Messages in this thread | | | Date | Thu, 11 Aug 2011 15:33:51 +0200 | From | Michal Marek <> | Subject | Re: [PATCH] scripts: add extract-vmlinux |
| |
On 11.8.2011 15:08, Corentin Chary wrote: > On Thu, Aug 11, 2011 at 1:28 PM, Paul Bolle <pebolle@tiscali.nl> wrote: >> On Thu, 2011-08-11 at 10:53 +0200, Corentin Chary wrote: >>> +try_decompress() >>> +{ >>> + 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 >> >> Perhaps a few comments on the above lines would be nice. Without those >> comments I must guess you're finding compressed data somewhere in the >> input file. It also seems you're looping through the entire input file. >> Or are (sequences of) commands like the above considered obvious? > > It's copied from extract-ikconfig, there was no comment in it, so I > assumed it's obvious. > Basically it uses brute force (tm) to find well known headers and try > to decompress from here.
And explanation of the "tr" trick would not hurt though. It replaces the binary magic with an ascii sequence on a new line (for older grep versions to get it right) and tries all occurrences of that sequence, am I right? But I wouldn't call it "obvious" :).
>>> +# 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' >> >> Perhaps you could first test whether these commands are available before >> running try_decompress() with them? > > Same as before, if it's ok for extract-ikconfig not to check the > command, then it's ok for me. > If it's not, then we should patch both.
Also, if you have lzma to build a lzma-compressed kernel, then you very likely also have unlzma.
Michal
| |