);

Subscribes to signals on connection and invokes callback with a whenever the signal is received. Note that callback will be invoked in the thread-default main context of the thread you are calling this method from.

If connection is not a message bus connection, sender must be NULL.

If sender is a well-known name note that callback is invoked with the unique name for the owner of sender , not the well-known name as one would expect. This is because the message bus rewrites the name. As such, to avoid certain race conditions, users should be tracking the name owner of the well-known name and use that when processing the received signal.

If one of G_DBUS_SIGNAL_FLAGS_MATCH_ARG0_NAMESPACE or G_DBUS_SIGNAL_FLAGS_MATCH_ARG0_PATH are given, arg0 is interpreted as part of a namespace or path. The first argument of a signal is matched against that part as specified by D-Bus.

If user_data_free_func is non-NULL, it will be called (in the thread-default main context of the thread you are calling this method from) at some point after user_data is no longer needed. (It is not guaranteed to be called synchronously when the signal is unsubscribed from, and may be called after connection has been destroyed.)

As callback is potentially invoked in a different thread from where it’s emitted, it’s possible for this to happen after g_dbus_connection_signal_unsubscribe() has been called in another thread. Due to this, user_data should have a strong reference which is freed with user_data_free_func , rather than pointing to data whose lifecycle is tied to the signal subscription. For example, if a GObject is used to store the subscription ID from g_dbus_connection_signal_subscribe(), a strong reference to that GObject must be passed to user_data , and g_object_unref() passed to user_data_free_func . You are responsible for breaking the resulting reference count cycle by explicitly unsubscribing from the signal when dropping the last external reference to the GObject. Alternatively, a weak reference may be used.

It is guaranteed that if you unsubscribe from a signal using g_dbus_connection_signal_unsubscribe() from the same thread which made the corresponding g_dbus_connection_signal_subscribe() call, callback will not be invoked after g_dbus_connection_signal_unsubscribe() returns.

The returned subscription identifier is an opaque value which is guaranteed to never be zero.

This function can never fail.

Since: 2.26

g_dbus_connection_signal_unsubscribe ()

void
g_dbus_connection_signal_unsubscribe (GDBusConnection *connection,
                                      guint subscription_id);

Unsubscribes from signals.

Note that there may still be D-Bus traffic to process (relating to this signal subscription) in the current thread-default GMainContext after this function has returned. You should continue to iterate the GMainContext until the GDestroyNotify function passed to g_dbus_connection_signal_subscribe() is called, in order to avoid memory leaks through callbacks queued on the GMainContext after it’s stopped being iterated.

Since: 2.26

g_dbus_connection_send_message ()

gboolean
g_dbus_connection_send_message (GDBusConnection *connection,
                                GDBusMessage *message,
                                GDBusSendMessageFlags flags,
                                volatile guint32 *out_serial,
                                GError **error);

Asynchronously sends message to the peer represented by connection .

Unless flags contain the G_DBUS_SEND_MESSAGE_FLAGS_PRESERVE_SERIAL flag, the serial number will be assigned by connection and set on message via g_dbus_message_set_serial(). If out_serial is not NULL, then the serial number used will be written to this location prior to submitting the message to the underlying transport. While it has a volatile qualifier, this is a historical artifact and the argument passed to it should not be volatile.

If connection is closed then the operation will fail with G_IO_ERROR_CLOSED. If message is not well-formed, the operation fails with G_IO_ERROR_INVALID_ARGUMENT.

See this server and client for an example of how to use this low-level API to send and receive UNIX file descriptors.

Note that message must be unlocked, unless flags contain the G_DBUS_SEND_MESSAGE_FLAGS_PRESERVE_SERIAL flag.

Since: 2.26

g_dbus_connection_send_message_with_reply ()

void
g_dbus_connection_send_message_with_reply
                               (GDBusConnection *connection,
                                GDBusMessage *message,
                                GDBusSendMessageFlags flags,
                                gint timeout_msec,
                                volatile guint32 *out_serial,
                                GCancellable *cancellable,
                                GAsyncReadyCallback callback,
                                gpointer user_data);

Asynchronously sends message to the peer represented by connection .

