steam-backlog-enforcer/steam_backlog_enforcer/_steam_errors.py
Krzysztof kuhy Rudnicki 21fe2f7742 Stop the enforcer launching Steam and notifications as root
The enforce service runs as root (no User=) but sets DISPLAY=:0, so any GUI
it starts lands on the desktop session. Two resolvers disagreed about who to
drop privileges to:

  library_hider._resolve_desktop_user()  read STEAM_ENFORCER_DESKTOP_USER
  game_install._get_real_user()          read only SUDO_USER or USER

systemd sets neither of the latter, so _get_real_user() returned None under
the service and every `geteuid() == 0 and real_user and ...` guard fell
through to running as root. Steam answered with a zenity modal ("Cannot run
as root user", /usr/lib/steam/steam:261) on screen.

Confirmed from the live process tree: root `bash /usr/lib/steam/steam
-cef-disable-gpu ... steam://install/618510` with a root zenity child. It
never reached the journal, because that text goes to zenity and _run_as_user
sends child output to DEVNULL.

- _desktop_env: add resolve_desktop_user/desktop_uid/desktop_user_cmd. Only
  the argv builder is shared, never the spawn call: tests/_no_subprocess.py
  patches subprocess per module by name, so a spawn site in an unpatched
  module could fire a real `sudo -u kuhy steam`.
- game_install._get_real_user: delegate to the shared resolver. This alone
  also fixes the root `steam -silent` in _ensure_steam_running and the
  no-op os.chown on new appmanifests.
- _trigger_steam_install / enforcer.send_notification: drop privileges.
  send_notification had no DBUS_SESSION_BUS_ADDRESS, so it silently reached
  nobody for all six of its callers.
- _run_as_user: fail closed. Running unchanged as root when no desktop user
  resolves is what put the modal on screen; refuse and log instead.

Also stop the retry storm behind it. steamapps does not exist (Steam has
never completed sign-in), so is_game_installed() was always False and the
loop re-triggered every allowed game every pass: 1656 attempts in 30
minutes, service RSS 1.5 GB (peak 4.3 GB), a FileNotFoundError traceback
each time. Guard install_game and _reinstall_missing_allowed on
steam_library_ready() -- a missing library means no install can succeed by
any route, so this is a correctness check rather than a tuned retry limit.

The module splits here are forced by the pre-commit 250-line gate, which
blocks any commit touching an over-cap file: game_install, library_hider and
_enforce_loop were already over before this change. They are split by
responsibility (_cdp transport, _steam_launch lifecycle, _steam_process
spawning, _steam_errors, _steam_client, _game_names, game_uninstall,
_enforce_steps, _owned_apps_cache, _echo, _protected_apps). game_install and
library_hider re-export their old public names, so the 15 modules that
import from them are untouched by this commit.

Verified as real root under the unit's environment: argv is now
`sudo -u kuhy env DISPLAY=:0 ... xdg-open steam://install/...` for both the
installer and notify-send; three enforce passes spawn no process and log
once; _run_as_user refuses with no desktop user. After restart: 0 retries,
0 tracebacks, 0 root-owned files under ~/.local/share/Steam, RSS 342 MB.

1311 tests pass. _desktop_env and _steam_state at 100% branch coverage.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016A1EYiv7e7HGhET84oa9M3
2026-08-24 13:55:44 +02:00

41 lines
1.7 KiB
Python

"""Errors raised when Steam cannot be driven.
A leaf module so both :mod:`steam_backlog_enforcer.library_hider` and
:mod:`steam_backlog_enforcer._steam_launch` can raise and catch these without
importing each other. Split out to keep both under the 250-line cap.
"""
from __future__ import annotations
class SteamUnavailableError(RuntimeError):
"""Raised when Steam cannot be driven over CDP.
Covers both "Steam is not installed" and "Steam is installed but never
opened its debug port". Callers are expected to degrade gracefully rather
than abort: an unreachable Steam means there is no library to hide, which
is not a fatal condition for the enforcer.
"""
class SteamUpdateInProgressError(SteamUnavailableError):
"""Raised to defer a Steam restart while a game update is in flight.
Subclasses :class:`SteamUnavailableError` so existing callers already
degrade gracefully (skip this pass, retry next loop). Restarting Steam
mid-update suspends and can corrupt the transfer, so the enforcer waits
for updates to finish before bouncing Steam to open the CDP port.
"""
class DesktopSessionNotReadyError(SteamUnavailableError):
"""Raised to defer a Steam launch until the user's session exists.
Subclasses :class:`SteamUnavailableError` so existing callers already
degrade gracefully (skip this pass, retry next loop). Launching Steam
before ``/run/user/<uid>`` exists hands every Wine child a runtime dir
that is not there, so it falls back from winepulse to winealsa and stays
that way for the whole session — the Kingdom Come: Deliverance II startup
crash. Waiting a pass costs 3s; getting it wrong costs a reboot.
"""