#!/bin/rc

rfork e

switch($#*){
case 1
       vac=$1
case *
       echo 'usage: vacchain vac:score' >[1=2]
       exit usage
}

if(! ~ $vac vac:????????????????????????????????????????){
       echo bad score >[1=2]
       exit 'bad score'
}

score=`{echo $vac | sed 's/vac://'}

tmp=/tmp/vacchain.$pid
fn die{
       echo $* >[1=2]
       rm -f $tmp
       exit ''
}
nl='
'
while(){
       echo vac:$score
       if(! venti/read -h 127.1 $score >$tmp)
               die could not find $score
       if(! ~ `{ls -l $tmp | awk '{print $6}'} 300)
               die block $score too short
       score=`{dd -bs 1 -iseek 280 -count 20 -if $tmp >[2]/dev/null |
               xd -b | sed 's/^.......(  )?//' | tr -d $nl^' '}
}