appnote.txt

用BKZIP方式解压缩文件

          here.  Earlier versions of the software can then safely
          skip this file, and find the next file or header.  This
          field will be 0 length in version 1.0.

          In order to allow different programs and different types
          of information to be stored in the 'extra' field in .ZIP
          files, the following structure should be used for all
          programs storing data in this field:

          header1+data1 + header2+data2 . . .

          Each header should consist of:

            Header ID - 2 bytes
            Data Size - 2 bytes

          Note: all fields stored in Intel low-byte/high-byte order.

          The Header ID field indicates the type of data that is in
          the following data block.

          Header ID's of 0 thru 31 are reserved for use by PKWARE.
          The remaining ID's can be used by third party vendors for
          proprietary usage.

          The current Header ID mappings defined by PKWARE are:

          0x0007        AV Info
          0x0009        OS/2
          0x000a        NTFS 
          0x000c        VAX/VMS
          0x000d        Unix
          0x000f        Patch Descriptor

          Several third party mappings commonly used are:

          0x4b46        FWKCS MD5 (see below)
          0x07c8        Macintosh
          0x4341        Acorn/SparkFS 
          0x4453        Windows NT security descriptor (binary ACL)
          0x4704        VM/CMS
          0x470f        MVS
          0x4c41        OS/2 access control list (text ACL)
          0x4d49        Info-ZIP VMS (VAX or Alpha)
          0x5455        extended timestamp
          0x5855        Info-ZIP Unix (original, also OS/2, NT, etc)
          0x6542        BeOS/BeBox
          0x756e        ASi Unix
          0x7855        Info-ZIP Unix (new)
          0xfd4a        SMS/QDOS

          The Data Size field indicates the size of the following
          data block. Programs can use this value to skip to the
          next header block, passing over any data blocks that are
          not of interest.

          Note: As stated above, the size of the entire .ZIP file
                header, including the filename, comment, and extra
                field should not exceed 64K in size.

          In case two different programs should appropriate the same
          Header ID value, it is strongly recommended that each
          program place a unique signature of at least two bytes in
          size (and preferably 4 bytes or bigger) at the start of
          each data area.  Every program should verify that its
          unique signature is present, in addition to the Header ID
          value being correct, before assuming that it is a block of
          known type.

         -OS/2 Extra Field:

          The following is the layout of the OS/2 attributes "extra" 
          block.  (Last Revision  09/05/95)

          Note: all fields stored in Intel low-byte/high-byte order.

          Value       Size          Description
          -----       ----          -----------
  (OS/2)  0x0009      2 bytes       Tag for this "extra" block type
          TSize       2 bytes       Size for the following data block
          BSize       4 bytes       Uncompressed Block Size
          CType       2 bytes       Compression type
          EACRC       4 bytes       CRC value for uncompress block
          (var)       variable      Compressed block

        The OS/2 extended attribute structure (FEA2LIST) is 
        compressed and then stored in it's entirety within this 
        structure.  There will only ever be one "block" of data in 
        VarFields[].

         -UNIX Extra Field:

          The following is the layout of the Unix "extra" block.
          Note: all fields are stored in Intel low-byte/high-byte 
          order.

          Value       Size          Description
          -----       ----          -----------
  (UNIX)  0x000d      2 bytes       Tag for this "extra" block type
          TSize       2 bytes       Size for the following data block
          Atime       4 bytes       File last access time
          Mtime       4 bytes       File last modification time
          Uid         2 bytes       File user ID
          Gid         2 bytes       File group ID
          (var)       variable      Variable length data field

          The variable length data field will contain file type 
          specific data.  Currently the only values allowed are
          the original "linked to" file names for hard or symbolic 
          links.

         -VAX/VMS Extra Field:

          The following is the layout of the VAX/VMS attributes 
          "extra" block.

          Note: all fields stored in Intel low-byte/high-byte order.

          Value      Size       Description
          -----      ----       -----------
  (VMS)   0x000c     2 bytes    Tag for this "extra" block type
          TSize      2 bytes    Size of the total "extra" block
          CRC        4 bytes    32-bit CRC for remainder of the block
          Tag1       2 bytes    VMS attribute tag value #1
          Size1      2 bytes    Size of attribute #1, in bytes
          (var.)     Size1      Attribute #1 data
          .
          .
          .
          TagN       2 bytes    VMS attribute tage value #N
          SizeN      2 bytes    Size of attribute #N, in bytes
          (var.)     SizeN      Attribute #N data

          Rules:

          1. There will be one or more of attributes present, which 
             will each be preceded by the above TagX & SizeX values.  
             These values are identical to the ATR$C_XXXX and 
             ATR$S_XXXX constants which are defined in ATR.H under 
             VMS C.  Neither of these values will ever be zero.

