feat(input): SteamOS Game Mode support, Steam Controller exit chord, and controller grouping improvements by waterfoul · Pull Request #53 · hikaps/couchplay

waterfoul · 2026-07-14T01:15:59Z

Summary

This PR adds SteamOS Game Mode integration, migrates input device monitoring into the privileged helper daemon, adds Steam Controller exit chord detection via raw HID, and improves Bluetooth controller grouping. This adds full support for steamos game mode and allows couchplay to run while the steam client is also running in desktop mode. I plan to come through with some improvements / documentation on how to set this up to run it in game mode and big picture mode. I could have include all of those changes into this bransch / MR but this was already a monster so I wanted to send it over as it is since it works fully

Changes

refactor: Migrate input device watching to helper daemon

Removes the VirtualDeviceWatcher GUI-side manager entirely
The helper now watches /dev/input for new devices, grants uinput write access, and monitors assigned nodes for the Start+Select exit chord
SessionRunner delegates device watching to the helper via a new WatchDevice D-Bus call; the helper emits exitChordTriggered(username) back when the chord is held
This will enable better support for the flatpak deployment as it no longer needs device access. I plan to come through with another MR updating the flatpak to remove the bindings

feat: Steam Controller exit chord via hidraw

For Steam Controller / Wireless Receiver puck devices, the helper additionally opens the sibling /dev/hidrawN endpoint and parses raw HID reports (64-byte SC format and 16-byte puck format) to detect Start+Select independently of the evdev node, which Steam Input may be holding open exclusively

feat: SteamOS Game Mode support & robust controller isolation

Adds scripts/couchplay-gamemode.sh — a Game Mode hook script that re-runs CouchPlay's device isolation setup on Steam's gamemoderun entry/exit, ensuring udev seat stripping and uinput ACLs survive Steam's device resets
Adds scripts/update-sysext.sh to rebuild the SquashFS system extension image for immutable SteamOS deployments
- Note: This script will be cleaned up a bit when I come back with the flatpak changes. I plan to integrate those changes into the existing steamos install MR
Adds udev-rule-based seat stripping and driver unbind/rebind helpers (writeTempUdevRule, removeTempUdevRule, findHidrawPathForDeviceId) to CouchPlayHelper
Updates the .desktop file to invoke couchplay-gamemode.sh when launched via Steam

fix: Controller detection and grouping improvements

Fixes PlayStation controller Bluetooth detection (correct vendor/product parsing for BT transport)
Improves multi-device grouping logic in DeviceManager for controllers that expose multiple input nodes (e.g. motion + gamepad)
Adds unit tests in test_devicemanager covering the new grouping and BT detection paths

Testing

All 18 unit tests pass (ctest --test-dir build)

…tion to helper daemon

…idraw

…tion

hikaps

The security-critical part is solid: raw-HID reads bounded (uint8_t buf[64], every access guarded by bytesRead >= 10), isValidDevicePath rejects .. + enforces /dev/input|/dev/hidraw\d+ + char-device check, WatchDevice polkit-gated like ChangeDeviceOwner, and the VirtualDeviceWatcher removal is clean (CMake/includes/members/call-sites all gone, suite updated). None of the inline items are architectural — requesting changes for those.

Cross-PR (with #46): install.sh merges cleanly (disjoint regions). But both PRs add a SteamOS update script — update-sysext.sh here vs update-nonroot.sh in #46 — divergent; keep one (this one's the faster loop; fold #46's Flatpak-source rebuild in as a flag) and drop the other. Suggested order: #46 first, then this rebases + dedups + adds the gamemode launcher to packaging.

hikaps · 2026-07-20T23:14:08Z

+echo "Launching CouchPlay..."
+
+# Set environment so CouchPlay connects to the nested KWin's Wayland display
+# WAYLAND_DISPLAY is inherited from kwin_wayland's nested output


The nested kwin is never actually used. kwin_wayland … & is backgrounded, then only export QT_QPA_PLATFORM=wayland runs — WAYLAND_DISPLAY is never set to kwin's socket (a backgrounded child can't export env back to its parent; the "inherited" comment here is impossible). CouchPlay lands on the parent gamescope socket, so the KWin window-positioning this script exists for never applies. Capture kwin's socket (--wayland-display <name> + export WAYLAND_DISPLAY=<name>) before launching CouchPlay.

hikaps · 2026-07-20T23:14:08Z

+
+[Desktop Action GameMode]
+Name=CouchPlay (Game Mode)
+Exec=couchplay-gamemode


