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|
The following are the known types of zipfile extra fields as of this
writing. Extra fields are documented in PKWARE's appnote.txt and are
intended to allow for backward- and forward-compatible extensions to
the zipfile format. Multiple extra-field types may be chained together,
provided that the total length of all extra-field data is less than 64KB.
(In fact, PKWARE requires that the total length of the entire file header,
including timestamp, file attributes, filename, comment, extra field, etc.,
be no more than 64KB.)
Each extra-field type (or subblock) must contain a four-byte header con-
sisting of a two-byte header ID and a two-byte length (little-endian) for
the remaining data in the subblock. If there are additional subblocks
within the extra field, the header for each one will appear immediately
following the data for the previous subblock (i.e., with no padding for
alignment).
All integer fields in the descriptions below are in little-endian (Intel)
format unless otherwise specified. Note that "Short" means two bytes,
"Long" means four bytes, and "Long-Long" means eight bytes, regardless
of their native sizes. Unless specifically noted, all integer fields should
be interpreted as unsigned (non-negative) numbers.
Christian Spieler, 19990220
-------------------------
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 extended attributes (also Info-ZIP)
0x000a PKWARE Win95/WinNT FileTimes [undocumented!]
0x000c PKWARE VAX/VMS (also Info-ZIP)
0x000d PKWARE Unix
0x000f Patch Descriptor
The Header ID mappings defined by Info-ZIP and third parties are:
0x07c8 Info-ZIP Macintosh (old, J. Lee)
0x2605 ZipIt Macintosh (first version)
0x2705 ZipIt Macintosh v 1.3.5 and newer (w/o full filename)
0x334d Info-ZIP Macintosh (new, D. Haase's 'Mac3' field )
0x4154 Tandem NSK
0x4341 Acorn/SparkFS (David Pilling)
0x4453 Windows NT security descriptor (binary ACL)
0x4704 VM/CMS
0x470f MVS
0x4854 Theos, old inofficial port
0x4b46 FWKCS MD5 (third party, see below)
0x4c41 OS/2 access control list (text ACL)
0x4d49 Info-ZIP VMS (VAX or Alpha)
0x5356 AOS/VS (binary ACL)
0x5455 extended timestamp
0x5855 Info-ZIP Unix (original; also OS/2, NT, etc.)
0x6542 BeOS (BeBox, PowerMac, etc.)
0x6854 Theos
0x756e ASi Unix
0x7855 Info-ZIP Unix (new)
0xfb4a SMS/QDOS
The following are detailed descriptions of the known extra-field block types:
-OS/2 Extended Attributes Extra Field:
====================================
The following is the layout of the OS/2 extended attributes "extra"
block. (Last Revision 19960922)
Note: all fields stored in Intel low-byte/high-byte order.
Local-header version:
Value Size Description
----- ---- -----------
(OS/2) 0x0009 Short tag for this extra block type
TSize Short total data size for this block
BSize Long uncompressed EA data size
CType Short compression type
EACRC Long CRC value for uncompressed EA data
(var.) variable compressed EA data
Central-header version:
Value Size Description
----- ---- -----------
(OS/2) 0x0009 Short tag for this extra block type
TSize Short total data size for this block
BSize Long size of uncompressed local EA data
The value of CType is interpreted according to the "compression
method" section above; i.e., 0 for stored, 8 for deflated, etc.
The OS/2 extended attribute structure (FEA2LIST) is compressed and
then stored in its entirety within this structure. There will only
ever be one block of data in the variable-length field.
-OS/2 Access Control List Extra Field:
====================================
The following is the layout of the OS/2 ACL extra block.
(Last Revision 19960922)
Local-header version:
Value Size Description
----- ---- -----------
(ACL) 0x4c41 Short tag for this extra block type
TSize Short total data size for this block
BSize Long uncompressed ACL data size
CType Short compression type
EACRC Long CRC value for uncompressed ACL data
(var.) variable compressed ACL data
Central-header version:
Value Size Description
----- ---- -----------
(ACL) 0x4c41 Short tag for this extra block type
TSize Short total data size for this block
BSize Long size of uncompressed local ACL data
The value of CType is interpreted according to the "compression
method" section above; i.e., 0 for stored, 8 for deflated, etc.
The uncompressed ACL data consist of a text header of the form
"ACL1:%hX,%hd\n", where the first field is the OS/2 ACCINFO acc_attr
member and the second is acc_count, followed by acc_count strings
of the form "%s,%hx\n", where the first field is acl_ugname (user
group name) and the second acl_access. This block type will be
extended for other operating systems as needed.