          2. No word alignment or padding is performed.

          3. A well-behaved PKZIP/VMS program should never produce
             more than one sub-block with the same TagX value.  Also,
             there will never be more than one "extra" block of type
             0x000c in a particular directory record.

         -NTFS Extra Field:

          The following is the layout of the NTFS attributes 
          "extra" block.

          Note: all fields stored in Intel low-byte/high-byte order.

          Value      Size       Description
          -----      ----       -----------
  (NTFS)  0x000a     2 bytes    Tag for this "extra" block type
          TSize      2 bytes    Size of the total "extra" block
          Reserved   4 bytes    Reserved for future use
          Tag1       2 bytes    NTFS attribute tag value #1
          Size1      2 bytes    Size of attribute #1, in bytes
          (var.)     Size1      Attribute #1 data
          .
          .
          .
          TagN       2 bytes    NTFS attribute tage value #N
          SizeN      2 bytes    Size of attribute #N, in bytes
          (var.)     SizeN      Attribute #N data

          For NTFS, values for Tag1 through TagN are as follows:
          (currently only one set of attributes is defined for NTFS)

          Tag        Size       Description
          -----      ----       -----------
          0x0001     2 bytes    Tag for attribute #1 
          Size1      2 bytes    Size of attribute #1, in bytes
          Mtime      8 bytes    File last modification time
          Atime      8 bytes    File last access time
          Ctime      8 bytes    File creation time
          
         -PATCH Descriptor Extra Field:

          The following is the layout of the Patch Descriptor "extra"
          block.

          Note: all fields stored in Intel low-byte/high-byte order.

          Value     Size     Description
          -----     ----     -----------
  (Patch) 0x000f    2 bytes  Tag for this "extra" block type
          TSize     2 bytes  Size of the total "extra" block
          Version   2 bytes  Version of the descriptor
          Flags     4 bytes  Actions and reactions (see below) 
          OldSize   4 bytes  Size of the file about to be patched 
          OldCRC    4 bytes  32-bit CRC of the file to be patched 
          NewSize   4 bytes  Size of the resulting file 
          NewCRC    4 bytes  32-bit CRC of the resulting file 

          Actions and reactions

          Bits          Description
          ----          ----------------
          0             Use for autodetection
          1             Treat as selfpatch
          2-3           RESERVED
          4-5           Action (see below)
          6-7           RESERVED
          8-9           Reaction (see below) to absent file 
          10-11         Reaction (see below) to newer file
          12-13         Reaction (see below) to unknown file
          14-15         RESERVED
          16-31         RESERVED

          Actions

          Action       Value
          ------       ----- 
          none         0
          add          1
          delete       2
          patch        3

          Reactions
 
          Reaction     Value
          --------     -----
          ask          0
          skip         1
          ignore       2
          fail         3

          - FWKCS MD5 Extra Field:

          The FWKCS Contents_Signature System, used in
          automatically identifying files independent of filename,
          optionally adds and uses an extra field to support the
          rapid creation of an enhanced contents_signature:

              Header ID = 0x4b46
              Data Size = 0x0013
              Preface   = 'M','D','5'
              followed by 16 bytes containing the uncompressed file's
              128_bit MD5 hash(1), low byte first.

          When FWKCS revises a zipfile central directory to add
          this extra field for a file, it also replaces the
          central directory entry for that file's uncompressed
          filelength with a measured value.

          FWKCS provides an option to strip this extra field, if
          present, from a zipfile central directory. In adding
          this extra field, FWKCS preserves Zipfile Authenticity
          Verification; if stripping this extra field, FWKCS
          preserves all versions of AV through PKZIP version 2.04g.

          FWKCS, and FWKCS Contents_Signature System, are
          trademarks of Frederick W. Kantor.

          (1) R. Rivest, RFC1321.TXT, MIT Laboratory for Computer
              Science and RSA Data Security, Inc., April 1992.
              ll.76-77: "The MD5 algorithm is being placed in the
              public domain for review and possible adoption as a
              standard."

      file comment: (Variable)

          The comment for this file.

      number of this disk: (2 bytes)

          The number of this disk, which contains central
          directory end record.

      number of the disk with the start of the central
      directory: (2 bytes)

          The number of the disk on which the central
          directory starts.

      total number of entries in the central dir on 
      this disk: (2 bytes)

          The number of central directory entries on this disk.

      total number of entries in the central dir: (2 bytes)

          The total number of files in the zipfile.

      size of the central directory: (4 bytes)

          The size (in bytes) of the entire central directory.

      offset of start of central directory with respect to
      the starting disk number:  (4 bytes)

          Offset of the start of the central directory on the
          disk on which the central directory starts.