| 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, 20010517 |
| |
| Updated to include the Unicode extra fields. Added new Unix extra field. |
| |
| Ed Gordon, 20060819, 20070607, 20070909, 20080426, 20080509 |
| |
| ------------------------- |
| |
| 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: |
| |
| 0x0001 ZIP64 extended information extra field |
| 0x0007 AV Info |
| 0x0009 OS/2 extended attributes (also Info-ZIP) |
| 0x000a NTFS (Win9x/WinNT FileTimes) |
| 0x000c OpenVMS (also Info-ZIP) |
| 0x000d Unix |
| 0x000f Patch Descriptor |
| 0x0014 PKCS#7 Store for X.509 Certificates |
| 0x0015 X.509 Certificate ID and Signature for |
| individual file |
| 0x0016 X.509 Certificate ID for Central Directory |
| |
| The Header ID mappings defined by Info-ZIP and third parties are: |
| |
| 0x0065 IBM S/390 attributes - uncompressed |
| 0x0066 IBM S/390 attributes - compressed |
| 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 (see below) |
| 0x4c41 OS/2 access control list (text ACL) |
| 0x4d49 Info-ZIP OpenVMS (obsolete) |
| 0x4d63 Macintosh SmartZIP, by Macro Bambini |
| 0x4f4c Xceed original location extra field |
| 0x5356 AOS/VS (binary ACL) |
| 0x5455 extended timestamp |
| 0x5855 Info-ZIP Unix (original; also OS/2, NT, etc.) |
| 0x554e Xceed unicode extra field |
| 0x6375 Info-ZIP Unicode Comment |
| 0x6542 BeOS (BeBox, PowerMac, etc.) |
| 0x6854 Theos |
| 0x7075 Info-ZIP Unicode Path |
| 0x756e ASi Unix |
| 0x7855 Info-ZIP Unix (previous new) |
| 0x7875 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 (4) |
| 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 ("AL") |
| 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 ("AL") |
| TSize Short total data size for this block (4) |
| 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 ("SD") |
| 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 ("SD") |
| TSize Short total data size for this block (4) |
| 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 "NTFS" attributes |
| "extra" block, introduced with the release of PKZIP 2.50 for |
| Windows. (Last Revision 20001118) |
| |
| (Note: At this time the Mtime, Atime and Ctime values may |
| be used on any WIN32 system.) |
| [Info-ZIP note: In the current implementations, this field has |
| a fixed total data size of 32 bytes and is only stored as local |
| extra field.] |
| |
| Value Size Description |
| ----- ---- ----------- |
| (NTFS) 0x000a Short Tag for this "extra" block type |
| TSize Short Total Data Size for this block |
| Reserved Long for future use |
| Tag1 Short NTFS attribute tag value #1 |
| Size1 Short Size of attribute #1, in bytes |
| (var.) SubSize1 Attribute #1 data |
| . |
| . |
| . |
| TagN Short NTFS attribute tag value #N |
| SizeN Short Size of attribute #N, in bytes |
| (var.) SubSize1 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 (24) |
| Mtime 8 bytes 64-bit NTFS file last modification time |
| Atime 8 bytes 64-bit NTFS file last access time |
| Ctime 8 bytes 64-bit NTFS file creation time |
| |
| The total length for this block is 28 bytes, resulting in a |
| fixed size value of 32 for the TSize field of the NTFS block. |
| |
| 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 OpenVMS Extra Field: |
| ========================== |
| |
| The following is the layout of PKWARE's OpenVMS 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 OpenVMS attribute tag value #1 |
| Size1 Short Size of attribute #1, in bytes |
| (var.) Size1 Attribute #1 data |
| . |
| . |
| . |
| TagN Short OpenVMS 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 |
| OpenVMS C. Neither of these values will ever be zero. |
| |
| 2. No word alignment or padding is performed. |
| |
| 3. A well-behaved PKZIP/OpenVMS 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 ("JM") |
| 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 (12) |
| "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. |
| |
| |
| -SmartZIP Macintosh Extra Field: |
| ==================================== |
| |
| The following is the layout of the SmartZIP extra |
| block for Macintosh, designed by Marco Bambini. |
| |
| Local-header version: |
| |
| Value Size Description |
| ----- ---- ----------- |
| 0x4d63 Short tag for this extra block type ("cM") |
