#!/bin/sh

DAEMON="libvirtd"
EXECFILE="/usr/sbin/$DAEMON"
PIDFILE="/var/run/$DAEMON.pid"

LIBVIRTD_ARGS=""

# shellcheck source=/dev/null
[ -r "/etc/default/$DAEMON" ] && . "/etc/default/$DAEMON"

trap 'rm -f "$TMP_MODULE_LIST" "$TMP_PIDFILE_LIST"' EXIT

is_alive() {
	[ -e "$1" ] \
	&& exe="/proc/$(cat "$1" 2>/dev/null)/exe" \
	&& [ -s "$exe" ] \
	&& [ "$(readlink -f "$exe")" = "$2" ]
}

load_modules() {
	printf 'Loading kernel modules: '
	kver="$(uname -r)"
	TMP_MODULE_LIST="$(mktemp -q)" || {
		echo 'FAIL creating temporary modules list'
		exit 1
	}
	[ -d "/lib/modules/$kver/kernel/drivers/net" ] && \
		find "/lib/modules/$kver/kernel/drivers/net" \
		-name "tun.ko*" >> "$TMP_MODULE_LIST"
	[ -d "/lib/modules/$kver/kernel/drivers/vhost" ] && \
		find "/lib/modules/$kver/kernel/drivers/vhost" \
		-name "vhost?net.ko*" >> "$TMP_MODULE_LIST"
	[ -d "/lib/modules/$kver/kernel/drivers/net" ] && \
		find "/lib/modules/$kver/kernel/drivers/vfio" \
		-name "*.ko*" >> "$TMP_MODULE_LIST"
	while read -r f; do
		m="$(basename "${f%.ko*}")"
		if modprobe -q "$m"; then
			printf '%s ' "$m"
		else
			echo "FAIL on $m"
			exit 1
		fi
	done < "$TMP_MODULE_LIST"
	echo "OK"
}

#
# If libvirtd dies it leves behind one stale dnsmasq per virtual network that
# must be killed before starting libvirtd again.
#
rm_stale_dnsmasq() {
	[ -d /var/run/libvirt/network ] || return 0
	TMP_PIDFILE_LIST="$(mktemp -q)" || {
		echo "Could not create temporary pidfile list"
		exit 1
	}
	find /var/run/libvirt/network -name '*.pid' > "$TMP_PIDFILE_LIST"
	while read -r pidfile; do
		if is_alive "$pidfile" /usr/sbin/dnsmasq; then
			start-stop-daemon -K -q -p "$pidfile" -x /usr/sbin/dnsmasq
			status=$?
			if [ "$status" -ne 0 ]; then
				echo "Could not stop stale dnsmasq daemons"
				exit 1
			fi
			rm -f "$pidfile"
		fi
	done < "$TMP_PIDFILE_LIST"
}

start() {
	if is_alive "$PIDFILE" "$EXECFILE"; then
		# libvirtd is already running. Leave it alone.
		printf 'Starting %s: FAIL\n' "$DAEMON"
		return 1
	fi
	rm_stale_dnsmasq
	load_modules
	printf 'Starting %s: ' "$DAEMON"
	# shellcheck disable=SC2086 # we need the word splitting
	start-stop-daemon -S -q -p "$PIDFILE" -x "$EXECFILE" \
		-- -d $LIBVIRTD_ARGS
	status=$?
	if [ "$status" -eq 0 ]; then
		echo "OK"
	else
		echo "FAIL"
	fi
	return "$status"
}

stop() {
	printf 'Stopping %s: ' "$DAEMON"
	start-stop-daemon -K -q -p "$PIDFILE" -x "$EXECFILE"
	status=$?
	if [ "$status" -eq 0 ]; then
		rm_stale_dnsmasq
		echo "OK"
	else
		echo "FAIL"
	fi
	return "$status"
}

restart() {
	stop
	sleep 1
	start
}

# On receipt of SIGHUP libvirtd will reload its configuration.
reload() {
	printf 'Reloading %s: ' "$DAEMON"
	start-stop-daemon -K -s HUP -q -p "$PIDFILE" -x "$EXECFILE"
	status=$?
	if [ "$status" -eq 0 ]; then
		echo "OK"
	else
		echo "FAIL"
	fi
	return "$status"
}

case "$1" in
	start|stop|restart|reload)
		"$1";;
	*)
		echo "Usage: $0 {start|stop|restart|reload}"
		exit 1
esac