gd/rust/linux/dbus_projection/src/lib.rs - platform/system/bt - Git at Google

 //! This crate provides tools to automatically project generic API to D-Bus RPC.
 //!
 //! For D-Bus projection to work automatically, the API needs to follow certain restrictions:
 //!
 //! * API does not use D-Bus specific features: Signals, Properties, ObjectManager.
 //! * Interfaces (contain Methods) are hosted on statically allocated D-Bus objects.
 //! * When the service needs to notify the client about changes, callback objects are used. The
 //!   client can pass a callback object obeying a specified Interface by passing the D-Bus object
 //!   path.
 //!
 //! A good example is in
 //! [`manager_service`](https://android.googlesource.com/platform/system/bt/+/refs/heads/master/gd/rust/linux/mgmt)
 //! crate:
 //!
 //! * Define RPCProxy like in
 //! [here](https://android.googlesource.com/platform/system/bt/+/refs/heads/master/gd/rust/linux/mgmt/src/lib.rs)
 //! (TODO: We should remove this requirement in the future).
 //! * Generate `DBusArg` trait like in
 //! [here](https://android.googlesource.com/platform/system/bt/+/refs/heads/master/gd/rust/linux/mgmt/src/bin/btmanagerd/dbus_arg.rs).
 //! This trait is generated by a macro and cannot simply be imported because of Rust's
 //! [Orphan Rule](https://github.com/Ixrec/rust-orphan-rules).
 //! * Define D-Bus-agnostic traits like in
 //! [here](https://android.googlesource.com/platform/system/bt/+/refs/heads/master/gd/rust/linux/mgmt/src/iface_bluetooth_manager.rs).
 //! These traits can be projected into D-Bus Interfaces on D-Bus objects.  A method parameter can
 //! be of a Rust primitive type, structure, enum, or a callback specially typed as
 //! `Box<dyn SomeCallbackTrait + Send>`. Callback traits implement `RPCProxy`.
 //! * Implement the traits like in
 //! [here](https://android.googlesource.com/platform/system/bt/+/refs/heads/master/gd/rust/linux/mgmt/src/bin/btmanagerd/bluetooth_manager.rs),
 //! also D-Bus-agnostic.
 //! * Define D-Bus projection mappings like in
 //! [here](https://android.googlesource.com/platform/system/bt/+/refs/heads/master/gd/rust/linux/mgmt/src/bin/btmanagerd/bluetooth_manager_dbus.rs).
 //!   * Add [`generate_dbus_exporter`](dbus_macros::generate_dbus_exporter) macro to an `impl` of a
 //!     trait.
 //!   * Define a method name of each method with [`dbus_method`](dbus_macros::dbus_method) macro.
 //!   * Similarly, for callbacks use [`dbus_proxy_obj`](dbus_macros::dbus_proxy_obj) macro to define
 //!     the method mappings.
 //!   * Rust primitive types can be converted automatically to and from D-Bus types.
 //!   * Rust structures require implementations of `DBusArg` for the conversion. This is made easy
 //!     with the [`dbus_propmap`](dbus_macros::dbus_propmap) macro.
 //!   * Rust enums require implementations of `DBusArg` for the conversion. This is made easy with
 //!     the [`impl_dbus_arg_enum`](impl_dbus_arg_enum) macro.
 //! * To project a Rust object to a D-Bus, call the function generated by
 //!   [`generate_dbus_exporter`](dbus_macros::generate_dbus_exporter) like in
 //!   [here](https://android.googlesource.com/platform/system/bt/+/refs/heads/master/gd/rust/linux/mgmt/src/bin/btmanagerd/main.rs)
 //!   passing in the object path, D-Bus connection, Crossroads object, the Rust object to be
 //!   projected, and a [`DisconnectWatcher`](DisconnectWatcher) object.

 use dbus::channel::MatchingReceiver;
 use dbus::message::MatchRule;
 use dbus::nonblock::SyncConnection;
 use dbus::strings::BusName;

 use std::collections::HashMap;
 use std::sync::{Arc, Mutex};

 /// A D-Bus "NameOwnerChanged" handler that continuously monitors client disconnects.
 ///
 /// When the watched bus address disconnects, all the callbacks associated with it are called with
 /// their associated ids.
 pub struct DisconnectWatcher {
     /// Global counter to provide a unique id every time `get_next_id` is called.
     next_id: u32,

