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https://issues.apache.org/jira/browse/COMPRESS-124?focusedWorklogId=351558&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-351558
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ASF GitHub Bot logged work on COMPRESS-124:
-------------------------------------------

                Author: ASF GitHub Bot
            Created on: 30/Nov/19 19:47
            Start Date: 30/Nov/19 19:47
    Worklog Time Spent: 10m 
      Work Description: bodewig commented on issue #87: COMPRESS-124 : Add 
support for extracting sparse entries from tar archives
URL: https://github.com/apache/commons-compress/pull/87#issuecomment-560015609
 
 
   First of all, many thanks @PeterAlfreadLee 
   
   I agree with @tcurdt that providing the functionality via a single 
`TarArchiveInputStream` would be preferable. Maybe we could extract the meet of 
the read and skip methods into strategy implementations and make the handling 
of sparse entries another strategy that is triggered when reading said type of 
entry? That way we could extend the class without making it even more complex 
itself.
   
   Here I'm just thinking loud, I haven't got any code to show or even just 
tried to sketch it up. I must admit I haven't even looked at the code in 
detail, so maybe the idea is complete nonsense.
   
   BTW, star is a pretty old tar implementation by Jörg Schilling that used to 
be pretty popular before POSIX started to add support for many of the 
shortcoming that GNU tar addressed in its own way - long file names, big files, 
non-ASCII file names and all that. It is still available via Sourceforge, I 
found the manual page at 
http://schilytools.sourceforge.net/man/man1/star.1.html . IIRC it is BSD 
licensed so was preferred over GNU tar by the BSDs and some other Unices.
 
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Issue Time Tracking
-------------------

    Worklog Id:     (was: 351558)
    Time Spent: 2h 50m  (was: 2h 40m)

> Unable to extract a sparse entries from tar archives
> ----------------------------------------------------
>
>                 Key: COMPRESS-124
>                 URL: https://issues.apache.org/jira/browse/COMPRESS-124
>             Project: Commons Compress
>          Issue Type: New Feature
>          Components: Archivers
>    Affects Versions: 1.1, 1.2
>         Environment: Platform independent. However, I'm currently using 
> Window 7 Enterprise.
>            Reporter: Patrick Dreyer
>            Priority: Major
>              Labels: tar
>         Attachments: gnuSparseFile.patch
>
>          Time Spent: 2h 50m
>  Remaining Estimate: 0h
>
> Good news first: I already have the patch ready for that.
> I got several TAR files which I could not extract with any of the existing 
> Java implementations, but I could extract all those TAR files successfully 
> with GNU tar.
> It turned out that all the failing TAR files contained so called sparse 
> files. Investigating the source code of all existing Java TAR implementations 
> showed me that none of them even recognizes the existence of GNU sparse 
> entries.
> Actually, I don't need to process one of the contained sparse files and I'm 
> happy if I'm at least able to correctly untar all the non-sparsed files. 
> Thus, it would be sufficient recognizing sparse files without the need to 
> correctly un-sparse them while extracting. As long as all non-sparsed files 
> get extracted correctly, I'm fine.
> The TAR files in question have all been VMware Diagnostic File bundles.
> See 
> http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=653
>  to know how to get them.



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