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From "Dawid Weiss (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (COMPRESS-380) Support for ENHANCED_DEFLATED (Deflate64) in ZIP files
Date Mon, 08 Jan 2018 08:17:00 GMT

    [ https://issues.apache.org/jira/browse/COMPRESS-380?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16315853#comment-16315853
] 

Dawid Weiss commented on COMPRESS-380:
--------------------------------------

I'll check again once I get back home, thanks Stefan. I did look at the changes and they look
good. I can't decide whether those extensive sanity checks should be in there at all times
(and shouldn't be just in assertion-enabled mode); I think it'll slow down decompression by
a large factor. Whether this is of practical importance, I've no idea. 

I also looked at the bit reader yesterday and wondered if it'd be a better idea to make a
bit reader factory depending on byte order, then the returned implementation could be optimized
for a particular byte order and not do so many conditionals. While this would mean virtual
method calls, in practice these would be predominantly homogeneous and would inline fairly
quickly. 

Maybe worth taking a look at - if you agree and file an issue, I may take a look in a spare
moment. I am fond of bit-fiddling.

> Support for ENHANCED_DEFLATED (Deflate64) in ZIP files
> ------------------------------------------------------
>
>                 Key: COMPRESS-380
>                 URL: https://issues.apache.org/jira/browse/COMPRESS-380
>             Project: Commons Compress
>          Issue Type: New Feature
>            Reporter: Dawid Weiss
>             Fix For: 1.16
>
>         Attachments: archive-deflate.zip, archive-deflate64.zip, archive.zip, archive64.zip,
compress-380.diff, hello.world, input2
>
>
> Some of the (large) ZIP files we try to process currently will throw this:
> {code}
> UnsupportedZipFeatureException: unsupported feature method 'ENHANCED_DEFLATED' 
> {code}
> which is a bummer since JDK's implementation also doesn't support Deflate64. This seems
to be PKWare's extensions, although code to decrypt it exists in zlib (and is appropriately
licensed, I believe).
> https://github.com/madler/zlib/tree/master/contrib/infback9



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