src/sys/component_manager/src/builtin/log.rs

// Copyright 2020 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

use {
    crate::{builtin::capability::BuiltinCapability, capability::*},
    anyhow::Error,
    async_trait::async_trait,
    cm_rust::CapabilityName,
    fidl_fuchsia_boot as fboot,
    fuchsia_zircon::{self as zx, DebugLog, DebugLogOpts, HandleBased, Resource},
    futures::prelude::*,
    lazy_static::lazy_static,
    std::sync::Arc,
};

lazy_static! {
    static ref READ_ONLY_LOG_CAPABILITY_NAME: CapabilityName = "fuchsia.boot.ReadOnlyLog".into();
    static ref WRITE_ONLY_LOG_CAPABILITY_NAME: CapabilityName = "fuchsia.boot.WriteOnlyLog".into();
}

/// An implementation of the `fuchsia.boot.ReadOnlyLog` protocol.
pub struct ReadOnlyLog {
    resource: Resource,
}

impl ReadOnlyLog {
    /// Create a service to provide a read-only version of the kernel log.
    /// Note that the root resource is passed in here, rather than a read-only log handle to be
    /// duplicated, because a fresh debuglog (LogDispatcher) object needs to be returned for each call.
    /// This is because LogDispatcher holds the implicit read location for reading from the log, so if a
    /// handle to the same object was duplicated, this would mistakenly share read location amongst all
    /// retrievals.
    pub fn new(resource: Resource) -> Arc<Self> {
        Arc::new(Self { resource })
    }
}

#[async_trait]
impl BuiltinCapability for ReadOnlyLog {
    const NAME: &'static str = "ReadOnlyLog";
    type Marker = fboot::ReadOnlyLogMarker;

    async fn serve(
        self: Arc<Self>,
        mut stream: fboot::ReadOnlyLogRequestStream,
    ) -> Result<(), Error> {
        while let Some(fboot::ReadOnlyLogRequest::Get { responder }) = stream.try_next().await? {
            let debuglog = DebugLog::create(&self.resource, DebugLogOpts::READABLE)?;
            // If `READABLE` is set, then the rights for the debuglog include `READ`. However, we
            // must remove the `WRITE` right, as we want to provide a read-only debuglog.
            let readonly = debuglog
                .replace_handle(zx::Rights::BASIC | zx::Rights::READ | zx::Rights::SIGNAL)?;
            responder.send(readonly)?;
        }
        Ok(())
    }

    fn matches_routed_capability(&self, capability: &InternalCapability) -> bool {
        capability.matches_protocol(&READ_ONLY_LOG_CAPABILITY_NAME)
    }
}

/// An implementation of the `fuchsia.boot.WriteOnlyLog` protocol.
pub struct WriteOnlyLog {
    debuglog: DebugLog,
}

impl WriteOnlyLog {
    pub fn new(debuglog: DebugLog) -> Arc<Self> {
        Arc::new(Self { debuglog })
    }
}

#[async_trait]
impl BuiltinCapability for WriteOnlyLog {
    const NAME: &'static str = "WriteOnlyLog";
    type Marker = fboot::WriteOnlyLogMarker;

    async fn serve(
        self: Arc<Self>,
        mut stream: fboot::WriteOnlyLogRequestStream,
    ) -> Result<(), Error> {
        while let Some(fboot::WriteOnlyLogRequest::Get { responder }) = stream.try_next().await? {
            responder.send(self.debuglog.duplicate_handle(zx::Rights::SAME_RIGHTS)?)?;
        }
        Ok(())
    }

    fn matches_routed_capability(&self, capability: &InternalCapability) -> bool {
        capability.matches_protocol(&WRITE_ONLY_LOG_CAPABILITY_NAME)
    }
}

#[cfg(test)]
mod tests {
    use {
        super::*,
        crate::model::hooks::{Event, EventPayload, Hooks},
        fidl::endpoints::ClientEnd,
        fuchsia_async as fasync,
        fuchsia_zircon::AsHandleRef,
        fuchsia_zircon_sys as sys,
        futures::lock::Mutex,
        moniker::AbsoluteMoniker,
        std::path::PathBuf,
    };

    #[fasync::run_singlethreaded(test)]
    async fn has_correct_rights_for_read_only() -> Result<(), Error> {
        // The kernel does not currently require a valid `Resource` to be
        // provided when creating a `Debuglog`. This will change in the future.
        let read_only_log = ReadOnlyLog::new(Resource::from(zx::Handle::invalid()));
        let (proxy, stream) =
            fidl::endpoints::create_proxy_and_stream::<fboot::ReadOnlyLogMarker>()?;
        fasync::Task::local(
            read_only_log
                .serve(stream)
                .unwrap_or_else(|err| panic!("Error serving read-only log: {}", err)),
        )
        .detach();

        let read_only_log = proxy.get().await?;
        let info = zx::Handle::from(read_only_log).basic_info()?;
        assert_eq!(info.rights, zx::Rights::BASIC | zx::Rights::READ | zx::Rights::SIGNAL);
        Ok(())
    }

