Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

5 files changed, 1211 insertions, 0 deletions

diff --git a/third_party/rust/audioipc2-server/.cargo-checksum.json b/third_party/rust/audioipc2-server/.cargo-checksum.json
new file mode 100644
index 0000000000..733e618bb0
--- /dev/null
+++ b/third_party/rust/audioipc2-server/.cargo-checksum.json
@@ -0,0 +1 @@
+{"files":{"Cargo.toml":"4b00cd5b0ef67640c29a5b4c27ff0eb2bda60ea9bfaa0321625e2eb48714efa8","cbindgen.toml":"fb6abe1671497f432a06e40b1db7ed7cd2cceecbd9a2382193ad7534e8855e34","src/lib.rs":"06aff4fd1326aeabb16b01f81a6f3c59c1717ebe96285a063724830cdf30303a","src/server.rs":"ea839fe4607ba6b70a1ef5dfb2305eb668b148820c5590b87192609fbe3c9edd"},"package":null}
\ No newline at end of file
diff --git a/third_party/rust/audioipc2-server/Cargo.toml b/third_party/rust/audioipc2-server/Cargo.toml
new file mode 100644
index 0000000000..dbe87893a6
--- /dev/null
+++ b/third_party/rust/audioipc2-server/Cargo.toml
@@ -0,0 +1,40 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies.
+#
+# If you are reading this file be aware that the original Cargo.toml
+# will likely look very different (and much more reasonable).
+# See Cargo.toml.orig for the original contents.
+
+[package]
+edition = "2018"
+name = "audioipc2-server"
+version = "0.5.0"
+authors = [
+    "Matthew Gregan <kinetik@flim.org>",
+    "Dan Glastonbury <dan.glastonbury@gmail.com>",
+]
+description = "Remote cubeb server"
+license = "ISC"
+
+[dependencies]
+cubeb-core = "0.10.0"
+log = "0.4"
+once_cell = "1.2.0"
+slab = "0.4"
+
+[dependencies.audio_thread_priority]
+version = "0.26.1"
+features = ["winapi"]
+default-features = false
+
+[dependencies.audioipc]
+path = "../audioipc"
+package = "audioipc2"
+
+[dependencies.error-chain]
+version = "0.12.0"
+default-features = false
diff --git a/third_party/rust/audioipc2-server/cbindgen.toml b/third_party/rust/audioipc2-server/cbindgen.toml
new file mode 100644
index 0000000000..b3267889c6
--- /dev/null
+++ b/third_party/rust/audioipc2-server/cbindgen.toml
@@ -0,0 +1,28 @@
+header = """/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */"""
+autogen_warning = """/* DO NOT MODIFY THIS MANUALLY! This file was generated using cbindgen. */"""
+include_version = true
+braces = "SameLine"
+line_length = 100
+tab_width = 2
+language = "C++"
+namespaces = ["mozilla", "audioipc2"]
+
+[export]
+item_types = ["globals", "enums", "structs", "unions", "typedefs", "opaque", "functions", "constants"]
+
+[parse]
+parse_deps = true
+include = ["audioipc2"]
+
+[fn]
+args = "Vertical"
+rename_args = "GeckoCase"
+
+[struct]
+rename_fields = "GeckoCase"
+
+[defines]
+"windows" = "XP_WIN"
+"unix" = "XP_UNIX"
diff --git a/third_party/rust/audioipc2-server/src/lib.rs b/third_party/rust/audioipc2-server/src/lib.rs
new file mode 100644
index 0000000000..c90de38c66
--- /dev/null
+++ b/third_party/rust/audioipc2-server/src/lib.rs
@@ -0,0 +1,221 @@
+// Copyright © 2017 Mozilla Foundation
+//
+// This program is made available under an ISC-style license.  See the
+// accompanying file LICENSE for details
+#![warn(unused_extern_crates)]
+
+#[macro_use]
+extern crate error_chain;
+#[macro_use]
+extern crate log;
+
+use audio_thread_priority::promote_current_thread_to_real_time;
+use audioipc::ipccore;
+use audioipc::sys;
+use audioipc::PlatformHandleType;
+use once_cell::sync::Lazy;
+use std::ffi::{CStr, CString};
+use std::os::raw::c_void;
+use std::ptr;
+use std::sync::Mutex;
+use std::thread;
+
+mod server;
+
+struct CubebContextParams {
+    context_name: CString,
+    backend_name: Option<CString>,
+}
+
+static G_CUBEB_CONTEXT_PARAMS: Lazy<Mutex<CubebContextParams>> = Lazy::new(|| {
+    Mutex::new(CubebContextParams {
+        context_name: CString::new("AudioIPC Server").unwrap(),
+        backend_name: None,
+    })
+});
+
+#[allow(deprecated)]
+pub mod errors {
+    #![allow(clippy::upper_case_acronyms)]
+    error_chain! {
+        links {
+            AudioIPC(::audioipc::errors::Error, ::audioipc::errors::ErrorKind);
+        }
+        foreign_links {
+            Cubeb(cubeb_core::Error);
+            Io(::std::io::Error);
+        }
+    }
+}
+
+use crate::errors::*;
+
+struct ServerWrapper {
+    rpc_thread: ipccore::EventLoopThread,
+    callback_thread: ipccore::EventLoopThread,
+    device_collection_thread: ipccore::EventLoopThread,
+}
+
+fn register_thread(callback: Option<extern "C" fn(*const ::std::os::raw::c_char)>) {
