name : extract-ikconfig #!/bin/sh # ---------------------------------------------------------------------- # extract-ikconfig - Extract the .config file from a kernel image # # This will only work when the kernel was compiled with CONFIG_IKCONFIG. # # The obscure use of the "tr" filter is to work around older versions of # "grep" that report the byte offset of the line instead of the pattern. # # (c) 2009,2010 Dick Streefland <dick@streefland.net> # Licensed under the terms of the GNU General Public License. # ---------------------------------------------------------------------- cf1='IKCFG_ST\037\213\010' cf2='0123456789' dump_config() { if pos=`tr "$cf1\n$cf2" "\n$cf2=" < "$1" | grep -abo "^$cf2"` then pos=${pos%%:*} tail -c+$(($pos+8)) "$1" | zcat > $tmp1 2> /dev/null if [ $? != 1 ] then # exit status must be 0 or 2 (trailing garbage warning) cat $tmp1 exit 0 fi fi } try_decompress() { for pos in `tr "$1\n$2" "\n$2=" < "$img" | grep -abo "^$2"` do pos=${pos%%:*} tail -c+$pos "$img" | $3 > $tmp2 2> /dev/null dump_config $tmp2 done } # Check invocation: me=${0##*/} img=$1 if [ $# -ne 1 -o ! -s "$img" ] then echo "Usage: $me <kernel-image>" >&2 exit 2 fi # Prepare temp files: tmp1=/tmp/ikconfig$$.1 tmp2=/tmp/ikconfig$$.2 trap "rm -f $tmp1 $tmp2" 0 # Initial attempt for uncompressed images or objects: dump_config "$img" # That didn't work, so retry after decompression. try_decompress '\037\213\010' xy gunzip try_decompress '\3757zXZ\000' abcde unxz try_decompress 'BZh' xy bunzip2 try_decompress '\135\0\0\0' xxx unlzma try_decompress '\211\114\132' xy 'lzop -d' try_decompress '\002\041\114\030' xyy 'lz4 -d -l' try_decompress '\050\265\057\375' xxx unzstd # Bail out: echo "$me: Cannot find kernel config." >&2 exit 1