| TSize Short total data size for this block (64) |
| "dZip" beLong extra-field signature |
| fdType Byte[4] Type of the File (4-byte string) |
| fdCreator Byte[4] Creator of the File (4-byte string) |
| fdFlags beShort Finder Flags |
| fdLocation.v beShort Finder Icon Location |
| fdLocation.h beShort Finder Icon Location |
| fdFldr beShort Folder containing file |
| CrDat beLong HParamBlockRec fileParam.ioFlCrDat |
| MdDat beLong HParamBlockRec fileParam.ioFlMdDat |
| frScroll.v Byte vertical pos. of folder's scroll bar |
| fdScript Byte Script flag and number |
| frScroll.h Byte horizontal pos. of folder's scroll bar |
| fdXFlags Byte More flag bits |
| FileName Byte[32] full Macintosh filename (pascal string) |
| |
| All fields but the first two are in native Macintosh format |
| (big-endian Motorola order, not little-endian Intel). |
| The extra field size is fixed to 64 bytes. |
| The local-header and central-header versions are identical. |
| |
| |
| -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 ("AC") |
| TSize Short total data size for this block (20) |
| "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, and the major and minor device node numbers for |
| character and block device nodes. Since device nodes |
| cannot be either symbolic or hard links, only one set of |
| variable length data is stored. Link files will have the |
| name of the original file stored. This name is NOT NULL |
| terminated. Its size can be determined by checking TSize - |
| 12. Device entries will have eight bytes stored as two 4 |
| byte entries (in little-endian format). The first entry |
| will be the major device number, and the second the minor |
| device number. |
| |
| [Info-ZIP note: 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 |
| |
| |
| -PKCS#7 Store for X.509 Certificates: |
| =================================== |
| |
| This field is contains the information about each |
| certificate a file is signed with. This field should only |
| appear in the first central directory record, and will be |
| ignored in any other record. |
| |
| Note: all fields stored in Intel low-byte/high-byte order. |
| |
| Value Size Description |
| ----- ---- ----------- |
| (Store) 0x0014 2 bytes Tag for this "extra" block type |
| SSize 2 bytes Size of the store data |
| SData (variable) Data about the store |
| |
| SData |
| Value Size Description |
| ----- ---- ----------- |
| Version 2 bytes Version number, 0x0001 for now |
| StoreD (variable) Actual store data |
| |
| The StoreD member is suitable for passing as the pbData |
| member of a CRYPT_DATA_BLOB to the CertOpenStore() function |
| in Microsoft's CryptoAPI. The SSize member above will be |
| cbData + 6, where cbData is the cbData member of the same |
| CRYPT_DATA_BLOB. The encoding type to pass to |
| CertOpenStore() should be |
| PKCS_7_ANS_ENCODING | X509_ASN_ENCODING. |
| |
| |
| -X.509 Certificate ID and Signature for individual file: |
| ====================================================== |
| |
| This field contains the information about which certificate |
| in the PKCS#7 Store was used to sign the particular file. |
| It also contains the signature data. This field can appear |
| multiple times, but can only appear once per certificate. |
| |
| Note: all fields stored in Intel low-byte/high-byte order. |
| |
| Value Size Description |
| ----- ---- ----------- |
| (CID) 0x0015 2 bytes Tag for this "extra" block type |
| CSize 2 bytes Size of Method |
| Method (variable) |
| |
| Method |
| Value Size Description |
| ----- ---- ----------- |
| Version 2 bytes Version number, for now 0x0001 |
| AlgID 2 bytes Algorithm ID used for signing |
| IDSize 2 bytes Size of Certificate ID data |
| CertID (variable) Certificate ID data |
| SigSize 2 bytes Size of Signature data |
| Sig (variable) Signature data |
| |
| CertID |
| Value Size Description |
| ----- ---- ----------- |
| Size1 4 bytes Size of CertID, should be (IDSize - 4) |
| Size1 4 bytes A bug in version one causes this value |
| to appear twice. |
| IssSize 4 bytes Issuer data size |
| Issuer (variable) Issuer data |
| SerSize 4 bytes Serial Number size |
| Serial (variable) Serial Number data |
| |
| The Issuer and IssSize members are suitable for creating a |
