Other extended headers

• Capsule header : 0x7D
  
  
  • Introduction
    Capsule header contains a location and a size of file data(In Mac, it is data fork) in whole compressed data.(for example, MacBinary) Probably, it will be better not to use it without especially necessity. At older information, Extended header identifier is 0xFC in capsule header.
    
    
    
  • Construction

    offset	Capsule header level 3	Description
    00	Extended header identifier	This is the identifier for specifying an extended header. You must set 0x7D in Capsule header.
    01	Capsule header size(LL)	This is the byte count of OS dependence data which stores in front of main data, in the whole compressed data.
    02	Capsule header size(LH)
    03	Capsule header size(HL)
    04	Capsule header size(HH)
    05	file size(LL)	This is the byte count of main data.(data fork) You can divide into 3 parts from compressed data.
    06	file size(LH)
    07	file size(HL)
    08	file size(HH)
    09	Size of next extended header(LL)	This is the byte count of following extended header. Set this field as 0, when there is not following extended header.
    10	Size of next extended header(LH)
    11	Size of next extended header(HL)
    12	Size of next extended header(HH)

  
  
  
  

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• Extended attribute header : 0x7E
  
  
  • Introduction
    Extended attribute header contains the extended attribute of OS/2. It was also considered storing Resource fork of Mac and ACL of Unix. Extended attribute header is used by OS/2 only, so it will be better not to use it without especially necessity. At older information, Extended header identifier is 0xFD in Extended attribute header.
    
    
    
  • Construction

    offset	Extended attribute header level 3 OS/2	Description
    00	Extended header identifier	This is the identifier for specifying an extended header. You must set 0x7E in Extended attribute header.
    01	Extended attribute identifier	This is the identifier for specifying an extended attribute. This is open to interpretation of each implementation. In OS/2: 0x00 : no compression 0x01 : compression It is not known about compression algorithm in case of 0x01.
    02	Length of OS name	The byte count of following OS name.
    03	OS name(1)	This is a name of OS.
    ??	...
    02 + len	OS name(end)
    03 + len	Extended attribute(1)	This is extended attribute. The image of a structure output "as is".
    ??	...
    size - 5	Extended attribute(end)
    size - 4	Size of next extended header(LL)	This is the byte count of following extended header. Set this field as 0, when there is not following extended header.
    size - 3	Size of next extended header(LH)
    size - 2	Size of next extended header(HL)
    size - 1	Size of next extended header(HH)

  
  
  
  

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• New attribute header for Level 3 header(1) : 0x7F
  
  
  • Introduction
    New attribute header for Level 3 header(1) contains the infomations about UNIX and MS-DOS. New attribute header for Level 3 header(1) is used by LHA for OS/2 only, so it will be better not to use it without especially necessity.
    
    
    
  • Construction

    offset	New attribute header for Level 3 header(1) level 3 OS/2	Description
    00	Extended header identifier	This is the identifier for specifying an extended header. You must set 0x7F in New attribute header for Level 3 header(1).
    01	file attribute of MS-DOS(L)	This is file attribute of MS-DOS.
    02	file attribute of MS-DOS(H)
    03	Permission(L)	This is Permission of compressed file.
    04	Permission(H)
    05	Group ID(L)	This is a identifier of the group which is allowed the access to the compressed file.
    06	Group ID(H)
    07	User ID(L)	This is a identifier of the owner of the compressed file.
    08	User ID(H)
    09	Creation time(LL)	This is date and time the file was created. format is time_t.
    10	Creation time(LH)
    11	Creation time(HL)
    12	Creation time(HH)
    13	Last access time(LL)	This is date and time the file was last accessed. format is time_t.
    14	Last access time(LH)
    15	Last access time(HL)
    16	Last access time(HH)
    17	Size of next extended header(LL)	This is the byte count of following extended header. Set this field as 0, when there is not following extended header.
    18	Size of next extended header(LH)
    19	Size of next extended header(HL)
    20	Size of next extended header(HH)

  
  
  
  

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• Compressed comment header : 0xC4 - 0xC8
  
  
  • Introduction
    Compressed comment header contains a compressed comment. Compressed comment header is proposed in http://www.osirusoft.com/joejared/lzhformat.html. The comment header which is not compressed is not used effectively, either. So it will be better not to use it without especially necessity.
    
