#!/bin/bash
#
# vcached: VServer cache allocator
#
# Description: A script that preallocates vservers and stores them in
# a cache.  Preallocated vservers from the cache may be then used to
# instantiate real vservers. Requires that /var/run/vcached.pid does
# not exist on startup. Should run periodically as a cron job.
#
# Based on work by:
# 
# Brent Chun - bnc@intel-research.net
# Tristan Koo - tristan.koo@intel-research.net
# William Wung - wungism@uclink.berkeley.edu
#
# Mark Huang <mlhuang@cs.princeton.edu>
# Copyright (c) 2004-2005 The Trustees of Princeton University
#
# $Id$
#

PATH=/sbin:/usr/sbin:$PATH

# number of images to keep cached
slots=32

# PID file
pidfile=/var/run/vcached.pid

# log file
logfile=/var/log/vcached.log

# debug
debug=0

usage()
{
    echo "usage: vcached [OPTION...]"
    echo "	-s [slots]	number of images to keep cached"
    echo "	-p [pidfile]	PID file"
    echo "	-l [logfile]	log file"
    echo "	-d		debug"
    exit 1
}

# parse options
while getopts 's:p:l:dh' OPT ; do
    case "$OPT" in
	s) slots=$OPTARG ;;
	p) pidfile=$OPTARG ;;
	l) logfile=$OPTARG ;;
        d) debug=1 ;;
	h|*) usage ;;
    esac
done

# append output to log file
exec 1>>$logfile
exec 2>>$logfile

# check if we are already running
if [ -f $pidfile ] && kill -0 `cat $pidfile` >/dev/null 2>&1 ; then
    echo "vcached(`cat $pidfile`) already running"
    exit 1
fi
echo $$ > $pidfile

# clean up lock file before exiting
trap "rm -f $pidfile" EXIT

: ${UTIL_VSERVER_VARS:=/usr/lib/util-vserver/util-vserver-vars}
test -e "$UTIL_VSERVER_VARS" || {
    echo "Can not find util-vserver installation; aborting..."
    exit 1
}
. "$UTIL_VSERVER_VARS"

# make sure barrier bit is set on /vservers to prevent chroot() escapes
setattr --barrier $__DEFAULT_VSERVERDIR

# take out the trash
#rm -rf "$__DEFAULT_VSERVERDIR/.vtmp"

mkdir -p "$__DEFAULT_VSERVERDIR/.vcache"
mkdir -p "$__DEFAULT_VSERVERDIR/.vtmp"

[ $debug -ne 0 ] && echo "$(date) Checking the cache"
for i in $(seq 0 $(($slots - 1))) ; do
    if [ ! -d "$__DEFAULT_VSERVERDIR/.vcache/v$i" ] ; then
	echo "$(date) Caching v$i"
	# build image in .vtmp
	TMP=$(mktemp -d "$__DEFAULT_VSERVERDIR/.vtmp/v$i.XXXXXX")
	"$_VCLONE" "$__DEFAULT_VSERVERDIR/.vref/default/" "$TMP"/
	RETVAL=$?
	# move it to .vcache when complete
	if [ $RETVAL -eq 0 ] ; then
	    mv "$TMP" "$__DEFAULT_VSERVERDIR/.vcache/v$i"
	    echo "$(date) v$i ready"
	else
	    echo "$(date) Error $RETVAL building v$i"
	    rm -rf "$TMP"
	fi
    fi
done

exit 0