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feat: M2 — gamescope input via its EIS socket (SteamOS-like input path)

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gamescope runs its own EIS server and exports the socket to its children as LIBEI_SOCKET —
no portal involved. The gamescope backend now launches the nested app through a tiny shell
wrapper that relays that value to /tmp/lumen-gamescope-ei; the libei injector gains an
EiSource enum (Portal | SocketPathFile) and connects a UnixStream directly to gamescope's
socket (polling until the app has started), then runs the identical reis sender flow.
Backend::GamescopeEi is auto-selected when LUMEN_COMPOSITOR=gamescope
(LUMEN_INPUT_BACKEND=gamescope overrides).

Validated end-to-end: input-test against a headless gamescope running xev — 129
MotionNotify/KeyPress/ButtonPress events delivered into the nested X app ("Gamescope
Virtual Input" device bound, sender handshake + emulation working).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
Enrico Bühler
2026-06-09 22:34:27 +00:00
parent c8f9032dec
commit 7f3897e0d3
4 changed files with 134 additions and 38 deletions
Download Patch File Download Diff File Expand all files Collapse all files
crates/lumen-host/src/inject.rs
+24 -2
View File
@@ -26,6 +26,9 @@ pub enum Backend {
WlrVirtual,
/// libei via `reis` — Wayland-native (RemoteDesktop portal). Not yet implemented.
Libei,
/// libei directly against gamescope's own EIS socket (no portal): input lands in the
/// nested game — the SteamOS-like session.
GamescopeEi,
/// `/dev/uinput` — universal fallback (but invisible to `WLR_LIBINPUT_NO_DEVICES=1`).
Uinput,
}
@@ -52,19 +55,35 @@ pub fn open(backend: Backend) -> Result<Box<dyn InputInjector>> {
anyhow::bail!("libei input requires Linux + a RemoteDesktop portal")
}
}
Backend::GamescopeEi => {
#[cfg(target_os = "linux")]
{
Ok(Box::new(libei::LibeiInjector::open_with(
libei::EiSource::SocketPathFile(
crate::vdisplay::gamescope_ei_socket_file().into(),
),
)?))
}
#[cfg(not(target_os = "linux"))]
{
anyhow::bail!("gamescope EIS input requires Linux")
}
}
other => anyhow::bail!("injection backend {other:?} not implemented"),
}
}
/// Pick the injection backend for the current session. wlroots/Sway only implements the
/// Pick the injection backend for the current session. gamescope hosts its own EIS server (no
/// portal), so a gamescope session injects directly into it. wlroots/Sway only implements the
/// ScreenCast portal (no RemoteDesktop), so libei can't run there — use the wlr virtual-input
/// protocols. KWin and GNOME implement RemoteDesktop but not the wlr protocols, so use libei.
/// `LUMEN_INPUT_BACKEND=wlr|libei` overrides the auto-detection.
/// `LUMEN_INPUT_BACKEND=wlr|libei|gamescope|uinput` overrides the auto-detection.
pub fn default_backend() -> Backend {
if let Ok(v) = std::env::var("LUMEN_INPUT_BACKEND") {
match v.trim().to_ascii_lowercase().as_str() {
"wlr" | "wlroots" | "wlrvirtual" => return Backend::WlrVirtual,
"libei" | "ei" | "portal" => return Backend::Libei,
"gamescope" | "gamescope-ei" => return Backend::GamescopeEi,
"uinput" => return Backend::Uinput,
other => tracing::warn!(
value = other,
@@ -72,6 +91,9 @@ pub fn default_backend() -> Backend {
),
}
}
if std::env::var("LUMEN_COMPOSITOR").is_ok_and(|v| v.trim().eq_ignore_ascii_case("gamescope")) {
return Backend::GamescopeEi;
}
let desktop = std::env::var("XDG_CURRENT_DESKTOP").unwrap_or_default();
let d = desktop.to_ascii_uppercase();
if d.contains("KDE") || d.contains("GNOME") {
crates/lumen-host/src/inject/libei.rs
+88 -35
View File
@@ -1,14 +1,18 @@
//! libei input injection via the RemoteDesktop portal — the portable path for KWin and
//! GNOME/Mutter, which (unlike wlroots/Sway) implement `org.freedesktop.portal.RemoteDesktop`
//! and route emulated input through libei/EIS rather than the wlr virtual-input protocols.
