99b2cdde83
Support for kernel image LZ4 compression was added around 3.11, but not the corresponding kernel .config extraction. This makes possible extracting the kernel config for LZ4-compressed kernels you're not running, or the current LZ4-compressed kernel if compiled without /proc/config.gz support. Signed-off-by: Alex Pilon <alp+linux@alexpilon.ca> Signed-off-by: Michal Marek <mmarek@suse.cz>
1.7 KiB
Executable File
#!/bin/sh
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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.
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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 " >&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'
Bail out:
echo "$me: Cannot find kernel config." >&2 exit 1