[jira] [Commented] (COMPRESS-474) xlsx zip64 compatibility

["Krzysztof Rzymkowski (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/COMPRESS-474?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16747881#comment-16747881 ] 

Krzysztof Rzymkowski commented on COMPRESS-474:
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Ad.1. Yes, Excel needs to see 45 in LFH. Central directory is not enough.

Ad.3. It might be not supported. I've just tried to make xlsx bigger then 4gb in Excel by duplication a 700mb (compressed) sheet. Excel refused to make the 5th sheet.

> xlsx zip64 compatibility
> ------------------------
>
>                 Key: COMPRESS-474
>                 URL: https://issues.apache.org/jira/browse/COMPRESS-474
>             Project: Commons Compress
>          Issue Type: Bug
>          Components: Archivers
>    Affects Versions: 1.19
>            Reporter: Krzysztof Rzymkowski
>            Priority: Major
>
> Excel's xlsx files are generally zip archives. But Excel has a very specific and strict ZIP64 implementation.
> Connected Apache POI issue: [https://bz.apache.org/bugzilla/show_bug.cgi?id=57342
>  ]My blog post with all the details: [https://rzymek.github.io/post/excel-zip64/]
> My observations on Excel requirements:
>  # If file size is > 4gb, then zip spec version 4.5 must be set in Local Header File
>  # In streaming creation the zero file sizes must be in 32 field, not in LHF's ZIP64 extra field data.
>  # ZIP64 extra field in Central Directory must not include relativeHeaderOffset. Only size or size and compressed size
>  # ZIP64 Central Directory is not supported
> I did verify these in a +prototype+ repository at [https://github.com/rzymek/commons-compress/pull/1/files]. This is just a playground where I've tested the changes to verify that Excel opens the generated file.
> Test project: https://github.com/rzymek/xlsx-compress64-test
>  
>  



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