udev: Add udev listener service

This service lives in the user daemon and has the path
/com/steampowered/SteamOSManager1/UdevEvents

Cargo.lock

@@ -563,6 +563,17 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "io-lifetimes"
+version = "1.0.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eae7b9aee968036d54dce06cebaefd919e4472e753296daccd6d344e3e2df0c2"
+dependencies = [
+ "hermit-abi",
+ "libc",
+ "windows-sys 0.48.0",
+]
+
 [[package]]
 name = "itertools"
 version = "0.12.1"
@@ -584,6 +595,16 @@ version = "0.2.154"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ae743338b92ff9146ce83992f766a31066a91a8c84a45e0e9f21e7cf6de6d346"
 
+[[package]]
+name = "libudev-sys"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3c8469b4a23b962c1396b9b451dda50ef5b283e8dd309d69033475fa9b334324"
+dependencies = [
+ "libc",
+ "pkg-config",
+]
+
 [[package]]
 name = "linux-raw-sys"
 version = "0.4.13"
@@ -724,6 +745,12 @@ dependencies = [
  "futures-io",
 ]
 
+[[package]]
+name = "pkg-config"
+version = "0.3.30"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d231b230927b5e4ad203db57bbcbee2802f6bce620b1e4a9024a07d94e2907ec"
+
 [[package]]
 name = "polling"
 version = "3.7.0"
@@ -945,6 +972,7 @@ dependencies = [
  "toml",
  "tracing",
  "tracing-subscriber",
+ "udev",
  "xdg",
  "zbus",
  "zbus_xml",
@@ -1141,6 +1169,18 @@ version = "1.17.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "42ff0bf0c66b8238c6f3b578df37d0b7848e55df8577b3f74f92a69acceeb825"
 
+[[package]]
+name = "udev"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "50051c6e22be28ee6f217d50014f3bc29e81c20dc66ff7ca0d5c5226e1dcc5a1"
+dependencies = [
+ "io-lifetimes",
+ "libc",
+ "libudev-sys",
+ "pkg-config",
+]
+
 [[package]]
 name = "uds_windows"
 version = "1.1.0"

Cargo.toml

@@ -18,7 +18,7 @@ config = { version = "0.14", default-features = false, features = ["async", "tom
 inotify = { version = "0.10", default-features = false, features = ["stream"] }
 libc = "0.2"
 itertools = "0.12"
-nix = { version = "0.28", default-features = false, features = ["fs", "signal"] }
+nix = { version = "0.28", default-features = false, features = ["fs", "poll", "signal"] }
 serde = { version = "1.0", default-features = false, features = ["derive"] }
 tokio = { version = "1", default-features = false, features = ["fs", "io-std", "io-util", "macros", "process", "rt-multi-thread", "signal", "sync"] }
 tokio-stream = { version = "0.1", default-features = false }
@@ -26,5 +26,6 @@ tokio-util = { version = "0.7", default-features = false }
 toml = "0.8"
 tracing = { version = "0.1", default-features = false }
 tracing-subscriber = { version = "0.3", default-features = false, features = ["fmt"] }
+udev = "0.8"
 xdg = "2.5"
 zbus = { version = "4", default-features = false, features = ["tokio"] }

com.steampowered.SteamOSManager1.xml

@@ -346,4 +346,18 @@
       </method>
   </interface>
 
+  <!--
+      com.steampowered.SteamOSManager1.UdevEvents
+      @short_description: Specific udev events that are monitored to be
+      bubbled up to the desktop interface
+
+      Version available: 9
+  -->
+  <interface name="com.steampowered.SteamOSManager1.UdevEvents">
+      <signal name="OverCurrent">
+        <arg type="s" name="devpath"/>
+        <arg type="s" name="port"/>
+        <arg type="t" name="count"/>
+      </signal>
+  </interface>
 </node>

src/daemon/user.rs

@@ -19,6 +19,7 @@ use zbus::ConnectionBuilder;
 use crate::daemon::{channel, Daemon, DaemonContext};
 use crate::manager::user::SteamOSManager;
 use crate::path;
+use crate::udev::UdevMonitor;
 
