extra.fld

完整的解压zip文件的源码。包含密码功能

          or no timestamp at all.  TSize is used to flag its presence or
          absence.  But note:

              If "Flags" indicates that Modtime is present in the local header
              field, it MUST be present in the central header field, too!
              This correspondence is required because the modification time
              value may be used to support trans-timezone freshening and
              updating operations with zip archives.

          The time values are in standard Unix signed-long format, indicating
          the number of seconds since 1 January 1970 00:00:00.  The times
          are relative to Coordinated Universal Time (UTC), also sometimes
          referred to as Greenwich Mean Time (GMT).  To convert to local time,
          the software must know the local timezone offset from UTC/GMT.

          The lower three bits of Flags in both headers indicate which time-
          stamps are present in the LOCAL extra field:

                bit 0           if set, modification time is present
                bit 1           if set, access time is present
                bit 2           if set, creation time is present
                bits 3-7        reserved for additional timestamps; not set

          Those times that are present will appear in the order indicated, but
          any combination of times may be omitted.  (Creation time may be
          present without access time, for example.)  TSize should equal
          (1 + 4*(number of set bits in Flags)), as the block is currently
          defined.  Other timestamps may be added in the future.


         -Info-ZIP Unix Extra Field (type 1):
          ==================================

          The following is the layout of the old Info-ZIP extra block for
          Unix.  It has been replaced by the extended-timestamp extra block
          (0x5455) and the Unix type 2 extra block (0x7855).
          (Last Revision 19970118)

          Local-header version:

          Value         Size            Description
          -----         ----            -----------
  (Unix1) 0x5855        Short           tag for this extra block type
          TSize         Short           total data size for this block
          AcTime        Long            time of last access (UTC/GMT)
          ModTime       Long            time of last modification (UTC/GMT)
          UID           Short           Unix user ID
          GID           Short           Unix group ID

          Central-header version:

          Value         Size            Description
          -----         ----            -----------
  (Unix1) 0x5855        Short           tag for this extra block type
          TSize         Short           total data size for this block
          AcTime        Long            time of last access (GMT/UTC)
          ModTime       Long            time of last modification (GMT/UTC)

          The file access and modification times are in standard Unix signed-
          long format, indicating the number of seconds since 1 January 1970
          00:00:00.  The times are relative to Coordinated Universal Time
          (UTC), also sometimes referred to as Greenwich Mean Time (GMT).  To
          convert to local time, the software must know the local timezone
          offset from UTC/GMT.  The modification time may be used by non-Unix
          systems to support inter-timezone freshening and updating of zip
          archives.

          The local-header extra block may optionally contain UID and GID
          info for the file.  The local-header TSize value is the only
          indication of this.  Note that Unix UIDs and GIDs are usually
          specific to a particular machine, and they generally require root
          access to restore.

          This extra field type is obsolete, but it has been in use since
          mid-1994.  Therefore future archiving software should continue to
          support it.  Some guidelines:

              An archive member should either contain the old "Unix1"
              extra field block or the new extra field types "time" and/or
              "Unix2".

              If both the old "Unix1" block type and one or both of the new
              block types "time" and "Unix2" are found, the "Unix1" block
              should be considered invalid and ignored.

              Unarchiving software should recognize both old and new extra
              field block types, but the info from new types overrides the
              old "Unix1" field.

              Archiving software should recognize "Unix1" extra fields for
              timestamp comparison but never create it for updated, freshened
              or new archive members.  When copying existing members to a new
              archive, any "Unix1" extra field blocks should be converted to
              the new "time" and/or "Unix2" types.


