gio/

dbus_connection.rs

// Take a look at the license at the top of the repository in the LICENSE file.

use std::{boxed::Box as Box_, future::Future, marker::PhantomData, num::NonZeroU32};

use crate::{
    ffi, ActionGroup, DBusConnection, DBusInterfaceInfo, DBusMessage, DBusMethodInvocation,
    DBusSignalFlags, MenuModel,
};
use glib::{prelude::*, translate::*};

pub trait DBusMethodCall: Sized {
    fn parse_call(
        obj_path: &str,
        interface: &str,
        method: &str,
        params: glib::Variant,
    ) -> Result<Self, glib::Error>;
}

// rustdoc-stripper-ignore-next
/// Handle method invocations.
pub struct MethodCallBuilder<'a, T> {
    registration: RegistrationBuilder<'a>,
    capture_type: PhantomData<T>,
}

impl<'a, T: DBusMethodCall> MethodCallBuilder<'a, T> {
    // rustdoc-stripper-ignore-next
    /// Handle invocation of a parsed method call.
    ///
    /// For each DBus method call parse the call, and then invoke the given closure
    /// with
    ///
    /// 1. the DBus connection object,
    /// 2. the name of the sender of the method call,
    /// 3. the parsed call, and
    /// 4. the method invocation object.
    ///
    /// The closure **must** return a value through the invocation object in all
    /// code paths, using any of its `return_` functions, such as
    /// [`DBusMethodInvocation::return_result`] or
    /// [`DBusMethodInvocation::return_future_local`], to finish the call.
    ///
    /// If direct access to the invocation object is not needed,
    /// [`invoke_and_return`] and [`invoke_and_return_future_local`] provide a
    /// safer interface where the callback returns a result directly.
    pub fn invoke<F>(self, f: F) -> RegistrationBuilder<'a>
    where
        F: Fn(DBusConnection, &str, T, DBusMethodInvocation) + 'static,
    {
        self.registration.method_call(
            move |connection, sender, obj_path, interface, method, params, invocation| {
                match T::parse_call(obj_path, interface, method, params) {
                    Ok(call) => f(connection, sender, call, invocation),
                    Err(error) => invocation.return_gerror(error),
                }
            },
        )
    }

    // rustdoc-stripper-ignore-next
    /// Handle invocation of a parsed method call.
    ///
    /// For each DBus method call parse the call, and then invoke the given closure
    /// with
    ///
    /// 1. the DBus connection object,
    /// 2. the name of the sender of the method call, and
    /// 3. the parsed call.
    ///
    /// The return value of the closure is then returned on the method call.
    /// If the returned variant value is not a tuple, it is automatically wrapped
    /// in a single element tuple, as DBus methods must always return tuples.
    /// See [`DBusMethodInvocation::return_result`] for details.
    pub fn invoke_and_return<F>(self, f: F) -> RegistrationBuilder<'a>
    where
        F: Fn(DBusConnection, &str, T) -> Result<Option<glib::Variant>, glib::Error> + 'static,
    {
        self.invoke(move |connection, sender, call, invocation| {
            invocation.return_result(f(connection, sender, call))
        })
    }

    // rustdoc-stripper-ignore-next
    /// Handle an async invocation of a parsed method call.
    ///
    /// For each DBus method call parse the call, and then invoke the given closure
    /// with
    ///
    /// 1. the DBus connection object,
    /// 2. the name of the sender of the method call, and
    /// 3. the parsed call.
    ///
    /// The output of the future is then returned on the method call.
    /// If the returned variant value is not a tuple, it is automatically wrapped
    /// in a single element tuple, as DBus methods must always return tuples.
    /// See [`DBusMethodInvocation::return_future_local`] for details.
    pub fn invoke_and_return_future_local<F, Fut>(self, f: F) -> RegistrationBuilder<'a>
    where
        F: Fn(DBusConnection, &str, T) -> Fut + 'static,
        Fut: Future<Output = Result<Option<glib::Variant>, glib::Error>> + 'static,
    {
        self.invoke(move |connection, sender, call, invocation| {
            invocation.return_future_local(f(connection, sender, call));
        })
    }
}

