#!/bin/sh

pkg=$1

if [ "$pkg" = "" -o ! -e "$pkg" ]; then

echo "no package supplied" 1>&2

exit 1

fi

leadsize=96

o=`expr $leadsize + 8`

set `od -j $o -N 8 -t u1 $pkg`

il=`expr 256 \* \( 256 \* \( 256 \* $2 + $3 \) + $4 \) + $5`

dl=`expr 256 \* \( 256 \* \( 256 \* $6 + $7 \) + $8 \) + $9`

# echo "sig il: $il dl: $dl"

sigsize=`expr 8 + 16 \* $il + $dl`

o=`expr $o + $sigsize + \( 8 - \( $sigsize \% 8 \) \) \% 8 + 8`

set `od -j $o -N 8 -t u1 $pkg`

il=`expr 256 \* \( 256 \* \( 256 \* $2 + $3 \) + $4 \) + $5`

dl=`expr 256 \* \( 256 \* \( 256 \* $6 + $7 \) + $8 \) + $9`

# echo "hdr il: $il dl: $dl"

hdrsize=`expr 8 + 16 \* $il + $dl`

o=`expr $o + $hdrsize`

dd if=$pkg ibs=$o skip=1 2>/dev/null | gunzip