//! libei input injection — the portable EI-sender path.
//!
//! We use `ashpd` to open a RemoteDesktop session and obtain the EIS socket fd, then `reis` to
//! drive it as an EI *sender*: bind the seat's pointer/keyboard/scroll/button capabilities and,
//! per device, `start_emulating` → emit → `frame`. The portal session and the EIS connection
//! must stay alive and the event stream must be polled continuously (resume/pause/ping/modifier
//! traffic), so the whole thing runs on a dedicated thread with its own tokio runtime; the
//! synchronous control thread reaches it through an unbounded channel and [`LibeiInjector::inject`]
//! merely enqueues.
//! Two ways to reach an EIS server ([`EiSource`]):
//! * **Portal** — `org.freedesktop.portal.RemoteDesktop` via `ashpd` (KWin, GNOME/Mutter),
//! which hands us the EIS socket fd after the session grant.
//! * **Socket** — connect directly to a compositor's own EIS socket. gamescope runs an EIS
//! server and exports its path to its children as `LIBEI_SOCKET`; our gamescope backend
//! relays that path through a file so the injector can connect (no portal involved).
//!
//! Either way, `reis` drives the connection as an EI *sender*: bind the seat's
//! pointer/keyboard/scroll/button capabilities and, per device, `start_emulating` → emit →
//! `frame`. The session and the EIS connection must stay alive and the event stream must be
//! polled continuously (resume/pause/ping/modifier traffic), so the whole thing runs on a
//! dedicated thread with its own tokio runtime; the synchronous control thread reaches it
//! through an unbounded channel and [`LibeiInjector::inject`] merely enqueues.
//!
//! Keyboard codes are Linux evdev (the same space our VK→evdev table produces) and the
//! compositor supplies the keymap, so — unlike the wlr path — there is no keymap to upload and
@@ -34,6 +38,16 @@ use tokio::sync::mpsc::{unbounded_channel, UnboundedReceiver, UnboundedSender};
/// `code` value marking a horizontal scroll event (mirrors `gamestream::input`).
const SCROLL_HORIZONTAL: u32 = 1;
/// Where to find the EIS server.
#[derive(Clone, Debug)]
pub enum EiSource {
/// `org.freedesktop.portal.RemoteDesktop` (KWin, GNOME/Mutter).
Portal,
/// A file containing the EIS socket path/name (gamescope's relayed `LIBEI_SOCKET`); polled
/// until it appears, since the compositor may still be starting.
SocketPathFile(std::path::PathBuf),
}
/// Handle held by the control thread; forwards events to the libei worker thread.
pub struct LibeiInjector {
tx: UnboundedSender<InputEvent>,
@@ -41,15 +55,19 @@ pub struct LibeiInjector {
impl LibeiInjector {
pub fn open() -> Result<Self> {
Self::open_with(EiSource::Portal)
}
pub fn open_with(source: EiSource) -> Result<Self> {
let (tx, rx) = unbounded_channel::<InputEvent>();
std::thread::Builder::new()
.name("lumen-libei".into())
.spawn(move || worker(rx))
.spawn(move || worker(rx, source))
.map_err(|e| anyhow!("spawn libei worker thread: {e}"))?;
// Return immediately — the portal handshake must NOT run on the caller's (control)
// thread, or a slow/denied portal would freeze the ENet control stream and drop the
// client. The worker establishes the session asynchronously and logs its status;
// events enqueue until devices resume (a few startup events may be dropped).
// Return immediately — the portal/socket handshake must NOT run on the caller's
// (control) thread, or a slow/denied setup would freeze the ENet control stream and
// drop the client. The worker establishes the session asynchronously and logs its
// status; events enqueue until devices resume (a few startup events may be dropped).