| CRYPT_DATA_BLOB to be the Issuer member of a CERT_INFO |
| struct. The Serial and SerSize members would be the |
| SerialNumber member of the same CERT_INFO struct. This |
| struct would be used to find the certificate in the store |
| the file was signed with. Those structures are from the MS |
| CryptoAPI. |
| |
| Sig and SigSize are the actual signature data and size |
| generated by signing the file with the MS CryptoAPI using a |
| hash created with the given AlgID. |
| |
| |
| -X.509 Certificate ID and Signature for central directory: |
| ======================================================== |
| |
| This field contains the information about which certificate |
| in the PKCS#7 Store was used to sign the central directory. |
| It should only appear with the first central directory |
| record, along with the store. The data structure is the |
| same as the CID, except that SigSize will be 0, and there |
| will be no Sig member. |
| |
| This field is also kept after the last central directory |
| record, as the signature data (ID 0x05054b50, it looks like |
| a central directory record of a different type). This |
| second copy of the data is the Signature Data member of the |
| record, and will have a SigSize that is non-zero, and will |
| have Sig data. |
| |
| Note: all fields stored in Intel low-byte/high-byte order. |
| |
| Value Size Description |
| ----- ---- ----------- |
| (CDID) 0x0016 2 bytes Tag for this "extra" block type |
| CSize 2 bytes Size of Method |
| Method (variable) |
| |
| |
| -ZIP64 Extended Information Extra Field: |
| ====================================== |
| |
| The following is the layout of the ZIP64 extended |
| information "extra" block. If one of the size or |
| offset fields in the Local or Central directory |
| record is too small to hold the required data, |
| a ZIP64 extended information record is created. |
| The order of the fields in the ZIP64 extended |
| information record is fixed, but the fields will |
| only appear if the corresponding Local or Central |
| directory record field is set to 0xFFFF or 0xFFFFFFFF. |
| |
| Note: all fields stored in Intel low-byte/high-byte order. |
| |
| Value Size Description |
| ----- ---- ----------- |
| (ZIP64) 0x0001 2 bytes Tag for this "extra" block type |
| Size 2 bytes Size of this "extra" block |
| Original |
| Size 8 bytes Original uncompresseed file size |
| Compressed |
| Size 8 bytes Size of compressed data |
| Relative Header |
| Offset 8 bytes Offset of local header record |
| Disk Start |
| Number 4 bytes Number of the disk on which |
| this file starts |
| |
| This entry in the Local header must include BOTH original |
| and compressed file sizes. |
| |
| |
| -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 ("UT") |
| 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 ("UT") |
| 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 ("UX") |
| 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 (optional) |
| GID Short Unix group ID (optional) |
| |
| Central-header version: |
| |
| Value Size Description |
| ----- ---- ----------- |
| (Unix1) 0x5855 Short tag for this extra block type ("UX") |
| 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 ("Ux") |
| TSize Short total data size for this block (4) |
| 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 ("Ux") |
| TSize Short total data size for this block (0) |
| |
| 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 ("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) |
| 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 ("VS") |
| 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 (20) |
| 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 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. |
| 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 ("FK") |
| 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 |
| (low byte first) |
| |
| When FWKCS revises a .ZIP file central directory to add |
| this extra field for a file, it also replaces the |
| central directory entry for that file's uncompressed |
| file length with a measured value. |
| |
| FWKCS provides an option to strip this extra field, if |
| present, from a .ZIP file central directory. In adding |
