Fix cups-browsed removal migration
This commit is contained in:
Ryan Hughes
+39
-116
@@ -1,149 +1,72 @@
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echo "Temporarily remove automatic printer discovery"
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# cups-browsed is the daemon that watches the network and creates print queues
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# by itself. Hardening it (1787815267) took a root daemon with a predictable
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# cache down to a confined service account, but a daemon that turns anything
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# advertising itself on the network into a print queue is a lot of exposure for
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# a convenience, so it comes out of the default install while that is reworked.
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# Temporarily, and only the discovery half: CUPS itself stays, printing keeps
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# working, and a printer is added by hand in Print Settings instead of
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# appearing on its own.
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machine_marker="${OMARCHY_CUPS_BROWSED_REMOVAL_MARKER:-/var/lib/omarchy/migrations/1788009111}"
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[[ ! -e $machine_marker ]] || exit 0
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# Nothing to do on a machine that never had it. Checked before any sudo so those
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# runs never prompt for a password, and before the marker so no machine pays a
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# password prompt for a removal it does not need.
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omarchy-pkg-present cups-browsed || exit 0
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# Ask pacman whether the removal is possible before touching the service. If
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# something here depends on cups-browsed, the alternative is a machine whose
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# discovery daemon has been stopped and whose package removal then failed --
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# broken rather than removed.
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if ! pacman -R --print cups-browsed >/dev/null 2>&1; then
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echo " Something else on this machine still depends on cups-browsed, so it is staying installed."
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exit 0
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fi
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# Check the full removal transaction before changing the service or queues.
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pacman -Rs --print cups-browsed >/dev/null
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# Disable before removing, and this is the only window in which it works.
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# pacman deletes the unit file but not the enable symlink systemd wrote under
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# /etc, and once the unit is gone `systemctl disable` refuses it by name and
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# leaves the symlink dangling with nothing left that can clean it. Stopping is
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# part of the same step: a daemon whose executable has been unlinked keeps
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# running until it is told not to. A masked or already-disabled unit reports
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# not-enabled and is left alone. Doing it before the queue list is read also
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# means the list cannot grow a new entry while it is being acted on.
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# Disable the unit while its package still owns the unit file so systemd can
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# remove the enable symlink cleanly.
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if systemctl is-enabled --quiet cups-browsed.service 2>/dev/null; then
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sudo systemctl disable --now cups-browsed.service
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sudo systemctl disable --now cups-browsed.service >/dev/null
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elif systemctl is-active --quiet cups-browsed.service 2>/dev/null; then
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sudo systemctl stop cups-browsed.service
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sudo systemctl stop cups-browsed.service >/dev/null
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fi
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# cups-browsed keeps the queues it generated when it stops --
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# KeepGeneratedQueuesOnShutdown defaults to Yes and nothing here overrides it --
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# and those queues route through its own implicitclass backend, which goes with
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# the package, so none of them can print again. The idle ones are removed rather
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# than left in Print Settings looking like printers; the ones with jobs on them
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# are handled below. Only queues on that backend: a printer added by hand has an
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# ipp:// or usb:// device and is left alone.
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# cups-browsed leaves its implicitclass queues behind when stopped. Remove idle
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# discovery queues before removing the backend they require, but leave queues
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# with jobs for the user to resolve.
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#
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# LC_ALL=C because lpstat translates "device for", and on a German or French
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# machine the untranslated pattern would match nothing and read exactly like a
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# machine that had no queues to clean up. Captured rather than piped so that
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# failing to reach cupsd is distinguishable from finding nothing. The name is
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# matched greedily because CUPS allows a colon in a queue name but never a
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# space, so the last ": implicitclass://" is the separator and an earlier colon
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# belongs to the name.
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if ! queue_report=$(LC_ALL=C lpstat -v 2>/dev/null); then
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echo " Could not ask CUPS which queues discovery had created."
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echo " Discovery is off, but cups-browsed stays installed; remove it by hand once CUPS answers."
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exit 0
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# A healthy CUPS server with no configured printers reports this condition on
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# stderr and exits 1. Treat that as an empty queue list; every other failure
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# keeps the migration pending so it can be retried.
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if queue_report=$(LC_ALL=C lpstat -v 2>&1); then
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:
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elif [[ $queue_report == "lpstat: No destinations added." ]]; then
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queue_report=""
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else
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printf '%s\n' "$queue_report" >&2
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exit 1
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fi
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generated_queues=$(printf '%s\n' "$queue_report" |
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sed -n 's|^device for \(.*\): implicitclass://.*|\1|p')
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unremoved=0
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while IFS= read -r queue; do
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[[ -n $queue ]] || continue
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# A queue name is whatever the printer advertised, put through cups-browsed's
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# own sanitizer. `lpstat -o` takes its destination as an optional argument, so
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# a leading dash reads as the next option and a comma as a list separator, and
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# "all" is its word for every destination. The jobs on such a queue cannot be
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# asked about, so it is left alone and named. Never a reason to keep the
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# package, though: that would hand a printer that picked its own name a veto
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# over the removal.
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if [[ $queue == -* || $queue == *,* || $queue == "all" ]]; then
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echo " Cannot safely ask about jobs on the queue named '$queue'; remove it in Print Settings."
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continue
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fi
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# Close the queue to new jobs before looking at what is on it. Otherwise a job
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# submitted between the check and the removal -- the sudo below can sit at a
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# password prompt for as long as someone takes to type it -- is cancelled by a
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# deletion that decided the queue was empty. It also stops more jobs piling
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# onto a queue that is being left behind and can no longer route them.
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if ! sudo cupsreject -r "Printer discovery has been removed from Omarchy" "$queue"; then
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echo " Could not stop $queue accepting new jobs, so it is being left alone."
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unremoved=1
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continue
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fi
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# Removing a queue cancels the jobs on it. implicitclass needs cups-browsed
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# only to pick a destination, so a job already past that point finishes on its
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# own; one still waiting cannot, because the daemon that would route it has
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# stopped. Neither is this migration's to throw away, so the queue is left for
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# whoever owns them, and what will and will not happen is said rather than
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# implied.
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if job_report=$(LC_ALL=C lpstat -o "$queue" 2>/dev/null); then
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if [[ -n $job_report ]]; then
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echo " $queue still has jobs and is no longer taking new ones, so it is being left alone."
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echo " Anything already sent to the printer finishes; anything still waiting cannot be routed now."
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echo " Cancel what is left and remove the queue in Print Settings."
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if ! reject_error=$(sudo cupsreject -r "Printer discovery has been removed from Omarchy" "$queue" 2>&1); then
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if LC_ALL=C lpstat -p "$queue" >/dev/null 2>&1; then
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printf '%s\n' "$reject_error" >&2
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exit 1
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else
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continue
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fi
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fi
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if job_report=$(LC_ALL=C lpstat -o "$queue" 2>&1); then
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[[ -z $job_report ]] || continue
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elif LC_ALL=C lpstat -p "$queue" >/dev/null 2>&1; then
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printf '%s\n' "$job_report" >&2
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exit 1
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else
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echo " Could not check for jobs on $queue, so it is being left alone."
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# The queue disappeared after the initial snapshot, which is already the
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# desired state.
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continue
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fi
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# A queue another administrator removed while this was running is a queue that
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# is gone, which is the outcome wanted -- not a failure worth keeping the
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# package for.
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if ! sudo lpadmin -x "$queue"; then
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if ! delete_error=$(sudo lpadmin -x "$queue" 2>&1); then
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# Treat a concurrent disappearance as success. A queue that still exists
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# means CUPS did not complete the deletion, so retry the migration later.
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if LC_ALL=C lpstat -p "$queue" >/dev/null 2>&1; then
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echo " Could not remove the queue $queue."
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unremoved=1
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printf '%s\n' "$delete_error" >&2
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exit 1
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fi
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fi
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done <<<"$generated_queues"
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# A queue that would not delete is a CUPS that is not answering as expected, so
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# the package stays rather than deleting the backend out from under it. Discovery
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# is stopped either way, which is the half that mattered. omarchy-migrate records
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# this migration for the user as soon as it exits zero, so this is where the
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# machine stays until someone removes the package by hand -- said plainly rather
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# than dressed up as a retry.
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if ((unremoved)); then
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echo " Leaving cups-browsed installed. Discovery is off; remove the package by hand once those queues are gone."
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exit 0
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fi
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# Raw pacman rather than omarchy-pkg-drop, which passes -n: that discards the
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# files pacman has marked as backups instead of renaming them .pacsave, and
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# /etc/cups/cups-browsed.conf is one of them. A removal meant to be temporary
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# should leave the machine's copy of its own configuration behind. Plain -R
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# rather than -Rs, so this only ever removes the one package it names: -s also
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# sweeps dependencies that have become unneeded, which is nothing today but is
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# a promise the dependency graph of a rolling distribution cannot keep.
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# pacman's systemd hook reloads the system manager once the unit file goes.
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sudo pacman -R --noconfirm cups-browsed
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# Migration state is per user, so every account on this machine runs every
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# migration. Without machine-wide state, an account whose first run comes after
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# someone deliberately reinstalled cups-browsed would quietly take it back out
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# again. This records that the machine has had its one removal.
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omarchy-pkg-drop cups-browsed >/dev/null
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sudo install -Dm644 /dev/null "$machine_marker"
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