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Re: [Bug-tar] 7z support for GNU tar

From: Joerg Schilling
Subject: Re: [Bug-tar] 7z support for GNU tar
Date: Thu, 03 Nov 2005 11:58:06 +0100
User-agent: nail 11.2 8/15/04

"Rene Leonhardt" <address@hidden> wrote:

> I am wondering if there are any plans to support the LGPL 7-Zip compression
> format besides the already supported compress, gzip and bzip2 formats.
> From my point of view it is already very stable and useful, i.e. the
> Wikipedia database is downloadable in the 7z format since a few weeks.
> I believe that the acceptance would grow even faster if GNU tar would
> support a 7z archive filter.
> http://en.wikipedia.org/wiki/Wikipedia:Download
> http://download.wikimedia.org/wikipedia/en/
> http://en.wikipedia.org/wiki/7-zip
> http://en.wikipedia.org/wiki/P7zip

First, thank you for the hint!

Yesterday, I did check two 7z implementations:

lzma_0.03.orig.tar.gz   Source Debian (hacked version of the
                        disappeared lzma_0.01.tar.gz)

                        Conslusion: contains non portable
                        (pre C++ standard) source code that
                        misses at least something like:

                        using namespace std;

                        It compiles with g++, but it does not
                        write a "magic" number into the file,
                        so it is not really usable.

                        My tests with the revent star source tree
                        show that it could compress 13% better 
                        than bzip2 -9

                        Decompression speed is 2.5x the speed of

lzma427.tar.bz2         Source from a pointer frm Wiki.

                        This source does not compile at all because
                        the source code is using illegal "\\\r\n"
                        sequences and most likely has other problems

                        From checking the source, it seems to use
                        a "magic" number in the file.

If there was a usable implementation, I would be happy to add support
to the compress detection algorithm in star....


 EMail:address@hidden (home) Jörg Schilling D-13353 Berlin
       address@hidden           (uni)  
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