1#!/bin/sh
2# SPDX-License-Identifier: GPL-2.0-only
3# ----------------------------------------------------------------------
4# extract-vmlinux - Extract uncompressed vmlinux from a kernel image
5#
6# Inspired from extract-ikconfig
7# (c) 2009,2010 Dick Streefland <dick@streefland.net>
8#
9# (c) 2011 Corentin Chary <corentin.chary@gmail.com>
10#
11# ----------------------------------------------------------------------
12
13check_vmlinux()
14{
15 # Use readelf to check if it's a valid ELF
16 # TODO: find a better to way to check that it's really vmlinux
17 # and not just an elf
18 readelf -h $1 > /dev/null 2>&1 || return 1
19
20 cat $1
21 exit 0
22}
23
24try_decompress()
25{
26 # The obscure use of the "tr" filter is to work around older versions of
27 # "grep" that report the byte offset of the line instead of the pattern.
28
29 # Try to find the header ($1) and decompress from here
30 for pos in `tr "$1\n$2" "\n$2=" < "$img" | grep -abo "^$2"`
31 do
32 pos=${pos%%:*}
33 tail -c+$pos "$img" | $3 > $tmp 2> /dev/null
34 check_vmlinux $tmp
35 done
36}
37
38# Check invocation:
39me=${0##*/}
40img=$1
41if [ $# -ne 1 -o ! -s "$img" ]
42then
43 echo "Usage: $me <kernel-image>" >&2
44 exit 2
45fi
46
47# Prepare temp files:
48tmp=$(mktemp /tmp/vmlinux-XXX)
49trap "rm -f $tmp" 0
50
51# That didn't work, so retry after decompression.
52try_decompress '\037\213\010' xy gunzip
53try_decompress '\3757zXZ\000' abcde unxz
54try_decompress 'BZh' xy bunzip2
55try_decompress '\135\0\0\0' xxx unlzma
56try_decompress '\211\114\132' xy 'lzop -d'
57try_decompress '\002!L\030' xxx 'lz4 -d'
58try_decompress '(\265/\375' xxx unzstd
59
60# Finally check for uncompressed images or objects:
61check_vmlinux $img
62
63# Bail out:
64echo "$me: Cannot find vmlinux." >&2
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