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 Python generated by Kaitai Struct depends on the Python runtime library. You have to install it before you can parse data.
The Python runtime library can be installed from PyPI:
python3 -m pip install kaitaistructParse a local file and get structure in memory:
data = AppleSingleDouble.from_file("path/to/local/file.bin")
Or parse structure from a bytes:
from kaitaistruct import KaitaiStream, BytesIO
raw = b"\x00\x01\x02..."
data = AppleSingleDouble(KaitaiStream(BytesIO(raw)))
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
import kaitaistruct
from kaitaistruct import KaitaiStruct, KaitaiStream, BytesIO
from enum import Enum
if getattr(kaitaistruct, 'API_VERSION', (0, 9)) < (0, 9):
raise Exception("Incompatible Kaitai Struct Python API: 0.9 or later is required, but you have %s" % (kaitaistruct.__version__))
class AppleSingleDouble(KaitaiStruct):
"""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(Enum):
apple_single = 333312
apple_double = 333319
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
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):
self.entries.append(AppleSingleDouble.Entry(self._io, self, self._root))
class Entry(KaitaiStruct):
class Types(Enum):
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, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
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()
@property
def body(self):
if hasattr(self, '_m_body'):
return self._m_body
_pos = self._io.pos()
self._io.seek(self.ofs_body)
_on = self.type
if _on == AppleSingleDouble.Entry.Types.finder_info:
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)
else:
self._m_body = self._io.read_bytes(self.len_body)
self._io.seek(_pos)
return getattr(self, '_m_body', None)
class FinderInfo(KaitaiStruct):
"""Information specific to Finder.
.. seealso::
older Inside Macintosh, Volume II page 84 or Volume IV page 104.
"""
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
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.folder_id = self._io.read_u2be()
class Point(KaitaiStruct):
"""Specifies 2D coordinate in QuickDraw grid."""
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.x = self._io.read_u2be()
self.y = self._io.read_u2be()