Unless flags contain the G_DBUS_SEND_MESSAGE_FLAGS_PRESERVE_SERIAL flag, the serial number will be assigned by connection and set on message via g_dbus_message_set_serial(). If out_serial is not NULL, then the serial number used will be written to this location prior to submitting the message to the underlying transport. While it has a volatile qualifier, this is a historical artifact and the argument passed to it should not be volatile.

If connection is closed then the operation will fail with G_IO_ERROR_CLOSED. If cancellable is canceled, the operation will fail with G_IO_ERROR_CANCELLED. If message is not well-formed, the operation fails with G_IO_ERROR_INVALID_ARGUMENT.

This is an asynchronous method. When the operation is finished, callback will be invoked in the thread-default main context of the thread you are calling this method from. You can then call g_dbus_connection_send_message_with_reply_finish() to get the result of the operation. See g_dbus_connection_send_message_with_reply_sync() for the synchronous version.

Note that message must be unlocked, unless flags contain the G_DBUS_SEND_MESSAGE_FLAGS_PRESERVE_SERIAL flag.

See this server and client for an example of how to use this low-level API to send and receive UNIX file descriptors.

Since: 2.26

g_dbus_connection_send_message_with_reply_finish ()

GDBusMessage *
g_dbus_connection_send_message_with_reply_finish
                               (GDBusConnection *connection,
                                GAsyncResult *res,
                                GError **error);

Finishes an operation started with g_dbus_connection_send_message_with_reply().

Note that error is only set if a local in-process error occurred. That is to say that the returned GDBusMessage object may be of type G_DBUS_MESSAGE_TYPE_ERROR. Use g_dbus_message_to_gerror() to transcode this to a GError.

See this server and client for an example of how to use this low-level API to send and receive UNIX file descriptors.

Since: 2.26

g_dbus_connection_send_message_with_reply_sync ()

GDBusMessage *
g_dbus_connection_send_message_with_reply_sync
                               (GDBusConnection *connection,
                                GDBusMessage *message,
                                GDBusSendMessageFlags flags,
                                gint timeout_msec,
                                volatile guint32 *out_serial,
                                GCancellable *cancellable,
                                GError **error);

Synchronously sends message to the peer represented by connection and blocks the calling thread until a reply is received or the timeout is reached. See g_dbus_connection_send_message_with_reply() for the asynchronous version of this method.

Unless flags contain the G_DBUS_SEND_MESSAGE_FLAGS_PRESERVE_SERIAL flag, the serial number will be assigned by connection and set on message via g_dbus_message_set_serial(). If out_serial is not NULL, then the serial number used will be written to this location prior to submitting the message to the underlying transport. While it has a volatile qualifier, this is a historical artifact and the argument passed to it should not be volatile.

If connection is closed then the operation will fail with G_IO_ERROR_CLOSED. If cancellable is canceled, the operation will fail with G_IO_ERROR_CANCELLED. If message is not well-formed, the operation fails with G_IO_ERROR_INVALID_ARGUMENT.

Note that error is only set if a local in-process error occurred. That is to say that the returned GDBusMessage object may be of type G_DBUS_MESSAGE_TYPE_ERROR. Use g_dbus_message_to_gerror() to transcode this to a GError.

See this server and client for an example of how to use this low-level API to send and receive UNIX file descriptors.

Note that message must be unlocked, unless flags contain the G_DBUS_SEND_MESSAGE_FLAGS_PRESERVE_SERIAL flag.

Since: 2.26

GDBusMessageFilterFunction ()

GDBusMessage *
(*GDBusMessageFilterFunction) (GDBusConnection *connection,
                               GDBusMessage *message,
                               gboolean incoming,
                               gpointer user_data);

Signature for function used in g_dbus_connection_add_filter().