Ok(Self { tx })
}
}
@@ -63,7 +81,7 @@ impl InputInjector for LibeiInjector {
}
/// Worker thread entry: build a tokio runtime and run the session to completion.
fn worker(rx: UnboundedReceiver<InputEvent>) {
fn worker(rx: UnboundedReceiver<InputEvent>, source: EiSource) {
let rt = match tokio::runtime::Builder::new_multi_thread()
.worker_threads(1)
.enable_all()
@@ -75,17 +93,17 @@ fn worker(rx: UnboundedReceiver<InputEvent>) {
return;
}
};
rt.block_on(session_main(rx));
rt.block_on(session_main(rx, source));
}
/// Open the portal + EIS (bounded), then pump events until disconnect or shutdown.
async fn session_main(mut rx: UnboundedReceiver<InputEvent>) {
/// Open the portal/socket + EIS (bounded), then pump events until disconnect or shutdown.
async fn session_main(mut rx: UnboundedReceiver<InputEvent>, source: EiSource) {
// Keep `_rd`/`_session` bound for the whole loop — dropping the portal session closes the
// EIS connection. Bound the setup so a headless approval dialog (un-bypassed grant) can't
// hang the worker forever.
let (_rd, _session, context, mut events) = match tokio::time::timeout(
let (_portal, context, mut events) = match tokio::time::timeout(
Duration::from_secs(30),
connect(),
connect(source),
)
.await
{
@@ -96,7 +114,7 @@ async fn session_main(mut rx: UnboundedReceiver<InputEvent>) {
}
Err(_) => {
tracing::error!(
"libei: portal setup timed out (headless approval needed, or kde-authorized grant not seeded / app-id mismatch)"
"libei: EIS setup timed out (headless approval needed / kde-authorized grant not seeded / gamescope socket never appeared)"
);
return;
}
@@ -119,17 +137,37 @@ async fn session_main(mut rx: UnboundedReceiver<InputEvent>) {
}
}
/// Tie down the verbose tuple the connect step returns.
/// Tie down the verbose tuple the connect step returns. The portal pair must stay alive for
/// the whole session (dropping it closes the EIS connection); `None` for the direct-socket path.
type Connected = (
RemoteDesktop,
ashpd::desktop::Session<RemoteDesktop>,
Option<(RemoteDesktop, ashpd::desktop::Session<RemoteDesktop>)>,
ei::Context,
reis::tokio::EiConvertEventStream,
);
/// Open a RemoteDesktop portal session (pointer + keyboard), connect to EIS, and run the EI
/// sender handshake. Returns the live portal + EI objects.
async fn connect() -> Result<Connected> {
/// Reach an EIS server per `source` and run the EI sender handshake.
async fn connect(source: EiSource) -> Result<Connected> {
let (portal, stream) = match source {
EiSource::Portal => {
let (rd, session, fd) = connect_portal().await?;
(Some((rd, session)), UnixStream::from(fd))
}
EiSource::SocketPathFile(file) => (None, connect_socket_file(&file).await?),
};
let context = ei::Context::new(stream).map_err(|e| anyhow!("reis EI context: {e}"))?;
let (_conn, events) = context
.handshake_tokio("lumen-host", ei::handshake::ContextType::Sender)
.await
.map_err(|e| anyhow!("EI handshake: {e}"))?;
Ok((portal, context, events))
}
/// Open a RemoteDesktop portal session (pointer + keyboard) and obtain the EIS socket fd.
async fn connect_portal() -> Result<(
RemoteDesktop,
ashpd::desktop::Session<RemoteDesktop>,
std::os::fd::OwnedFd,
)> {
let rd = RemoteDesktop::new()
.await
.map_err(|e| anyhow!("open RemoteDesktop portal (is xdg-desktop-portal-kde/gnome running and XDG_CURRENT_DESKTOP set?): {e}"))?;
@@ -160,14 +198,29 @@ async fn connect() -> Result<Connected> {
.connect_to_eis(&session, ConnectToEISOptions::default())
.await
.map_err(|e| anyhow!("connect_to_eis (RemoteDesktop portal version < 2?): {e}"))?;
let context =
ei::Context::new(UnixStream::from(fd)).map_err(|e| anyhow!("reis EI context: {e}"))?;
let (_conn, events) = context
.handshake_tokio("lumen-host", ei::handshake::ContextType::Sender)
.await
.map_err(|e| anyhow!("EI handshake: {e}"))?;
Ok((rd, session, fd))
}
Ok((rd, session, context, events))
/// Poll `file` for the EIS socket path (the gamescope backend relays `LIBEI_SOCKET` there once
/// the nested app launches), then connect. A bare name is resolved against `XDG_RUNTIME_DIR`,
/// mirroring libei's own `LIBEI_SOCKET` semantics.