     /// Map of disconnect callbacks by bus address and callback id.
     callbacks: Arc<Mutex<HashMap<BusName<'static>, HashMap<u32, Box<dyn Fn(u32) + Send>>>>>,
 }

 impl DisconnectWatcher {
     /// Creates a new DisconnectWatcher with empty callbacks.
     pub fn new() -> DisconnectWatcher {
         DisconnectWatcher { next_id: 0, callbacks: Arc::new(Mutex::new(HashMap::new())) }
     }

     /// Get the next unique id for this watcher.
     fn get_next_id(&mut self) -> u32 {
         self.next_id = self.next_id + 1;
         self.next_id
     }
 }

 impl DisconnectWatcher {
     /// Adds a client address to be monitored for disconnect events.
     pub fn add(&mut self, address: BusName<'static>, callback: Box<dyn Fn(u32) + Send>) -> u32 {
         if !self.callbacks.lock().unwrap().contains_key(&address) {
             self.callbacks.lock().unwrap().insert(address.clone(), HashMap::new());
         }

         let id = self.get_next_id();
         (*self.callbacks.lock().unwrap().get_mut(&address).unwrap()).insert(id, callback);

         return id;
     }

     /// Sets up the D-Bus handler that monitors client disconnects.
     pub async fn setup_watch(&mut self, conn: Arc<SyncConnection>) {
         let mr = MatchRule::new_signal("org.freedesktop.DBus", "NameOwnerChanged");

         conn.add_match_no_cb(&mr.match_str()).await.unwrap();
         let callbacks_map = self.callbacks.clone();
         conn.start_receive(
             mr,
             Box::new(move |msg, _conn| {
                 // The args are "address", "old address", "new address".
                 // https://dbus.freedesktop.org/doc/dbus-specification.html#bus-messages-name-owner-changed
                 let (addr, old, new) = msg.get3::<String, String, String>();

                 if addr.is_none() || old.is_none() || new.is_none() {
                     return true;
                 }

                 if old.unwrap().eq("") || !new.unwrap().eq("") {
                     return true;
                 }

                 // If old address exists but new address is empty, that means that client is
                 // disconnected. So call the registered callbacks to be notified of this client
                 // disconnect.
                 let addr = BusName::new(addr.unwrap()).unwrap().into_static();
                 if !callbacks_map.lock().unwrap().contains_key(&addr) {
                     return true;
                 }

                 for (id, callback) in callbacks_map.lock().unwrap()[&addr].iter() {
                     callback(*id);
                 }

                 callbacks_map.lock().unwrap().remove(&addr);

                 true
             }),
         );
     }

     /// Removes callback by id if owned by the specific busname.
     ///
     /// If the callback can be removed, the callback will be called before being removed.
     pub fn remove(&mut self, address: BusName<'static>, target_id: u32) -> bool {
         if !self.callbacks.lock().unwrap().contains_key(&address) {
             return false;
         }

         match self.callbacks.lock().unwrap().get(&address).and_then(|m| m.get(&target_id)) {
             Some(cb) => {
                 cb(target_id);
                 let _ = self
                     .callbacks
                     .lock()
                     .unwrap()
                     .get_mut(&address)
                     .and_then(|m| m.remove(&target_id));
                 true
             }
             None => false,
         }
     }
 }

 /// Implements `DBusArg` for an enum.
 ///
 /// A Rust enum is converted to D-Bus INT32 type.
 #[macro_export]
 macro_rules! impl_dbus_arg_enum {
     ($enum_type:ty) => {
         impl DBusArg for $enum_type {
             type DBusType = u32;
             fn from_dbus(
                 data: u32,
                 _conn: Option<Arc<SyncConnection>>,
                 _remote: Option<dbus::strings::BusName<'static>>,
                 _disconnect_watcher: Option<
                     Arc<std::sync::Mutex<dbus_projection::DisconnectWatcher>>,
                 >,
             ) -> Result<$enum_type, Box<dyn std::error::Error>> {
                 match <$enum_type>::from_u32(data) {
                     Some(x) => Ok(x),
                     None => Err(Box::new(DBusArgError::new(String::from(format!(
                         "error converting {} to {}",
                         data,
                         stringify!($enum_type)
                     ))))),
                 }
             }

