#!/bin/bash
#
# Copyright (c) 2017-2019 Virtuozzo International GmbH, All rights reserved.

# Define PATH manually because udev nullifies it
export PATH=/sbin:/usr/sbin:/bin:/usr/bin:/usr/local/sbin:/usr/local/bin

LOCKNAME="vz-guest-tools-lin"
LOCKFILE="9:/var/lock/$LOCKNAME.lock"
LOCKFILE_BG="8:/var/lock/$LOCKNAME-bg.lock"

function find_util() {
	local util=$1
	for dir in /sbin /usr/sbin /bin /usr/bin; do
		[ ! -x $dir/$util ] && continue
		echo $dir/$util
		return
	done
	# Last chance: it's in PATH
	echo $util
}

PID=$$
function syslogger() {
	[ ! -x $LOGGER ] && return
	$LOGGER -t "VZTOOLS_udev{$PID}" $*
}

function cleanup() {
	if [ $1 -eq 0 -a -x $EJECT ]; then
		umount $DIR 2>&1 | syslogger
		if ! findmnt $DEVNAME >/dev/null 2>&1; then
			# CD is not mounted elsewhere => eject the disk
			# Note: If you need to always eject the disk make sure to unmount all mount
			# points first: eject unmounts only the latest one and leaves the rest
			# of them mounted.
			$EJECT $DEVNAME 2>&1 | syslogger
			[ $? -ne 0 ] && syslogger "Failed to eject $DEVNAME"
		fi
	else
		# For debugging
		umount $DIR 2>&1 | syslogger
		[ $? -ne 0 ] && syslogger "Failed to umount $DEVNAME"
	fi
	rm -rf $DIR > /dev/null 2>&1
	restore_root_options
	lock_end "$LOCKFILE"
	exit $1
}

function error() {
	echo $*
	syslogger $*
	cleanup 1
}

function lock_begin() {
	local LOCK_FILE=${1##*:}
	local LOCK_HDL=${1%%:*}
	# Open lock file for protection from simultaneous running of several instances
	if ! eval "exec $LOCK_HDL>$LOCK_FILE"; then
		syslogger "Failed to open lock file '$LOCK_FILE', aborting"
		exit 1
	fi

	# Grab the lock, if not already grabbed by another instance
	if ! flock -xn $LOCK_HDL; then
		syslogger "Another installer instance is running, aborting"
		exit 0
	fi
}

function lock_end() {
	local LOCK_FILE=${1##*:}
	local LOCK_HDL=${1%%:*}
	rm -f "$LOCK_FILE"
	flock -u $LOCK_HDL
}

function ensure_rw_root() {
	# In Debian/Ubuntu udev is started when root is read-only, and it remains read-only
	# within the udev namespace; installer cannot change anything.
	# Check if this is the case and force remount root as read-write.
	findmnt -o OPTIONS -n / | while read -d ',' opt; do
		if [ "$opt" == "ro" ]; then
			syslogger "Root is read-only, remounting as read-write"
			mount -o remount,rw /
			REMOUNTED=1
			break
		fi
	done
}

function restore_root_options() {
	if [ "$REMOUNTED" == "1" ]; then
		syslogger "Restoring read-only root"
		sync
		mount -o remount,ro /
	fi
}

LOGGER=`find_util logger`
EJECT=`find_util eject`
BLKID=`find_util blkid`
TOOLS_INSTALLER="install"
LABEL="vz-tools-lin"

lock_begin "$LOCKFILE"

# Restart as background process to avoid killing by udev on timeout
if [ "x$1" == "xbackground" ]; then
	lock_begin "$LOCKFILE_BG"
	shift
	syslogger "Restarting $0 in background"
	# Free the lock
	lock_end "$LOCKFILE"
	if which at >/dev/null 2>&1; then
		syslogger "Using 'at' for background"
		echo $0 "$@" | at now
	elif ps aux | grep -q '\(/usr\)\?/s\?bin/crond\?'; then
		syslogger "Using cron for background, may take up to 1 minute to activate the job"
		ensure_rw_root
		CRONFILE=$(mktemp /etc/cron.d/install-tools-XXXX)
		echo "* * * * * root rm -f $CRONFILE; $0 \"$@\"" >$CRONFILE
		restore_root_options
	else
		# Fallback: just start in background and hope for the best
		syslogger "'at' not found, cron is not running, using shell '&' for background"
		$0 "$@" & >/dev/null 2>&1
	fi
	lock_end "$LOCKFILE_BG"
	exit 0
fi

ensure_rw_root

DIR=`mktemp -d /tmp/toolsXXX`

# Check that started manually or from udev
if [ "x$DEVNAME" = "x" ]; then
	DEVNAME=`$BLKID -l -o device -t LABEL=$LABEL 2>/dev/null | grep -E -m 1 ".*"`
	[ "x$DEVNAME" = "x" ] && error "Can't find ISO with label $LABEL"
else
	# Check that udev failed
	[ "x$ID_FS_LABEL" != "x$LABEL" ] && error "Incorrect tools ISO"
fi

mount -r $DEVNAME $DIR > /dev/null 2>&1 || error "Failed to mount $DEVNAME $LABEL disk"

[ ! -x $DIR/$TOOLS_INSTALLER ] && error "Incorrect tools ISO"

$DIR/$TOOLS_INSTALLER 2>&1 | syslogger
test ${PIPESTATUS[0]} -eq 0 || error "Failed to install tools"

syslogger "Virtuozzo guest tools successfully installed"

cleanup 0