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Thread: can zip directory entries share file entries?

  1. #1
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    Question can zip directory entries share file entries?

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    Can the file entries and the directory entries be in any order? Must file entry 1 correspond to directory entry 1?

    can the directory entries in a zip file point to the same file data as another directory entry? E.g. if a zip file contained an exactly-duplicate file, could the two entries point to the same compressed data or would the data need to be duplicated?

    Would this cause problems for normal zip tools extracting files successfully, or updating an archive?
    Last edited by willvarfar; 23rd February 2011 at 15:11.

  2. #2
    Administrator Shelwien's Avatar
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    "Header Offset" in ZIPDIRENTRY points to a header, not to file data.
    So you'd get things like:
    Z:\@3>unzip -t PKFIXED.ZIP
    Archive:  PKFIXED.ZIP
        testing: 1/                       OK
        testing: 1/print.css              OK
    print.css:  mismatching "local" filename (1/print.css),
             continuing with "central" filename version
        testing: print.css                OK
    At least one warning-error was detected in PKFIXED.ZIP.
    Z:\@3>7z t PKFIXED.ZIP
    7-Zip 9.20  Copyright (c) 1999-2010 Igor Pavlov  2010-11-18
    Processing archive: PKFIXED.ZIP
    Testing     1
    Testing     1\print.css
    Testing     print.css     Unsupported Method
    Sub items Errors: 1

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