[projects/geninitrd.git] / 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=$(mktemp)
tmp2=$(mktemp)
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' xy  xzdec
try_decompress 'BZh'          xy  bunzip2
try_decompress '\135\0\0\0'   xxx unlzma
try_decompress '\211\114\132' xy  'lzop -d'

# Bail out:
echo "$me: Cannot find kernel config." >&2
exit 1
Commit	Line	Data
8eb849e6 ER	1	#!/bin/sh
	2	# ----------------------------------------------------------------------
	3	# extract-ikconfig - Extract the .config file from a kernel image
	4	#
	5	# This will only work when the kernel was compiled with CONFIG_IKCONFIG.
	6	#
	7	# The obscure use of the "tr" filter is to work around older versions of
	8	# "grep" that report the byte offset of the line instead of the pattern.
	9	#
	10	# (c) 2009,2010 Dick Streefland <dick@streefland.net>
	11	# Licensed under the terms of the GNU General Public License.
	12	# ----------------------------------------------------------------------
	13
	14	cf1='IKCFG_ST\037\213\010'
	15	cf2='0123456789'
	16
	17	dump_config()
	18	{
	19	if pos=`tr "$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
	31	try_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 $tmp2
	38	done
	39	}
	40
	41	# Check invocation:
	42	me=${0##*/}
	43	img=$1
	44	if [ $# -ne 1 -o ! -s "$img" ]
	45	then
	46	echo "Usage: $me <kernel-image>" >&2
	47	exit 2
	48	fi
	49
	50	# Prepare temp files:
3969b8b1 ER	51	tmp1=$(mktemp)
3969b8b1 ER	52	tmp2=$(mktemp)
8eb849e6 ER	53	trap "rm -f $tmp1 $tmp2" 0
	54
	55	# Initial attempt for uncompressed images or objects:
	56	dump_config "$img"
	57
	58	# That didn't work, so retry after decompression.
	59	try_decompress '\037\213\010' xy gunzip
f41055ab	60	try_decompress '\3757zXZ\000' xy xzdec
8eb849e6 ER	61	try_decompress 'BZh' xy bunzip2
	62	try_decompress '\135\0\0\0' xxx unlzma
	63	try_decompress '\211\114\132' xy 'lzop -d'
	64
	65	# Bail out:
	66	echo "$me: Cannot find kernel config." >&2
	67	exit 1