#!/bin/bash

# Copyright © Sébastien Luttringer
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

# Check running systemd services for binary update
# Convenient way to restart updated systemd service after upgrade

# disable grep options to avoid non default behaviour
unset GREP_OPTIONS

# Systemd cgroup path
SYSTEMD_CGROUP_BASE_PATH='/sys/fs/cgroup/systemd'

# colors
if [[ -t 1 ]]; then
	shopt -s xpg_echo
	c_title='\e[1;33m'
	c_svc='\e[1;35m'
	c_warn='\e[5;30;43m'
	c_error='\e[5;30;41m'
	c_rst='\e[m'
fi

# default options
dbus=1				# relauch when dbus
debug=0				# debug mode
failed=1			# display failed service at the end
pacdiff=1 			# run pacdiff
reload=1 			# reload systemd
restart=1			# restart services
serialize=0			# run in parallel
status=1 			# display status after systemctl
timeout=5			# timeout duration
user_slice=0		# act on users services

# display application usage and exit 2
usage() {
	echo "usage ${0##*/} [options]"
	echo "description: check for updated files in a service"
	echo 'options:'
	echo '  -h: this help' >&2
	echo "  -t: timeout before restart (default: ${timeout}s)" >&2
	echo "  -d: debug mode" >&2
	echo "  -b/-B: restart (or not) ${0##*/} if dbus was updated (default: $dbus)" >&2
	echo "  -l/-L: call (or not) systemd daemon-reload (default: $reload)" >&2
	echo "  -f/-F: display (or not) failed services before quit (default: $failed)" >&2
	echo "  -p/-P: call (or not) pacdiff before act (default: $pacdiff)" >&2
	echo "  -r/-R: restart (or not) services with updated files (default: $restart)" >&2
	echo "  -s/-S: display (or not) status of restarted service (default: $status)" >&2
	echo "  -u/-U: act (or not) on services in users slice (default: $user_slice)" >&2
	echo "  -z/-Z: serialize (or not) action (default: $serialize)" >&2
	exit 2
}

# usage : in_array( $needle, $haystack )
# return : 0 - found
#          1 - not found
in_array() {
	local needle=$1; shift
	local item
	for item in "$@"; do
	   [[ $item = $needle ]] && return 0 # Found
	done
	return 1 # Not Found
}

while getopts 'hBbdFfLlPpRrSst:UuZz' opt; do
	case $opt in
		B) dbus=0;; 			b) dbus=1;;
		d) debug=1;;
		F) failed=0;;			f) failed=1;;
		L) reload=0;;			l) reload=1;;
		P) pacdiff=0;;			p) pacdiff=1;;
		R) restart=0;; 			r) restart=1;;
		S) status=0;;			s) status=1;;
		t) timeout="$OPTARG";;
		U) user_slice=0;;		u) user_slice=1;;
		Z) serialize=0;;		z) serialize=1;;
		*) usage;;
	esac
done
shift $((OPTIND - 1));
(( $# > 0 )) && usage

# avoid to be sighup'ed by interactive shell
trap '' SIGHUP

# from now, we need to be root
(( $UID != 0 )) && echo 'You need to be root' && exit 1

# call pacdiff
(( $pacdiff )) && pacdiff

# reload units list
(( $reload )) && systemctl --system daemon-reload

# list of running services
declare -a services
services=($(systemctl --no-legend --full --type service --state running|cut -f1 -d' '))

# list of bus names
declare -a buses
buses=($(dbus-send --system --dest=org.freedesktop.DBus --type=method_call \--print-reply \
/org/freedesktop/DBus org.freedesktop.DBus.ListNames|sed -rn 's/\s*string "(.*)"/\1/p'))

# count beggar services
declare -a needy=() pids=()
declare -i pid=0
for svc in "${services[@]}"; do
	unit_path="$(systemctl -p ControlGroup show "$svc"|cut -f 2 -d=)"
	busname="$(systemctl -p BusName show "$svc"|cut -f 2 -d=)"
	tasks_path="$SYSTEMD_CGROUP_BASE_PATH/$unit_path/tasks"
	[[ -e "$tasks_path" ]] || {
		echo "${c_error}** Unable to get pid of $svc: No tasks file: $tasks_path${c_rst}" >&2
		continue
	}
	# check if unit is in system slice
	(( $user_slice == 0 )) && [[ "$unit_path" =~ /user\.slice/ ]] && continue
	pids=( $(< "$SYSTEMD_CGROUP_BASE_PATH/$unit_path/tasks") )
	if (( "${#pids[*]}" == 0 )); then
		echo "${c_error}** Unable to get pid of $svc: Tasks file is empty${c_rst}" >&2
		continue
	fi
	for pid in "${pids[@]}"; do
		maps_path="/proc/$pid/maps"
		[[ -e "$maps_path" ]] || {
			echo "${c_error}** Unable to get maps file of $svc for pid $pid${c_rst}" >&2
			continue
		}
		deleted=$(grep -F '(deleted)' "$maps_path" |sed -nr 's|^\S+ ..x. \S+ \S+ \S+ \s+||p'|sort|uniq)
		if [[ -n $deleted ]] || { [[ -n "$busname" ]] && ! in_array "$busname" "${buses[@]}"; }; then
			needy+=("$svc")
			if (( $debug )); then
				echo "${c_title}Service:${c_svc} $svc${c_rst}"
				echo "${c_title}Pid:${c_rst} $pid"
				echo "${c_title}Bus:${c_rst} $busname"
				echo -n "${c_title}BusName matching on the system bus: ${c_rst}"
				in_array "$busname" "${buses[@]}" && echo 'Yes' || echo 'No'
				echo "${c_title}Deleted files:${c_rst}"
				echo "$deleted"
				echo
			fi
			break
		fi
	done
done

# display what we will do
(( "${#needy[*]}" )) && echo '-------8<-------------------------------8<---------'
for svc in "${needy[@]}"; do
	echo "systemctl restart '$svc'"
done
(( "${#needy[*]}" )) && echo '-------8<-------------------------------8<---------'

# if nothing to restart we have done
(( $restart == 0 || ${#needy[*]} == 0 )) && exit 0

# wait the timeout
(( $timeout > 0 )) && {
	echo "Waiting for ${timeout} seconds"
	echo "Use ctrl+c to undo"
	for i in $(seq $timeout -1 1); do
		echo -n "$i..."
		sleep 1
	done
	echo 0
}

# do the job, restart updated services
for svc in "${needy[@]}"; do
	echo "Restarting ${c_svc}$svc${c_rst}"
	systemctl restart "$svc" &
	(( $serialize )) && wait
	# display status directly when serialize and not quiet
	(( $serialize )) && (( $status )) && systemctl --lines=0 status "$svc"
done
wait

# show units status
if (( $serialize == 0 )) && (( $status )); then
	systemctl --lines=0 status "${needy[@]}"
fi

(( $failed )) && systemctl --failed --all --no-pager --no-legend --full list-units

# warn if dbus was restart
if in_array dbus.service "${needy[@]}"; then
	echo "${c_warn}After dbus restart, you should run ${0##*/} twice${c_rst}" >&2
	if (( $dbus )) && [[ -z "$CHECKSERVICE_WAS_RESTARTED" ]]; then
		echo "${c_warn}Doing it for you. No need to thanks me!${c_rst}" >&2
		export CHECKSERVICE_WAS_RESTARTED=1
		exec "$0" "$@"
	fi
fi

exit 0