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.
# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
# type: ignore
import kaitaistruct
from kaitaistruct import ReadWriteKaitaiStruct, KaitaiStream, BytesIO
from enum import IntEnum
if getattr(kaitaistruct, 'API_VERSION', (0, 9)) < (0, 11):
raise Exception("Incompatible Kaitai Struct Python API: 0.11 or later is required, but you have %s" % (kaitaistruct.__version__))
class AppleSingleDouble(ReadWriteKaitaiStruct):
"""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.
.. seealso::
Source - http://kaiser-edv.de/documents/AppleSingle_AppleDouble.pdf
"""
class FileType(IntEnum):
apple_single = 333312
apple_double = 333319
def __init__(self, _io=None, _parent=None, _root=None):
super(AppleSingleDouble, self).__init__(_io)
self._parent = _parent
self._root = _root or self
def _read(self):
self.magic = KaitaiStream.resolve_enum(AppleSingleDouble.FileType, self._io.read_u4be())
self.version = self._io.read_u4be()
self.reserved = self._io.read_bytes(16)
self.num_entries = self._io.read_u2be()
self.entries = []
for i in range(self.num_entries):
_t_entries = AppleSingleDouble.Entry(self._io, self, self._root)
try:
_t_entries._read()
finally:
self.entries.append(_t_entries)
self._dirty = False
def _fetch_instances(self):
pass
for i in range(len(self.entries)):
pass
self.entries[i]._fetch_instances()
def _write__seq(self, io=None):
super(AppleSingleDouble, self)._write__seq(io)
self._io.write_u4be(int(self.magic))
self._io.write_u4be(self.version)
self._io.write_bytes(self.reserved)
self._io.write_u2be(self.num_entries)
for i in range(len(self.entries)):
pass
self.entries[i]._write__seq(self._io)
def _check(self):
if len(self.reserved) != 16:
raise kaitaistruct.ConsistencyError(u"reserved", 16, len(self.reserved))
if len(self.entries) != self.num_entries:
raise kaitaistruct.ConsistencyError(u"entries", self.num_entries, len(self.entries))
for i in range(len(self.entries)):
pass
if self.entries[i]._root != self._root:
raise kaitaistruct.ConsistencyError(u"entries", self._root, self.entries[i]._root)
if self.entries[i]._parent != self:
raise kaitaistruct.ConsistencyError(u"entries", self, self.entries[i]._parent)
self._dirty = False
class Entry(ReadWriteKaitaiStruct):
class Types(IntEnum):
data_fork = 1
resource_fork = 2
real_name = 3
comment = 4
icon_bw = 5
icon_color = 6
file_dates_info = 8
finder_info = 9
macintosh_file_info = 10
prodos_file_info = 11
msdos_file_info = 12
afp_short_name = 13
afp_file_info = 14
afp_directory_id = 15
def __init__(self, _io=None, _parent=None, _root=None):
super(AppleSingleDouble.Entry, self).__init__(_io)
self._parent = _parent
self._root = _root
self._should_write_body = False
self.body__enabled = True
def _read(self):
self.type = KaitaiStream.resolve_enum(AppleSingleDouble.Entry.Types, self._io.read_u4be())
self.ofs_body = self._io.read_u4be()
self.len_body = self._io.read_u4be()
self._dirty = False
def _fetch_instances(self):
pass
_ = self.body
if hasattr(self, '_m_body'):
pass
_on = self.type
if _on == AppleSingleDouble.Entry.Types.finder_info:
pass
self._m_body._fetch_instances()
else:
pass
def _write__seq(self, io=None):
super(AppleSingleDouble.Entry, self)._write__seq(io)
self._should_write_body = self.body__enabled
self._io.write_u4be(int(self.type))
self._io.write_u4be(self.ofs_body)
self._io.write_u4be(self.len_body)
def _check(self):
if self.body__enabled:
pass
_on = self.type
if _on == AppleSingleDouble.Entry.Types.finder_info:
pass
if self._m_body._root != self._root:
raise kaitaistruct.ConsistencyError(u"body", self._root, self._m_body._root)
if self._m_body._parent != self:
raise kaitaistruct.ConsistencyError(u"body", self, self._m_body._parent)
else:
pass
if len(self._m_body) != self.len_body:
raise kaitaistruct.ConsistencyError(u"body", self.len_body, len(self._m_body))
self._dirty = False
@property
def body(self):
if self._should_write_body:
self._write_body()
if hasattr(self, '_m_body'):
return self._m_body
if not self.body__enabled:
return None
_pos = self._io.pos()
self._io.seek(self.ofs_body)
_on = self.type
if _on == AppleSingleDouble.Entry.Types.finder_info:
pass
self._raw__m_body = self._io.read_bytes(self.len_body)
_io__raw__m_body = KaitaiStream(BytesIO(self._raw__m_body))
self._m_body = AppleSingleDouble.FinderInfo(_io__raw__m_body, self, self._root)
self._m_body._read()
else:
pass
self._m_body = self._io.read_bytes(self.len_body)
self._io.seek(_pos)
return getattr(self, '_m_body', None)
@body.setter
def body(self, v):
self._dirty = True
self._m_body = v
def _write_body(self):
self._should_write_body = False
_pos = self._io.pos()
self._io.seek(self.ofs_body)
_on = self.type
if _on == AppleSingleDouble.Entry.Types.finder_info:
pass
_io__raw__m_body = KaitaiStream(BytesIO(bytearray(self.len_body)))
self._io.add_child_stream(_io__raw__m_body)
_pos2 = self._io.pos()
self._io.seek(self._io.pos() + (self.len_body))
def handler(parent, _io__raw__m_body=_io__raw__m_body):
self._raw__m_body = _io__raw__m_body.to_byte_array()
if len(self._raw__m_body) != self.len_body:
raise kaitaistruct.ConsistencyError(u"raw(body)", self.len_body, len(self._raw__m_body))
parent.write_bytes(self._raw__m_body)
_io__raw__m_body.write_back_handler = KaitaiStream.WriteBackHandler(_pos2, handler)
self._m_body._write__seq(_io__raw__m_body)
else:
pass
self._io.write_bytes(self._m_body)
self._io.seek(_pos)
class FinderInfo(ReadWriteKaitaiStruct):
"""Information specific to Finder.
.. seealso::
older Inside Macintosh, Volume II page 84 or Volume IV page 104.
"""
def __init__(self, _io=None, _parent=None, _root=None):
super(AppleSingleDouble.FinderInfo, self).__init__(_io)
self._parent = _parent
self._root = _root
def _read(self):
self.file_type = self._io.read_bytes(4)
self.file_creator = self._io.read_bytes(4)
self.flags = self._io.read_u2be()
self.location = AppleSingleDouble.Point(self._io, self, self._root)
self.location._read()
self.folder_id = self._io.read_u2be()
self._dirty = False
def _fetch_instances(self):
pass
self.location._fetch_instances()
def _write__seq(self, io=None):
super(AppleSingleDouble.FinderInfo, self)._write__seq(io)
self._io.write_bytes(self.file_type)
self._io.write_bytes(self.file_creator)
self._io.write_u2be(self.flags)
self.location._write__seq(self._io)
self._io.write_u2be(self.folder_id)
def _check(self):
if len(self.file_type) != 4:
raise kaitaistruct.ConsistencyError(u"file_type", 4, len(self.file_type))
if len(self.file_creator) != 4:
raise kaitaistruct.ConsistencyError(u"file_creator", 4, len(self.file_creator))
if self.location._root != self._root:
raise kaitaistruct.ConsistencyError(u"location", self._root, self.location._root)
if self.location._parent != self:
raise kaitaistruct.ConsistencyError(u"location", self, self.location._parent)
self._dirty = False
class Point(ReadWriteKaitaiStruct):
"""Specifies 2D coordinate in QuickDraw grid."""
def __init__(self, _io=None, _parent=None, _root=None):
super(AppleSingleDouble.Point, self).__init__(_io)
self._parent = _parent
self._root = _root
def _read(self):
self.x = self._io.read_u2be()
self.y = self._io.read_u2be()
self._dirty = False
def _fetch_instances(self):
pass
def _write__seq(self, io=None):
super(AppleSingleDouble.Point, self)._write__seq(io)
self._io.write_u2be(self.x)
self._io.write_u2be(self.y)
def _check(self):
self._dirty = False