+    if let Some(func) = callback {
+        let name = CString::new(thread::current().name().unwrap()).unwrap();
+        func(name.as_ptr());
+    }
+}
+
+fn unregister_thread(callback: Option<extern "C" fn()>) {
+    if let Some(func) = callback {
+        func();
+    }
+}
+
+fn init_threads(
+    thread_create_callback: Option<extern "C" fn(*const ::std::os::raw::c_char)>,
+    thread_destroy_callback: Option<extern "C" fn()>,
+) -> Result<ServerWrapper> {
+    let rpc_name = "AudioIPC Server RPC";
+    let rpc_thread = ipccore::EventLoopThread::new(
+        rpc_name.to_string(),
+        None,
+        move || {
+            trace!("Starting {} thread", rpc_name);
+            register_thread(thread_create_callback);
+            audioipc::server_platform_init();
+        },
+        move || {
+            unregister_thread(thread_destroy_callback);
+            trace!("Stopping {} thread", rpc_name);
+        },
+    )
+    .map_err(|e| {
+        debug!("Failed to start {} thread: {:?}", rpc_name, e);
+        e
+    })?;
+
+    let callback_name = "AudioIPC Server Callback";
+    let callback_thread = ipccore::EventLoopThread::new(
+        callback_name.to_string(),
+        None,
+        move || {
+            trace!("Starting {} thread", callback_name);
+            if let Err(e) = promote_current_thread_to_real_time(0, 48000) {
+                debug!(
+                    "Failed to promote {} thread to real-time: {:?}",
+                    callback_name, e
+                );
+            }
+            register_thread(thread_create_callback);
+        },
+        move || {
+            unregister_thread(thread_destroy_callback);
+            trace!("Stopping {} thread", callback_name);
+        },
+    )
+    .map_err(|e| {
+        debug!("Failed to start {} thread: {:?}", callback_name, e);
+        e
+    })?;
+
+    let device_collection_name = "AudioIPC DeviceCollection RPC";
+    let device_collection_thread = ipccore::EventLoopThread::new(
+        device_collection_name.to_string(),
+        None,
+        move || {
+            trace!("Starting {} thread", device_collection_name);
+            register_thread(thread_create_callback);
+        },
+        move || {
+            unregister_thread(thread_destroy_callback);
+            trace!("Stopping {} thread", device_collection_name);
+        },
+    )
+    .map_err(|e| {
+        debug!("Failed to start {} thread: {:?}", device_collection_name, e);
+        e
+    })?;
+
+    Ok(ServerWrapper {
+        rpc_thread,
+        callback_thread,
+        device_collection_thread,
+    })
+}
+
+#[repr(C)]
+#[derive(Clone, Copy, Debug)]
+pub struct AudioIpcServerInitParams {
+    // Fields only need to be public for ipctest.
+    pub thread_create_callback: Option<extern "C" fn(*const ::std::os::raw::c_char)>,
+    pub thread_destroy_callback: Option<extern "C" fn()>,
+}
+
+#[allow(clippy::missing_safety_doc)]
+#[no_mangle]
+pub unsafe extern "C" fn audioipc2_server_start(
+    context_name: *const std::os::raw::c_char,
+    backend_name: *const std::os::raw::c_char,
+    init_params: *const AudioIpcServerInitParams,
+) -> *mut c_void {
+    assert!(!init_params.is_null());
+    let mut params = G_CUBEB_CONTEXT_PARAMS.lock().unwrap();
+    if !context_name.is_null() {
+        params.context_name = CStr::from_ptr(context_name).to_owned();
+    }
+    if !backend_name.is_null() {
+        let backend_string = CStr::from_ptr(backend_name).to_owned();
+        params.backend_name = Some(backend_string);
+    }
+    match init_threads(
+        (*init_params).thread_create_callback,
+        (*init_params).thread_destroy_callback,
+    ) {
+        Ok(server) => Box::into_raw(Box::new(server)) as *mut _,
+        Err(_) => ptr::null_mut() as *mut _,
+    }
+}
+
+// A `shm_area_size` of 0 allows the server to calculate an appropriate shm size for each stream.
+// A non-zero `shm_area_size` forces all allocations to the specified size.
+#[no_mangle]
+pub extern "C" fn audioipc2_server_new_client(
+    p: *mut c_void,
+    shm_area_size: usize,
+) -> PlatformHandleType {
+    let wrapper: &ServerWrapper = unsafe { &*(p as *mut _) };
+
+    // We create a connected pair of anonymous IPC endpoints. One side
+    // is registered with the event loop core, the other side is returned
+    // to the caller to be remoted to the client to complete setup.