async fn connect_socket_file(file: &std::path::Path) -> Result<UnixStream> {
let path = loop {
match std::fs::read_to_string(file) {
Ok(s) if !s.trim().is_empty() => break s.trim().to_string(),
_ => tokio::time::sleep(Duration::from_millis(300)).await,
}
};
let full = if path.starts_with('/') {
std::path::PathBuf::from(&path)
} else {
let runtime = std::env::var("XDG_RUNTIME_DIR").map_err(|_| {
anyhow!("XDG_RUNTIME_DIR unset (needed to resolve EIS socket '{path}')")
})?;
std::path::Path::new(&runtime).join(&path)
};
tracing::info!(socket = %full.display(), "libei: connecting to EIS socket");
UnixStream::connect(&full).map_err(|e| anyhow!("connect EIS socket {}: {e}", full.display()))
}
/// One EI device and its emulation state.
crates/lumen-host/src/vdisplay.rs
+7
View File
@@ -109,6 +109,13 @@ pub fn open(compositor: Compositor) -> Result<Box<dyn VirtualDisplay>> {
}
}
/// Path of the file where the gamescope backend relays the nested session's `LIBEI_SOCKET`
/// (gamescope's EIS server) for the input injector.
#[cfg(target_os = "linux")]
pub fn gamescope_ei_socket_file() -> &'static str {
gamescope::EI_SOCKET_FILE
}
#[cfg(target_os = "linux")]
mod gamescope;
#[cfg(target_os = "linux")]
crates/lumen-host/src/vdisplay/gamescope.rs
+15 -1
View File
@@ -71,17 +71,31 @@ impl VirtualDisplay for GamescopeDisplay {
}
}
/// File where the wrapper below writes gamescope's `LIBEI_SOCKET` (its EIS server socket),
/// read by the libei injector to drive input into the nested app. See [`crate::inject`].
pub const EI_SOCKET_FILE: &str = "/tmp/lumen-gamescope-ei";
/// Spawn `gamescope --backend headless -W w -H h -r hz -- <app>`. The app comes from
/// `LUMEN_GAMESCOPE_APP` (default a no-op that just keeps gamescope alive — set it to a real
/// game/GL app for actual content). stdout/stderr go to `/tmp/lumen-gamescope.log`.
/// game/GL app for actual content, e.g. `steam -gamepadui` for the SteamOS-like session).
/// stdout/stderr go to `/tmp/lumen-gamescope.log`. The app is launched through a tiny shell
/// wrapper that relays gamescope's `LIBEI_SOCKET` (set for its children) to [`EI_SOCKET_FILE`]
/// so the input injector can connect to gamescope's EIS server from outside.
fn spawn(w: u32, h: u32, hz: u32) -> Result<Child> {
let app = std::env::var("LUMEN_GAMESCOPE_APP").unwrap_or_else(|_| "sleep infinity".to_string());
let _ = std::fs::remove_file(EI_SOCKET_FILE); // stale socket path from a previous session
let mut cmd = Command::new("gamescope");
cmd.args(["--backend", "headless"])
.args(["-W", &w.to_string()])
.args(["-H", &h.to_string()])
.args(["-r", &hz.to_string()])
.args(["--xwayland-count", "1", "--"])
.args([
"sh",
"-c",
&format!("printf %s \"$LIBEI_SOCKET\" > {EI_SOCKET_FILE}; exec \"$@\""),
"sh",
])
.args(app.split_whitespace())
// Prefer the NVIDIA GL vendor for the nested session (harmless on a pure-NVIDIA box).
.env("__GLX_VENDOR_LIBRARY_NAME", "nvidia");