-Windows NT Security Descriptor Extra Field:
==========================================
The following is the layout of the NT Security Descriptor (another
type of ACL) extra block. (Last Revision 19960922)
Local-header version:
Value Size Description
----- ---- -----------
(SD) 0x4453 Short tag for this extra block type
TSize Short total data size for this block
BSize Long uncompressed SD data size
Version Byte version of uncompressed SD data format
CType Short compression type
EACRC Long CRC value for uncompressed SD data
(var.) variable compressed SD data
Central-header version:
Value Size Description
----- ---- -----------
(SD) 0x4453 Short tag for this extra block type
TSize Short total data size for this block
BSize Long size of uncompressed local SD data
The value of CType is interpreted according to the "compression
method" section above; i.e., 0 for stored, 8 for deflated, etc.
Version specifies how the compressed data are to be interpreted
and allows for future expansion of this extra field type. Currently
only version 0 is defined.
For version 0, the compressed data are to be interpreted as a single
valid Windows NT SECURITY_DESCRIPTOR data structure, in self-relative
format.
-PKWARE Win95/WinNT Extra Field:
==============================
The following description covers PKWARE's undocumented
Windows 95 & Windows NT extra field, introduced with the
release of PKZIP for Windows 2.50. (Last Revision 19980425)
This field has a fixed data size of 32 bytes and is only stored
as local extra field.
Value Size Description
----- ---- -----------
(WinNT) 0x000a Short Tag for this "extra" block type
TSize Short Total Data Size for this block
Unknwn1 Long ???? (all 0 ?)
Unknwn2 Long ????
ModTime Long-Long 64-bit NTFS last-modified filetime
AccTime Long-Long 64-bit NTFS last-access filetime
CreTime Long-Long 64-bit NTFS creation filetime
The NTFS filetimes are 64-bit unsigned integers, stored in Intel
(least significant byte first) byte order. They determine the
number of 1.0E-07 seconds (1/10th microseconds!) past WinNT "epoch",
which is "01-Jan-1601 00:00:00 UTC".
-PKWARE VAX/VMS Extra Field:
==========================
The following is the layout of PKWARE's VAX/VMS attributes "extra"
block. (Last Revision 12/17/91)
Note: all fields stored in Intel low-byte/high-byte order.
Value Size Description
----- ---- -----------
(VMS) 0x000c Short Tag for this "extra" block type
TSize Short Total Data Size for this block
CRC Long 32-bit CRC for remainder of the block
Tag1 Short VMS attribute tag value #1
Size1 Short Size of attribute #1, in bytes
(var.) Size1 Attribute #1 data
.
.
.
TagN Short VMS attribute tage value #N
SizeN Short 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.
-Info-ZIP VMS Extra Field:
========================
The following is the layout of Info-ZIP's VMS attributes extra
block for VAX or Alpha AXP. The local-header and central-header
versions are identical. (Last Revision 19960922)
Value Size Description
----- ---- -----------
(VMS2) 0x4d49 Short tag for this extra block type
TSize Short total data size for this block
ID Long block ID
Flags Short info bytes
BSize Short uncompressed block size
Reserved Long (reserved)
(var.) variable compressed VMS file-attributes block
The block ID is one of the following unterminated strings:
"VFAB" struct FAB
"VALL" struct XABALL
"VFHC" struct XABFHC
"VDAT" struct XABDAT
"VRDT" struct XABRDT
"VPRO" struct XABPRO
"VKEY" struct XABKEY
"VMSV" version (e.g., "V6.1"; truncated at hyphen)
"VNAM" reserved
The lower three bits of Flags indicate the compression method. The
currently defined methods are:
0 stored (not compressed)
1 simple "RLE"
2 deflated
The "RLE" method simply replaces zero-valued bytes with zero-valued
bits and non-zero-valued bytes with a "1" bit followed by the byte
value.
The variable-length compressed data contains only the data corre-
sponding to the indicated structure or string. Typically multiple
VMS2 extra fields are present (each with a unique block type).
-Info-ZIP Macintosh Extra Field:
==============================
The following is the layout of the (old) Info-ZIP resource-fork extra
block for Macintosh. The local-header and central-header versions
are identical. (Last Revision 19960922)
Value Size Description
----- ---- -----------
(Mac) 0x07c8 Short tag for this extra block type
TSize Short total data size for this block
"JLEE" beLong extra-field signature
FInfo 16 bytes Macintosh FInfo structure
CrDat beLong HParamBlockRec fileParam.ioFlCrDat
MdDat beLong HParamBlockRec fileParam.ioFlMdDat
Flags beLong info bits
DirID beLong HParamBlockRec fileParam.ioDirID
VolName 28 bytes volume name (optional)
All fields but the first two are in native Macintosh format
(big-endian Motorola order, not little-endian Intel). The least
significant bit of Flags is 1 if the file is a data fork, 0 other-
wise. In addition, if this extra field is present, the filename
has an extra 'd' or 'r' appended to indicate data fork or resource
fork. The 28-byte VolName field may be omitted.