#[derive(Debug, Eq, PartialEq)]
pub struct RegistrationId(NonZeroU32);
#[derive(Debug, Eq, PartialEq)]
pub struct WatcherId(NonZeroU32);
#[derive(Debug, Eq, PartialEq)]
pub struct ActionGroupExportId(NonZeroU32);
#[derive(Debug, Eq, PartialEq)]
pub struct MenuModelExportId(NonZeroU32);
#[derive(Debug, Eq, PartialEq)]
pub struct FilterId(NonZeroU32);
#[derive(Debug, Eq, PartialEq)]
pub struct SignalSubscriptionId(NonZeroU32);

// rustdoc-stripper-ignore-next
/// Build a registered DBus object, by handling different parts of DBus.
#[must_use = "The builder must be built to be used"]
pub struct RegistrationBuilder<'a> {
    connection: &'a DBusConnection,
    object_path: &'a str,
    interface_info: &'a DBusInterfaceInfo,
    #[allow(clippy::type_complexity)]
    method_call: Option<
        Box_<dyn Fn(DBusConnection, &str, &str, &str, &str, glib::Variant, DBusMethodInvocation)>,
    >,
    #[allow(clippy::type_complexity)]
    get_property: Option<Box_<dyn Fn(DBusConnection, &str, &str, &str, &str) -> glib::Variant>>,
    #[allow(clippy::type_complexity)]
    set_property:
        Option<Box_<dyn Fn(DBusConnection, &str, &str, &str, &str, glib::Variant) -> bool>>,
}

impl<'a> RegistrationBuilder<'a> {
    pub fn method_call<
        F: Fn(DBusConnection, &str, &str, &str, &str, glib::Variant, DBusMethodInvocation) + 'static,
    >(
        mut self,
        f: F,
    ) -> Self {
        self.method_call = Some(Box_::new(f));
        self
    }

    // rustdoc-stripper-ignore-next
    /// Handle method calls on this object.
    ///
    /// Return a builder for method calls which parses method names and
    /// parameters with the given [`DBusMethodCall`] and then allows to dispatch
    /// the parsed call either synchronously or asynchronously.
    pub fn typed_method_call<T: DBusMethodCall>(self) -> MethodCallBuilder<'a, T> {
        MethodCallBuilder {
            registration: self,
            capture_type: Default::default(),
        }
    }

    #[doc(alias = "get_property")]
    pub fn property<F: Fn(DBusConnection, &str, &str, &str, &str) -> glib::Variant + 'static>(
        mut self,
        f: F,
    ) -> Self {
        self.get_property = Some(Box_::new(f));
        self
    }

    pub fn set_property<
        F: Fn(DBusConnection, &str, &str, &str, &str, glib::Variant) -> bool + 'static,
    >(
        mut self,
        f: F,
    ) -> Self {
        self.set_property = Some(Box_::new(f));
        self
    }

