view release on metacpan or  search on metacpan

unzip-6.0/proginfo/extrafld.txt  view on Meta::CPAN

          Note that Unix UIDs and GIDs are usually specific to a particular
          machine, and they generally require root access to restore.


         -Info-ZIP New Unix Extra Field:
          ====================================

          Currently stores Unix UIDs/GIDs up to 32 bits.
          (Last Revision 20080509)

          Value         Size        Description
          -----         ----        -----------
  (UnixN) 0x7875        Short       tag for this extra block type ("ux")
          TSize         Short       total data size for this block
          Version       1 byte      version of this extra field, currently 1
          UIDSize       1 byte      Size of UID field
          UID           Variable    UID for this entry
          GIDSize       1 byte      Size of GID field
          GID           Variable    GID for this entry

          Currently Version is set to the number 1.  If there is a need
          to change this field, the version will be incremented.  Changes
          may not be backward compatible so this extra field should not be
          used if the version is not recognized.

          UIDSize is the size of the UID field in bytes.  This size should
          match the size of the UID field on the target OS.

          UID is the UID for this entry in standard little endian format.

          GIDSize is the size of the GID field in bytes.  This size should
          match the size of the GID field on the target OS.

          GID is the GID for this entry in standard little endian format.

          If both the old 16-bit Unix extra field (tag 0x7855, Info-ZIP Unix2)
          and this extra field are present, the values in this extra field
          supercede the values in that extra field.


         -ASi UNIX Extra Field:
          ====================

          The following is the layout of the ASi extra block for Unix.  The
          local-header and central-header versions are identical.
          (Last Revision 19960916)

          Value         Size        Description
          -----         ----        -----------
  (Unix3) 0x756e        Short       tag for this extra block type ("nu")
          TSize         Short       total data size for this block
          CRC           Long        CRC-32 of the remaining data
          Mode          Short       file permissions
          SizDev        Long        symlink'd size OR major/minor dev num
          UID           Short       user ID
          GID           Short       group ID
          (var.)        variable    symbolic link filename

          Mode is the standard Unix st_mode field from struct stat, containing
          user/group/other permissions, setuid/setgid and symlink info, etc.

          If Mode indicates that this file is a symbolic link, SizDev is the
          size of the file to which the link points.  Otherwise, if the file
          is a device, SizDev contains the standard Unix st_rdev field from
          struct stat (includes the major and minor numbers of the device).
          SizDev is undefined in other cases.

          If Mode indicates that the file is a symbolic link, the final field
          will be the name of the file to which the link points.  The file-
          name length can be inferred from TSize.

          [Note that TSize may incorrectly refer to the data size not counting
           the CRC; i.e., it may be four bytes too small.]


         -BeOS Extra Field:
          ================

          The following is the layout of the file-attributes extra block for
          BeOS.  (Last Revision 19970531)

          Local-header version:

          Value         Size        Description
          -----         ----        -----------
  (BeOS)  0x6542        Short       tag for this extra block type ("Be")
          TSize         Short       total data size for this block
          BSize         Long        uncompressed file attribute data size
          Flags         Byte        info bits
          (CType)       Short       compression type
          (CRC)         Long        CRC value for uncompressed file attribs
          Attribs       variable    file attribute data

          Central-header version:

          Value         Size        Description
          -----         ----        -----------
  (BeOS)  0x6542        Short       tag for this extra block type ("Be")
          TSize         Short       total data size for this block (5)
          BSize         Long        size of uncompr. local EF block data
          Flags         Byte        info bits

          The least significant bit of Flags in both headers indicates whether
          the LOCAL extra field is uncompressed (and therefore whether CType
          and CRC are omitted):

                bit 0           if set, Attribs is uncompressed (no CType, CRC)
                bits 1-7        reserved; if set, assume error or unknown data

          Currently the only supported compression types are deflated (type 8)
          and stored (type 0); the latter is not used by Info-ZIP's Zip but is
          supported by UnZip.

          Attribs is a BeOS-specific block of data in big-endian format with
          the following structure (if compressed, uncompress it first):

              Value     Size        Description
              -----     ----        -----------
              Name      variable    attribute name (null-terminated string)
              Type      Long        attribute type (32-bit unsigned integer)