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) 2009,2010 Dick Streefland <dick@streefland.net> 11# Licensed under the terms of the GNU General Public License. 12# ---------------------------------------------------------------------- 13 14cf1='IKCFG_ST\037\213\010' 15cf2='0123456789' 16 17dump_config() 18{ 19 if pos=`tr "$cf1\n$cf2" "\n$cf2=" < "$1" | grep -abo "^$cf2"` 20 then 21 pos=${pos%%:*} 22 tail -c+$(($pos+8)) "$1" | zcat > $tmp1 2> /dev/null 23 if [ $? != 1 ] 24 then # exit status must be 0 or 2 (trailing garbage warning) 25 cat $tmp1 26 exit 0 27 fi 28 fi 29} 30 31try_decompress() 32{ 33 for pos in `tr "$1\n$2" "\n$2=" < "$img" | grep -abo "^$2"` 34 do 35 pos=${pos%%:*} 36 tail -c+$pos "$img" | $3 > $tmp2 2> /dev/null 37 dump_config $tmp2 38 done 39} 40 41# Check invocation: 42me=${0##*/} 43img=$1 44if [ $# -ne 1 -o ! -s "$img" ] 45then 46 echo "Usage: $me <kernel-image>" >&2 47 exit 2 48fi 49 50# Prepare temp files: 51tmp1=/tmp/ikconfig$$.1 52tmp2=/tmp/ikconfig$$.2 53trap "rm -f $tmp1 $tmp2" 0 54 55# Initial attempt for uncompressed images or objects: 56dump_config "$img" 57 58# That didn't work, so retry after decompression. 59try_decompress '\037\213\010' xy gunzip 60try_decompress '\3757zXZ\000' abcde unxz 61try_decompress 'BZh' xy bunzip2 62try_decompress '\135\0\0\0' xxx unlzma 63try_decompress '\211\114\132' xy 'lzop -d' 64try_decompress '\002\041\114\030' xyy 'lz4 -d -l' 65 66# Bail out: 67echo "$me: Cannot find kernel config." >&2 68exit 1 69