A filter function is passed a GDBusMessage and expected to return a GDBusMessage too. Passive filter functions that don't modify the message can simply return the message object:

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static GDBusMessage *
passive_filter (GDBusConnection *connection
                GDBusMessage    *message,
                gboolean         incoming,
                gpointer         user_data)
{
  // inspect @message
  return message;
}

Filter functions that wants to drop a message can simply return NULL:

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static GDBusMessage *
drop_filter (GDBusConnection *connection
             GDBusMessage    *message,
             gboolean         incoming,
             gpointer         user_data)
{
  if (should_drop_message)
    {
      g_object_unref (message);
      message = NULL;
    }
  return message;
}

Finally, a filter function may modify a message by copying it:

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static GDBusMessage *
modifying_filter (GDBusConnection *connection
                  GDBusMessage    *message,
                  gboolean         incoming,
                  gpointer         user_data)
{
  GDBusMessage *copy;
  GError *error;

  error = NULL;
  copy = g_dbus_message_copy (message, &error);
  // handle @error being set
  g_object_unref (message);

  // modify @copy

  return copy;
}

If the returned GDBusMessage is different from message and cannot be sent on connection (it could use features, such as file descriptors, not compatible with connection ), then a warning is logged to standard error. Applications can check this ahead of time using g_dbus_message_to_blob() passing a GDBusCapabilityFlags value obtained from connection .

Since: 2.26

g_dbus_connection_add_filter ()

guint
g_dbus_connection_add_filter (GDBusConnection *connection,
                              GDBusMessageFilterFunction filter_function,
                              gpointer user_data,
                              GDestroyNotify user_data_free_func);

Adds a message filter. Filters are handlers that are run on all incoming and outgoing messages, prior to standard dispatch. Filters are run in the order that they were added. The same handler can be added as a filter more than once, in which case it will be run more than once. Filters added during a filter callback won't be run on the message being processed. Filter functions are allowed to modify and even drop messages.

Note that filters are run in a dedicated message handling thread so they can't block and, generally, can't do anything but signal a worker thread. Also note that filters are rarely needed - use API such as g_dbus_connection_send_message_with_reply(), g_dbus_connection_signal_subscribe() or g_dbus_connection_call() instead.

If a filter consumes an incoming message the message is not dispatched anywhere else - not even the standard dispatch machinery (that API such as g_dbus_connection_signal_subscribe() and g_dbus_connection_send_message_with_reply() relies on) will see the message. Similarly, if a filter consumes an outgoing message, the message will not be sent to the other peer.

If user_data_free_func is non-NULL, it will be called (in the thread-default main context of the thread you are calling this method from) at some point after user_data is no longer needed. (It is not guaranteed to be called synchronously when the filter is removed, and may be called after connection has been destroyed.)

Since: 2.26

g_dbus_connection_remove_filter ()

void
g_dbus_connection_remove_filter (GDBusConnection *connection,
                                 guint filter_id);

Removes a filter.

Note that since filters run in a different thread, there is a race condition where it is possible that the filter will be running even after calling g_dbus_connection_remove_filter(), so you cannot just free data that the filter might be using. Instead, you should pass a GDestroyNotify to g_dbus_connection_add_filter(), which will be called when it is guaranteed that the data is no longer needed.

Since: 2.26

GDBusInterfaceMethodCallFunc ()

void
(*GDBusInterfaceMethodCallFunc) (GDBusConnection *connection,
                                 const gchar *sender,
                                 const gchar *object_path,
                                 const gchar *interface_name,
                                 const gchar *method_name,
                                 GVariant *parameters,
                                 GDBusMethodInvocation *invocation,
                                 gpointer user_data);

The type of the method_call function in GDBusInterfaceVTable.

Since: 2.26

GDBusInterfaceGetPropertyFunc ()

GVariant *
(*GDBusInterfaceGetPropertyFunc) (GDBusConnection *connection,
                                  const gchar *sender,
                                  const gchar *object_path,
                                  const gchar *interface_name,
                                  const gchar *property_name,
                                  GError **error,
                                  gpointer user_data);

The type of the get_property function in GDBusInterfaceVTable.

Since: 2.26

GDBusInterfaceSetPropertyFunc ()

gboolean
(*GDBusInterfaceSetPropertyFunc) (GDBusConnection *connection,
                                  const gchar *sender,
                                  const gchar *object_path,
                                  const gchar *interface_name,
                                  const gchar *property_name,
                                  GVariant *value,
                                  GError **error,
                                  gpointer user_data);

The type of the set_property function in GDBusInterfaceVTable.

