#!/bin/sh

# ----------------------------------------------------------------------

# extract-vmlinux - Extract uncompressed vmlinux from a kernel image

#

# Inspired from extract-ikconfig

# (c) 2009,2010 Dick Streefland <dick@streefland.net>

#

# (c) 2011 Corentin Chary <corentin.chary@gmail.com>

#

# Licensed under the GNU General Public License, version 2 (GPLv2).

# ----------------------------------------------------------------------

check_vmlinux()

{

# Use readelf to check if it's a valid ELF

# TODO: find a better to way to check that it's really vmlinux

# and not just an elf

readelf -h $1 > /dev/null 2>&1 || return 1

cat $1

exit 0

}

try_decompress()

{

# 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.

# Try to find the header ($1) and decompress from here

for pos in `tr "$1\n$2" "\n$2=" < "$img" | grep -abo "^$2"`

do

pos=${pos%%:*}

tail -c+$pos "$img" | $3 > $tmp 2> /dev/null

check_vmlinux $tmp

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:

tmp=$(mktemp /tmp/vmlinux-XXX)

trap "rm -f $tmp" 0

# Initial attempt for uncompressed images or objects:

check_vmlinux $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!L\030' xxx 'lz4 -d'

try_decompress '(\265/\375' xxx unzstd

# Bail out:

echo "$me: Cannot find vmlinux." >&2