XZ in SharpCompress

[adamhathcock]

Looks like there's a XZ implementation that might be primed to be included:

sambott/XZ.NET#1

[adamhathcock]

Don't know if @weltkante is interested

[weltkante]

Might be interesting if we can clarify the quality of the LZMA encoders (or replace them), though I'm probably not going to spend any time on XZ before I have finished lzma/7z and issue #91. So if someone else wants to look into XZ before that, feel free to do so.

[adamhathcock]

Definitely finish updating LZMA encoders. Just thought integrating XZ might be easy after that as when I looked at it last it was very ZIP like as a container format.

[claunia]

It would be a good idea when it is implemented to make use of the block index XZ files can contain to allow for XZStream to be seekable.

[adamhathcock]

@claunia sounds good. Any chance of a contribution? :)

[adamhathcock]

Still want this. Need licensing changed though sambott/XZ.NET#3

[adamhathcock]

Started a branch here from @sambott 's code: #247

Going to do read-only as I'm doing LZip writing for LZMA

[claunia]

@adamhathcock you can add .lzma support. It can be done in a few lines:
https://github.com/claunia/osrepodbmgr/blob/eto/osrepodbmgr.Core/Workers/Compression.cs#L218 for writing
https://github.com/claunia/osrepodbmgr/blob/eto/osrepodbmgr.Core/Workers/Compression.cs#L743 for reading

Sorry cannot send you a patch right now :(

[adamhathcock]

I'm not sure what you mean. If .lzma has a spec then sure. It looks like it's just a byte stream that's compressed with LZMA which isn't really a format.

[claunia]

@adamhathcock yes, looks like that, because it's the most simple specification ever done: https://svn.python.org/projects/external/xz-5.0.3/doc/lzma-file-format.txt

the tools to create them were deprecated by xz that can (and don't recommend) create them and extract them.

[adamhathcock]

I can add a stream to read it. Not sure I want to go further if it's not highly used.

[claunia]

It was used quite extensively in Linux from its inception until XZ deprecated it. From 2004 it was the default LZMA compressor for *NIX, til XZ was launched in 2008. LZIP was created to replace .lzma, but I've never seen it used in a single place, while .lzma was used for the Linux kernel source distribution and even the package managers in some Linux distributions before being replaced by XZ altogether.

So, in a nutshell, .lzma is more common than .lzip.