Since: 2.26

g_dbus_connection_register_object ()

guint
g_dbus_connection_register_object (GDBusConnection *connection,
                                   const gchar *object_path,
                                   GDBusInterfaceInfo *interface_info,
                                   const GDBusInterfaceVTable *vtable,
                                   gpointer user_data,
                                   GDestroyNotify user_data_free_func,
                                   GError **error);

Registers callbacks for exported objects at object_path with the D-Bus interface that is described in interface_info .

Calls to functions in vtable (and user_data_free_func ) will happen in the thread-default main context of the thread you are calling this method from.

Note that all GVariant values passed to functions in vtable will match the signature given in interface_info - if a remote caller passes incorrect values, the org.freedesktop.DBus.Error.InvalidArgs is returned to the remote caller.

Additionally, if the remote caller attempts to invoke methods or access properties not mentioned in interface_info the org.freedesktop.DBus.Error.UnknownMethod resp. org.freedesktop.DBus.Error.InvalidArgs errors are returned to the caller.

It is considered a programming error if the GDBusInterfaceGetPropertyFunc function in vtable returns a GVariant of incorrect type.

If an existing callback is already registered at object_path and interface_name , then error is set to G_IO_ERROR_EXISTS.

GDBus automatically implements the standard D-Bus interfaces org.freedesktop.DBus.Properties, org.freedesktop.DBus.Introspectable and org.freedesktop.Peer, so you don't have to implement those for the objects you export. You can implement org.freedesktop.DBus.Properties yourself, e.g. to handle getting and setting of properties asynchronously.

Note that the reference count on interface_info will be incremented by 1 (unless allocated statically, e.g. if the reference count is -1, see g_dbus_interface_info_ref()) for as long as the object is exported. Also note that vtable will be copied.

See this server for an example of how to use this method.

Since: 2.26

g_dbus_connection_unregister_object ()

gboolean
g_dbus_connection_unregister_object (GDBusConnection *connection,
                                     guint registration_id);

Unregisters an object.

Since: 2.26

g_dbus_connection_register_object_with_closures ()

guint
g_dbus_connection_register_object_with_closures
                               (GDBusConnection *connection,
                                const gchar *object_path,
                                GDBusInterfaceInfo *interface_info,
                                GClosure *method_call_closure,
                                GClosure *get_property_closure,
                                GClosure *set_property_closure,
                                GError **error);

Version of g_dbus_connection_register_object() using closures instead of a GDBusInterfaceVTable for easier binding in other languages.

[rename-to g_dbus_connection_register_object]

Since: 2.46

GDBusSubtreeEnumerateFunc ()

gchar **
(*GDBusSubtreeEnumerateFunc) (GDBusConnection *connection,
                              const gchar *sender,
                              const gchar *object_path,
                              gpointer user_data);

The type of the enumerate function in GDBusSubtreeVTable.

This function is called when generating introspection data and also when preparing to dispatch incoming messages in the event that the G_DBUS_SUBTREE_FLAGS_DISPATCH_TO_UNENUMERATED_NODES flag is not specified (ie: to verify that the object path is valid).

Hierarchies are not supported; the items that you return should not contain the / character.

The return value will be freed with g_strfreev().

Since: 2.26

GDBusSubtreeIntrospectFunc ()

GDBusInterfaceInfo **
(*GDBusSubtreeIntrospectFunc) (GDBusConnection *connection,
                               const gchar *sender,
                               const gchar *object_path,
                               const gchar *node,
                               gpointer user_data);

The type of the introspect function in GDBusSubtreeVTable.

Subtrees are flat. node , if non-NULL, is always exactly one segment of the object path (ie: it never contains a slash).

This function should return NULL to indicate that there is no object at this node.

If this function returns non-NULL, the return value is expected to be a NULL-terminated array of pointers to GDBusInterfaceInfo structures describing the interfaces implemented by node . This array will have g_dbus_interface_info_unref() called on each item before being freed with g_free().

The difference between returning NULL and an array containing zero items is that the standard DBus interfaces will returned to the remote introspector in the empty array case, but not in the NULL case.

