ISO9660 CD filesystem: Lua parsing library

ISO9660 is standard filesystem used on read-only optical discs (mostly CD-ROM). The standard was based on earlier High Sierra Format (HSF), proposed for CD-ROMs in 1985, and, after several revisions, it was accepted as ISO9960:1998.

The format emphasizes portability (thus having pretty minimal features and very conservative file names standards) and sequential access (which favors disc devices with relatively slow rotation speed).

File extension

iso

KS implementation details

License: CC0-1.0

References

This page hosts a formal specification of ISO9660 CD filesystem using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

Lua source code to parse ISO9660 CD filesystem

iso9660.lua

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-- This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
--
-- This file is compatible with Lua 5.3

local class = require("class")
require("kaitaistruct")
local str_decode = require("string_decode")
local stringstream = require("string_stream")

-- 
-- ISO9660 is standard filesystem used on read-only optical discs
-- (mostly CD-ROM). The standard was based on earlier High Sierra
-- Format (HSF), proposed for CD-ROMs in 1985, and, after several
-- revisions, it was accepted as ISO9960:1998.
-- 
-- The format emphasizes portability (thus having pretty minimal
-- features and very conservative file names standards) and sequential
-- access (which favors disc devices with relatively slow rotation
-- speed).
Iso9660 = class.class(KaitaiStruct)

function Iso9660:_init(io, parent, root)
  KaitaiStruct._init(self, io)
  self._parent = parent
  self._root = root or self
  self:_read()
end

function Iso9660:_read()
end

Iso9660.property.sector_size = {}
function Iso9660.property.sector_size:get()
  if self._m_sector_size ~= nil then
    return self._m_sector_size
  end

  self._m_sector_size = 2048
  return self._m_sector_size
end

Iso9660.property.primary_vol_desc = {}
function Iso9660.property.primary_vol_desc:get()
  if self._m_primary_vol_desc ~= nil then
    return self._m_primary_vol_desc
  end

  local _pos = self._io:pos()
  self._io:seek((16 * self.sector_size))
  self._m_primary_vol_desc = Iso9660.VolDesc(self._io, self, self._root)
  self._io:seek(_pos)
  return self._m_primary_vol_desc
end


-- 
-- See also: Source (https://wiki.osdev.org/ISO_9660#The_Primary_Volume_Descriptor)
Iso9660.VolDescPrimary = class.class(KaitaiStruct)

function Iso9660.VolDescPrimary:_init(io, parent, root)
  KaitaiStruct._init(self, io)
  self._parent = parent
  self._root = root or self
  self:_read()
end

function Iso9660.VolDescPrimary:_read()
  self.unused1 = self._io:read_bytes(1)
  if not(self.unused1 == "\000") then
    error("not equal, expected " ..  "\000" .. ", but got " .. self.unused1)
  end
  self.system_id = str_decode.decode(self._io:read_bytes(32), "UTF-8")
  self.volume_id = str_decode.decode(self._io:read_bytes(32), "UTF-8")
  self.unused2 = self._io:read_bytes(8)
  if not(self.unused2 == "\000\000\000\000\000\000\000\000") then
    error("not equal, expected " ..  "\000\000\000\000\000\000\000\000" .. ", but got " .. self.unused2)
  end
  self.vol_space_size = Iso9660.U4bi(self._io, self, self._root)
  self.unused3 = self._io:read_bytes(32)
  if not(self.unused3 == "\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000") then
    error("not equal, expected " ..  "\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000" .. ", but got " .. self.unused3)
  end
  self.vol_set_size = Iso9660.U2bi(self._io, self, self._root)
  self.vol_seq_num = Iso9660.U2bi(self._io, self, self._root)
  self.logical_block_size = Iso9660.U2bi(self._io, self, self._root)
  self.path_table_size = Iso9660.U4bi(self._io, self, self._root)
  self.lba_path_table_le = self._io:read_u4le()
  self.lba_opt_path_table_le = self._io:read_u4le()
  self.lba_path_table_be = self._io:read_u4be()
  self.lba_opt_path_table_be = self._io:read_u4be()
  self._raw_root_dir = self._io:read_bytes(34)
  local _io = KaitaiStream(stringstream(self._raw_root_dir))
  self.root_dir = Iso9660.DirEntry(_io, self, self._root)
  self.vol_set_id = str_decode.decode(self._io:read_bytes(128), "UTF-8")
  self.publisher_id = str_decode.decode(self._io:read_bytes(128), "UTF-8")
  self.data_preparer_id = str_decode.decode(self._io:read_bytes(128), "UTF-8")
  self.application_id = str_decode.decode(self._io:read_bytes(128), "UTF-8")
  self.copyright_file_id = str_decode.decode(self._io:read_bytes(38), "UTF-8")
  self.abstract_file_id = str_decode.decode(self._io:read_bytes(36), "UTF-8")
  self.bibliographic_file_id = str_decode.decode(self._io:read_bytes(37), "UTF-8")
  self.vol_create_datetime = Iso9660.DecDatetime(self._io, self, self._root)
  self.vol_mod_datetime = Iso9660.DecDatetime(self._io, self, self._root)
  self.vol_expire_datetime = Iso9660.DecDatetime(self._io, self, self._root)
  self.vol_effective_datetime = Iso9660.DecDatetime(self._io, self, self._root)
  self.file_structure_version = self._io:read_u1()
  self.unused4 = self._io:read_u1()
  self.application_area = self._io:read_bytes(512)
end

