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#!/bin/sh

# Option ROM Signing utility

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, see <http://www.gnu.org/licenses/>.

#

# Copyright Novell Inc, 2009

#   Authors: Alexander Graf <agraf@suse.de>

#

# Syntax: signrom.sh <input> <output>

# did we get proper arguments?

test "$1" -a "$2" || exit 1

sum=0

# find out the file size

x=`dd if="$1" bs=1 count=1 skip=2 2>/dev/null | od -t u1 -A n`

#size=`expr $x \* 512 - 1`

size=$(( $x * 512 - 1 ))

# now get the checksum

nums=`od -A n -t u1 -v -N $size "$1"`

for i in ${nums}; do

    # add each byte's value to sum

    sum=`expr \( $sum + $i \) % 256`

done

sum=$(( (256 - $sum) % 256 ))

sum_octal=$( printf "%o" $sum )

# and write the output file

cp "$1" "$2"

printf "\\$sum_octal" | dd of="$2" bs=1 count=1 seek=$size conv=notrunc 2>/dev/null