-ZipIt Macintosh Extra Field (long):
==================================
The following is the layout of the ZipIt extra block for Macintosh.
The local-header and central-header versions are identical.
(Last Revision 19970130)
Value Size Description
----- ---- -----------
(Mac2) 0x2605 Short tag for this extra block type
TSize Short total data size for this block
"ZPIT" beLong extra-field signature
FnLen Byte length of FileName
FileName variable full Macintosh filename
FileType Byte[4] four-byte Mac file type string
Creator Byte[4] four-byte Mac creator string
-ZipIt Macintosh Extra Field (short):
===================================
The following is the layout of a shortened variant of the
ZipIt extra block for Macintosh (without "full name" entry).
This variant is used by ZipIt 1.3.5 and newer for entries that
do not need a "full Mac filename" record.
The local-header and central-header versions are identical.
(Last Revision 19980903)
Value Size Description
----- ---- -----------
(Mac2b) 0x2705 Short tag for this extra block type
TSize Short total data size for this block
"ZPIT" beLong extra-field signature
FileType Byte[4] four-byte Mac file type string
Creator Byte[4] four-byte Mac creator string
-Info-ZIP Macintosh Extra Field (new):
====================================
The following is the layout of the (new) Info-ZIP extra
block for Macintosh, designed by Dirk Haase.
All values are in little-endian.
(Last Revision 19981005)
Local-header version:
Value Size Description
----- ---- -----------
(Mac3) 0x334d Short tag for this extra block type ("M3")
TSize Short total data size for this block
BSize Long uncompressed finder attribute data size
Flags Short info bits
fdType Byte[4] Type of the File (4-byte string)
fdCreator Byte[4] Creator of the File (4-byte string)
(CType) Short compression type
(CRC) Long CRC value for uncompressed MacOS data
Attribs variable finder attribute data (see below)
Central-header version:
Value Size Description
----- ---- -----------
(Mac3) 0x334d Short tag for this extra block type ("M3")
TSize Short total data size for this block
BSize Long uncompressed finder attribute data size
Flags Short info bits
fdType Byte[4] Type of the File (4-byte string)
fdCreator Byte[4] Creator of the File (4-byte string)
The third bit of Flags in both headers indicates whether
the LOCAL extra field is uncompressed (and therefore whether CType
and CRC are omitted):
Bits of the Flags:
bit 0 if set, file is a data fork; otherwise unset
bit 1 if set, filename will be not changed
bit 2 if set, Attribs is uncompressed (no CType, CRC)
bit 3 if set, date and times are in 64 bit
if zero date and times are in 32 bit.
bit 4 if set, timezone offsets fields for the native
Mac times are omitted (UTC support deactivated)
bits 5-15 reserved;
Attributes:
Attribs is a Mac-specific block of data in little-endian format with
the following structure (if compressed, uncompress it first):
Value Size Description
----- ---- -----------
fdFlags Short Finder Flags
fdLocation.v Short Finder Icon Location
fdLocation.h Short Finder Icon Location
fdFldr Short Folder containing file
FXInfo 16 bytes Macintosh FXInfo structure
FXInfo-Structure:
fdIconID Short
fdUnused[3] Short unused but reserved 6 bytes
fdScript Byte Script flag and number
fdXFlags Byte More flag bits
fdComment Short Comment ID
fdPutAway Long Home Dir ID
FVersNum Byte file version number
may be not used by MacOS
ACUser Byte directory access rights
FlCrDat ULong date and time of creation
FlMdDat ULong date and time of last modification
FlBkDat ULong date and time of last backup
These time numbers are original Mac FileTime values (local time!).
Currently, date-time width is 32-bit, but future version may
support be 64-bit times (see flags)
CrGMTOffs Long(signed!) difference "local Creat. time - UTC"
MdGMTOffs Long(signed!) difference "local Modif. time - UTC"
BkGMTOffs Long(signed!) difference "local Backup time - UTC"
These "local time - UTC" differences (stored in seconds) may be
used to support timestamp adjustment after inter-timezone transfer.
These fields are optional; bit 4 of the flags word controls their
presence.
Charset Short TextEncodingBase (Charset)
valid for the following two fields
FullPath variable Path of the current file.
Zero terminated string (C-String)
Currently coded in the native Charset.
Comment variable Finder Comment of the current file.