Since: 2.26

GDBusSubtreeDispatchFunc ()

const GDBusInterfaceVTable *
(*GDBusSubtreeDispatchFunc) (GDBusConnection *connection,
                             const gchar *sender,
                             const gchar *object_path,
                             const gchar *interface_name,
                             const gchar *node,
                             gpointer *out_user_data,
                             gpointer user_data);

The type of the dispatch function in GDBusSubtreeVTable.

Subtrees are flat. node , if non-NULL, is always exactly one segment of the object path (ie: it never contains a slash).

Since: 2.26

g_dbus_connection_register_subtree ()

guint
g_dbus_connection_register_subtree (GDBusConnection *connection,
                                    const gchar *object_path,
                                    const GDBusSubtreeVTable *vtable,
                                    GDBusSubtreeFlags flags,
                                    gpointer user_data,
                                    GDestroyNotify user_data_free_func,
                                    GError **error);

Registers a whole subtree of dynamic objects.

The enumerate and introspection functions in vtable are used to convey, to remote callers, what nodes exist in the subtree rooted by object_path .

When handling remote calls into any node in the subtree, first the enumerate function is used to check if the node exists. If the node exists or the G_DBUS_SUBTREE_FLAGS_DISPATCH_TO_UNENUMERATED_NODES flag is set the introspection function is used to check if the node supports the requested method. If so, the dispatch function is used to determine where to dispatch the call. The collected GDBusInterfaceVTable and gpointer will be used to call into the interface vtable for processing the request.

All calls into user-provided code will be invoked in the thread-default main context of the thread you are calling this method from.

If an existing subtree is already registered at object_path or then error is set to G_IO_ERROR_EXISTS.

Note that it is valid to register regular objects (using g_dbus_connection_register_object()) in a subtree registered with g_dbus_connection_register_subtree() - if so, the subtree handler is tried as the last resort. One way to think about a subtree handler is to consider it a fallback handler for object paths not registered via g_dbus_connection_register_object() or other bindings.

Note that vtable will be copied so you cannot change it after registration.

See this server for an example of how to use this method.

Since: 2.26

g_dbus_connection_unregister_subtree ()

gboolean
g_dbus_connection_unregister_subtree (GDBusConnection *connection,
                                      guint registration_id);

Unregisters a subtree.

Since: 2.26

enum GBusType

An enumeration for well-known message buses.

Since: 2.26

GDBusConnection

typedef struct _GDBusConnection GDBusConnection;

The GDBusConnection structure contains only private data and should only be accessed using the provided API.

Since: 2.26

enum GDBusConnectionFlags

Flags used when creating a new GDBusConnection.

Since: 2.26

enum GDBusCapabilityFlags

Capabilities negotiated with the remote peer.

Since: 2.26

enum GDBusCallFlags

Flags used in g_dbus_connection_call() and similar APIs.

Since: 2.26

enum GDBusSignalFlags

Flags used when subscribing to signals via g_dbus_connection_signal_subscribe().

Since: 2.26

enum GDBusSendMessageFlags

Flags used when sending GDBusMessages on a GDBusConnection.

Since: 2.26

GDBusInterfaceVTable

typedef struct {
  GDBusInterfaceMethodCallFunc  method_call;
  GDBusInterfaceGetPropertyFunc get_property;
  GDBusInterfaceSetPropertyFunc set_property;
} GDBusInterfaceVTable;

Virtual table for handling properties and method calls for a D-Bus interface.

Since 2.38, if you want to handle getting/setting D-Bus properties asynchronously, give NULL as your get_property() or set_property() function. The D-Bus call will be directed to your method_call function, with the provided interface_name set to "org.freedesktop.DBus.Properties".

Ownership of the GDBusMethodInvocation object passed to the method_call() function is transferred to your handler; you must call one of the methods of GDBusMethodInvocation to return a reply (possibly empty), or an error. These functions also take ownership of the passed-in invocation object, so unless the invocation object has otherwise been referenced, it will be then be freed. Calling one of these functions may be done within your method_call() implementation but it also can be done at a later point to handle the method asynchronously.

The usual checks on the validity of the calls is performed. For Get calls, an error is automatically returned if the property does not exist or the permissions do not allow access. The same checks are performed for Set calls, and the provided value is also checked for being the correct type.

For both Get and Set calls, the GDBusMethodInvocation passed to the method_call handler can be queried with g_dbus_method_invocation_get_property_info() to get a pointer to the GDBusPropertyInfo of the property.

