#!/bin/bash -e

DIR=$(readlink -f "$0") && DIR=$(dirname "$DIR") && cd "$DIR" || exit 1

. ./common.sh

if [ -n "$PID_FILE" ] && [ -f "$PID_FILE" ]; then
	PID=$(cat "$PID_FILE" 2>/dev/null|| :)
fi
if [ -z "$PID" ] || [ -z "$EXE" ]; then
	>&2 echo no pid or exec
	exit 1
fi

EXE_LINK="/proc/${PID}/exe"

if [ ! -L "$EXE_LINK" ]; then
	>&2 echo "no pid $PID"
	exit 2
fi
if [ ! -r "$EXE_LINK" ]; then
	>&2 echo "can not read pid $PID"
	exit 3
fi

EXE_READLINK=$(readlink -f "$EXE_LINK" || :)
if [ -z "$EXE_READLINK" ]; then
	>&2 echo "unknown pid $PID"
	exit 4
fi
if [ "$EXE_READLINK" != "$EXE" ]; then
	>&2 echo "pid $PID not file $EXE (${EXE_READLINK})"
	exit 5
fi

echo "$PID"