+    let (server_pipe, client_pipe) = match sys::make_pipe_pair() {
+        Ok((server_pipe, client_pipe)) => (server_pipe, client_pipe),
+        Err(e) => {
+            error!(
+                "audioipc_server_new_client - make_pipe_pair failed: {:?}",
+                e
+            );
+            return audioipc::INVALID_HANDLE_VALUE;
+        }
+    };
+
+    let rpc_thread = wrapper.rpc_thread.handle();
+    let callback_thread = wrapper.callback_thread.handle();
+    let device_collection_thread = wrapper.device_collection_thread.handle();
+
+    let server = server::CubebServer::new(
+        callback_thread.clone(),
+        device_collection_thread.clone(),
+        shm_area_size,
+    );
+    if let Err(e) = rpc_thread.bind_server(server, server_pipe) {
+        error!("audioipc_server_new_client - bind_server failed: {:?}", e);
+        return audioipc::INVALID_HANDLE_VALUE;
+    }
+
+    unsafe { client_pipe.into_raw() }
+}
+
+#[no_mangle]
+pub extern "C" fn audioipc2_server_stop(p: *mut c_void) {
+    let wrapper = unsafe { Box::<ServerWrapper>::from_raw(p as *mut _) };
+    drop(wrapper);
+}
diff --git a/third_party/rust/audioipc2-server/src/server.rs b/third_party/rust/audioipc2-server/src/server.rs
new file mode 100644
index 0000000000..0094a17681
--- /dev/null
+++ b/third_party/rust/audioipc2-server/src/server.rs
@@ -0,0 +1,921 @@
+// Copyright © 2017 Mozilla Foundation
+//
+// This program is made available under an ISC-style license.  See the
+// accompanying file LICENSE for details
+
+#[cfg(target_os = "linux")]
+use audio_thread_priority::{promote_thread_to_real_time, RtPriorityThreadInfo};
+use audioipc::messages::SerializableHandle;
+use audioipc::messages::{
+    CallbackReq, CallbackResp, ClientMessage, Device, DeviceCollectionReq, DeviceCollectionResp,
+    DeviceInfo, RegisterDeviceCollectionChanged, ServerMessage, StreamCreate, StreamCreateParams,
+    StreamInitParams, StreamParams,
+};
+use audioipc::shm::SharedMem;
+use audioipc::{ipccore, rpccore, sys, PlatformHandle};
+use cubeb_core as cubeb;
+use cubeb_core::ffi;
+use std::convert::{From, TryInto};
+use std::ffi::CStr;
+use std::mem::size_of;
+use std::os::raw::{c_long, c_void};
+use std::rc::Rc;
+use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
+use std::{cell::RefCell, sync::Mutex};
+use std::{panic, slice};
+
+use crate::errors::*;
+
+fn error(error: cubeb::Error) -> ClientMessage {
+    ClientMessage::Error(error.raw_code())
+}
+
+struct CubebDeviceCollectionManager {
+    servers: Mutex<Vec<(Rc<DeviceCollectionChangeCallback>, cubeb::DeviceType)>>,
+}
+
+impl CubebDeviceCollectionManager {
+    fn new() -> CubebDeviceCollectionManager {
+        CubebDeviceCollectionManager {
+            servers: Mutex::new(Vec::new()),
+        }
+    }
+
+    fn register(
+        &self,
+        context: &cubeb::Context,
+        server: &Rc<DeviceCollectionChangeCallback>,
+        devtype: cubeb::DeviceType,
+    ) -> cubeb::Result<()> {
+        let mut servers = self.servers.lock().unwrap();
+        if servers.is_empty() {
+            self.internal_register(context, true)?;
+        }
+        servers.push((server.clone(), devtype));
+        Ok(())
+    }
+
+    fn unregister(
+        &self,
+        context: &cubeb::Context,
+        server: &Rc<DeviceCollectionChangeCallback>,
+        devtype: cubeb::DeviceType,
+    ) -> cubeb::Result<()> {
+        let mut servers = self.servers.lock().unwrap();
+        servers.retain(|(s, d)| !Rc::ptr_eq(s, server) || d != &devtype);
+        if servers.is_empty() {
+            self.internal_register(context, false)?;
+        }
+        Ok(())
+    }
+
+    fn internal_register(&self, context: &cubeb::Context, enable: bool) -> cubeb::Result<()> {
+        for &(dir, cb) in &[
+            (
+                cubeb::DeviceType::INPUT,
+                device_collection_changed_input_cb_c as _,
+            ),
+            (
+                cubeb::DeviceType::OUTPUT,
+                device_collection_changed_output_cb_c as _,
+            ),
+        ] {
+            unsafe {
+                context.register_device_collection_changed(
+                    dir,
+                    if enable { Some(cb) } else { None },
+                    if enable {
+                        self as *const CubebDeviceCollectionManager as *mut c_void
+                    } else {
+                        std::ptr::null_mut()
+                    },
+                )?;
+            }
+        }
+        Ok(())
+    }
+
+    unsafe fn device_collection_changed_callback(&self, device_type: ffi::cubeb_device_type) {
+        let servers = self.servers.lock().unwrap();
+        servers.iter().for_each(|(s, d)| {
+            if d.contains(cubeb::DeviceType::from_bits_truncate(device_type)) {
+                s.device_collection_changed_callback(device_type)
+            }
+        });
+    }
+}
+
+impl Drop for CubebDeviceCollectionManager {
+    fn drop(&mut self) {
+        assert!(self.servers.lock().unwrap().is_empty());
+    }
+}
+
+struct DevIdMap {
+    devices: Vec<usize>,
+}
+
+// A cubeb_devid is an opaque type which may be implemented with a stable
+// pointer in a cubeb backend.  cubeb_devids received remotely must be
+// validated before use, so DevIdMap provides a simple 1:1 mapping between a
+// cubeb_devid and an IPC-transportable value suitable for use as a unique
+// handle.
+impl DevIdMap {
+    fn new() -> DevIdMap {
+        let mut d = DevIdMap {
+            devices: Vec::with_capacity(32),
+        };
+        // A null cubeb_devid is used for selecting the default device.
+        // Pre-populate the mapping with 0 -> 0 to handle nulls.
+        d.devices.push(0);
+        d
+    }
+
+    // Given a cubeb_devid, return a unique stable value suitable for use
+    // over IPC.
+    fn make_handle(&mut self, devid: usize) -> usize {
+        if let Some(i) = self.devices.iter().position(|&d| d == devid) {
+            return i;
+        }
+        self.devices.push(devid);
+        self.devices.len() - 1
+    }
+
+    // Given a handle produced by `make_handle`, return the associated
+    // cubeb_devid.  Invalid handles result in a panic.
+    fn handle_to_id(&self, handle: usize) -> usize {
+        self.devices[handle]
+    }
+}
+
+struct CubebContextState {
+    // `manager` must be dropped before the `context` is destroyed.
