LHA (LHarc, LZH) is a file format used by a popular freeware eponymous archiver, created in 1988 by Haruyasu Yoshizaki. Over the years, many ports and implementations were developed, sporting many extensions to original 1988 LZH.
File format is pretty simple and essentially consists of a stream of records.
This page hosts a formal specification of .lzh file format of LHA (AKA LHarc) by Yoshizaki Haruyasu using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
All parsing code for C# generated by Kaitai Struct depends on the C# runtime library. You have to install it before you can parse data.
The C# runtime library is available in the NuGet Gallery. Installation instructions can also be found there.
Parse a local file and get structure in memory:
var data = Lzh.FromFile("path/to/local/file.lzh");
Or parse structure from a byte array:
byte[] someArray = new byte[] { ... };
var data = new Lzh(new KaitaiStream(someArray));
After that, one can get various attributes from the structure by accessing properties like:
data.Entries // => get entries
// This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
using System.Collections.Generic;
namespace Kaitai
{
/// <summary>
/// LHA (LHarc, LZH) is a file format used by a popular freeware
/// eponymous archiver, created in 1988 by Haruyasu Yoshizaki. Over the
/// years, many ports and implementations were developed, sporting many
/// extensions to original 1988 LZH.
///
/// File format is pretty simple and essentially consists of a stream of
/// records.
/// </summary>
public partial class Lzh : KaitaiStruct
{
public static Lzh FromFile(string fileName)
{
return new Lzh(new KaitaiStream(fileName));
}
public Lzh(KaitaiStream p__io, KaitaiStruct p__parent = null, Lzh p__root = null) : base(p__io)
{
m_parent = p__parent;
m_root = p__root ?? this;
_read();
}
private void _read()
{
_entries = new List<Record>();
{
var i = 0;
while (!m_io.IsEof) {
_entries.Add(new Record(m_io, this, m_root));
i++;
}
}
}
public partial class Record : KaitaiStruct
{
public static Record FromFile(string fileName)
{
return new Record(new KaitaiStream(fileName));
}
public Record(KaitaiStream p__io, Lzh p__parent = null, Lzh p__root = null) : base(p__io)
{
m_parent = p__parent;
m_root = p__root;
_read();
}
private void _read()
{
_headerLen = m_io.ReadU1();
if (HeaderLen > 0) {
_fileRecord = new FileRecord(m_io, this, m_root);
}
}
private byte _headerLen;
private FileRecord _fileRecord;
private Lzh m_root;
private Lzh m_parent;
public byte HeaderLen { get { return _headerLen; } }
public FileRecord FileRecord { get { return _fileRecord; } }
public Lzh M_Root { get { return m_root; } }
public Lzh M_Parent { get { return m_parent; } }
}
public partial class FileRecord : KaitaiStruct
{
public static FileRecord FromFile(string fileName)
{
return new FileRecord(new KaitaiStream(fileName));
}
public FileRecord(KaitaiStream p__io, Lzh.Record p__parent = null, Lzh p__root = null) : base(p__io)
{
m_parent = p__parent;
m_root = p__root;
_read();
}
private void _read()
{
__raw_header = m_io.ReadBytes((M_Parent.HeaderLen - 1));
var io___raw_header = new KaitaiStream(__raw_header);
_header = new Header(io___raw_header, this, m_root);
if (Header.Header1.LhaLevel == 0) {
_fileUncomprCrc16 = m_io.ReadU2le();
}
_body = m_io.ReadBytes(Header.Header1.FileSizeCompr);
}
private Header _header;
private ushort? _fileUncomprCrc16;
private byte[] _body;
private Lzh m_root;
private Lzh.Record m_parent;
private byte[] __raw_header;
public Header Header { get { return _header; } }
public ushort? FileUncomprCrc16 { get { return _fileUncomprCrc16; } }
public byte[] Body { get { return _body; } }
public Lzh M_Root { get { return m_root; } }
public Lzh.Record M_Parent { get { return m_parent; } }
public byte[] M_RawHeader { get { return __raw_header; } }
}
public partial class Header : KaitaiStruct
{
public static Header FromFile(string fileName)
{
return new Header(new KaitaiStream(fileName));
}
public Header(KaitaiStream p__io, Lzh.FileRecord p__parent = null, Lzh p__root = null) : base(p__io)
{
m_parent = p__parent;
m_root = p__root;
_read();
}
private void _read()
{
_header1 = new Header1(m_io, this, m_root);
if (Header1.LhaLevel == 0) {
_filenameLen = m_io.ReadU1();
}
if (Header1.LhaLevel == 0) {
_filename = System.Text.Encoding.GetEncoding("ASCII").GetString(m_io.ReadBytes(FilenameLen));
}
if (Header1.LhaLevel == 2) {
_fileUncomprCrc16 = m_io.ReadU2le();
}
if (Header1.LhaLevel == 2) {
_os = m_io.ReadU1();
}
if (Header1.LhaLevel == 2) {
_extHeaderSize = m_io.ReadU2le();
}
}
private Header1 _header1;
private byte? _filenameLen;
private string _filename;
private ushort? _fileUncomprCrc16;
private byte? _os;
private ushort? _extHeaderSize;
private Lzh m_root;
private Lzh.FileRecord m_parent;
/// <summary>
/// Level-neutral header, same for all LHA levels. Subsequent fields order and meaning varies, based on LHA level specified in this header.
