#!/bin/sh

# This check uses the debian tool 'checkrestart' (contained in 'debian-goodies' package) to find processes that use libraries that have been upgraded
# if checkrestart is not available there is a fallback to parse the lsof output for deleted libraries that are still in use
# The check needs to be executed 'root' (if possible: use sudo for the check command only!)

# TODO
# 1. It's not tested on platforms that run some kind of lightweight virtualiztation such as Linux vServer, LXC, docker or OpenVZ
#    since this check is based on checkrestart which itself is based on lsof there are probably some quircks when it comes to the host seeing all processes
#    possible solutions:
#    - only run this check on the virtualization host
#    - fix this check to only consider processes in the current PID namespace. If it's the root PID namespace, ignore all processes NOT belonging to the root PID namespace


EXIT=3
MESSAGE="Oops! Something I have not foreseen must have gone wrong!"

# sanity checks (do 'lsof' and 'checkrestart' exist and are they executable)
LSOF=$(command -v lsof)
CHECKRESTART=$(command -v checkrestart)
if [ -z "$LSOF" ]; then
	MESSAGE="Oops! 'lsof' is not availabe or not executable. Please make sure to install 'lsof' or fix other issues that prevent lsof from being executed."
	EXIT=2
else
	if [ -z "$CHECKRESTART" ]; then
		# no checkrestart found, falling back to parsing of 'lsof' output
		COMMAND_OUTPUT=$(for PID in `lsof | grep "DEL\|deleted" | awk '/\.so/ {print $2}'`; do ps --no-headers --pid $PID | awk {'print $4'}; done | sort -u)
	else
		# unfortunately 'checkrestart' gives an output even though nothing has been found
		COMMAND_OUTPUT=$(/usr/sbin/checkrestart | awk '/\// {print $2}' | sort -u)
		CHECKRESTART_CLUE=" use 'checkrestart' to check which processes are affected or"
	fi

	if [ -z "$COMMAND_OUTPUT" ]; then
		MESSAGE="OK - No old version of upgraded libraries seem (!) to be in use by any process."
		EXIT=0
	else
		FINAL_OUTPUT=$(echo $COMMAND_OUTPUT | tr '\n' ' ')
		MESSAGE="CRITICAL - Old versions of upgraded libraries seem (!) to be in use. Please$CHECKRESTART_CLUE investigate further on the basis of the following list of processes: $FINAL_OUTPUT"
		EXIT=2
	fi
fi

echo $MESSAGE
exit $EXIT