+    manager: CubebDeviceCollectionManager,
+    context: cubeb::Result<cubeb::Context>,
+}
+
+thread_local!(static CONTEXT_KEY: RefCell<Option<CubebContextState>> = RefCell::new(None));
+
+fn cubeb_init_from_context_params() -> cubeb::Result<cubeb::Context> {
+    let params = super::G_CUBEB_CONTEXT_PARAMS.lock().unwrap();
+    let context_name = Some(params.context_name.as_c_str());
+    let backend_name = params.backend_name.as_deref();
+    let r = cubeb::Context::init(context_name, backend_name);
+    r.map_err(|e| {
+        info!("cubeb::Context::init failed r={:?}", e);
+        e
+    })
+}
+
+fn with_local_context<T, F>(f: F) -> T
+where
+    F: FnOnce(&cubeb::Result<cubeb::Context>, &mut CubebDeviceCollectionManager) -> T,
+{
+    CONTEXT_KEY.with(|k| {
+        let mut state = k.borrow_mut();
+        if state.is_none() {
+            *state = Some(CubebContextState {
+                manager: CubebDeviceCollectionManager::new(),
+                context: cubeb_init_from_context_params(),
+            });
+        }
+        let CubebContextState { manager, context } = state.as_mut().unwrap();
+        // Always reattempt to initialize cubeb, OS config may have changed.
+        if context.is_err() {
+            *context = cubeb_init_from_context_params();
+        }
+        f(context, manager)
+    })
+}
+
+struct DeviceCollectionClient;
+
+impl rpccore::Client for DeviceCollectionClient {
+    type ServerMessage = DeviceCollectionReq;
+    type ClientMessage = DeviceCollectionResp;
+}
+
+struct CallbackClient;
+
+impl rpccore::Client for CallbackClient {
+    type ServerMessage = CallbackReq;
+    type ClientMessage = CallbackResp;
+}
+
+struct ServerStreamCallbacks {
+    /// Size of input frame in bytes
+    input_frame_size: u16,
+    /// Size of output frame in bytes
+    output_frame_size: u16,
+    /// Shared memory buffer for transporting audio data to/from client
+    shm: SharedMem,
+    /// RPC interface for data_callback (on OS audio thread) to server callback thread
+    data_callback_rpc: rpccore::Proxy<CallbackReq, CallbackResp>,
+    /// RPC interface for state_callback (on any thread) to server callback thread
+    state_callback_rpc: rpccore::Proxy<CallbackReq, CallbackResp>,
+    /// RPC interface for device_change_callback (on any thread) to server callback thread
+    device_change_callback_rpc: rpccore::Proxy<CallbackReq, CallbackResp>,
+    /// Indicates stream is connected to client side.  Callbacks received before
+    /// the stream is in the connected state cannot be sent to the client side, so
+    /// are logged and otherwise ignored.
+    connected: AtomicBool,
+}
+
+impl ServerStreamCallbacks {
+    fn data_callback(&mut self, input: &[u8], output: &mut [u8], nframes: isize) -> isize {
+        trace!(
+            "Stream data callback: {} {} {}",
+            nframes,
+            input.len(),
+            output.len()
+        );
+        if !self.connected.load(Ordering::Acquire) {
+            warn!("Stream data callback triggered before stream connected");
+            return cubeb::ffi::CUBEB_ERROR.try_into().unwrap();
+        }
+
+        if self.input_frame_size != 0 {
+            if input.len() > self.shm.get_size() {
+                debug!(
+                    "bad input size: input={} shm={}",
+                    input.len(),
+                    self.shm.get_size()
+                );
+                return cubeb::ffi::CUBEB_ERROR.try_into().unwrap();
+            }
+            unsafe {
+                self.shm
+                    .get_mut_slice(input.len())
+                    .unwrap()
+                    .copy_from_slice(input);
+            }
+        }
+
+        if self.output_frame_size != 0 && output.len() > self.shm.get_size() {
+            debug!(
+                "bad output size: output={} shm={}",
+                output.len(),
+                self.shm.get_size()
+            );
+            return cubeb::ffi::CUBEB_ERROR.try_into().unwrap();
+        }
+
+        let r = self.data_callback_rpc.call(CallbackReq::Data {
+            nframes,
+            input_frame_size: self.input_frame_size as usize,
+            output_frame_size: self.output_frame_size as usize,
+        });
+
+        match r {
+            Ok(CallbackResp::Data(frames)) => {
+                if frames >= 0 && self.output_frame_size != 0 {
+                    let nbytes = frames as usize * self.output_frame_size as usize;
+                    unsafe {
+                        output[..nbytes].copy_from_slice(self.shm.get_slice(nbytes).unwrap());
+                    }
+                }
+                frames
+            }
+            _ => {
+                debug!("Unexpected message {:?} during data_callback", r);
+                cubeb::ffi::CUBEB_ERROR.try_into().unwrap()
+            }
+        }
+    }
+
+    fn state_callback(&self, state: cubeb::State) {
+        trace!("Stream state callback: {:?}", state);
+        if !self.connected.load(Ordering::Acquire) {
+            warn!("Stream state callback triggered before stream connected");
+            return;
+        }
+
+        let r = self
+            .state_callback_rpc
+            .call(CallbackReq::State(state.into()));
+        match r {
+            Ok(CallbackResp::State) => {}
+            _ => {
+                debug!("Unexpected message {:?} during state callback", r);
+            }
+        }
+    }
+
+    fn device_change_callback(&self) {
+        trace!("Stream device change callback");
+        if !self.connected.load(Ordering::Acquire) {
+            warn!("Stream device_change callback triggered before stream connected");
+            return;
+        }
+        let r = self
+            .device_change_callback_rpc
+            .call(CallbackReq::DeviceChange);
+        match r {
+            Ok(CallbackResp::DeviceChange) => {}
+            _ => {
+                debug!("Unexpected message {:?} during device change callback", r);
+            }
+        }
+    }
+}
+
+static SHM_ID: AtomicUsize = AtomicUsize::new(0);
+
+// Generate a temporary shm_id fragment that is unique to the process.  This
+// path is used temporarily to create a shm segment, which is then
+// immediately deleted from the filesystem while retaining handles to the
+// shm to be shared between the server and client.