    pub fn build(self) -> Result<RegistrationId, glib::Error> {
        unsafe {
            let mut error = std::ptr::null_mut();
            let id = ffi::g_dbus_connection_register_object_with_closures(
                self.connection.to_glib_none().0,
                self.object_path.to_glib_none().0,
                self.interface_info.to_glib_none().0,
                self.method_call
                    .map(|f| {
                        glib::Closure::new_local(move |args| {
                            let conn = args[0].get::<DBusConnection>().unwrap();
                            let sender = args[1].get::<&str>().unwrap();
                            let object_path = args[2].get::<&str>().unwrap();
                            let interface_name = args[3].get::<&str>().unwrap();
                            let method_name = args[4].get::<&str>().unwrap();
                            let parameters = args[5].get::<glib::Variant>().unwrap();
                            let invocation = args[6].get::<DBusMethodInvocation>().unwrap();
                            f(
                                conn,
                                sender,
                                object_path,
                                interface_name,
                                method_name,
                                parameters,
                                invocation,
                            );
                            None
                        })
                    })
                    .to_glib_none()
                    .0,
                self.set_property
                    .map(|f| {
                        glib::Closure::new_local(move |args| {
                            let conn = args[0].get::<DBusConnection>().unwrap();
                            let sender = args[1].get::<&str>().unwrap();
                            let object_path = args[2].get::<&str>().unwrap();
                            let interface_name = args[3].get::<&str>().unwrap();
                            let property_name = args[4].get::<&str>().unwrap();
                            let value = args[5].get::<glib::Variant>().unwrap();
                            let result = f(
                                conn,
                                sender,
                                object_path,
                                interface_name,
                                property_name,
                                value,
                            );
                            Some(result.to_value())
                        })
                    })
                    .to_glib_none()
                    .0,
                self.get_property
                    .map(|f| {
                        glib::Closure::new_local(move |args| {
                            let conn = args[0].get::<DBusConnection>().unwrap();
                            let sender = args[1].get::<&str>().unwrap();
                            let object_path = args[2].get::<&str>().unwrap();
                            let interface_name = args[3].get::<&str>().unwrap();
                            let property_name = args[4].get::<&str>().unwrap();
                            let result =
                                f(conn, sender, object_path, interface_name, property_name);
                            Some(result.to_value())
                        })
                    })
                    .to_glib_none()
                    .0,
                &mut error,
            );

            if error.is_null() {
                Ok(RegistrationId(NonZeroU32::new_unchecked(id)))
            } else {
                Err(from_glib_full(error))
            }
        }
    }
}

impl DBusConnection {
    /// 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][g-main-context-push-thread-default]
    /// 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 [`IOErrorEnum::Exists`][crate::IOErrorEnum::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][gdbus-server] for an example of how to use this method.
    /// ## `object_path`
    /// the object path to register at
    /// ## `interface_info`
    /// introspection data for the interface
    /// ## `vtable`
    /// a #GDBusInterfaceVTable to call into or [`None`]
    ///
    /// # Returns
    ///
    /// 0 if @error is set, otherwise a registration id (never 0)
    ///     that can be used with g_dbus_connection_unregister_object()
    #[doc(alias = "g_dbus_connection_register_object")]
    #[doc(alias = "g_dbus_connection_register_object_with_closures")]
    pub fn register_object<'a>(
        &'a self,
        object_path: &'a str,
        interface_info: &'a DBusInterfaceInfo,
    ) -> RegistrationBuilder<'a> {
        RegistrationBuilder {
            connection: self,
            object_path,
            interface_info,
            method_call: None,
            get_property: None,
            set_property: None,
        }
    }

    /// Unregisters an object.
    /// ## `registration_id`
    /// a registration id obtained from
    ///     g_dbus_connection_register_object()
    ///
    /// # Returns
    ///
    /// [`true`] if the object was unregistered, [`false`] otherwise
    #[doc(alias = "g_dbus_connection_unregister_object")]
    pub fn unregister_object(
        &self,
        registration_id: RegistrationId,
    ) -> Result<(), glib::error::BoolError> {
        unsafe {
            glib::result_from_gboolean!(
                ffi::g_dbus_connection_unregister_object(
                    self.to_glib_none().0,
                    registration_id.0.into()
                ),
                "Failed to unregister D-Bus object"
            )
        }
    }