Iso9660.VolDescPrimary.property.path_table = {}
function Iso9660.VolDescPrimary.property.path_table:get()
  if self._m_path_table ~= nil then
    return self._m_path_table
  end

  local _pos = self._io:pos()
  self._io:seek((self.lba_path_table_le * self._root.sector_size))
  self._raw__m_path_table = self._io:read_bytes(self.path_table_size.le)
  local _io = KaitaiStream(stringstream(self._raw__m_path_table))
  self._m_path_table = Iso9660.PathTableLe(_io, self, self._root)
  self._io:seek(_pos)
  return self._m_path_table
end


Iso9660.VolDescBootRecord = class.class(KaitaiStruct)

function Iso9660.VolDescBootRecord:_init(io, parent, root)
  KaitaiStruct._init(self, io)
  self._parent = parent
  self._root = root or self
  self:_read()
end

function Iso9660.VolDescBootRecord:_read()
  self.boot_system_id = str_decode.decode(self._io:read_bytes(32), "UTF-8")
  self.boot_id = str_decode.decode(self._io:read_bytes(32), "UTF-8")
end


Iso9660.Datetime = class.class(KaitaiStruct)

function Iso9660.Datetime:_init(io, parent, root)
  KaitaiStruct._init(self, io)
  self._parent = parent
  self._root = root or self
  self:_read()
end

function Iso9660.Datetime:_read()
  self.year = self._io:read_u1()
  self.month = self._io:read_u1()
  self.day = self._io:read_u1()
  self.hour = self._io:read_u1()
  self.minute = self._io:read_u1()
  self.sec = self._io:read_u1()
  self.timezone = self._io:read_u1()
end


Iso9660.DirEntry = class.class(KaitaiStruct)

function Iso9660.DirEntry:_init(io, parent, root)
  KaitaiStruct._init(self, io)
  self._parent = parent
  self._root = root or self
  self:_read()
end

function Iso9660.DirEntry:_read()
  self.len = self._io:read_u1()
  if self.len > 0 then
    self._raw_body = self._io:read_bytes((self.len - 1))
    local _io = KaitaiStream(stringstream(self._raw_body))
    self.body = Iso9660.DirEntryBody(_io, self, self._root)
  end
end


Iso9660.VolDesc = class.class(KaitaiStruct)

function Iso9660.VolDesc:_init(io, parent, root)
  KaitaiStruct._init(self, io)
  self._parent = parent
  self._root = root or self
  self:_read()
end

function Iso9660.VolDesc:_read()
  self.type = self._io:read_u1()
  self.magic = self._io:read_bytes(5)
  if not(self.magic == "\067\068\048\048\049") then
    error("not equal, expected " ..  "\067\068\048\048\049" .. ", but got " .. self.magic)
  end
  self.version = self._io:read_u1()
  if self.type == 0 then
    self.vol_desc_boot_record = Iso9660.VolDescBootRecord(self._io, self, self._root)
  end
  if self.type == 1 then
    self.vol_desc_primary = Iso9660.VolDescPrimary(self._io, self, self._root)
  end
end


Iso9660.PathTableEntryLe = class.class(KaitaiStruct)

function Iso9660.PathTableEntryLe:_init(io, parent, root)
  KaitaiStruct._init(self, io)
  self._parent = parent
  self._root = root or self
  self:_read()
end

function Iso9660.PathTableEntryLe:_read()
  self.len_dir_name = self._io:read_u1()
  self.len_ext_attr_rec = self._io:read_u1()
  self.lba_extent = self._io:read_u4le()
  self.parent_dir_idx = self._io:read_u2le()
  self.dir_name = str_decode.decode(self._io:read_bytes(self.len_dir_name), "UTF-8")
  if (self.len_dir_name % 2) == 1 then
    self.padding = self._io:read_u1()
  end
end


Iso9660.DirEntries = class.class(KaitaiStruct)

function Iso9660.DirEntries:_init(io, parent, root)
  KaitaiStruct._init(self, io)
  self._parent = parent
  self._root = root or self
  self:_read()
end

function Iso9660.DirEntries:_read()
  self.entries = {}
  local i = 0
  while true do
    local _ = Iso9660.DirEntry(self._io, self, self._root)
    self.entries[i + 1] = _
    if _.len == 0 then
      break
    end
    i = i + 1
  end
end