+fn get_shm_id() -> String {
+    format!(
+        "cubeb-shm-{}-{}",
+        std::process::id(),
+        SHM_ID.fetch_add(1, Ordering::SeqCst)
+    )
+}
+
+struct ServerStream {
+    stream: Option<cubeb::Stream>,
+    cbs: Box<ServerStreamCallbacks>,
+    client_pipe: Option<PlatformHandle>,
+}
+
+impl Drop for ServerStream {
+    fn drop(&mut self) {
+        // `stream` *must* be dropped before `cbs`.
+        drop(self.stream.take());
+    }
+}
+
+struct DeviceCollectionChangeCallback {
+    rpc: rpccore::Proxy<DeviceCollectionReq, DeviceCollectionResp>,
+}
+
+impl DeviceCollectionChangeCallback {
+    fn device_collection_changed_callback(&self, device_type: ffi::cubeb_device_type) {
+        // TODO: Assert device_type is in devtype.
+        debug!(
+            "Sending device collection ({:?}) changed event",
+            device_type
+        );
+        let _ = self
+            .rpc
+            .call(DeviceCollectionReq::DeviceChange(device_type));
+    }
+}
+
+pub struct CubebServer {
+    callback_thread: ipccore::EventLoopHandle,
+    device_collection_thread: ipccore::EventLoopHandle,
+    streams: slab::Slab<ServerStream>,
+    remote_pid: Option<u32>,
+    device_collection_change_callbacks: Option<Rc<DeviceCollectionChangeCallback>>,
+    devidmap: DevIdMap,
+    shm_area_size: usize,
+}
+
+impl Drop for CubebServer {
+    fn drop(&mut self) {
+        if let Some(device_collection_change_callbacks) = &self.device_collection_change_callbacks {
+            debug!("CubebServer: dropped with device_collection_change_callbacks registered");
+            CONTEXT_KEY.with(|k| {
+                let mut state = k.borrow_mut();
+                if let Some(CubebContextState {
+                    manager,
+                    context: Ok(context),
+                }) = state.as_mut()
+                {
+                    for devtype in [cubeb::DeviceType::INPUT, cubeb::DeviceType::OUTPUT] {
+                        let r = manager.unregister(
+                            context,
+                            device_collection_change_callbacks,
+                            devtype,
+                        );
+                        if r.is_err() {
+                            debug!("CubebServer: unregister failed: {:?}", r);
+                        }
+                    }
+                }
+            })
+        }
+    }
+}
+
+#[allow(unknown_lints)] // non_send_fields_in_send_ty is Nightly-only as of 2021-11-29.
+#[allow(clippy::non_send_fields_in_send_ty)]
+// XXX: required for server setup, verify this is safe.
+unsafe impl Send for CubebServer {}
+
+impl rpccore::Server for CubebServer {
+    type ServerMessage = ServerMessage;
+    type ClientMessage = ClientMessage;
+
+    fn process(&mut self, req: Self::ServerMessage) -> Self::ClientMessage {
+        if let ServerMessage::ClientConnect(pid) = req {
+            self.remote_pid = Some(pid);
+        }
+        with_local_context(|context, manager| match *context {
+            Err(_) => error(cubeb::Error::error()),
+            Ok(ref context) => self.process_msg(context, manager, &req),
+        })
+    }
+}
+
+// Debugging for BMO 1594216/1612044.
+macro_rules! try_stream {
+    ($self:expr, $stm_tok:expr) => {
+        if $self.streams.contains($stm_tok) {
+            $self.streams[$stm_tok]
+                .stream
+                .as_mut()
+                .expect("uninitialized stream")
+        } else {
+            error!(
+                "{}:{}:{} - Stream({}): invalid token",
+                file!(),
+                line!(),
+                column!(),
+                $stm_tok
+            );
+            return error(cubeb::Error::invalid_parameter());
+        }
+    };
+}
+
+impl CubebServer {
+    pub fn new(
+        callback_thread: ipccore::EventLoopHandle,
+        device_collection_thread: ipccore::EventLoopHandle,
+        shm_area_size: usize,
+    ) -> Self {
+        CubebServer {
+            callback_thread,
+            device_collection_thread,
+            streams: slab::Slab::<ServerStream>::new(),
+            remote_pid: None,
+            device_collection_change_callbacks: None,
+            devidmap: DevIdMap::new(),
+            shm_area_size,
+        }
+    }
+
+    // Process a request coming from the client.
+    fn process_msg(
+        &mut self,
+        context: &cubeb::Context,
+        manager: &mut CubebDeviceCollectionManager,
+        msg: &ServerMessage,
+    ) -> ClientMessage {
+        let resp: ClientMessage = match *msg {
+            ServerMessage::ClientConnect(_) => {
+                // remote_pid is set before cubeb initialization, just verify here.
