1#!/bin/sh 2# ---------------------------------------------------------------------- 3# extract-ikconfig - Extract the .config file from a kernel image 4# 5# This will only work when the kernel was compiled with CONFIG_IKCONFIG. 6# 7# The obscure use of the "tr" filter is to work around older versions of 8# "grep" that report the byte offset of the line instead of the pattern. 9# 10# (c) 2009, Dick Streefland <dick@streefland.net> 11# Licensed under the terms of the GNU General Public License. 12# ---------------------------------------------------------------------- 13 14gz1='\037\213\010' 15gz2='01' 16cf1='IKCFG_ST\037\213\010' 17cf2='0123456789' 18 19dump_config() 20{ 21 if pos=`tr "$cf1\n$cf2" "\n$cf2=" < "$1" | grep -abo "^$cf2"` 22 then 23 pos=${pos%%:*} 24 tail -c+$(($pos+8)) "$1" | zcat -q 25 exit 0 26 fi 27} 28 29# Check invocation: 30me=${0##*/} 31img=$1 32if [ $# -ne 1 -o ! -s "$img" ] 33then 34 echo "Usage: $me <kernel-image>" >&2 35 exit 2 36fi 37 38# Initial attempt for uncompressed images or objects: 39dump_config "$img" 40 41# That didn't work, so decompress and try again: 42tmp=/tmp/ikconfig$$ 43trap "rm -f $tmp" 0 44for pos in `tr "$gz1\n$gz2" "\n$gz2=" < "$img" | grep -abo "^$gz2"` 45do 46 pos=${pos%%:*} 47 tail -c+$pos "$img" | zcat 2> /dev/null > $tmp 48 dump_config $tmp 49done 50 51# Bail out: 52echo "$me: Cannot find kernel config." >&2 53exit 1 54