| this extra field, FWKCS preserves .ZIP file 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." |
| |
| |
| -Info-ZIP Unicode Path Extra Field: |
| ================================= |
| |
| Stores the UTF-8 version of the entry path as stored in the |
| local header and central directory header. |
| (Last Revision 20070912) |
| |
| Value Size Description |
| ----- ---- ----------- |
| (UPath) 0x7075 Short tag for this extra block type ("up") |
| TSize Short total data size for this block |
| Version 1 byte version of this extra field, currently 1 |
| NameCRC32 4 bytes File Name Field CRC32 Checksum |
| UnicodeName Variable UTF-8 version of the entry File Name |
| |
| 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. |
| |
| The NameCRC32 is the standard zip CRC32 checksum of the File Name |
| field in the header. This is used to verify that the header |
| File Name field has not changed since the Unicode Path extra field |
| was created. This can happen if a utility renames the entry but |
| does not update the UTF-8 path extra field. If the CRC check fails, |
| this UTF-8 Path Extra Field should be ignored and the File Name field |
| in the header used instead. |
| |
| The UnicodeName is the UTF-8 version of the contents of the File Name |
| field in the header. As UnicodeName is defined to be UTF-8, no UTF-8 |
| byte order mark (BOM) is used. The length of this field is determined |
| by subtracting the size of the previous fields from TSize. If both |
| the File Name and Comment fields are UTF-8, the new General Purpose |
| Bit Flag, bit 11 (Language encoding flag (EFS)), can be used to |
| indicate that both the header File Name and Comment fields are UTF-8 |
| and, in this case, the Unicode Path and Unicode Comment extra fields |
| are not needed and should not be created. Note that, for backward |
| compatibility, bit 11 should only be used if the native character set |
| of the paths and comments being zipped up are already in UTF-8. The |
| same method, either bit 11 or extra fields, should be used in both |
| the local and central directory headers. |
| |
| |
| -Info-ZIP Unicode Comment Extra Field: |
| ==================================== |
| |
| Stores the UTF-8 version of the entry comment as stored in the |
| central directory header. |
| (Last Revision 20070912) |
| |
| Value Size Description |
| ----- ---- ----------- |
| (UCom) 0x6375 Short tag for this extra block type ("uc") |
| TSize Short total data size for this block |
| Version 1 byte version of this extra field, currently 1 |
| ComCRC32 4 bytes Comment Field CRC32 Checksum |
| UnicodeCom Variable UTF-8 version of the entry comment |
| |
| 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. |
| |
| The ComCRC32 is the standard zip CRC32 checksum of the Comment |
| field in the central directory header. This is used to verify that |
| the comment field has not changed since the Unicode Comment extra field |
| was created. This can happen if a utility changes the Comment field |
| but does not update the UTF-8 Comment extra field. If the CRC check |
| fails, this Unicode Comment extra field should be ignored and the |
| Comment field in the header used. |
| |
| The UnicodeCom field is the UTF-8 version of the entry comment field |
| in the header. As UnicodeCom is defined to be UTF-8, no UTF-8 byte |
| order mark (BOM) is used. The length of this field is determined by |
| subtracting the size of the previous fields from TSize. If both the |
| File Name and Comment fields are UTF-8, the new General Purpose Bit |
| Flag, bit 11 (Language encoding flag (EFS)), can be used to indicate |
| both the header File Name and Comment fields are UTF-8 and, in this |
| case, the Unicode Path and Unicode Comment extra fields are not |
| needed and should not be created. Note that, for backward |
| compatibility, bit 11 should only be used if the native character set |
| of the paths and comments being zipped up are already in UTF-8. The |
| same method, either bit 11 or extra fields, should be used in both |
| the local and central directory headers. |
| |
| |
| -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 Unix) |
| and this extra field are present, the values in this extra field |
| supercede the values in that extra field. |