 #[derive(Copy, Clone, Default, Deserialize, Serialize, Debug)]
 struct UserConfig {
@@ -36,7 +37,9 @@ struct UserState {
 #[derive(Copy, Clone, Default, Deserialize, Serialize, Debug)]
 pub(crate) struct UserServicesState {}
 
-struct UserContext {}
+struct UserContext {
+    session: Connection,
+}
 
 impl DaemonContext for UserContext {
     type State = UserState;
@@ -66,9 +69,11 @@ impl DaemonContext for UserContext {
         &mut self,
         _state: UserState,
         _config: UserConfig,
-        _daemon: &mut Daemon<UserContext>,
+        daemon: &mut Daemon<UserContext>,
     ) -> Result<()> {
-        // Nothing to do yet
+        let udev = UdevMonitor::init(&self.session).await?;
+        daemon.add_service(udev);
+
         Ok(())
     }
 
@@ -115,7 +120,7 @@ pub async fn daemon() -> Result<()> {
     let subscriber = Registry::default().with(stdout_log);
     let (_tx, rx) = channel::<UserContext>();
 
-    let (_session, system) = match create_connections().await {
+    let (session, system) = match create_connections().await {
         Ok(c) => c,
         Err(e) => {
             let _guard = tracing::subscriber::set_default(subscriber);
@@ -124,7 +129,7 @@ pub async fn daemon() -> Result<()> {
         }
     };
 
-    let context = UserContext {};
+    let context = UserContext { session };
     let mut daemon = Daemon::new(subscriber, system, rx).await?;
 
     daemon.run(context).await

src/lib.rs

@@ -20,6 +20,7 @@ mod process;
 mod sls;
 mod systemd;
 mod thread;
+mod udev;
 
 pub mod cec;
 pub mod daemon;