+                assert!(self.remote_pid.is_some());
+                ClientMessage::ClientConnected
+            }
+
+            ServerMessage::ClientDisconnect => {
+                // TODO:
+                //self.connection.client_disconnect();
+                ClientMessage::ClientDisconnected
+            }
+
+            ServerMessage::ContextGetBackendId => {
+                ClientMessage::ContextBackendId(context.backend_id().to_string())
+            }
+
+            ServerMessage::ContextGetMaxChannelCount => context
+                .max_channel_count()
+                .map(ClientMessage::ContextMaxChannelCount)
+                .unwrap_or_else(error),
+
+            ServerMessage::ContextGetMinLatency(ref params) => {
+                let format = cubeb::SampleFormat::from(params.format);
+                let layout = cubeb::ChannelLayout::from(params.layout);
+
+                let params = cubeb::StreamParamsBuilder::new()
+                    .format(format)
+                    .rate(params.rate)
+                    .channels(params.channels)
+                    .layout(layout)
+                    .take();
+
+                context
+                    .min_latency(&params)
+                    .map(ClientMessage::ContextMinLatency)
+                    .unwrap_or_else(error)
+            }
+
+            ServerMessage::ContextGetPreferredSampleRate => context
+                .preferred_sample_rate()
+                .map(ClientMessage::ContextPreferredSampleRate)
+                .unwrap_or_else(error),
+
+            ServerMessage::ContextGetDeviceEnumeration(device_type) => context
+                .enumerate_devices(cubeb::DeviceType::from_bits_truncate(device_type))
+                .map(|devices| {
+                    let v: Vec<DeviceInfo> = devices
+                        .iter()
+                        .map(|i| {
+                            let mut tmp: DeviceInfo = i.as_ref().into();
+                            // Replace each cubeb_devid with a unique handle suitable for IPC.
+                            tmp.devid = self.devidmap.make_handle(tmp.devid);
+                            tmp
+                        })
+                        .collect();
+                    ClientMessage::ContextEnumeratedDevices(v)
+                })
+                .unwrap_or_else(error),
+
+            ServerMessage::StreamCreate(ref params) => self
+                .process_stream_create(params)
+                .unwrap_or_else(|_| error(cubeb::Error::error())),
+
+            ServerMessage::StreamInit(stm_tok, ref params) => self
+                .process_stream_init(context, stm_tok, params)
+                .unwrap_or_else(|_| error(cubeb::Error::error())),
+
+            ServerMessage::StreamDestroy(stm_tok) => {
+                if self.streams.contains(stm_tok) {
+                    debug!("Unregistering stream {:?}", stm_tok);
+                    self.streams.remove(stm_tok);
+                } else {
+                    // Debugging for BMO 1594216/1612044.
+                    error!("StreamDestroy({}): invalid token", stm_tok);
+                    return error(cubeb::Error::invalid_parameter());
+                }
+                ClientMessage::StreamDestroyed
+            }
+
+            ServerMessage::StreamStart(stm_tok) => try_stream!(self, stm_tok)
+                .start()
+                .map(|_| ClientMessage::StreamStarted)
+                .unwrap_or_else(error),
+
+            ServerMessage::StreamStop(stm_tok) => try_stream!(self, stm_tok)
+                .stop()
+                .map(|_| ClientMessage::StreamStopped)
+                .unwrap_or_else(error),
+
+            ServerMessage::StreamGetPosition(stm_tok) => try_stream!(self, stm_tok)
+                .position()
+                .map(ClientMessage::StreamPosition)
+                .unwrap_or_else(error),
+
+            ServerMessage::StreamGetLatency(stm_tok) => try_stream!(self, stm_tok)
+                .latency()
+                .map(ClientMessage::StreamLatency)
+                .unwrap_or_else(error),
+
+            ServerMessage::StreamGetInputLatency(stm_tok) => try_stream!(self, stm_tok)
+                .input_latency()
+                .map(ClientMessage::StreamInputLatency)
+                .unwrap_or_else(error),
+
+            ServerMessage::StreamSetVolume(stm_tok, volume) => try_stream!(self, stm_tok)
+                .set_volume(volume)
+                .map(|_| ClientMessage::StreamVolumeSet)
+                .unwrap_or_else(error),
+
+            ServerMessage::StreamSetName(stm_tok, ref name) => try_stream!(self, stm_tok)
+                .set_name(name)
+                .map(|_| ClientMessage::StreamNameSet)
+                .unwrap_or_else(error),
+
+            ServerMessage::StreamGetCurrentDevice(stm_tok) => try_stream!(self, stm_tok)
+                .current_device()
+                .map(|device| ClientMessage::StreamCurrentDevice(Device::from(device)))
+                .unwrap_or_else(error),
+
+            ServerMessage::StreamRegisterDeviceChangeCallback(stm_tok, enable) => {
+                try_stream!(self, stm_tok)
+                    .register_device_changed_callback(if enable {
+                        Some(device_change_cb_c)
+                    } else {
+                        None
+                    })
+                    .map(|_| ClientMessage::StreamRegisterDeviceChangeCallback)
+                    .unwrap_or_else(error)
+            }
+
+            ServerMessage::ContextSetupDeviceCollectionCallback => {
+                let (server_pipe, client_pipe) = match sys::make_pipe_pair() {
+                    Ok((server_pipe, client_pipe)) => (server_pipe, client_pipe),
+                    Err(e) => {
+                        debug!(
+                            "ContextSetupDeviceCollectionCallback - make_pipe_pair failed: {:?}",
+                            e
+                        );
+                        return error(cubeb::Error::error());
+                    }
+                };
+
+                // TODO: this should bind the client_pipe and send the server_pipe to the remote, but
+                //       additional work is required as it's not possible to convert a Windows sys::Pipe into a raw handle.
+                // TODO: Use the rpc_thread instead of an extra device_collection_thread, but a reentrant bind_client
+                //       is required to support that.
