1use std::{
2 any::{Any, TypeId},
3 collections::HashMap,
4 fmt::Write,
5 future::Future,
6 pin::Pin,
7};
8
9use async_trait::async_trait;
10use zbus::MessageFlags;
11use zbus_names::{InterfaceName, MemberName};
12use zvariant::{DynamicType, OwnedValue, Value};
13
14use crate::{fdo, Connection, Message, ObjectServer, Result, SignalContext};
15use tracing::trace;
16
17/// A helper type returned by [`Interface`] callbacks.
18pub enum DispatchResult<'a> {
19 /// This interface does not support the given method
20 NotFound,
21
22 /// Retry with [Interface::call_mut].
23 ///
24 /// This is equivalent to NotFound if returned by call_mut.
25 RequiresMut,
26
27 /// The method was found and will be completed by running this Future
28 Async(Pin<Box<dyn Future<Output = Result<()>> + Send + 'a>>),
29}
30
31impl<'a> DispatchResult<'a> {
32 /// Helper for creating the Async variant
33 pub fn new_async<F, T, E>(conn: &'a Connection, msg: &'a Message, f: F) -> Self
34 where
35 F: Future<Output = ::std::result::Result<T, E>> + Send + 'a,
36 T: serde::Serialize + DynamicType + Send + Sync,
37 E: zbus::DBusError + Send,
38 {
39 DispatchResult::Async(Box::pin(async move {
40 let hdr = msg.header()?;
41 let ret = f.await;
42 if !hdr
43 .primary()
44 .flags()
45 .contains(MessageFlags::NoReplyExpected)
46 {
47 match ret {
48 Ok(r) => conn.reply(msg, &r).await,
49 Err(e) => conn.reply_dbus_error(&hdr, e).await,
50 }
51 .map(|_seq| ())
52 } else {
53 trace!("No reply expected for {:?} by the caller.", msg);
54 Ok(())
55 }
56 }))
57 }
58}
59
60/// The trait used to dispatch messages to an interface instance.
61///
62/// Note: It is not recommended to manually implement this trait. The [`dbus_interface`] macro
63/// implements it for you.
64///
65/// [`dbus_interface`]: attr.dbus_interface.html
66#[async_trait]
67pub trait Interface: Any + Send + Sync {
68 /// Return the name of the interface. Ex: "org.foo.MyInterface"
69 fn name() -> InterfaceName<'static>
70 where
71 Self: Sized;
72
73 /// Get a property value. Returns `None` if the property doesn't exist.
74 async fn get(&self, property_name: &str) -> Option<fdo::Result<OwnedValue>>;
75
76 /// Return all the properties.
77 async fn get_all(&self) -> HashMap<String, OwnedValue>;
78
79 /// Set a property value.
80 ///
81 /// Return [`DispatchResult::NotFound`] if the property doesn't exist, or
82 /// [`DispatchResult::RequiresMut`] if `set_mut` should be used instead. The default
83 /// implementation just returns `RequiresMut`.
84 fn set<'call>(
85 &'call self,
86 property_name: &'call str,
87 value: &'call Value<'_>,
88 ctxt: &'call SignalContext<'_>,
89 ) -> DispatchResult<'call> {
90 let _ = (property_name, value, ctxt);
91 DispatchResult::RequiresMut
92 }
93
94 /// Set a property value.
95 ///
96 /// Returns `None` if the property doesn't exist.
97 ///
98 /// This will only be invoked if `set` returned `RequiresMut`.
99 async fn set_mut(
100 &mut self,
101 property_name: &str,
102 value: &Value<'_>,
103 ctxt: &SignalContext<'_>,
104 ) -> Option<fdo::Result<()>>;
105
106 /// Call a method.
107 ///
108 /// Return [`DispatchResult::NotFound`] if the method doesn't exist, or
109 /// [`DispatchResult::RequiresMut`] if `call_mut` should be used instead.
110 ///
111 /// It is valid, though inefficient, for this to always return `RequiresMut`.
112 fn call<'call>(
113 &'call self,
114 server: &'call ObjectServer,
115 connection: &'call Connection,
116 msg: &'call Message,
117 name: MemberName<'call>,
118 ) -> DispatchResult<'call>;
119
120 /// Call a `&mut self` method.
121 ///
122 /// This will only be invoked if `call` returned `RequiresMut`.
123 fn call_mut<'call>(
124 &'call mut self,
125 server: &'call ObjectServer,
126 connection: &'call Connection,
127 msg: &'call Message,
128 name: MemberName<'call>,
129 ) -> DispatchResult<'call>;
130
131 /// Write introspection XML to the writer, with the given indentation level.
132 fn introspect_to_writer(&self, writer: &mut dyn Write, level: usize);
133}
134
135// Note: while it is possible to implement this without `unsafe`, it currently requires a helper
136// trait with a blanket impl that creates `dyn Any` refs. It's simpler (and more performant) to
137// just check the type ID and do the downcast ourself.
138//
139// See https://github.com/rust-lang/rust/issues/65991 for a rustc feature that will make it
140// possible to get a `dyn Any` ref directly from a `dyn Interface` ref; once that is stable, we can
141// remove this unsafe code.
142impl dyn Interface {
143 /// Return Any of self
144 pub(crate) fn downcast_ref<T: Any>(&self) -> Option<&T> {
145 if <dyn Interface as Any>::type_id(self) == TypeId::of::<T>() {
146 // SAFETY: If type ID matches, it means object is of type T
147 Some(unsafe { &*(self as *const dyn Interface as *const T) })
148 } else {
149 None
150 }
151 }
152
153 /// Return Any of self
154 pub(crate) fn downcast_mut<T: Any>(&mut self) -> Option<&mut T> {
155 if <dyn Interface as Any>::type_id(self) == TypeId::of::<T>() {
156 // SAFETY: If type ID matches, it means object is of type T
157 Some(unsafe { &mut *(self as *mut dyn Interface as *mut T) })
158 } else {
159 None
160 }
161 }
162}
163