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  1. Commons Compress
  2. COMPRESS-394

[Zip] Local `Version Needed To Extract` does not match Central Directory

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    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Minor
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 1.15
    • Component/s: Archivers
    • Labels:

      Description

      Hi,

      This is followup on an issue reported on Plexus Archiver - https://github.com/codehaus-plexus/plexus-archiver/issues/57

      Plexus Archiver uses ZipArchiveOutputStream to create zip archives. It constructs the ZipArchiveOutputStream using BufferedOutputStream. As a result the output do not provide random access and additional data descriptor records are added. Unfortunately this leads to different values being set for version needed to extract field in the local file header and in the central directory. It looks like that the root cause is the way the local header version needed to extract field value is calculated:

              if (phased &&  !isZip64Required(entry.entry, zip64Mode)){
                  putShort(INITIAL_VERSION, buf, LFH_VERSION_NEEDED_OFFSET);
              } else {
                  putShort(versionNeededToExtract(zipMethod, hasZip64Extra(ze)), buf, LFH_VERSION_NEEDED_OFFSET);
              }
      

      As you can see the need for data descriptors is not taken into account. On other hand when the central directory is created the following is used to determine the minimum required version

          private int versionNeededToExtract(final int zipMethod, final boolean zip64) {
              if (zip64) {
                  return ZIP64_MIN_VERSION;
              }
              // requires version 2 as we are going to store length info
              // in the data descriptor
              return (isDeflatedToOutputStream(zipMethod)) ?
                      DATA_DESCRIPTOR_MIN_VERSION :
                      INITIAL_VERSION;
          }
      

      As a side note: I'm not a zip expert by any means so I could be wrong, but my understanding is that if Deflate compression is used then the minimum required version should be 2.0 regardless if data descriptors are used or not.

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              • Assignee:
                Unassigned
                Reporter:
                plamenttv Plamen Totev
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                • Created:
                  Updated:
                  Resolved: