dotfiles/.local/bin/s6-user-init

#!/bin/sh --
# vim: ft=sh

set -ue

: "${XDG_RUNTIME_DIR:=${TMPDIR:-/tmp}/runtime-${USER:-$(id -un)}}"
: "${XDG_DATA_HOME:=${HOME:?}/.local/share}"

: "${S6_SYSPATH:=${XDG_DATA_HOME}/s6/user}"
: "${S6_RUNPATH:=${XDG_RUNTIME_DIR}/s6/user}"

: "${S6_LIVE:=${S6_RUNPATH}/s6-rc}"
: "${S6_COMPILED:=${S6_SYSPATH}/rc/compiled}"
: "${S6_SVDIR:=${S6_RUNPATH}/service}"

: "${S6_CONFIG_DIR:=${S6_SYSPATH}/config}"
: "${S6_LOG_DIR:=${S6_RUNPATH}/log}"

: "${S6_OWNER_PID_FILE:=${S6_SVDIR}/.s6-svscan/owner.pid}"

: "${S6_WAIT_FOR_STOP_MS:=1000}" # how many miliseconds wait for services to stop

unexport_env() {
	# unexport unneeded variables that may be exported to configure this script
	# for example if run as:
	# S6_RUNPATH=some/other/path s6-user-init start ...
	unset \
		S6_RUNPATH \
		S6_LIVE \
		S6_COMPILED \
		S6_SVDIR \
		S6_OWNER_PID_FILE \
		S6_WAIT_FOR_STOP_MS
}

start() {
	pid="${1:?}"

	mkdir -p "${S6_SVDIR}"

	if s6-svscanctl -a "${S6_SVDIR}" 2>/dev/null; then
		echo "s6-svscan already running on '${S6_SVDIR}'" 1>&2
		exit 1
	fi

	echo "${pid}" | install -Dm600 /proc/self/fd/0 "${S6_OWNER_PID_FILE}"

	export S6_CONFIG_DIR
	export S6_LOG_DIR
	export S6_SYSPATH

	live="${S6_LIVE}"
	compiled="${S6_COMPILED}"
	svdir="${S6_SVDIR}"

	unexport_env

	exec s6-rc-svscan \
		-l "${live}" \
		-c "${compiled}" \
		-s "${svdir}"
}

stop() {
	pid="${1:?}"

	[ -f "${S6_OWNER_PID_FILE}" ] || {
		echo "pid file does not exist: '${S6_OWNER_PID_FILE}'" 1>&2
		exit 1
	}

	IFS= read -r owner <"${S6_OWNER_PID_FILE}"
	[ "${owner}" = "${pid}" ]

	s6-rc -l "${S6_LIVE}" -bda change || : # stop all services

	(
		cd "${S6_SVDIR}" &&
			exec s6-svwait -D -t "${S6_WAIT_FOR_STOP_MS}" ./* 2>/dev/null
	) || : # wati for services to stop

	s6-svscanctl -n "${S6_SVDIR}" || : # stop svscan

	cd "${S6_LIVE%/*}"

	dir="$(readlink "${S6_LIVE}")"
	rm -rf -- "${dir:?}"
	unlink "${S6_LIVE}"

	rm -rf -- "${S6_SVDIR:?}"
}

usage() {
	printf '%s\n' \
		"Usage: ${0##*/} [action]" \
		'    start <pid> - start user services' \
		'    stop <pid> - stop user services' \
		'    help - show this help'

	exit "${1:-0}"
}

case "${1:?}" in
start) start "${2:?provide owner pid}" ;;
stop) stop "${2:?provide owner pid}" ;;
help | -h) usage 0 ;;
*) usage 1 ;;
esac