hatd

#!/usr/bin/env bash

# Wrapper script that starts/stops the hat-daemon
# by calling daemon_front.py/client.py directly
# with proper argument(s).

export PATH='/bin:/usr/bin:/sbin:/usr/sbin'

print_msg() {
    printf '%s\n' "$@"
}

PYTHON_BIN="$(command -v python3)"
[ -z "${PYTHON_BIN}" ] && print_msg "hatd requires python3" >&2 \
				  && exit 1

HATD_RUN_DIR='/var/run/hatd'
HATD_PID_FILE='/var/run/hatd/hatd.pid'

DAEMON_FRONT='hat/daemon_front.py'  # relative
CLIENT='hat/client.py'  # relative


# Daemon running->ret=0, Not running->ret=1
check_daemon() {
    if [ ! -f "${HATD_PID_FILE}" ]; then
	return 1
    else
	pid="$(cat <"${HATD_PID_FILE}")"
	if ! out="$(ps -p "$pid" -o cmd= >/dev/null 2>&1)"; then
	    return 1
	else
	    case "hat/daemon_front.py" in
		*${out}*)
		    return 0
		    ;;
		*)
		    return 1
		    ;;
	    esac
	fi
    fi
}


# Create or unlink necessary files (mostly FIFOs)
mk_rm_files() {
    files=(
	"${HATD_RUN_DIR}/ipc/runner_in.fifo"
	"${HATD_RUN_DIR}/ipc/runner_out.fifo"
	"${HATD_RUN_DIR}/ipc/daemon_in.fifo"
	"${HATD_RUN_DIR}/ipc/daemon_out.fifo"
	"${HATD_PID_FILE}"
    )
    if [[ $1 == "create" ]]; then
	for file in "${files[@]}"; do
	    rm -f "${file}"
	    if [[ $file == *_in.fifo ]]; then
		mkfifo "${file}" && chmod 0660 "${file}"
	    elif [[ $file == *_out.fifo ]]; then
		mkfifo "${file}" && chmod 0640 "${file}"
	    else
		: >"${file}" && chmod 0644 "${file}"
	    fi
	done
    elif [[ $1 == "remove" ]]; then
	rm -f "${files[@]}"
	rm -f "${HATD_RUN_DIR}"/locks/._*
    fi
}


# Create relevant dirs and meke them SETGID
create_setgid_dirs() {
    for dir in ipc locks; do
	mkdir -p "${HATD_RUN_DIR}/${dir}"
	chown :hatd "${HATD_RUN_DIR}/${dir}"
	chmod 0770 "${HATD_RUN_DIR}/${dir}"
	chmod g+s "${HATD_RUN_DIR}/${dir}"
    done
    chmod 0755 "${HATD_RUN_DIR}"
}


case "$1" in
    "start")
	if check_daemon; then
	    print_msg "Daemon is already running" && exit 0
	else
	    create_setgid_dirs
	    mk_rm_files "create"
	    exec "${PYTHON_BIN}" "${DAEMON_FRONT}" start
	fi
	;;
    "stop")
	if check_daemon; then
	    mk_rm_files "remove"
	    exec "${PYTHON_BIN}" "${CLIENT}" stop_daemon
	else
	    print_msg "Daemon is not running" && exit 0
	fi
	;;
    *)
	print_msg "Valid arguments are start/stop" >&2
	exit 2
	;;
esac