    #[fasync::run_singlethreaded(test)]
    async fn can_connect_to_read_only() -> Result<(), Error> {
        // The kernel does not currently require a valid `Resource` to be
        // provided when creating a `Debuglog`. This will change in the future.
        let read_only_log = ReadOnlyLog::new(Resource::from(zx::Handle::invalid()));
        let hooks = Hooks::new(None);
        hooks.install(read_only_log.hooks()).await;

        let provider = Arc::new(Mutex::new(None));
        let source = CapabilitySource::Builtin {
            capability: InternalCapability::Protocol(READ_ONLY_LOG_CAPABILITY_NAME.clone()),
        };

        let event = Event::new_for_test(
            AbsoluteMoniker::root(),
            "fuchsia-pkg://root",
            Ok(EventPayload::CapabilityRouted { source, capability_provider: provider.clone() }),
        );
        hooks.dispatch(&event).await?;

        let (client, mut server) = zx::Channel::create()?;
        if let Some(provider) = provider.lock().await.take() {
            provider.open(0, 0, PathBuf::new(), &mut server).await?;
        }

        let client = ClientEnd::<fboot::ReadOnlyLogMarker>::new(client)
            .into_proxy()
            .expect("Failed to create proxy");
        let handle = client.get().await?;
        assert_ne!(handle.raw_handle(), sys::ZX_HANDLE_INVALID);

        let mut record = Vec::new();
        handle.read(&mut record)?;
        let message: [u8; 0] = [];
        assert!(handle.write(&message).is_err());

        Ok(())
    }

    #[fasync::run_singlethreaded(test)]
    async fn has_correct_rights_for_write_only() -> Result<(), Error> {
        // The kernel does not currently require a valid `Resource` to be
        // provided when creating a `Debuglog`. This will change in the future.
        let resource = Resource::from(zx::Handle::invalid());
        let write_only_log =
            WriteOnlyLog::new(zx::DebugLog::create(&resource, zx::DebugLogOpts::empty()).unwrap());
        let (proxy, stream) =
            fidl::endpoints::create_proxy_and_stream::<fboot::WriteOnlyLogMarker>()?;
        fasync::Task::local(
            write_only_log
                .serve(stream)
                .unwrap_or_else(|err| panic!("Error serving write-only log: {}", err)),
        )
        .detach();

        let write_only_log = proxy.get().await?;
        let info = zx::Handle::from(write_only_log).basic_info()?;
        assert_eq!(info.rights, zx::Rights::BASIC | zx::Rights::WRITE | zx::Rights::SIGNAL);

        Ok(())
    }

    #[fasync::run_singlethreaded(test)]
    async fn can_connect_to_write_only() -> Result<(), Error> {
        // The kernel does not currently require a valid `Resource` to be
        // provided when creating a `Debuglog`. This will change in the future.
        let resource = Resource::from(zx::Handle::invalid());
        let write_only_log =
            WriteOnlyLog::new(zx::DebugLog::create(&resource, zx::DebugLogOpts::empty()).unwrap());
        let hooks = Hooks::new(None);
        hooks.install(write_only_log.hooks()).await;

        let provider = Arc::new(Mutex::new(None));
        let source = CapabilitySource::Builtin {
            capability: InternalCapability::Protocol(WRITE_ONLY_LOG_CAPABILITY_NAME.clone()),
        };

        let event = Event::new_for_test(
            AbsoluteMoniker::root(),
            "fuchsia-pkg://root",
            Ok(EventPayload::CapabilityRouted { source, capability_provider: provider.clone() }),
        );
        hooks.dispatch(&event).await?;

        let (client, mut server) = zx::Channel::create()?;
        if let Some(provider) = provider.lock().await.take() {
            provider.open(0, 0, PathBuf::new(), &mut server).await?;
        }

        let client = ClientEnd::<fboot::WriteOnlyLogMarker>::new(client)
            .into_proxy()
            .expect("Failed to create proxy");
        let handle = client.get().await?;
        assert_ne!(handle.raw_handle(), sys::ZX_HANDLE_INVALID);

        let mut record = Vec::new();
        assert!(handle.read(&mut record).is_err());
        let message: [u8; 0] = [];
        handle.write(&message)?;

        Ok(())
    }
}