+                let rpc = match self
+                    .device_collection_thread
+                    .bind_client::<DeviceCollectionClient>(server_pipe)
+                {
+                    Ok(rpc) => rpc,
+                    Err(e) => {
+                        debug!(
+                            "ContextSetupDeviceCollectionCallback - bind_client: {:?}",
+                            e
+                        );
+                        return error(cubeb::Error::error());
+                    }
+                };
+
+                self.device_collection_change_callbacks =
+                    Some(Rc::new(DeviceCollectionChangeCallback { rpc }));
+                let fd = RegisterDeviceCollectionChanged {
+                    platform_handle: SerializableHandle::new(client_pipe, self.remote_pid.unwrap()),
+                };
+
+                ClientMessage::ContextSetupDeviceCollectionCallback(fd)
+            }
+
+            ServerMessage::ContextRegisterDeviceCollectionChanged(device_type, enable) => self
+                .process_register_device_collection_changed(
+                    context,
+                    manager,
+                    cubeb::DeviceType::from_bits_truncate(device_type),
+                    enable,
+                )
+                .unwrap_or_else(error),
+
+            #[cfg(target_os = "linux")]
+            ServerMessage::PromoteThreadToRealTime(thread_info) => {
+                let info = RtPriorityThreadInfo::deserialize(thread_info);
+                match promote_thread_to_real_time(info, 0, 48000) {
+                    Ok(_) => {
+                        info!("Promotion of content process thread to real-time OK");
+                    }
+                    Err(_) => {
+                        warn!("Promotion of content process thread to real-time error");
+                    }
+                }
+                ClientMessage::ThreadPromoted
+            }
+        };
+
+        trace!("process_msg: req={:?}, resp={:?}", msg, resp);
+
+        resp
+    }
+
+    fn process_register_device_collection_changed(
+        &mut self,
+        context: &cubeb::Context,
+        manager: &mut CubebDeviceCollectionManager,
+        devtype: cubeb::DeviceType,
+        enable: bool,
+    ) -> cubeb::Result<ClientMessage> {
+        if devtype == cubeb::DeviceType::UNKNOWN {
+            return Err(cubeb::Error::invalid_parameter());
+        }
+
+        assert!(self.device_collection_change_callbacks.is_some());
+        let cbs = self.device_collection_change_callbacks.as_ref().unwrap();
+
+        if enable {
+            manager.register(context, cbs, devtype)
+        } else {
+            manager.unregister(context, cbs, devtype)
+        }
+        .map(|_| ClientMessage::ContextRegisteredDeviceCollectionChanged)
+    }
+
+    // Stream create is special, so it's been separated from process_msg.
+    fn process_stream_create(&mut self, params: &StreamCreateParams) -> Result<ClientMessage> {
+        fn frame_size_in_bytes(params: Option<&StreamParams>) -> u16 {
+            params
+                .map(|p| {
+                    let format = p.format.into();
+                    let sample_size = match format {
+                        cubeb::SampleFormat::S16LE
+                        | cubeb::SampleFormat::S16BE
+                        | cubeb::SampleFormat::S16NE => 2,
+                        cubeb::SampleFormat::Float32LE
+                        | cubeb::SampleFormat::Float32BE
+                        | cubeb::SampleFormat::Float32NE => 4,
+                    };
+                    let channel_count = p.channels as u16;
+                    sample_size * channel_count
+                })
+                .unwrap_or(0u16)
+        }
+
+        // Create the callback handling struct which is attached the cubeb stream.
+        let input_frame_size = frame_size_in_bytes(params.input_stream_params.as_ref());
+        let output_frame_size = frame_size_in_bytes(params.output_stream_params.as_ref());
+
+        // Estimate a safe shmem size for this stream configuration.  If the server was configured with a fixed
+        // shm_area_size override, use that instead.
+        // TODO: Add a new cubeb API to query the precise buffer size required for a given stream config.
+        // https://github.com/mozilla/audioipc-2/issues/124
+        let shm_area_size = if self.shm_area_size == 0 {
+            let frame_size = output_frame_size.max(input_frame_size) as u32;
+            let in_rate = params.input_stream_params.map(|p| p.rate).unwrap_or(0);
+            let out_rate = params.output_stream_params.map(|p| p.rate).unwrap_or(0);
+            let rate = out_rate.max(in_rate);
+            // 1s of audio, rounded up to the nearest 64kB.
+            // Stream latency is capped at 1s in process_stream_init.
+            (((rate * frame_size) + 0xffff) & !0xffff) as usize
+        } else {
+            self.shm_area_size
+        };
+        debug!("shm_area_size = {}", shm_area_size);
+
+        let shm = SharedMem::new(&get_shm_id(), shm_area_size)?;
+        let shm_handle = unsafe { shm.make_handle()? };
+
+        let (server_pipe, client_pipe) = sys::make_pipe_pair()?;
+        // TODO: this should bind the client_pipe and send the server_pipe to the remote, but
+        //       additional work is required as it's not possible to convert a Windows sys::Pipe into a raw handle.
+        let rpc = self
+            .callback_thread
+            .bind_client::<CallbackClient>(server_pipe)?;
+
+        let cbs = Box::new(ServerStreamCallbacks {
+            input_frame_size,
+            output_frame_size,
+            shm,
+            state_callback_rpc: rpc.clone(),
+            device_change_callback_rpc: rpc.clone(),
+            data_callback_rpc: rpc,
+            connected: AtomicBool::new(false),
+        });
+
+        let entry = self.streams.vacant_entry();
+        let key = entry.key();
+        debug!("Registering stream {:?}", key);
+
+        entry.insert(ServerStream {
+            stream: None,
+            cbs,
+            client_pipe: Some(client_pipe),
+        });
+
+        Ok(ClientMessage::StreamCreated(StreamCreate {
+            token: key,
+            shm_handle: SerializableHandle::new(shm_handle, self.remote_pid.unwrap()),
+            shm_area_size,
+        }))
+    }
+
+    // Stream init is special, so it's been separated from process_msg.
+    fn process_stream_init(
+        &mut self,
+        context: &cubeb::Context,
+        stm_tok: usize,
+        params: &StreamInitParams,
+    ) -> Result<ClientMessage> {
+        // Create cubeb stream from params
+        let stream_name = params
+            .stream_name
+            .as_ref()
+            .and_then(|name| CStr::from_bytes_with_nul(name).ok());
+
+        // Map IPC handle back to cubeb_devid.