         -Info-ZIP Unix Extra Field (type 2):
          ==================================

          The following is the layout of the new Info-ZIP extra block for
          Unix.  (Last Revision 19960922)

          Local-header version:

          Value         Size            Description
          -----         ----            -----------
  (Unix2) 0x7855        Short           tag for this extra block type
          TSize         Short           total data size for this block
          UID           Short           Unix user ID
          GID           Short           Unix group ID

          Central-header version:

          Value         Size            Description
          -----         ----            -----------
  (Unix2) 0x7855        Short           tag for this extra block type
          TSize         Short           total data size for this block

          The data size of the central-header version is zero; it is used
          solely as a flag that UID/GID info is present in the local-header
          extra field.  If additional fields are ever added to the local
          version, the central version may be extended to indicate this.

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


         -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
          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
          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
          TSize         Short           total data size for this block
          BSize         Long            size of uncompressed 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)
              Size      Long Long       data size for this sub-block (64 bits)
              Data      variable        attribute data

          The attribute structure is repeated for every attribute.  The Data
          field may contain anything--text, flags, bitmaps, etc.


         -SMS/QDOS Extra Field:
          ====================

          The following is the layout of the file-attributes extra block for
          SMS/QDOS.  The local-header and central-header versions are identical.
          (Last Revision 19960929)

          Value         Size            Description
          -----         ----            -----------
  (QDOS)  0xfb4a        Short           tag for this extra block type
          TSize         Short           total data size for this block
          LongID        Long            extra-field signature
          (ExtraID)     Long            additional signature/flag bytes
          QDirect       64 bytes        qdirect structure

          LongID may be "QZHD" or "QDOS".  In the latter case, ExtraID will
          be present.  Its first three bytes are "02\0"; the last byte is
          currently undefined.

          QDirect contains the file's uncompressed directory info (qdirect
          struct).  Its elements are in native (big-endian) format:

          d_length      beLong          file length
          d_access      byte            file access type
          d_type        byte            file type
          d_datalen     beLong          data length
          d_reserved    beLong          unused
          d_szname      beShort         size of filename
          d_name        36 bytes        filename
          d_update      beLong          time of last update
          d_refdate     beLong          file version number
          d_backup      beLong          time of last backup (archive date)


         -AOS/VS Extra Field:
          ==================

          The following is the layout of the extra block for Data General
          AOS/VS.  The local-header and central-header versions are identical.
          (Last Revision 19961125)

          Value         Size            Description
          -----         ----            -----------
  (AOSVS) 0x5356        Short           tag for this extra block type
          TSize         Short           total data size for this block
          "FCI\0"       Long            extra-field signature
          Version       Byte            version of AOS/VS extra block (10 = 1.0)
          Fstat         variable        fstat packet
          AclBuf        variable        raw ACL data ($MXACL bytes)

          Fstat contains the file's uncompressed fstat packet, which is one of
          the following:

                normal fstat packet             (P_FSTAT struct)
                DIR/CPD fstat packet            (P_FSTAT_DIR struct)
                unit (device) fstat packet      (P_FSTAT_UNIT struct)
                IPC file fstat packet           (P_FSTAT_IPC struct)

          AclBuf contains the raw ACL data; its length is $MXACL.


         -FWKCS MD5 Extra Field:
          =====================

          The following is the layout of the optional extra block used by the
          FWKCS utility.  There is no local-header version; the following
          applies only to the central header.  (Last Revision 19961207)

          Central-header version:

          Value         Size            Description
          -----         ----            -----------
  (MD5)   0x4b46        Short           tag for this extra block type
          TSize         Short           total data size for this block (19)
          "MD5"         3 bytes         extra-field signature
          MD5hash       16 bytes        128-bit MD5 hash of uncompressed data

          The MD5 hash in this extra block is used to automatically identify
          files independent of their filenames; it is an an enhanced contents-
          signature.

          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.

          ``The MD5 algorithm is being placed in the public domain for review
          and possible adoption as a standard.'' (Ron Rivest, MIT Laboratory
          for Computer Science and RSA Data Security, Inc., April 1992, RFC
          1321, 11.76-77).  FWKCS, and FWKCS Contents_Signature System, are
          trademarks of Frederick W. Kantor.