routing/bedrock/
lazy_get.rs

1// Copyright 2024 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5use crate::bedrock::dict_ext::request_with_dictionary_replacement;
6use crate::{DictExt, RoutingError};
7use async_trait::async_trait;
8use capability_source::CapabilitySource;
9use cm_types::IterablePath;
10use fidl_fuchsia_component_runtime::RouteRequest;
11use moniker::ExtendedMoniker;
12use router_error::RouterError;
13use runtime_capabilities::{CapabilityBound, Dictionary, Routable, Router, WeakInstanceToken};
14use std::fmt::Debug;
15
16/// Implements the `lazy_get` function for [`Routable<Dictionary>`].
17pub trait LazyGet<T: CapabilityBound>: Routable<Dictionary> {
18    /// Returns a router that requests a dictionary from the specified `path` relative to
19    /// the base routable or fails the request with `not_found_error` if the member is not
20    /// found.
21    fn lazy_get<P>(self, path: P, not_found_error: RoutingError) -> Router<T>
22    where
23        P: IterablePath + Debug + 'static;
24}
25
26impl<R: Routable<Dictionary> + 'static, T: CapabilityBound> LazyGet<T> for R {
27    fn lazy_get<P>(self, path: P, not_found_error: RoutingError) -> Router<T>
28    where
29        P: IterablePath + Debug + 'static,
30    {
31        #[derive(Debug)]
32        struct ScopedDictRouter<P: IterablePath + Debug + 'static> {
33            router: Router<Dictionary>,
34            path: P,
35            not_found_error: RoutingError,
36        }
37
38        #[async_trait]
39        impl<P: IterablePath + Debug + 'static, T: CapabilityBound> Routable<T> for ScopedDictRouter<P> {
40            async fn route(
41                &self,
42                request: RouteRequest,
43                target: WeakInstanceToken,
44            ) -> Result<Option<T>, RouterError> {
45                let get_init_request = || request_with_dictionary_replacement(&request);
46
47                let init_request = (get_init_request)()?;
48                match self.router.route(init_request, target.clone()).await? {
49                    Some(dict) => {
50                        let moniker: ExtendedMoniker = self.not_found_error.clone().into();
51                        match dict.get_with_request(&moniker, &self.path, request, target).await {
52                            Err(router_error)
53                                if let Ok(RoutingError::BedrockNotPresentInDictionary {
54                                    ..
55                                }) = router_error.clone().try_into() =>
56                            {
57                                Err(self.not_found_error.clone().into())
58                            }
59                            Err(e) => Err(e),
60                            Ok(None) => Ok(None),
61                            Ok(Some(cap)) => {
62                                let actual_type_name = cap.debug_typename();
63                                let cap = T::try_from(cap).map_err(|_| {
64                                    RoutingError::BedrockWrongCapabilityType {
65                                        expected: T::debug_typename().into(),
66                                        actual: actual_type_name.into(),
67                                        moniker,
68                                    }
69                                })?;
70                                Ok(Some(cap))
71                            }
72                        }
73                    }
74                    None => Ok(None),
75                }
76            }
77
78            async fn route_debug(
79                &self,
80                request: RouteRequest,
81                target: WeakInstanceToken,
82            ) -> Result<CapabilitySource, RouterError> {
83                let get_init_request = || request_with_dictionary_replacement(&request);
84
85                // When performing a debug route, we only want to call `route_debug` on the
86                // capability at `path`. Here we're looking up the containing dictionary, so we do
87                // non-debug routing, to obtain the actual Dictionary and not its debug info.
88                let init_request = (get_init_request)()?;
89                match self.router.route(init_request, target.clone()).await? {
90                    Some(dict) => {
91                        let moniker: ExtendedMoniker = self.not_found_error.clone().into();
92                        match dict
93                            .get_with_request_debug(&moniker, &self.path, request, target)
94                            .await
95                        {
96                            Err(router_error)
97                                if let Ok(RoutingError::BedrockNotPresentInDictionary {
98                                    ..
99                                }) = router_error.clone().try_into() =>
100                            {
101                                Err(self.not_found_error.clone().into())
102                            }
103                            other_result => other_result,
104                        }
105                    }
106                    None => {
107                        // The above route was non-debug, but the routing operation failed. Call
108                        // the router again with the same arguments but with `route_debug` so that
109                        // we return the debug info to the caller (which ought to be
110                        // [`CapabilitySource::Void`]).
111                        let init_request = (get_init_request)()?;
112                        self.router.route_debug(init_request, target).await
113                    }
114                }
115            }
116        }
117
118        Router::<T>::new(ScopedDictRouter {
119            router: Router::<Dictionary>::new(self),
120            path,
121            not_found_error: not_found_error.into(),
122        })
123    }
124}
routing/bedrock/lazy_get.rs

routing/bedrock/
lazy_get.rs