src/udev.rs

@@ -0,0 +1,172 @@
+/*
+ * Copyright © 2023 Collabora Ltd.
+ * Copyright © 2024 Valve Software
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+use anyhow::{anyhow, bail, ensure, Result};
+use nix::poll::{poll, PollFd, PollFlags, PollTimeout};
+use nix::unistd::pipe;
+use std::os::fd::{AsFd, AsRawFd, OwnedFd};
+use tokio::net::unix::pipe::Sender;
+use tokio::sync::mpsc::{unbounded_channel, UnboundedSender};
+use tracing::debug;
+use udev::{Event, EventType, MonitorBuilder};
+use zbus::{self, interface, Connection, InterfaceRef, SignalContext};
+
+use crate::thread::spawn;
+use crate::Service;
+
+const PATH: &str = "/com/steampowered/SteamOSManager1/UdevEvents";
+
+pub(crate) struct UdevMonitor
+where
+    Self: 'static + Send,
+{
+    shutdown_sender: Sender,
+    shutdown_receiver: Option<OwnedFd>,
+    udev_object: InterfaceRef<UdevDbusObject>,
+}
+
+struct UdevDbusObject
+where
+    Self: 'static + Send, {}
+
+#[derive(Debug)]
+enum UdevEvent {
+    OverCurrent {
+        devpath: String,
+        port: String,
+        count: u64,
+    },
+}
+
+impl Service for UdevMonitor {
+    const NAME: &'static str = "udev-monitor";
+
+    async fn run(&mut self) -> Result<()> {
+        let (ev_sender, mut ev_receiver) = unbounded_channel();
+        let shutdown_receiver = self
+            .shutdown_receiver
+            .take()
+            .ok_or(anyhow!("UdevMonitor cannot be run twice"))?;
+        let mut handle = spawn(move || run_udev(ev_sender, shutdown_receiver));
+
+        loop {
+            let handle = &mut handle;
+            let ev = tokio::select! {
+                r = handle => break r,
+                r = ev_receiver.recv() => r.ok_or(anyhow!("udev event pipe broke"))?,
+            };
+            match ev {
+                UdevEvent::OverCurrent {
+                    devpath,
+                    port,
+                    count,
+                } => {
+                    UdevDbusObject::over_current(
+                        self.udev_object.signal_context(),
+                        devpath.as_str(),
+                        port.as_str(),
+                        count,
+                    )
+                    .await?
+                }
+            }
+        }
+    }
+
+    async fn shutdown(&mut self) -> Result<()> {
+        self.shutdown_sender.try_write(&[0u8])?;
+        Ok(())
+    }
+}
+
+impl UdevMonitor {
+    pub async fn init(connection: &Connection) -> Result<UdevMonitor> {
+        let object_server = connection.object_server();
+        ensure!(
+            object_server.at(PATH, UdevDbusObject {}).await?,
+            "Could not register UdevEvents"
+        );
+        let udev_object: InterfaceRef<UdevDbusObject> = object_server.interface(PATH).await?;
+        let (shutdown_receiver, shutdown_sender) = pipe()?;
+        Ok(UdevMonitor {
+            udev_object,
+            shutdown_sender: Sender::from_owned_fd(shutdown_sender)?,
+            shutdown_receiver: Some(shutdown_receiver),
+        })
+    }
+}
+
+#[interface(name = "com.steampowered.SteamOSManager1.UdevEvents")]
+impl UdevDbusObject {
+    #[zbus(signal)]
+    async fn over_current(
+        signal_ctxt: &SignalContext<'_>,
+        devpath: &str,
+        port: &str,
+        count: u64,
+    ) -> zbus::Result<()>;
+}
+
+fn run_udev(tx: UnboundedSender<UdevEvent>, rx: OwnedFd) -> Result<()> {
+    let usb_monitor = MonitorBuilder::new()?
+        .match_subsystem_devtype("usb", "usb_interface")?
+        .listen()?;
+    let fd = usb_monitor.as_fd();
+    let mut iter = usb_monitor.iter();
+    let ev_poller = PollFd::new(fd, PollFlags::POLLIN);
+    let shutdown_poller = PollFd::new(rx.as_fd(), PollFlags::POLLIN);
+    debug!(
+        "Listening on event poller {} and shutdown poller {}",
+        ev_poller.as_fd().as_raw_fd(),
+        shutdown_poller.as_fd().as_raw_fd()
+    );
+    loop {
+        let fds = &mut [ev_poller, shutdown_poller];
+        let ret = poll(fds, PollTimeout::NONE)?;
+        if ret < 0 {
+            return Err(std::io::Error::from_raw_os_error(-ret).into());
+        }
+        let [ev_poller, shutdown_poller] = fds;
+        match ev_poller.any() {
+            None => bail!("Event poller encountered unknown flags"),
+            Some(true) => {
+                let ev = iter
+                    .next()
+                    .ok_or(anyhow!("Poller said event was present, but it was not"))?;
+                process_usb_event(ev, &tx)?;
+            }
+            Some(false) => (),
+        }
+        match shutdown_poller.any() {
+            None => bail!("Shutdown poller encountered unknown flags"),
+            Some(true) => break Ok(()),
+            Some(false) => (),
+        }
+    }
+}
+
+fn process_usb_event(ev: Event, tx: &UnboundedSender<UdevEvent>) -> Result<()> {
+    debug!("Got USB event {ev:?}");
+    if ev.event_type() != EventType::Change {
+        return Ok(());
+    }
+    let port = match ev.property_value("OVER_CURRENT_PORT") {
+        None => return Ok(()),
+        Some(port) => port.to_string_lossy().to_string(),
+    };
+    let count: u64 = match ev.property_value("OVER_CURRENT_COUNT") {
+        None => return Ok(()),
+        Some(count) => count.to_string_lossy().parse()?,
+    };
+    let devpath = ev.devpath().to_string_lossy().to_string();
+    tx.send(UdevEvent::OverCurrent {
+        devpath,
+        port,
+        count,
+    })?;
+    Ok(())
+}