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    SubjectRe: [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 <> 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.


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      Last update: 2011-08-11 15:37    [W:0.022 / U:32.692 seconds]
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