    The byte count of comment before compression must be less than 65536 bytes. And, compression algorithm is "-lh5-", dictionary size if specified by extended header identifier.
    

    Extended header identifier	dictionary size
    0xC4	4096
    0xC5	8192
    0xC6	16384
    0xC7	32768
    0xC8	65536

    
    
  • Construction

    offset	Compressed comment header level 1 or 2	Description
    00	Extended header identifier	This is the identifier for specifying an extended header. You must set identifier for each dictionary size.
    01	Compressed comment(1)	This is data of compressed comment.
    ??	...
    size - 3	Compressed comment(end)
    size - 2	Size of next extended header(L)	This is the byte count of following extended header. Set this field as 0, when there is not following extended header.
    size - 1	Size of next extended header(H)

  
  
  
  

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• New attribute header for Level 3 header(2) : 0xFF
  
  
  • Introduction
    New attribute header for Level 3 header(2) contains the infomations about UNIX. New attribute header for Level 3 header(2) is used by UNLHA32.DLL only, so it will be better not to use it without especially necessity.
    
    
    
  • Construction

    offset	New attribute header for Level 3 header(2) level 3 UNLHA	Description
    00	Extended header identifier	This is the identifier for specifying an extended header. You must set 0xFF in New attribute header for Level 3 header(2).
    01	Permission(LL)	This is Permission of compressed file. t.okamoto(administrator of LHa for Unix) says that use high 2 bytes. However it is not known which is "high" (offset 03,04 is "high" of LittleEndian 4bytes or offset 01,02 as is "high" ).
    02	Permission(LH)
    03	Permission(HL)
    04	Permission(HH)
    05	Group ID(LL)	This is Permission of compressed file. t.okamoto(administrator of LHa for Unix) says that use high 2 bytes. However it is not known which is "high" (offset 03,04 is "high" of LittleEndian 4bytes or offset 01,02 as is "high" ).
    06	Group ID(LH)
    07	Group ID(HL)
    08	Group ID(HH)
    09	User ID(LL)	This is a identifier of the owner of the compressed file. t.okamoto(administrator of LHa for Unix) says that use high 2 bytes. However it is not known which is "high" (offset 03,04 is "high" of LittleEndian 4bytes or offset 01,02 as is "high" ).
    10	User ID(LH)
    11	User ID(HL)
    12	User ID(HH)
    13	Creation time(LL)	This is date and time the file was created. format is time_t.
    14	Creation time(LH)
    15	Creation time(HL)
    16	Creation time(HH)
    17	Last access time(LL)	This is date and time the file was last accessed. format is time_t.
    18	Last access time(LH)
    19	Last access time(HL)
    20	Last access time(HH)
    21	Size of next extended header(LL)	This is the byte count of following extended header. Set this field as 0, when there is not following extended header.
    22	Size of next extended header(LH)
    23	Size of next extended header(HL)
    24	Size of next extended header(HH)

  
  
  
  

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• Reference
  • Eriko Tachibana's document of LHA header (Japanese)
    http://kuwa.omosiro.com/KGARC2/ARC/LHAHED15.ZIP
    
    
  • Satoshi Hiramatsu's header.tex which is attached to LHA for OS/2(Japanese)
    http://www02.so-net.ne.jp/~hiramatu/lha/lha2-2.08.lzh
    
    
  • Micco's header.txt which is attached to UNLHA32.DLL(Japanese)
    http://www2.nsknet.or.jp/~micco/unlha32.htm
    
    
  • Satoshi Hiramatsu's propose of Level 3 header Nifty FLABO MES3(669) 94/08/14 (Japanese)
    (when you access this file, Nifty is required ID and password.)
    https://enter.nifty.com/iw/nifty/flabo/mes/3/669.html
    
    
  • Tsugio Okamoto's propose of Level 3 header Nifty FLABO MES3(820) 95/06/25 (Japanese)
    (when you access this file, Nifty is required ID and password.)
    https://enter.nifty.com/iw/nifty/flabo/mes/3/820.html