If you have readable properties specified in your interface info, you must ensure that you either provide a non-NULL get_property() function or provide implementations of both the Get and GetAll methods on org.freedesktop.DBus.Properties interface in your method_call function. Note that the required return type of the Get call is (v), not the type of the property. GetAll expects a return value of type a{sv}.

If you have writable properties specified in your interface info, you must ensure that you either provide a non-NULL set_property() function or provide an implementation of the Set call. If implementing the call, you must return the value of type G_VARIANT_TYPE_UNIT.

Since: 2.26

GDBusSubtreeVTable

typedef struct {
  GDBusSubtreeEnumerateFunc  enumerate;
  GDBusSubtreeIntrospectFunc introspect;
  GDBusSubtreeDispatchFunc   dispatch;
} GDBusSubtreeVTable;

Virtual table for handling subtrees registered with g_dbus_connection_register_subtree().

Since: 2.26

enum GDBusSubtreeFlags

Flags passed to g_dbus_connection_register_subtree().

Since: 2.26

The “address” property

  “address”                  char *

A D-Bus address specifying potential endpoints that can be used when establishing the connection.

Owner: GDBusConnection

Flags: Write / Construct Only

Default value: NULL

Since: 2.26

The “authentication-observer” property

  “authentication-observer”  GDBusAuthObserver *

A GDBusAuthObserver object to assist in the authentication process or NULL.

Owner: GDBusConnection

Flags: Write / Construct Only

Since: 2.26

The “capabilities” property

  “capabilities”             GDBusCapabilityFlags

Flags from the GDBusCapabilityFlags enumeration representing connection features negotiated with the other peer.

Owner: GDBusConnection

Flags: Read

Since: 2.26

The “closed” property

  “closed”                   gboolean

A boolean specifying whether the connection has been closed.

Owner: GDBusConnection

Flags: Read

Default value: FALSE

Since: 2.26

The “exit-on-close” property

  “exit-on-close”            gboolean

A boolean specifying whether the process will be terminated (by calling raise(SIGTERM)) if the connection is closed by the remote peer.

Note that GDBusConnection objects returned by g_bus_get_finish() and g_bus_get_sync() will (usually) have this property set to TRUE.

Owner: GDBusConnection

Flags: Read / Write

Default value: FALSE

Since: 2.26

The “flags” property

  “flags”                    GDBusConnectionFlags

Flags from the GDBusConnectionFlags enumeration.

Owner: GDBusConnection

Flags: Read / Write / Construct Only

Since: 2.26

The “guid” property

  “guid”                     char *

The GUID of the peer performing the role of server when authenticating.

If you are constructing a GDBusConnection and pass G_DBUS_CONNECTION_FLAGS_AUTHENTICATION_SERVER in the “flags” property then you **must** also set this property to a valid guid.

If you are constructing a GDBusConnection and pass G_DBUS_CONNECTION_FLAGS_AUTHENTICATION_CLIENT in the “flags” property you will be able to read the GUID of the other peer here after the connection has been successfully initialized.

Owner: GDBusConnection

Flags: Read / Write / Construct Only

Default value: NULL

Since: 2.26

The “stream” property

  “stream”                   GIOStream *

The underlying GIOStream used for I/O.

If this is passed on construction and is a GSocketConnection, then the corresponding GSocket will be put into non-blocking mode.

While the GDBusConnection is active, it will interact with this stream from a worker thread, so it is not safe to interact with the stream directly.

Owner: GDBusConnection

Flags: Read / Write / Construct Only

Since: 2.26

The “unique-name” property

  “unique-name”              char *

The unique name as assigned by the message bus or NULL if the connection is not open or not a message bus connection.

Owner: GDBusConnection

Flags: Read

Default value: NULL

Since: 2.26

The “closed” signal

void
user_function (GDBusConnection *connection,
               gboolean         remote_peer_vanished,
               GError          *error,
               gpointer         user_data)

Emitted when the connection is closed.

The cause of this event can be

Upon receiving this signal, you should give up your reference to connection . You are guaranteed that this signal is emitted only once.

Flags: Run Last

Since: 2.26