             fn to_dbus(data: $enum_type) -> Result<u32, Box<dyn std::error::Error>> {
                 return Ok(data.to_u32().unwrap());
             }
         }
     };
 }
	//! This crate provides tools to automatically project generic API to D-Bus RPC.
	//!
	//! For D-Bus projection to work automatically, the API needs to follow certain restrictions:
	//!
	//! * API does not use D-Bus specific features: Signals, Properties, ObjectManager.
	//! * Interfaces (contain Methods) are hosted on statically allocated D-Bus objects.
	//! * When the service needs to notify the client about changes, callback objects are used. The
	//! client can pass a callback object obeying a specified Interface by passing the D-Bus object
	//! path.
	//!
	//! A good example is in
	//! [`manager_service`](https://android.googlesource.com/platform/system/bt/+/refs/heads/master/gd/rust/linux/mgmt)
	//! crate:
	//!
	//! * Define RPCProxy like in
	//! [here](https://android.googlesource.com/platform/system/bt/+/refs/heads/master/gd/rust/linux/mgmt/src/lib.rs)
	//! (TODO: We should remove this requirement in the future).
	//! * Generate `DBusArg` trait like in
	//! [here](https://android.googlesource.com/platform/system/bt/+/refs/heads/master/gd/rust/linux/mgmt/src/bin/btmanagerd/dbus_arg.rs).
	//! This trait is generated by a macro and cannot simply be imported because of Rust's
	//! [Orphan Rule](https://github.com/Ixrec/rust-orphan-rules).
	//! * Define D-Bus-agnostic traits like in
	//! [here](https://android.googlesource.com/platform/system/bt/+/refs/heads/master/gd/rust/linux/mgmt/src/iface_bluetooth_manager.rs).
	//! These traits can be projected into D-Bus Interfaces on D-Bus objects. A method parameter can
	//! be of a Rust primitive type, structure, enum, or a callback specially typed as
	//! `Box<dyn SomeCallbackTrait + Send>`. Callback traits implement `RPCProxy`.
	//! * Implement the traits like in
	//! [here](https://android.googlesource.com/platform/system/bt/+/refs/heads/master/gd/rust/linux/mgmt/src/bin/btmanagerd/bluetooth_manager.rs),
	//! also D-Bus-agnostic.
	//! * Define D-Bus projection mappings like in
	//! [here](https://android.googlesource.com/platform/system/bt/+/refs/heads/master/gd/rust/linux/mgmt/src/bin/btmanagerd/bluetooth_manager_dbus.rs).
	//! * Add [`generate_dbus_exporter`](dbus_macros::generate_dbus_exporter) macro to an `impl` of a
	//! trait.
	//! * Define a method name of each method with [`dbus_method`](dbus_macros::dbus_method) macro.
	//! * Similarly, for callbacks use [`dbus_proxy_obj`](dbus_macros::dbus_proxy_obj) macro to define
	//! the method mappings.
	//! * Rust primitive types can be converted automatically to and from D-Bus types.
	//! * Rust structures require implementations of `DBusArg` for the conversion. This is made easy
	//! with the [`dbus_propmap`](dbus_macros::dbus_propmap) macro.
	//! * Rust enums require implementations of `DBusArg` for the conversion. This is made easy with
	//! the [`impl_dbus_arg_enum`](impl_dbus_arg_enum) macro.
	//! * To project a Rust object to a D-Bus, call the function generated by
	//! [`generate_dbus_exporter`](dbus_macros::generate_dbus_exporter) like in
	//! [here](https://android.googlesource.com/platform/system/bt/+/refs/heads/master/gd/rust/linux/mgmt/src/bin/btmanagerd/main.rs)
	//! passing in the object path, D-Bus connection, Crossroads object, the Rust object to be
	//! projected, and a [`DisconnectWatcher`](DisconnectWatcher) object.

	use dbus::channel::MatchingReceiver;
	use dbus::message::MatchRule;
	use dbus::nonblock::SyncConnection;
	use dbus::strings::BusName;

	use std::collections::HashMap;
	use std::sync::{Arc, Mutex};

	/// A D-Bus "NameOwnerChanged" handler that continuously monitors client disconnects.
	///
	/// When the watched bus address disconnects, all the callbacks associated with it are called with
	/// their associated ids.
	pub struct DisconnectWatcher {
	/// Global counter to provide a unique id every time `get_next_id` is called.
	next_id: u32,

