ARJ Archive Format(ARJ.rfh):
Class: Archive, Status: Headers only, Last change: 05.03.2008 14:16:20

include DosFTime.rfi

const
  HdrMagic=0xEA60;

type

THostOS enum byte (
  MSDOS=0, PRIMOS=1, UNIX=2, AMIGA=3, MAC_OS=4,
  OS_2=5, APPLE_GS=6, ATARI_ST=7, NEXT=8, VAX_VMS=9
)

TArjFlags set 8 of (
  OLD_SECURED ^ 0x02,
  VOLUME  ^ 0x04, // indicates presence of succeeding volume
  PATHSYM ^ 0x10, // indicates archive name translated ("\" changed to "/")
  BACKUP  ^ 0x20, // indicates backup type archive
  SECURED ^ 0x40
)

// Structure of main header:

TFirstHdr struc
  byte size // 1 first_hdr_size (size up to and including 'extra data')
  byte Ver         // 1   archiver version number
  byte ExtrVer     // 1   minimum archiver version to extract
  THostOS hostOS   // 1   host OS   
  TArjFlags Flags  // 1   arj flags
  byte SecurityVer // 1   security version (2 = current)
  byte file_type   // 1   (must equal 2)
  byte rsrv1       // 1   reserved
  TFileTime CreTime     // 4   date time when original archive was created
  TFileTime LastModTime // 4   date time when archive was last modified
  ulong ArchSz     // 4   archive size (currently used only for secured archives)
  ulong SeqEnvPos  // 4   security envelope file position
  word FileSpecOfs // 2   filespec position in filename
  word SeqEnvSize  // 2   length in bytes of security envelope data
  word rsrv2       // 2   (currently not used)
  raw[] ExtraData  // ?   (currently none)
ends:[@:Size = @.size]:assert[@.file_type=2]

TBasicHdr(Sz) struc
  TFirstHdr Hdr1
  pchar FName   // ?   filename of archive when created (null-terminated string)
  pchar Comment // ?   archive comment  (null-terminated string)
ends:[@:Size=@:Sz]:assert[@.Hdr1:assert]

TExtHeader struc
  word Sz    // 2  extended header size (0 if none)
  raw[@.Sz] Data // ?   1st extended header (currently not used)
  ulong CRC    // 4   1st extended header's CRC (not present when 0 extended header size)
ends

TExtHeaders array of TExtHeader ?@.Sz=0!word;

TMainHdr struc
  word Magic     // 2   header id (main and local file) = 0x60 0xEA
  word BasicSz   // 2   basic header size (from 'first_hdr_size' thru 'comment' below)
		 // = first_hdr_size + strlen(filename) + 1 + strlen(comment) + 1
		 // = 0 if end of archive
		 // maximum header size is 2600
  TBasicHdr(@.BasicSz) BasicHdr
  ulong BasicHdrCRC //4   basic header CRC
  TExtHeaders ExtHdr
ends:assert[@.Magic=HdrMagic, @.BasicSz<=2600,@.BasicHdr:assert]

data

0 TMainHdr Hdr

assert Hdr:assert;

descr ('ARJ Archive File Format.',NL,
  'Info Source: ARJ TECHNICAL INFORMATION (arj.zip at www.wotsit.org)',NL,
  'April 1993',NL)

type

// Structure of local file header:

TArjFileFlags set 8 of (
  GARBLED ^ 0x01, // indicates passworded file
  VOLUME  ^ 0x04, // indicates continued file to next volume (file is split)
  EXTFILE ^ 0x08, // indicates file starting position field (for split files)
  PATHSYM ^ 0x10, // indicates filename translated ("\" changed to "/")
  BACKUP  ^ 0x20  // indicates file marked as backup
)

TComprMethod enum byte (
  stored = 0, 
  maximum = 1,
  normal = 2,
  small = 3,
  fastest = 4
)

TArjFileType enum byte (
  binary=0, 
  text7bit=1, //7-bit text
  dir=3, //directory, 
  volLbl=4 //volume label
)

TFirstFileHdr struc
  byte size // 1 first_hdr_size (size up to and including 'extra data')
  byte Ver         // 1   archiver version number
  byte ExtrVer     // 1   minimum archiver version to extract
  THostOS hostOS   // 1   host OS   
  TArjFileFlags Flags  // 1 arj flags
  TComprMethod  Method // 1 method
  TArjFileType file_type // 1 file type
  byte rsrv1       // 1   reserved
  TFileTime LastModTime // 4   date time modified
  ulong ComprSz    // 4   compressed size
  ulong OrigSz     // 4   original size (this will be different for text mode compression)
  ulong OrigCRC    // 4   original file's CRC
  word FileSpecOfs // 2   filespec position in filename
  word AccessMode  // 2   file access mode
  word HostData    // 2   host data (currently not used)
  word rsrv2       // 2   (currently not used)
  raw[] ExtraData  // ?   (currently none)
  case @.Flags and 0x08 of
    0: void
  else ulong
  endc StartPos    // ?   extra data
	// 4 bytes for extended file starting position when used
	// (these bytes are present when EXTFILE_FLAG is set).
	// 0 bytes otherwise.
ends:[@:Size = @.size]

TBasicFileHdr(Sz) struc
  TFirstFileHdr Hdr1
  pchar FName   // ?
  pchar Comment // ?
ends:[@:Size=@:Sz]

TLocFile struc
  word Magic     // 2   header id (main and local file) = 0x60 0xEA
  word BasicSz   // 2   basic header size (from 'first_hdr_size' thru 'comment' below)
		 // = first_hdr_size + strlen(filename) + 1 + strlen(comment) + 1
		 // = 0 if end of archive
		 // maximum header size is 2600
  TBasicFileHdr(@.BasicSz) BasicHdr
  ulong BasicHdrCRC //4   basic header CRC
  TExtHeaders ExtHdr
  raw[@.BasicHdr.Hdr1.ComprSz] Data     //    ?   compressed file
ends:assert[@.Magic=HdrMagic, @.BasicSz<=2600]

TEndRec struc
  word Magic     // 2   header id (main and local file) = 0x60 0xEA
  word BasicSz   // 2   basic header size 
ends

TLocFiles array of TLocFile ?@.BasicSz=0!TEndRec;

data
Hdr:Size; TLocFiles Files


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