extra.fld

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	  Value		Size		Description
	  -----		----		-----------
  (MVS)   0x470f	Short		tag for this extra block type
	  TSize		Short		total data size for this block
	  flData	variable	file attributes data

	  flData is an uncompressed fldata_t struct.


	 -Extended Timestamp Extra Field:
	  ==============================

	  The following is the layout of the extended-timestamp extra block.
	  (Last Revision 970118)

	  Local-header version:

	  Value		Size		Description
	  -----		----		-----------
  (time)  0x5455	Short		tag for this extra block type
	  TSize		Short		total data size for this block
	  Flags		Byte		info bits
	  (ModTime)	Long		time of last modification (UTC/GMT)
	  (AcTime)	Long		time of last access (UTC/GMT)
	  (CrTime)	Long		time of original creation (UTC/GMT)

	  Central-header version:

	  Value		Size		Description
	  -----		----		-----------
  (time)  0x5455	Short		tag for this extra block type
	  TSize		Short		total data size for this block
	  Flags		Byte		info bits (refers to local header!)
	  (ModTime)	Long		time of last modification (UTC/GMT)

	  The central-header extra field contains the modification time only,
	  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 970118)

	  Local-header version:

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

	  The file modification and access 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 960922)

	  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 960916)

	  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 970531)

	  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 960929)

	  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 961125)

	  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 961207)

	  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.  Adding or removing this block should preserve the PKWARE
	  AV (Authenticity Verification) signature.

	  ``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 is a trademark of Frederick W. Kantor.