	/// Map of disconnect callbacks by bus address and callback id.
	callbacks: Arc<Mutex<HashMap<BusName<'static>, HashMap<u32, Box<dyn Fn(u32) + Send>>>>>,
	}

	impl DisconnectWatcher {
	/// Creates a new DisconnectWatcher with empty callbacks.
	pub fn new() -> DisconnectWatcher {
	DisconnectWatcher { next_id: 0, callbacks: Arc::new(Mutex::new(HashMap::new())) }
	}

	/// Get the next unique id for this watcher.
	fn get_next_id(&mut self) -> u32 {
	self.next_id = self.next_id + 1;
	self.next_id
	}
	}

	impl DisconnectWatcher {
	/// Adds a client address to be monitored for disconnect events.
	pub fn add(&mut self, address: BusName<'static>, callback: Box<dyn Fn(u32) + Send>) -> u32 {
	if !self.callbacks.lock().unwrap().contains_key(&address) {
	self.callbacks.lock().unwrap().insert(address.clone(), HashMap::new());
	}

	let id = self.get_next_id();
	(*self.callbacks.lock().unwrap().get_mut(&address).unwrap()).insert(id, callback);

	return id;
	}

	/// Sets up the D-Bus handler that monitors client disconnects.
	pub async fn setup_watch(&mut self, conn: Arc<SyncConnection>) {
	let mr = MatchRule::new_signal("org.freedesktop.DBus", "NameOwnerChanged");

	conn.add_match_no_cb(&mr.match_str()).await.unwrap();
	let callbacks_map = self.callbacks.clone();
	conn.start_receive(
	mr,
	Box::new(move \|msg, _conn\| {
	// The args are "address", "old address", "new address".
	// https://dbus.freedesktop.org/doc/dbus-specification.html#bus-messages-name-owner-changed
	let (addr, old, new) = msg.get3::<String, String, String>();

	if addr.is_none() \|\| old.is_none() \|\| new.is_none() {
	return true;
	}

	if old.unwrap().eq("") \|\| !new.unwrap().eq("") {
	return true;
	}

	// If old address exists but new address is empty, that means that client is
	// disconnected. So call the registered callbacks to be notified of this client
	// disconnect.
	let addr = BusName::new(addr.unwrap()).unwrap().into_static();
	if !callbacks_map.lock().unwrap().contains_key(&addr) {
	return true;
	}

	for (id, callback) in callbacks_map.lock().unwrap()[&addr].iter() {
	callback(*id);
	}

	callbacks_map.lock().unwrap().remove(&addr);

	true
	}),
	);
	}

	/// Removes callback by id if owned by the specific busname.
	///
	/// If the callback can be removed, the callback will be called before being removed.
	pub fn remove(&mut self, address: BusName<'static>, target_id: u32) -> bool {
	if !self.callbacks.lock().unwrap().contains_key(&address) {
	return false;
	}

	match self.callbacks.lock().unwrap().get(&address).and_then(\|m\| m.get(&target_id)) {
	Some(cb) => {
	cb(target_id);
	let _ = self
	.callbacks
	.lock()
	.unwrap()
	.get_mut(&address)
	.and_then(\|m\| m.remove(&target_id));
	true
	}
	None => false,
	}
	}
	}

	/// Implements `DBusArg` for an enum.
	///
	/// A Rust enum is converted to D-Bus INT32 type.
	#[macro_export]
	macro_rules! impl_dbus_arg_enum {
	($enum_type:ty) => {
	impl DBusArg for $enum_type {
	type DBusType = u32;
	fn from_dbus(
	data: u32,
	_conn: Option<Arc<SyncConnection>>,
	_remote: Option<dbus::strings::BusName<'static>>,
	_disconnect_watcher: Option<
	Arc<std::sync::Mutex<dbus_projection::DisconnectWatcher>>,
	>,
	) -> Result<$enum_type, Box<dyn std::error::Error>> {
	match <$enum_type>::from_u32(data) {
	Some(x) => Ok(x),
	None => Err(Box::new(DBusArgError::new(String::from(format!(
	"error converting {} to {}",
	data,
	stringify!($enum_type)
	))))),
	}
	}

	fn to_dbus(data: $enum_type) -> Result<u32, Box<dyn std::error::Error>> {
	return Ok(data.to_u32().unwrap());
	}
	}
	};
	}