ducoterra
7d4bcf7e23
Auto-login succeeded and the wall kept streaming, but about ten seconds after the kiosk session came up GDM autospawned a greeter on the same GPU and a login screen covered it. gnome-kiosk ships X-GDM-SessionRegisters=false, so nothing ever registers and GDM concludes the display is still free — which is why every remote check (loginctl, the mirror roster) stayed green while the physical screen showed a password prompt. Override that session file with the flag set to true, keeping the file name and session id identical: inventing an id makes GDM quietly fall back to the plain GNOME session, top bar and all. Add a per-minute guard that reclaims the foreground VT, because this class of failure is invisible from the outside, and have the checker assert both the foreground VT and the greeter-session count. That count had a silent false green: journalctl has no --no-legend, so the check read an empty stream and passed unconditionally. Also keep a copy of the payload in /usr/local/share/mirror-kiosk. /tmp is cleared at every boot, which deletes the checker just after the one event you are most likely to want to re-run it for. Verified on the reference client: a cold boot now creates no greeter session at all, the kiosk compositor and Firefox come up undisturbed, and a console stolen with chvt is taken back within a minute. LLM-Generated: true
55 lines
2.3 KiB
Bash
55 lines
2.3 KiB
Bash
#!/bin/sh
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# mirror-kiosk-console-guard — make sure the kiosk owns the console.
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#
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# Run by mirror-kiosk-console-guard.timer once a minute as root.
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#
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# The failure this exists for is invisible remotely: the kiosk session keeps
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# running (loginctl says active, the mirror roster counts the wall as a viewer)
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# while some other session holds the foreground VT, so the screen shows a login
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# prompt and every check says everything is fine. That is exactly how the
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# greeter-autospawn bug presented itself.
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#
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# It deliberately does very little: if the kiosk HAS a seat0 session and that
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# session is not the foreground one, activate it. It never restarts gdm and
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# never logs anyone out, because a display manager is a bad thing to fight
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# automatically. If there is no kiosk session at all it only says so — that is a
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# problem for a human, and the message lands in the journal.
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#
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# Debugging the console by hand? Stop the fight:
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# sudo systemctl stop mirror-kiosk-console-guard.timer
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set -eu
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KIOSK_USER="${KIOSK_USER:-kiosk}"
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FG_VT=/sys/class/tty/tty0/active
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say() { logger -t mirror-kiosk-guard -- "$*"; }
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[ "$(id -u)" -eq 0 ] || { printf 'run me as root\n' >&2; exit 1; }
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# SESSION UID USER SEAT ... — the kiosk's own session on the physical seat. The
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# greeter also sits on seat0 but under the gdm-greeter user, so the name filter
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# is what keeps this from chasing the greeter.
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session=$(loginctl list-sessions --no-legend 2>/dev/null |
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awk -v u="$KIOSK_USER" '$3 == u && $4 == "seat0" { print $1; exit }')
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if [ -z "$session" ]; then
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say "no $KIOSK_USER session on seat0: auto-login did not produce one. Not touching gdm."
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exit 0
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fi
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active=$(loginctl show-session "$session" -p Active --value 2>/dev/null || echo unknown)
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tty=$(loginctl show-session "$session" -p TTY --value 2>/dev/null || echo "")
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foreground=$(cat "$FG_VT" 2>/dev/null || echo "")
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if [ "$active" = "yes" ] && [ -n "$tty" ] && [ "$foreground" = "$tty" ]; then
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exit 0 # the wall already has the screen
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fi
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say "console is on ${foreground:-unknown}, kiosk session $session is on ${tty:-unknown} (Active=$active) — activating it"
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if loginctl activate "$session" 2>/dev/null; then
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say "kiosk session $session brought back to the foreground"
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else
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say "could not activate kiosk session $session — look at journalctl -b -u gdm"
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fi
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