    /// Exports @action_group on @self at @object_path.
    ///
    /// The implemented D-Bus API should be considered private.  It is
    /// subject to change in the future.
    ///
    /// A given object path can only have one action group exported on it.
    /// If this constraint is violated, the export will fail and 0 will be
    /// returned (with @error set accordingly).
    ///
    /// You can unexport the action group using
    /// [`unexport_action_group()`][Self::unexport_action_group()] with the return value of
    /// this function.
    ///
    /// The thread default main context is taken at the time of this call.
    /// All incoming action activations and state change requests are
    /// reported from this context.  Any changes on the action group that
    /// cause it to emit signals must also come from this same context.
    /// Since incoming action activations and state change requests are
    /// rather likely to cause changes on the action group, this effectively
    /// limits a given action group to being exported from only one main
    /// context.
    /// ## `object_path`
    /// a D-Bus object path
    /// ## `action_group`
    /// an action group
    ///
    /// # Returns
    ///
    /// the ID of the export (never zero), or 0 in case of failure
    #[doc(alias = "g_dbus_connection_export_action_group")]
    pub fn export_action_group<P: IsA<ActionGroup>>(
        &self,
        object_path: &str,
        action_group: &P,
    ) -> Result<ActionGroupExportId, glib::Error> {
        unsafe {
            let mut error = std::ptr::null_mut();
            let id = ffi::g_dbus_connection_export_action_group(
                self.to_glib_none().0,
                object_path.to_glib_none().0,
                action_group.as_ref().to_glib_none().0,
                &mut error,
            );
            if error.is_null() {
                Ok(ActionGroupExportId(NonZeroU32::new_unchecked(id)))
            } else {
                Err(from_glib_full(error))
            }
        }
    }

    /// Reverses the effect of a previous call to
    /// [`export_action_group()`][Self::export_action_group()].
    ///
    /// It is an error to call this function with an ID that wasn’t returned from
    /// [`export_action_group()`][Self::export_action_group()] or to call it with the same
    /// ID more than once.
    /// ## `export_id`
    /// the ID from [`export_action_group()`][Self::export_action_group()]
    #[doc(alias = "g_dbus_connection_unexport_action_group")]
    pub fn unexport_action_group(&self, export_id: ActionGroupExportId) {
        unsafe {
            ffi::g_dbus_connection_unexport_action_group(self.to_glib_none().0, export_id.0.into());
        }
    }

    /// Exports @menu on @self at @object_path.
    ///
    /// The implemented D-Bus API should be considered private.
    /// It is subject to change in the future.
    ///
    /// An object path can only have one menu model exported on it. If this
    /// constraint is violated, the export will fail and 0 will be
    /// returned (with @error set accordingly).
    ///
    /// Exporting menus with sections containing more than
    /// `G_MENU_EXPORTER_MAX_SECTION_SIZE` items is not supported and results in
    /// undefined behavior.
    ///
    /// You can unexport the menu model using
    /// g_dbus_connection_unexport_menu_model() with the return value of
    /// this function.
    /// ## `object_path`
    /// a D-Bus object path
    /// ## `menu`
    /// a #GMenuModel
    ///
    /// # Returns
    ///
    /// the ID of the export (never zero), or 0 in case of failure
    #[doc(alias = "g_dbus_connection_export_menu_model")]
    pub fn export_menu_model<P: IsA<MenuModel>>(
        &self,
        object_path: &str,
        menu: &P,
    ) -> Result<MenuModelExportId, glib::Error> {
        unsafe {
            let mut error = std::ptr::null_mut();
            let id = ffi::g_dbus_connection_export_menu_model(
                self.to_glib_none().0,
                object_path.to_glib_none().0,
                menu.as_ref().to_glib_none().0,
                &mut error,
            );
            if error.is_null() {
                Ok(MenuModelExportId(NonZeroU32::new_unchecked(id)))
            } else {
                Err(from_glib_full(error))
            }
        }
    }

