room_glitch/tools/launch/pi_service.py

#!/usr/bin/env python3
"""Install a user service from a Pi desktop terminal; no root or SSH changes."""
import argparse
import os
from pathlib import Path
import subprocess
import sys

HERE = Path(__file__).resolve().parent
MARKER = '# Managed by Arcade Escape pi_service.py'


def quoted(value):
    value=str(value)
    if any(c in value for c in ('\n','\r','\0')): raise ValueError('Paths must not contain control characters')
    return '"'+value.replace('\\','\\\\').replace('"','\\"').replace('%','%%')+'"'


def working_directory(value):
    # Unlike ExecStart arguments, systemd reads this as a single unquoted path.
    value = str(value)
    if any(ord(c) < 32 or ord(c) == 127 for c in value):
        raise ValueError('Paths must not contain control characters')
    return value.replace('%', '%%')


def reload_service():
    subprocess.run(['systemctl', '--user', 'daemon-reload'], check=True)
    result = subprocess.run(
        ['systemctl', '--user', 'show', 'arcade-cabinet.service',
         '--property=LoadState', '--value'],
        check=True, capture_output=True, text=True)
    if result.stdout.strip() != 'loaded':
        raise ValueError(
            'systemd rejected arcade-cabinet.service (LoadState: '
            + result.stdout.strip() + '). Inspect it with: '
            'systemctl --user status arcade-cabinet.service --no-pager -l')


def render_unit(python, launcher, config):
    return f"""{MARKER}
[Unit]
Description=Arcade Escape managed cabinet
PartOf=graphical-session.target

[Service]
Type=exec
EnvironmentFile=%t/arcade-cabinet-display.env
UnsetEnvironment=ARCADE_ROOM_URL ARCADE_CABINET_TOKEN ARCADE_OPERATOR_TOKEN ARCADE_CABINET_TOKENS
WorkingDirectory={working_directory(Path(launcher).resolve().parents[2])}
ExecStart=:{quoted(python)} {quoted(launcher)} cabinet --config {quoted(config)}
Restart=no
KillMode=mixed
TimeoutStopSec=15
"""


def render_desktop(python, script):
    # Desktop Exec quoting also needs escaping of $ and backticks inside quotes.
    def desktop_quote(value):
        return quoted(value).replace('$','\\$').replace('`','\\`')
    return f"""{MARKER}
[Desktop Entry]
Type=Application
Name=Arcade cabinet display setup
Exec={desktop_quote(python)} {desktop_quote(script)} refresh-session
Terminal=false
NoDisplay=true
"""


def refresh_session():
    if not os.environ.get('DISPLAY') and not os.environ.get('WAYLAND_DISPLAY'):
        raise ValueError('Run this from a terminal on the Pi desktop, not a plain SSH session')
    runtime=Path(os.environ.get('XDG_RUNTIME_DIR',f'/run/user/{os.getuid()}'))
    if not runtime.is_dir(): raise ValueError('The Pi desktop user runtime directory is unavailable')
    values={k:os.environ[k] for k in ('DISPLAY','WAYLAND_DISPLAY','XAUTHORITY','XDG_RUNTIME_DIR','XDG_SESSION_TYPE') if os.environ.get(k)}
    text=''
    for key,value in values.items():
        if any(c in value for c in ('\n','\r','\0')): raise ValueError('Invalid desktop environment value')
        text+=key+'="'+value.replace('\\','\\\\').replace('"','\\"')+'"\n'
    target=runtime/'arcade-cabinet-display.env'
    temporary=target.with_suffix('.tmp')
    temporary.write_text(text,encoding='utf-8')
    temporary.chmod(0o600)
    temporary.replace(target)
    print('Saved display environment for the current desktop login.')


def write_managed(path, text):
    if path.exists() and not path.read_text(encoding='utf-8').startswith(MARKER):
        raise ValueError('Refusing to overwrite an unrelated file: '+str(path))
    path.parent.mkdir(parents=True,exist_ok=True)
    path.write_text(text,encoding='utf-8')


def main():
    parser=argparse.ArgumentParser(description=__doc__)
    parser.add_argument('action',choices=['install','refresh-session'])
    parser.add_argument('--config',default=str(HERE/'launcher.ini'))
    parser.add_argument('--remote', action='store_true', help='Register from SSH; wait for the desktop helper if no display is available')
    args=parser.parse_args()
    try:
        if not sys.platform.startswith('linux') or os.getuid()==0:
            raise ValueError('Run as the normal Pi desktop user on Linux, without sudo')
        if args.action=='refresh-session':
            refresh_session()
            return 0
        from launch import plan
        config=Path(args.config).resolve()
        # Validate against the user's actual config; do not start games or GPIO here.
        plan(config,'cabinet')
        if not args.remote or os.environ.get('DISPLAY') or os.environ.get('WAYLAND_DISPLAY'):
            refresh_session()
        else:
            print('Remote installation: display helper will capture settings at the next desktop login.')
        home=Path.home()/'.config'
        unit=home/'systemd/user/arcade-cabinet.service'
        desktop=home/'autostart/arcade-cabinet-display.desktop'
        unit_text=render_unit(sys.executable,HERE/'launch.py',config)
        desktop_text=render_desktop(sys.executable,Path(__file__).resolve())
        for target in (unit,desktop):
            if target.exists() and not target.read_text(encoding='utf-8').startswith(MARKER):
                raise ValueError('Refusing to overwrite an unrelated file: '+str(target))
        write_managed(unit,unit_text)
        write_managed(desktop,desktop_text)
        reload_service()
        print('Installed arcade-cabinet.service (not started and not enabled at boot).')
        print('Start locally: systemctl --user start arcade-cabinet.service')
        print('The display helper will refresh settings at future desktop logins.')
        return 0
    except (ValueError,OSError,subprocess.CalledProcessError) as exc:
        print('Pi service setup failed: '+str(exc),file=sys.stderr)
        return 1


if __name__=='__main__': sys.exit(main())