DBusConnection.sendMessageWithReplySync

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 [gio.dbus_connection.DBusConnection.sendMessageWithReply] for the asynchronous version of this method.

Unless flags contain the [gio.types.DBusSendMessageFlags.PreserveSerial] flag, the serial number will be assigned by connection and set on message via [gio.dbus_message.DBusMessage.setSerial]. 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 [gio.types.IOErrorEnum.Closed]. If cancellable is canceled, the operation will fail with [gio.types.IOErrorEnum.Cancelled]. If message is not well-formed, the operation fails with [gio.types.IOErrorEnum.InvalidArgument].

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 [gio.types.DBusMessageType.Error]. Use [gio.dbus_message.DBusMessage.toGerror] to transcode this to a #GError.

See this [server][gdbus-server] and [client][gdbus-unix-fd-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 [gio.types.DBusSendMessageFlags.PreserveSerial] flag.