    /// Reverses the effect of a previous call to
    /// g_dbus_connection_export_menu_model().
    ///
    /// It is an error to call this function with an ID that wasn't returned
    /// from g_dbus_connection_export_menu_model() or to call it with the
    /// same ID more than once.
    /// ## `export_id`
    /// the ID from g_dbus_connection_export_menu_model()
    #[doc(alias = "g_dbus_connection_unexport_menu_model")]
    pub fn unexport_menu_model(&self, export_id: MenuModelExportId) {
        unsafe {
            ffi::g_dbus_connection_unexport_menu_model(self.to_glib_none().0, export_id.0.into());
        }
    }

    /// 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-[`None`], 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 @self has been
    /// destroyed.)
    /// ## `filter_function`
    /// a filter function
    ///
    /// # Returns
    ///
    /// a filter identifier that can be used with
    ///     g_dbus_connection_remove_filter()
    #[doc(alias = "g_dbus_connection_add_filter")]
    pub fn add_filter<
        P: Fn(&DBusConnection, &DBusMessage, bool) -> Option<DBusMessage> + 'static,
    >(
        &self,
        filter_function: P,
    ) -> FilterId {
        let filter_function_data: Box_<P> = Box_::new(filter_function);
        unsafe extern "C" fn filter_function_func<
            P: Fn(&DBusConnection, &DBusMessage, bool) -> Option<DBusMessage> + 'static,
        >(
            connection: *mut ffi::GDBusConnection,
            message: *mut ffi::GDBusMessage,
            incoming: glib::ffi::gboolean,
            user_data: glib::ffi::gpointer,
        ) -> *mut ffi::GDBusMessage {
            let connection = from_glib_borrow(connection);
            let message = from_glib_full(message);
            let incoming = from_glib(incoming);
            let callback: &P = &*(user_data as *mut _);
            let res = (*callback)(&connection, &message, incoming);
            res.into_glib_ptr()
        }
        let filter_function = Some(filter_function_func::<P> as _);
        unsafe extern "C" fn user_data_free_func_func<
            P: Fn(&DBusConnection, &DBusMessage, bool) -> Option<DBusMessage> + 'static,
        >(
            data: glib::ffi::gpointer,
        ) {
            let _callback: Box_<P> = Box_::from_raw(data as *mut _);
        }
        let destroy_call3 = Some(user_data_free_func_func::<P> as _);
        let super_callback0: Box_<P> = filter_function_data;
        unsafe {
            let id = ffi::g_dbus_connection_add_filter(
                self.to_glib_none().0,
                filter_function,
                Box_::into_raw(super_callback0) as *mut _,
                destroy_call3,
            );
            FilterId(NonZeroU32::new_unchecked(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.
    /// ## `filter_id`
    /// an identifier obtained from g_dbus_connection_add_filter()
    #[doc(alias = "g_dbus_connection_remove_filter")]
    pub fn remove_filter(&self, filter_id: FilterId) {
        unsafe {
            ffi::g_dbus_connection_remove_filter(self.to_glib_none().0, filter_id.0.into());
        }
    }