Zero terminated string (C-String)
Currently coded in the native Charset.
-Acorn SparkFS Extra Field:
=========================
The following is the layout of David Pilling's SparkFS extra block
for Acorn RISC OS. The local-header and central-header versions are
identical. (Last Revision 19960922)
Value Size Description
----- ---- -----------
(Acorn) 0x4341 Short tag for this extra block type
TSize Short total data size for this block
"ARC0" Long extra-field signature
LoadAddr Long load address or file type
ExecAddr Long exec address
Attr Long file permissions
Zero Long reserved; always zero
The following bits of Attr are associated with the given file
permissions:
bit 0 user-writable ('W')
bit 1 user-readable ('R')
bit 2 reserved
bit 3 locked ('L')
bit 4 publicly writable ('w')
bit 5 publicly readable ('r')
bit 6 reserved
bit 7 reserved
-VM/CMS Extra Field:
==================
The following is the layout of the file-attributes extra block for
VM/CMS. The local-header and central-header versions are
identical. (Last Revision 19960922)
Value Size Description
----- ---- -----------
(VM/CMS) 0x4704 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.
-MVS Extra Field:
===============
The following is the layout of the file-attributes extra block for
MVS. The local-header and central-header versions are identical.
(Last Revision 19960922)
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.
-PKWARE Unix Extra Field:
========================
The following is the layout of PKWARE's Unix "extra" block.
It was introduced with the release of PKZIP for Unix 2.50.
Note: all fields are stored in Intel low-byte/high-byte order.
(Last Revision 19980901)
This field has a minimum data size of 12 bytes and is only stored
as local extra field.
Value Size Description
----- ---- -----------
(Unix0) 0x000d 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
(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.
The fixed part of this field has the same layout as Info-ZIP's
abandoned "Unix1 timestamps & owner ID info" extra field;
only the two tag bytes are different.
-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 Short Tag for this "extra" block type
TSize Short Size of the total "extra" block
Version Short Version of the descriptor
Flags Long Actions and reactions (see below)
OldSize Long Size of the file about to be patched
OldCRC Long 32-bit CRC of the file about to be patched
NewSize Long Size of the resulting file
NewCRC Long 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
-Extended Timestamp Extra Field:
==============================
The following is the layout of the extended-timestamp extra block.
(Last Revision 19970118)
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 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.
-Tandem NSK Extra Field:
======================
The following is the layout of the file-attributes extra block for
Tandem NSK. The local-header and central-header versions are
identical. (Last Revision 19981221)
Value Size Description
----- ---- -----------
(TA) 0x4154 Short tag for this extra block type ("TA")
TSize Short total data size for this block
NSKattrs 20 Bytes NSK attributes
-THEOS Extra Field:
=================
The following is the layout of the file-attributes extra block for
Theos. The local-header and central-header versions are identical.
(Last Revision 19990206)
Value Size Description
----- ---- -----------
(Theos) 0x6854 Short 'Th' signature
size Short size of extra block
flags Byte reserved for future use
filesize Long file size
fileorg Byte type of file (see below)
keylen Short key length for indexed and keyed files,
data segment size for 16 bits programs
reclen Short record length for indexed,keyed and direct,
text segment size for 16 bits programs
filegrow Byte growing factor for indexed,keyed and direct
protect Byte protections (see below)
reserved Short reserved for future use
File types
==========
0x80 library (keyed access list of files)
0x40 directory
0x10 stream file
0x08 direct file
0x04 keyed file
0x02 indexed file
0x0e reserved
0x01 16 bits real mode program (obsolete)
0x21 16 bits protected mode program
0x41 32 bits protected mode program
Protection codes
================
User protection
---------------
0x01 non readable
0x02 non writable
0x04 non executable
0x08 non erasable
Other protection
----------------
0x10 non readable
0x20 non writable
0x40 non executable Theos before 4.0
0x40 modified Theos 4.x
0x80 not hidden
-THEOS old inofficial Extra Field:
================================
The following is the layout of an inoffical former version of a
Theos file-attributes extra blocks. This layout was never published
and is no longer created. However, UnZip can optionally support it
when compiling with the option flag OLD_THEOS_EXTRA defined.
Both the local-header and central-header versions are identical.
(Last Revision 19990206)
Value Size Description
----- ---- -----------
(THS0) 0x4854 Short 'TH' signature
size Short size of extra block
flags Short reserved for future use
filesize Long file size
reclen Short record length for indexed,keyed and direct,
text segment size for 16 bits programs
keylen Short key length for indexed and keyed files,
data segment size for 16 bits programs
filegrow Byte growing factor for indexed,keyed and direct
reserved 3 Bytes reserved for future use
-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.
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