AppleSingle and AppleDouble files are used by certain Mac applications (e.g. Finder) to store Mac-specific file attributes on filesystems that do not support that.
Syntactically, both formats are the same, the only difference is how they are being used:
._
to keep it hidden.In modern practice (Mac OS X), Finder only uses AppleDouble to keep compatibility with other OSes, as virtually nobody outside of Mac understands how to access data in AppleSingle container.
This page hosts a formal specification of AppleSingle / AppleDouble using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
All parsing code for Ruby generated by Kaitai Struct depends on the Ruby runtime library. You have to install it before you can parse data.
The Ruby runtime library can be installed from RubyGems:
gem install kaitai-struct
Parse a local file and get structure in memory:
data = AppleSingleDouble.from_file("path/to/local/file.bin")
Or parse structure from a string of bytes:
bytes = "\x00\x01\x02..."
data = AppleSingleDouble.new(Kaitai::Struct::Stream.new(bytes))
After that, one can get various attributes from the structure by invoking getter methods like:
data.reserved # => Must be all 0.
# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
require 'kaitai/struct/struct'
unless Gem::Version.new(Kaitai::Struct::VERSION) >= Gem::Version.new('0.9')
raise "Incompatible Kaitai Struct Ruby API: 0.9 or later is required, but you have #{Kaitai::Struct::VERSION}"
end
##
# AppleSingle and AppleDouble files are used by certain Mac
# applications (e.g. Finder) to store Mac-specific file attributes on
# filesystems that do not support that.
#
# Syntactically, both formats are the same, the only difference is how
# they are being used:
#
# * AppleSingle means that only one file will be created on external
# filesystem that will hold both the data (AKA "data fork" in Apple
# terminology), and the attributes (AKA "resource fork").
# * AppleDouble means that two files will be created: a normal file
# that keeps the data ("data fork") is kept separately from an
# auxiliary file that contains attributes ("resource fork"), which
# is kept with the same name, but starting with an extra dot and
# underscore `._` to keep it hidden.
#
# In modern practice (Mac OS X), Finder only uses AppleDouble to keep
# compatibility with other OSes, as virtually nobody outside of Mac
# understands how to access data in AppleSingle container.
# @see http://kaiser-edv.de/documents/AppleSingle_AppleDouble.pdf Source
class AppleSingleDouble < Kaitai::Struct::Struct
FILE_TYPE = {
333312 => :file_type_apple_single,
333319 => :file_type_apple_double,
}
I__FILE_TYPE = FILE_TYPE.invert
def initialize(_io, _parent = nil, _root = self)
super(_io, _parent, _root)
_read
end
def _read
@magic = Kaitai::Struct::Stream::resolve_enum(FILE_TYPE, @_io.read_u4be)
@version = @_io.read_u4be
@reserved = @_io.read_bytes(16)
@num_entries = @_io.read_u2be
@entries = []
(num_entries).times { |i|
@entries << Entry.new(@_io, self, @_root)
}
self
end
class Entry < Kaitai::Struct::Struct
TYPES = {
1 => :types_data_fork,
2 => :types_resource_fork,
3 => :types_real_name,
4 => :types_comment,
5 => :types_icon_bw,
6 => :types_icon_color,
8 => :types_file_dates_info,
9 => :types_finder_info,
10 => :types_macintosh_file_info,
11 => :types_prodos_file_info,
12 => :types_msdos_file_info,
13 => :types_afp_short_name,
14 => :types_afp_file_info,
15 => :types_afp_directory_id,
}
I__TYPES = TYPES.invert
def initialize(_io, _parent = nil, _root = self)
super(_io, _parent, _root)
_read
end
def _read
@type = Kaitai::Struct::Stream::resolve_enum(TYPES, @_io.read_u4be)
@ofs_body = @_io.read_u4be
@len_body = @_io.read_u4be
self
end
def body
return @body unless @body.nil?
_pos = @_io.pos
@_io.seek(ofs_body)
case type
when :types_finder_info
@_raw_body = @_io.read_bytes(len_body)
_io__raw_body = Kaitai::Struct::Stream.new(@_raw_body)
@body = FinderInfo.new(_io__raw_body, self, @_root)
else
@body = @_io.read_bytes(len_body)
end
@_io.seek(_pos)
@body
end
attr_reader :type
attr_reader :ofs_body
attr_reader :len_body
attr_reader :_raw_body
end
##
# Information specific to Finder
# @see '' older Inside Macintosh, Volume II page 84 or Volume IV page 104.
class FinderInfo < Kaitai::Struct::Struct
def initialize(_io, _parent = nil, _root = self)
super(_io, _parent, _root)
_read
end
def _read
@file_type = @_io.read_bytes(4)
@file_creator = @_io.read_bytes(4)
@flags = @_io.read_u2be
@location = Point.new(@_io, self, @_root)
@folder_id = @_io.read_u2be
self
end
attr_reader :file_type
attr_reader :file_creator
attr_reader :flags
##
# File icon's coordinates when displaying this folder.
attr_reader :location
##
# File folder ID (=window).
attr_reader :folder_id
end
##
# Specifies 2D coordinate in QuickDraw grid.
class Point < Kaitai::Struct::Struct
def initialize(_io, _parent = nil, _root = self)
super(_io, _parent, _root)
_read
end
def _read
@x = @_io.read_u2be
@y = @_io.read_u2be
self
end
attr_reader :x
attr_reader :y
end
attr_reader :magic
attr_reader :version
##
# Must be all 0.
attr_reader :reserved
attr_reader :num_entries
attr_reader :entries
end