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: 51 tmp1=/tmp/ikconfig$$.1 52 tmp2=/tmp/ikconfig$$.2 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 60 try_decompress '\3757zXZ\000' abcde unxz 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 try_decompress '\002\041\114\030' xyy 'lz4 -d -l' 65 try_decompress '\050\265\057\375' xxx unzstd 66 67 # Bail out: 68 echo "$me: Cannot find kernel config." >&2 69 exit 1
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