mirror of
https://github.com/kuhyx/steam-backlog-enforcer.git
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Krzysztof kuhy Rudnicki
bfdd69453e
The enforcer runs as root under systemd and launches Steam via `sudo -u <user> env DISPLAY=... XAUTHORITY=... DBUS_SESSION_BUS_ADDRESS=...`. sudo uses env_reset, so that list is the child's entire environment - an allowlist where every omission fails silently. XDG_RUNTIME_DIR was missing. Without it Wine cannot reach $XDG_RUNTIME_DIR/pulse/native, falls back from winepulse.drv to winealsa.drv, and hands FMOD raw ALSA devices instead of the session sink. Kingdom Come: Deliverance II died in its Bink startup video as a result. Across 18 sessions the split was total: 9/9 runs logging "PulseAudio Output" exited cleanly, 9/9 logging "HDA NVidia" crashed on the same line. It presented as a corrupt install - the apparent cure was a 92GB reinstall - but verify-integrity always passed. What actually fixed it was the Steam restart the reinstall incidentally performed. Extract the duplicated env construction into _desktop_env.desktop_env_args and derive XDG_RUNTIME_DIR from the target uid, never from the ambient environment: root's own value would point the child at /run/user/0. PULSE_SERVER is deliberately not exported. pressure-vessel reads XDG_RUNTIME_DIR to bind-mount the pulse socket into the Steam Linux Runtime container, whereas a hardcoded unix:/run/user/<uid>/pulse/native names a host path that need not resolve inside it. Also gate the launch on the session existing. The enforcer is ordered only After=network-online, while /run/user/<uid> is created by user-runtime-dir@<uid>.service; on a measured boot the enforcer started 54ms before that unit and won only by doing other work first. Launching in that window would name a runtime dir that is not there and reintroduce the same silent winealsa fallback for the whole session, so defer instead - the enforce loop already retries every 3s, and DesktopSessionNotReadyError subclasses SteamUnavailableError so existing callers degrade as before. An ordering dependency would not be reliable here, since logind may start user-runtime-dir outside the boot transaction. Verified on the failing path rather than a dev shell: after restarting the enforcer, the Steam it launched carried XDG_RUNTIME_DIR=/run/user/1000 and KCD2 ran 15 minutes on "PulseAudio Output" with no crash artifacts. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
73 lines
3.2 KiB
Python
73 lines
3.2 KiB
Python
"""Environment handed to processes launched into the user's desktop session.
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The enforcer runs as root under systemd, so anything it starts on the desktop
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user's behalf goes through ``sudo -u <user> env ...``. ``sudo`` resets the
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environment, which makes the list below an *allowlist*: every variable the
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desktop session needs must be named here explicitly, and every omission fails
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silently rather than erroring.
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Lives in its own module (like ``_steam_state``) so both ``library_hider`` and
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``game_install`` can share one builder without forming an import cycle.
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``XDG_RUNTIME_DIR`` is load-bearing and was missing here for a long time.
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Without it Wine cannot reach ``$XDG_RUNTIME_DIR/pulse/native``, silently falls
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back from ``winepulse.drv`` to ``winealsa.drv``, and every Proton game gets raw
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ALSA devices instead of the session's PulseAudio sink. That crashed Kingdom
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Come: Deliverance II during its startup video, and looked like a corrupt
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install because restarting Steam by hand - the thing a reinstall incidentally
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does - was what actually cleared it.
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Only ``XDG_RUNTIME_DIR`` is exported for audio, deliberately: pressure-vessel
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reads it to bind-mount the pulse socket into the Steam Linux Runtime container,
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whereas a hardcoded ``PULSE_SERVER=unix:/run/user/<uid>/pulse/native`` would
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name a *host* path that need not resolve inside that container.
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"""
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from __future__ import annotations
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import os
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from pathlib import Path
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def desktop_runtime_dir(uid: int) -> str:
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"""Path to the desktop user's XDG runtime directory."""
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return f"/run/user/{uid}"
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def desktop_session_ready(uid: int) -> bool:
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"""Whether the desktop user's runtime directory exists yet.
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The enforcer is a system service ordered only ``After=network-online``,
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while ``/run/user/<uid>`` is created by ``user-runtime-dir@<uid>.service``
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when logind opens the session. On a cold boot the enforcer can reach its
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first launch before that directory exists — measured on one boot, it
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started 54ms *before* the runtime-dir unit and only won by doing other
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work first.
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A Steam launched in that window would name a runtime dir that is not
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there, which is exactly the winealsa fallback this module exists to
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prevent, and it would stay broken for the whole session. Callers gate on
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this and retry on the next enforce pass instead.
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"""
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return Path(desktop_runtime_dir(uid)).is_dir()
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def desktop_env_args(user: str, uid: int) -> list[str]:
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"""Build the ``env`` arguments for a command run as the desktop *user*.
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Session paths are derived from *uid* rather than read from the current
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environment: the enforcer normally runs as root, and inheriting root's
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``XDG_RUNTIME_DIR`` would point the child at ``/run/user/0``, which it
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cannot use.
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"""
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runtime_dir = desktop_runtime_dir(uid)
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dbus_default = f"unix:path={runtime_dir}/bus"
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dbus_addr = os.environ.get("DBUS_SESSION_BUS_ADDRESS", dbus_default)
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xauth = os.environ.get("XAUTHORITY", f"/home/{user}/.Xauthority")
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return [
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f"DISPLAY={os.environ.get('DISPLAY', ':0')}",
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f"XAUTHORITY={xauth}",
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f"DBUS_SESSION_BUS_ADDRESS={dbus_addr}",
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f"XDG_RUNTIME_DIR={runtime_dir}",
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]
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