This desktop action ships nothing: beta.yml/release.yml only package scripts/install-helper.sh from scripts/, so couchplay-gamemode.sh is never in the tarball, and it's not on PATH inside the Flatpak (the primary distribution). The Exec=couchplay-gamemode is a dead action. Either add the script to CI packaging and provide a Flatpak-spawning Exec, or drop the action until then.

hikaps · 2026-07-20T23:14:08Z

        return;
    }

+    QFile logFile(QStringLiteral("/home/deck/couchplay.log"));


Hardcoded /home/deck/couchplay.log opened unbounded-append on every message; in the Flatpak that path isn't the real home (open silently fails), and where it works it grows without bound + persists runtime detail. Looks like leftover debug — move to QStandardPaths::GenericDataLocation and gate behind a debug flag.

hikaps · 2026-07-20T23:14:08Z

+        }
+
+        // 1. Write the temporary udev rule assigning this device/subsystem to the target user
+        if (writeTempUdevRule(hid, QString::fromLocal8Bit(pw->pw_name))) {


pw->pw_name is passed to writeTempUdevRule without the project's s_validUsername regex (^[a-z][a-z0-9_-]{0,31}$). The ChangeDeviceOwner path never calls validateUserAndAuth, unlike the username-taking slots. A username with a quote/comma/newline (feasible via NSS/LDAP) could corrupt the rule or inject a RUN+= key parsed by the privileged udev daemon. Low likelihood on a gaming box, but cheap + correct — sanitize before it reaches the rule.

hikaps · 2026-07-20T23:14:08Z

+    watcher->notifier = new QSocketNotifier(fd, QSocketNotifier::Read, this);
+    watcher->chordTimer = new QTimer(this);
+    watcher->chordTimer->setSingleShot(true);
+    watcher->chordTimer->setInterval(3000); // 3.0 seconds hold duration


Hold is 3s (and logs "held for 3s"), but the README, "Exiting a Session" section, and exitChordTriggered doxygen all say 2s — users release at ~2s and it won't fire. Make it 2000 (or fix all the docs to 3s).

hikaps · 2026-07-20T23:14:08Z

 void SessionRunner::onDeviceReconnected(const QString &stableId, int eventNumber, int instanceIndex)
 {
-    if (!isRunning()) {
+    if (m_status != QStringLiteral("Starting session...") && m_status != QStringLiteral("Session running")) {


isRunning() was replaced with a guard against magic status-string literals. That couples reconnection to exact strings set elsewhere (a rename silently disables it) and flips semantics (reconnects whenever the string says running, even if all instances died). Prefer a semantic predicate.

- S1: validate username (s_validUsername) in writeTempUdevRule before it reaches a root-written udev rule (was only checked in other slots). - C2: replace hardcoded /home/deck/couchplay.log with QStandardPaths + gate behind COUCHPLAY_LOG (was always-on unbounded append). - C4: chord hold 3000ms -> 2000ms to match README (was 3s in code, 2s in docs). - C5: restore semantic isRunning() guard in onDeviceReconnected (status-string literals coupled to exact strings + flipped semantics). - C1: wire the nested kwin socket (--wayland-display) + export WAYLAND_DISPLAY so CouchPlay connects to kwin, not the parent gamescope socket. - C3: include couchplay-gamemode.sh in the beta/release tarballs so the GameMode desktop action resolves (install.sh already installs it). Note: full Game Mode behavior (nested kwin rendering) needs SteamOS validation.

waterfoul added 5 commits July 13, 2026 20:02

refactor(input): migrate virtual device watching and exit chord detec…

a82d2f0

…tion to helper daemon

feat(input): support exit chord detection for Steam Controllers via h…

899a534

…idraw

feat(gamemode): support SteamOS Game Mode and robust controller isola…

f45e474

…tion

fix(input): improve controller grouping and device detection

583c8f9

docs: document Start+Select controller exit chord

ee3c906

hikaps mentioned this pull request Jul 20, 2026

feat: Add support for steamos without needing to break readonly mode #46

Merged

hikaps requested changes Jul 20, 2026

View reviewed changes

hikaps merged commit 7e5cc64 into hikaps:develop Jul 30, 2026
1 check passed

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feat(input): SteamOS Game Mode support, Steam Controller exit chord, and controller grouping improvements - #53

feat(input): SteamOS Game Mode support, Steam Controller exit chord, and controller grouping improvements#53
hikaps merged 6 commits into
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waterfoul commented Jul 14, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Summary

Changes

refactor: Migrate input device watching to helper daemon

feat: Steam Controller exit chord via hidraw

feat: SteamOS Game Mode support & robust controller isolation

fix: Controller detection and grouping improvements

Testing

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waterfoul commented Jul 14, 2026 •

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