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From "Stefan Bodewig (JIRA)" <>
Subject [jira] [Commented] (COMPRESS-36) Add Zip64 Suport
Date Thu, 21 Jul 2011 03:03:58 GMT


Stefan Bodewig commented on COMPRESS-36:

Just browsed through APPNOTE.TXT and
took some notes on what ZIP64 means

* new "end of central directory record" and "end of central directory locator" records

* sizes in data descriptor will be 8 bytes when written with ZIP64

* there are two different versions of "end of central directory record" for ZIP spec 4.5-6.1
and spec 6.2+

* will need to set "version needed to extract" to 4.5 or 6.2 depending on the "eocdr" version

* size is stored in an extra field if the archive uses ZIP64 and the size in the local file
header / central directory entry is 0xFFFFFFFF
  This is also true for disk number or file numbers (only with 0xFFFF rather than four bytes)
  This new extra field has varying structure, for example it may only contain the uncompressed
size but not the compressed size if the compressed size fits into four bytes.

* new zip64 extensible data sector
  We likely won't implement this (completely) because of

          {quote}Portions of this extended tape processing technology is
          covered under a pending patent application. The use or
          implementation in a product of certain technological
          aspects set forth in the current APPNOTE, including
          those with regard to strong encryption, patching or
          extended tape operations, requires a license from
          PKWARE.  Please contact PKWARE with regard to acquiring
          a license.{quote}

* note that the new sizes potentially exceed Long.MAX_VALUE as they are unsigned which will
cause trouble with ZipFile and its
  usage of RandomAccessFile
  Same is true for things like ZipArchiveEntry#getSize/setSize

> Add Zip64 Suport
> ----------------
>                 Key: COMPRESS-36
>                 URL:
>             Project: Commons Compress
>          Issue Type: New Feature
>          Components: Archivers
>            Reporter: Christian Grobmeier
>         Attachments:
> Add Zip64 support. This will make it work to deal with zipfiles > 2 GB. 
> Planned for compress 1.1

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