/// </summary>
public Header1 Header1 { get { return _header1; } }
public byte? FilenameLen { get { return _filenameLen; } }
public string Filename { get { return _filename; } }
public ushort? FileUncomprCrc16 { get { return _fileUncomprCrc16; } }
public byte? Os { get { return _os; } }
public ushort? ExtHeaderSize { get { return _extHeaderSize; } }
public Lzh M_Root { get { return m_root; } }
public Lzh.FileRecord M_Parent { get { return m_parent; } }
}
public partial class Header1 : KaitaiStruct
{
public static Header1 FromFile(string fileName)
{
return new Header1(new KaitaiStream(fileName));
}
public Header1(KaitaiStream p__io, Lzh.Header p__parent = null, Lzh p__root = null) : base(p__io)
{
m_parent = p__parent;
m_root = p__root;
_read();
}
private void _read()
{
_headerChecksum = m_io.ReadU1();
_methodId = System.Text.Encoding.GetEncoding("ASCII").GetString(m_io.ReadBytes(5));
_fileSizeCompr = m_io.ReadU4le();
_fileSizeUncompr = m_io.ReadU4le();
__raw_fileTimestamp = m_io.ReadBytes(4);
var io___raw_fileTimestamp = new KaitaiStream(__raw_fileTimestamp);
_fileTimestamp = new DosDatetime(io___raw_fileTimestamp);
_attr = m_io.ReadU1();
_lhaLevel = m_io.ReadU1();
}
private byte _headerChecksum;
private string _methodId;
private uint _fileSizeCompr;
private uint _fileSizeUncompr;
private DosDatetime _fileTimestamp;
private byte _attr;
private byte _lhaLevel;
private Lzh m_root;
private Lzh.Header m_parent;
private byte[] __raw_fileTimestamp;
public byte HeaderChecksum { get { return _headerChecksum; } }
public string MethodId { get { return _methodId; } }
/// <summary>
/// Compressed file size
/// </summary>
public uint FileSizeCompr { get { return _fileSizeCompr; } }
/// <summary>
/// Uncompressed file size
/// </summary>
public uint FileSizeUncompr { get { return _fileSizeUncompr; } }
/// <summary>
/// Original file date/time
/// </summary>
public DosDatetime FileTimestamp { get { return _fileTimestamp; } }
/// <summary>
/// File or directory attribute
/// </summary>
public byte Attr { get { return _attr; } }
public byte LhaLevel { get { return _lhaLevel; } }
public Lzh M_Root { get { return m_root; } }
public Lzh.Header M_Parent { get { return m_parent; } }
public byte[] M_RawFileTimestamp { get { return __raw_fileTimestamp; } }
}
private List<Record> _entries;
private Lzh m_root;
private KaitaiStruct m_parent;
public List<Record> Entries { get { return _entries; } }
public Lzh M_Root { get { return m_root; } }
public KaitaiStruct M_Parent { get { return m_parent; } }
}
}