+        let input_device = self.devidmap.handle_to_id(params.input_device) as *const _;
+        let input_stream_params = params.input_stream_params.as_ref().map(|isp| unsafe {
+            cubeb::StreamParamsRef::from_ptr(isp as *const StreamParams as *mut _)
+        });
+
+        // Map IPC handle back to cubeb_devid.
+        let output_device = self.devidmap.handle_to_id(params.output_device) as *const _;
+        let output_stream_params = params.output_stream_params.as_ref().map(|osp| unsafe {
+            cubeb::StreamParamsRef::from_ptr(osp as *const StreamParams as *mut _)
+        });
+
+        // TODO: Manage stream latency requests with respect to the RT deadlines the callback_thread was configured for.
+        fn round_up_pow2(v: u32) -> u32 {
+            debug_assert!(v >= 1);
+            1 << (32 - (v - 1).leading_zeros())
+        }
+        let rate = params
+            .output_stream_params
+            .map(|p| p.rate)
+            .unwrap_or_else(|| params.input_stream_params.map(|p| p.rate).unwrap());
+        // Note: minimum latency supported by AudioIPC is currently ~5ms.  This restriction may be reduced by later IPC improvements.
+        let min_latency = round_up_pow2(5 * rate / 1000);
+        // Note: maximum latency is restricted by the SharedMem size.
+        let max_latency = rate;
+        let latency = params.latency_frames.clamp(min_latency, max_latency);
+        trace!(
+            "stream rate={} latency requested={} calculated={}",
+            rate,
+            params.latency_frames,
+            latency
+        );
+
+        let server_stream = &mut self.streams[stm_tok];
+        assert!(size_of::<Box<ServerStreamCallbacks>>() == size_of::<usize>());
+        let user_ptr = server_stream.cbs.as_ref() as *const ServerStreamCallbacks as *mut c_void;
+
+        let stream = unsafe {
+            let stream = context.stream_init(
+                stream_name,
+                input_device,
+                input_stream_params,
+                output_device,
+                output_stream_params,
+                latency,
+                Some(data_cb_c),
+                Some(state_cb_c),
+                user_ptr,
+            );
+            match stream {
+                Ok(stream) => stream,
+                Err(e) => {
+                    debug!("Unregistering stream {:?} (stream error {:?})", stm_tok, e);
+                    self.streams.remove(stm_tok);
+                    return Err(e.into());
+                }
+            }
+        };
+
+        server_stream.stream = Some(stream);
+
+        let client_pipe = server_stream
+            .client_pipe
+            .take()
+            .expect("invalid state after StreamCreated");
+        server_stream.cbs.connected.store(true, Ordering::Release);
+        Ok(ClientMessage::StreamInitialized(SerializableHandle::new(
+            client_pipe,
+            self.remote_pid.unwrap(),
+        )))
+    }
+}
+
+// C callable callbacks
+unsafe extern "C" fn data_cb_c(
+    _: *mut ffi::cubeb_stream,
+    user_ptr: *mut c_void,
+    input_buffer: *const c_void,
+    output_buffer: *mut c_void,
+    nframes: c_long,
+) -> c_long {
+    let ok = panic::catch_unwind(|| {
+        let cbs = &mut *(user_ptr as *mut ServerStreamCallbacks);
+        let input = if input_buffer.is_null() {
+            &[]
+        } else {
+            let nbytes = nframes * c_long::from(cbs.input_frame_size);
+            slice::from_raw_parts(input_buffer as *const u8, nbytes as usize)
+        };
+        let output: &mut [u8] = if output_buffer.is_null() {
+            &mut []
+        } else {
+            let nbytes = nframes * c_long::from(cbs.output_frame_size);
+            slice::from_raw_parts_mut(output_buffer as *mut u8, nbytes as usize)
+        };
+        cbs.data_callback(input, output, nframes as isize) as c_long
+    });
+    ok.unwrap_or(cubeb::ffi::CUBEB_ERROR as c_long)
+}
+
+unsafe extern "C" fn state_cb_c(
+    _: *mut ffi::cubeb_stream,
+    user_ptr: *mut c_void,
+    state: ffi::cubeb_state,
+) {
+    let ok = panic::catch_unwind(|| {
+        let state = cubeb::State::from(state);
+        let cbs = &mut *(user_ptr as *mut ServerStreamCallbacks);
+        cbs.state_callback(state);
+    });
+    ok.expect("State callback panicked");
+}
+
+unsafe extern "C" fn device_change_cb_c(user_ptr: *mut c_void) {
+    let ok = panic::catch_unwind(|| {
+        let cbs = &mut *(user_ptr as *mut ServerStreamCallbacks);
+        cbs.device_change_callback();
+    });
+    ok.expect("Device change callback panicked");
+}
+
+unsafe extern "C" fn device_collection_changed_input_cb_c(
+    _: *mut ffi::cubeb,
+    user_ptr: *mut c_void,
+) {
+    let ok = panic::catch_unwind(|| {
+        let manager = &mut *(user_ptr as *mut CubebDeviceCollectionManager);
+        manager.device_collection_changed_callback(ffi::CUBEB_DEVICE_TYPE_INPUT);
+    });
+    ok.expect("Collection changed (input) callback panicked");
+}
+
+unsafe extern "C" fn device_collection_changed_output_cb_c(
+    _: *mut ffi::cubeb,
+    user_ptr: *mut c_void,
+) {
+    let ok = panic::catch_unwind(|| {
+        let manager = &mut *(user_ptr as *mut CubebDeviceCollectionManager);
+        manager.device_collection_changed_callback(ffi::CUBEB_DEVICE_TYPE_OUTPUT);
+    });
+    ok.expect("Collection changed (output) callback panicked");
+}