muvm-guest: Add support for running as muvm-pwbridge

Support running the PipeWire bridge as a separate process, optionally
with systemd socket activation.

Signed-off-by: Val Packett <[email protected]>

Author: valpackett

Cargo.lock

@@ -29,6 +29,7 @@ tokio = { version = "1.38.0", default-features = false, features = ["io-util", "
 tokio-stream = { version = "0.1.15", default-features = false, features = ["net", "sync"] }
 udev = { version = "0.9.0", default-features = false, features = [] }
 uuid = { version = "1.10.0", default-features = false, features = ["serde", "std", "v7"] }
+listenfd = "1.0.2"
 
 [[bin]]
 name = "muvm"

crates/muvm/Cargo.toml

@@ -8,7 +8,8 @@ use std::{cmp, env, fs, thread};
 
 use anyhow::{anyhow, Context, Result};
 use muvm::guest::box64::setup_box;
-use muvm::guest::bridge::pipewire::start_pwbridge;
+use muvm::guest::bridge::common::{bridge_loop, bridge_loop_with_listenfd};
+use muvm::guest::bridge::pipewire::{pipewire_sock_path, PipeWireProtocolHandler};
 use muvm::guest::bridge::x11::start_x11bridge;
 use muvm::guest::fex::setup_fex;
 use muvm::guest::hidpipe::start_hidpipe;
@@ -32,6 +33,10 @@ fn main() -> Result<ExitCode> {
     let bb = binary_path.split('/').next_back().context("arg0 split")?;
     match bb {
         "muvm-configure-network" => return configure_network(),
+        "muvm-pwbridge" => {
+            bridge_loop_with_listenfd::<PipeWireProtocolHandler>(pipewire_sock_path);
+            return Ok(());
+        },
         "muvm-remote" => {
             let rt = tokio::runtime::Runtime::new().unwrap();
             let mut command_args = env::args().skip(1);
@@ -169,7 +174,7 @@ fn main() -> Result<ExitCode> {
     });
 
     thread::spawn(|| {
-        if catch_unwind(start_pwbridge).is_err() {
+        if catch_unwind(|| bridge_loop::<PipeWireProtocolHandler>(&pipewire_sock_path())).is_err() {
             eprintln!("pwbridge thread crashed, pipewire passthrough will no longer function");
         }
     });

crates/muvm/src/guest/bin/muvm-guest.rs

@@ -971,10 +971,24 @@ impl<'a, T: ProtocolHandler> SubPoll<'a, T> {
     }
 }
 
+pub fn bridge_loop_with_listenfd<T: ProtocolHandler>(fallback_sock_path: impl Fn() -> String) {
+    if let Some(listen_sock) = listenfd::ListenFd::from_env()
+        .take_unix_listener(0)
+        .unwrap()
+    {
+        bridge_loop_sock::<T>(listen_sock)
+    } else {
+        bridge_loop::<T>(&fallback_sock_path())
+    }
+}
+
 pub fn bridge_loop<T: ProtocolHandler>(sock_path: &str) {
-    let epoll = Epoll::new(EpollCreateFlags::empty()).unwrap();
     _ = fs::remove_file(sock_path);
-    let listen_sock = UnixListener::bind(sock_path).unwrap();
+    bridge_loop_sock::<T>(UnixListener::bind(sock_path).unwrap());
+}
+
+pub fn bridge_loop_sock<T: ProtocolHandler>(listen_sock: UnixListener) {
+    let epoll = Epoll::new(EpollCreateFlags::empty()).unwrap();
     epoll
         .add(
             &listen_sock,

crates/muvm/src/guest/bridge/common.rs

@@ -9,7 +9,6 @@ use nix::errno::Errno;
 use nix::sys::epoll::EpollFlags;
 use nix::sys::eventfd::{EfdFlags, EventFd};
 
-use crate::guest::bridge::common;
 use crate::guest::bridge::common::{
     Client, CrossDomainHeader, CrossDomainResource, MessageResourceFinalizer, ProtocolHandler,
     StreamRecvResult, StreamSendResult,
@@ -165,7 +164,7 @@ impl PipeWireHeader {
     }
 }
 
-struct PipeWireResourceFinalizer;
+pub struct PipeWireResourceFinalizer;
 
 impl MessageResourceFinalizer for PipeWireResourceFinalizer {
     type Handler = PipeWireProtocolHandler;
@@ -194,7 +193,7 @@ impl ClientNodeData {
     }
 }
 
-struct PipeWireProtocolHandler {
+pub struct PipeWireProtocolHandler {
     client_nodes: HashMap<u32, ClientNodeData>,
     guest_to_host_eventfds: HashMap<u64, CrossDomainEventFd>,
     host_to_guest_eventfds: HashMap<u32, CrossDomainEventFd>,
@@ -405,8 +404,6 @@ impl ProtocolHandler for PipeWireProtocolHandler {
     }
 }
 
-pub fn start_pwbridge() {
-    let sock_path = format!("{}/pipewire-0", env::var("XDG_RUNTIME_DIR").unwrap());
-
-    common::bridge_loop::<PipeWireProtocolHandler>(&sock_path)
+pub fn pipewire_sock_path() -> String {
+    format!("{}/pipewire-0", env::var("XDG_RUNTIME_DIR").unwrap())
 }