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::{DictExt, RoutingError};
6use async_trait::async_trait;
7use cm_types::IterablePath;
8use moniker::ExtendedMoniker;
9use router_error::RouterError;
10use sandbox::{CapabilityBound, Dict, Request, Routable, Router, RouterResponse};
11use std::fmt::Debug;
12
13/// Implements the `lazy_get` function for [`Routable<Dict>`].
14pub trait LazyGet<T: CapabilityBound>: Routable<Dict> {
15    /// Returns a router that requests a dictionary from the specified `path` relative to
16    /// the base routable or fails the request with `not_found_error` if the member is not
17    /// found.
18    fn lazy_get<P>(self, path: P, not_found_error: RoutingError) -> Router<T>
19    where
20        P: IterablePath + Debug + 'static;
21}
22
23impl<R: Routable<Dict> + 'static, T: CapabilityBound> LazyGet<T> for R {
24    fn lazy_get<P>(self, path: P, not_found_error: RoutingError) -> Router<T>
25    where
26        P: IterablePath + Debug + 'static,
27    {
28        #[derive(Debug)]
29        struct ScopedDictRouter<P: IterablePath + Debug + 'static> {
30            router: Router<Dict>,
31            path: P,
32            not_found_error: RoutingError,
33        }
34
35        #[async_trait]
36        impl<P: IterablePath + Debug + 'static, T: CapabilityBound> Routable<T> for ScopedDictRouter<P> {
37            async fn route(
38                &self,
39                request: Option<Request>,
40                debug: bool,
41            ) -> Result<RouterResponse<T>, RouterError> {
42                // If `debug` is true, that should only apply to the capability at `path`.
43                // Here we're looking up the containing dictionary, so set `debug = false`, to
44                // obtain the actual Dict and not its debug info.
45                let init_request = request.as_ref().map(|r| r.try_clone()).transpose()?;
46                match self.router.route(init_request, false).await? {
47                    RouterResponse::<Dict>::Capability(dict) => {
48                        let request = request.as_ref().map(|r| r.try_clone()).transpose()?;
49                        let moniker: ExtendedMoniker = self.not_found_error.clone().into();
50                        let resp =
51                            dict.get_with_request(&moniker, &self.path, request, debug).await?;
52                        let resp =
53                            resp.ok_or_else(|| RouterError::from(self.not_found_error.clone()))?;
54                        let resp = resp.try_into().map_err(|debug_name: &'static str| {
55                            RoutingError::BedrockWrongCapabilityType {
56                                expected: T::debug_typename().into(),
57                                actual: debug_name.into(),
58                                moniker,
59                            }
60                        })?;
61                        return Ok(resp);
62                    }
63                    _ => Err(RoutingError::BedrockMemberAccessUnsupported {
64                        moniker: self.not_found_error.clone().into(),
65                    }
66                    .into()),
67                }
68            }
69        }
70
71        Router::<T>::new(ScopedDictRouter {
72            router: Router::<Dict>::new(self),
73            path,
74            not_found_error: not_found_error.into(),
75        })
76    }
77}
routing/bedrock/lazy_get.rs

routing/bedrock/
lazy_get.rs