    /// Subscribes to signals on @self and invokes @callback whenever
    /// the signal is received. Note that @callback will be invoked in the
    /// [thread-default main context][g-main-context-push-thread-default]
    /// of the thread you are calling this method from.
    ///
    /// If @self is not a message bus connection, @sender must be
    /// [`None`].
    ///
    /// 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 [`DBusSignalFlags::MATCH_ARG0_NAMESPACE`][crate::DBusSignalFlags::MATCH_ARG0_NAMESPACE] or
    /// [`DBusSignalFlags::MATCH_ARG0_PATH`][crate::DBusSignalFlags::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-[`None`], 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 @self
    /// 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.
    /// ## `sender`
    /// sender name to match on (unique or well-known name)
    ///     or [`None`] to listen from all senders
    /// ## `interface_name`
    /// D-Bus interface name to match on or [`None`] to
    ///     match on all interfaces
    /// ## `member`
    /// D-Bus signal name to match on or [`None`] to match on
    ///     all signals
    /// ## `object_path`
    /// object path to match on or [`None`] to match on
    ///     all object paths
    /// ## `arg0`
    /// contents of first string argument to match on or [`None`]
    ///     to match on all kinds of arguments
    /// ## `flags`
    /// #GDBusSignalFlags describing how arg0 is used in subscribing to the
    ///     signal
    /// ## `callback`
    /// callback to invoke when there is a signal matching the requested data
    ///
    /// # Returns
    ///
    /// a subscription identifier that can be used with g_dbus_connection_signal_unsubscribe()
    #[doc(alias = "g_dbus_connection_signal_subscribe")]
    #[allow(clippy::too_many_arguments)]
    pub fn signal_subscribe<
        P: Fn(&DBusConnection, &str, &str, &str, &str, &glib::Variant) + 'static,
    >(
        &self,
        sender: Option<&str>,
        interface_name: Option<&str>,
        member: Option<&str>,
        object_path: Option<&str>,
        arg0: Option<&str>,
        flags: DBusSignalFlags,
        callback: P,
    ) -> SignalSubscriptionId {
        let callback_data: Box_<P> = Box_::new(callback);
        unsafe extern "C" fn callback_func<
            P: Fn(&DBusConnection, &str, &str, &str, &str, &glib::Variant) + 'static,
        >(
            connection: *mut ffi::GDBusConnection,
            sender_name: *const libc::c_char,
            object_path: *const libc::c_char,
            interface_name: *const libc::c_char,
            signal_name: *const libc::c_char,
            parameters: *mut glib::ffi::GVariant,
            user_data: glib::ffi::gpointer,
        ) {
            let connection = from_glib_borrow(connection);
            let sender_name: Borrowed<glib::GString> = from_glib_borrow(sender_name);
            let object_path: Borrowed<glib::GString> = from_glib_borrow(object_path);
            let interface_name: Borrowed<glib::GString> = from_glib_borrow(interface_name);
            let signal_name: Borrowed<glib::GString> = from_glib_borrow(signal_name);
            let parameters = from_glib_borrow(parameters);
            let callback: &P = &*(user_data as *mut _);
            (*callback)(
                &connection,
                sender_name.as_str(),
                object_path.as_str(),
                interface_name.as_str(),
                signal_name.as_str(),
                &parameters,
            );
        }
        let callback = Some(callback_func::<P> as _);
        unsafe extern "C" fn user_data_free_func_func<
            P: Fn(&DBusConnection, &str, &str, &str, &str, &glib::Variant) + 'static,
        >(
            data: glib::ffi::gpointer,
        ) {
            let _callback: Box_<P> = Box_::from_raw(data as *mut _);
        }
        let destroy_call9 = Some(user_data_free_func_func::<P> as _);
        let super_callback0: Box_<P> = callback_data;
        unsafe {
            let id = ffi::g_dbus_connection_signal_subscribe(
                self.to_glib_none().0,
                sender.to_glib_none().0,
                interface_name.to_glib_none().0,
                member.to_glib_none().0,
                object_path.to_glib_none().0,
                arg0.to_glib_none().0,
                flags.into_glib(),
                callback,
                Box_::into_raw(super_callback0) as *mut _,
                destroy_call9,
            );
            SignalSubscriptionId(NonZeroU32::new_unchecked(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.
    /// Alternatively, any idle source with a priority lower than `G_PRIORITY_DEFAULT`
    /// that was scheduled after unsubscription, also indicates that all resources
    /// of this subscription are released.
    /// ## `subscription_id`
    /// a subscription id obtained from
    ///     g_dbus_connection_signal_subscribe()
    #[doc(alias = "g_dbus_connection_signal_unsubscribe")]
    pub fn signal_unsubscribe(&self, subscription_id: SignalSubscriptionId) {
        unsafe {
            ffi::g_dbus_connection_signal_unsubscribe(
                self.to_glib_none().0,
                subscription_id.0.into(),
            );
        }
    }
}