Iso9660.U4bi = class.class(KaitaiStruct)

function Iso9660.U4bi:_init(io, parent, root)
  KaitaiStruct._init(self, io)
  self._parent = parent
  self._root = root or self
  self:_read()
end

function Iso9660.U4bi:_read()
  self.le = self._io:read_u4le()
  self.be = self._io:read_u4be()
end


Iso9660.U2bi = class.class(KaitaiStruct)

function Iso9660.U2bi:_init(io, parent, root)
  KaitaiStruct._init(self, io)
  self._parent = parent
  self._root = root or self
  self:_read()
end

function Iso9660.U2bi:_read()
  self.le = self._io:read_u2le()
  self.be = self._io:read_u2be()
end


-- 
-- See also: Source (https://wiki.osdev.org/ISO_9660#The_Path_Table)
Iso9660.PathTableLe = class.class(KaitaiStruct)

function Iso9660.PathTableLe:_init(io, parent, root)
  KaitaiStruct._init(self, io)
  self._parent = parent
  self._root = root or self
  self:_read()
end

function Iso9660.PathTableLe:_read()
  self.entries = {}
  local i = 0
  while not self._io:is_eof() do
    self.entries[i + 1] = Iso9660.PathTableEntryLe(self._io, self, self._root)
    i = i + 1
  end
end


-- 
-- See also: Source (https://wiki.osdev.org/ISO_9660#Date.2Ftime_format)
Iso9660.DecDatetime = class.class(KaitaiStruct)

function Iso9660.DecDatetime:_init(io, parent, root)
  KaitaiStruct._init(self, io)
  self._parent = parent
  self._root = root or self
  self:_read()
end

function Iso9660.DecDatetime:_read()
  self.year = str_decode.decode(self._io:read_bytes(4), "ASCII")
  self.month = str_decode.decode(self._io:read_bytes(2), "ASCII")
  self.day = str_decode.decode(self._io:read_bytes(2), "ASCII")
  self.hour = str_decode.decode(self._io:read_bytes(2), "ASCII")
  self.minute = str_decode.decode(self._io:read_bytes(2), "ASCII")
  self.sec = str_decode.decode(self._io:read_bytes(2), "ASCII")
  self.sec_hundreds = str_decode.decode(self._io:read_bytes(2), "ASCII")
  self.timezone = self._io:read_u1()
end


Iso9660.DirEntryBody = class.class(KaitaiStruct)

function Iso9660.DirEntryBody:_init(io, parent, root)
  KaitaiStruct._init(self, io)
  self._parent = parent
  self._root = root or self
  self:_read()
end

function Iso9660.DirEntryBody:_read()
  self.len_ext_attr_rec = self._io:read_u1()
  self.lba_extent = Iso9660.U4bi(self._io, self, self._root)
  self.size_extent = Iso9660.U4bi(self._io, self, self._root)
  self.datetime = Iso9660.Datetime(self._io, self, self._root)
  self.file_flags = self._io:read_u1()
  self.file_unit_size = self._io:read_u1()
  self.interleave_gap_size = self._io:read_u1()
  self.vol_seq_num = Iso9660.U2bi(self._io, self, self._root)
  self.len_file_name = self._io:read_u1()
  self.file_name = str_decode.decode(self._io:read_bytes(self.len_file_name), "UTF-8")
  if (self.len_file_name % 2) == 0 then
    self.padding = self._io:read_u1()
  end
  self.rest = self._io:read_bytes_full()
end

Iso9660.DirEntryBody.property.extent_as_dir = {}
function Iso9660.DirEntryBody.property.extent_as_dir:get()
  if self._m_extent_as_dir ~= nil then
    return self._m_extent_as_dir
  end

  if (self.file_flags & 2) ~= 0 then
    local _io = self._root._io
    local _pos = _io:pos()
    _io:seek((self.lba_extent.le * self._root.sector_size))
    self._raw__m_extent_as_dir = _io:read_bytes(self.size_extent.le)
    local _io = KaitaiStream(stringstream(self._raw__m_extent_as_dir))
    self._m_extent_as_dir = Iso9660.DirEntries(_io, self, self._root)
    _io:seek(_pos)
  end
  return self._m_extent_as_dir
end

Iso9660.DirEntryBody.property.extent_as_file = {}
function Iso9660.DirEntryBody.property.extent_as_file:get()
  if self._m_extent_as_file ~= nil then
    return self._m_extent_as_file
  end

  if (self.file_flags & 2) == 0 then
    local _io = self._root._io
    local _pos = _io:pos()
    _io:seek((self.lba_extent.le * self._root.sector_size))
    self._m_extent_as_file = _io:read_bytes(self.size_extent.le)
    _io:seek(_pos)
  end
  return self._m_extent_as_file
end