Microsoft Compound File Binary (CFB), AKA OLE (Object Linking and Embedding) file format: Python parsing library

This page hosts a formal specification of Microsoft Compound File Binary (CFB), AKA OLE (Object Linking and Embedding) file format using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

Usage

Runtime 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 kaitaistruct

Code

Parse a local file and get structure in memory:

data = MicrosoftCfb.from_file("path/to/local/file.Microsoft Compound File Binary (CFB), AKA OLE (Object Linking and Embedding) file format")

Or parse structure from a bytes:

from kaitaistruct import KaitaiStream, BytesIO

raw = b"\x00\x01\x02..."
data = MicrosoftCfb(KaitaiStream(BytesIO(raw)))

After that, one can get various attributes from the structure by invoking getter methods like:

data.header # => get header

Python source code to parse Microsoft Compound File Binary (CFB), AKA OLE (Object Linking and Embedding) file format

microsoft_cfb.py

# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild

from pkg_resources import parse_version
import kaitaistruct
from kaitaistruct import KaitaiStruct, KaitaiStream, BytesIO
from enum import Enum


if parse_version(kaitaistruct.__version__) < parse_version('0.9'):
    raise Exception("Incompatible Kaitai Struct Python API: 0.9 or later is required, but you have %s" % (kaitaistruct.__version__))

class MicrosoftCfb(KaitaiStruct):
    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.header = MicrosoftCfb.CfbHeader(self._io, self, self._root)

    class CfbHeader(KaitaiStruct):
        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.signature = self._io.read_bytes(8)
            if not self.signature == b"\xD0\xCF\x11\xE0\xA1\xB1\x1A\xE1":
                raise kaitaistruct.ValidationNotEqualError(b"\xD0\xCF\x11\xE0\xA1\xB1\x1A\xE1", self.signature, self._io, u"/types/cfb_header/seq/0")
            self.clsid = self._io.read_bytes(16)
            if not self.clsid == b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00":
                raise kaitaistruct.ValidationNotEqualError(b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", self.clsid, self._io, u"/types/cfb_header/seq/1")
            self.version_minor = self._io.read_u2le()
            self.version_major = self._io.read_u2le()
            self.byte_order = self._io.read_bytes(2)
            if not self.byte_order == b"\xFE\xFF":
                raise kaitaistruct.ValidationNotEqualError(b"\xFE\xFF", self.byte_order, self._io, u"/types/cfb_header/seq/4")
            self.sector_shift = self._io.read_u2le()
            self.mini_sector_shift = self._io.read_u2le()
            self.reserved1 = self._io.read_bytes(6)
            self.size_dir = self._io.read_s4le()
            self.size_fat = self._io.read_s4le()
            self.ofs_dir = self._io.read_s4le()
            self.transaction_seq = self._io.read_s4le()
            self.mini_stream_cutoff_size = self._io.read_s4le()
            self.ofs_mini_fat = self._io.read_s4le()
            self.size_mini_fat = self._io.read_s4le()
            self.ofs_difat = self._io.read_s4le()
            self.size_difat = self._io.read_s4le()
            self.difat = [None] * (109)
            for i in range(109):
                self.difat[i] = self._io.read_s4le()



    class FatEntries(KaitaiStruct):
        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.entries = []
            i = 0
            while not self._io.is_eof():
                self.entries.append(self._io.read_s4le())
                i += 1



    class DirEntry(KaitaiStruct):

        class ObjType(Enum):
            unknown = 0
            storage = 1
            stream = 2
            root_storage = 5

        class RbColor(Enum):
            red = 0
            black = 1
        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.name = (self._io.read_bytes(64)).decode(u"UTF-16LE")
            self.name_len = self._io.read_u2le()
            self.object_type = KaitaiStream.resolve_enum(MicrosoftCfb.DirEntry.ObjType, self._io.read_u1())
            self.color_flag = KaitaiStream.resolve_enum(MicrosoftCfb.DirEntry.RbColor, self._io.read_u1())
            self.left_sibling_id = self._io.read_s4le()
            self.right_sibling_id = self._io.read_s4le()
            self.child_id = self._io.read_s4le()
            self.clsid = self._io.read_bytes(16)
            self.state = self._io.read_u4le()
            self.time_create = self._io.read_u8le()
            self.time_mod = self._io.read_u8le()
            self.ofs = self._io.read_s4le()
            self.size = self._io.read_u8le()

        @property
        def mini_stream(self):
            if hasattr(self, '_m_mini_stream'):
                return self._m_mini_stream if hasattr(self, '_m_mini_stream') else None

            if self.object_type == MicrosoftCfb.DirEntry.ObjType.root_storage:
                io = self._root._io
                _pos = io.pos()
                io.seek(((self.ofs + 1) * self._root.sector_size))
                self._m_mini_stream = io.read_bytes(self.size)
                io.seek(_pos)

            return self._m_mini_stream if hasattr(self, '_m_mini_stream') else None

        @property
        def child(self):
            if hasattr(self, '_m_child'):
                return self._m_child if hasattr(self, '_m_child') else None

            if self.child_id != -1:
                io = self._root._io
                _pos = io.pos()
                io.seek((((self._root.header.ofs_dir + 1) * self._root.sector_size) + (self.child_id * 128)))
                self._m_child = MicrosoftCfb.DirEntry(io, self, self._root)
                io.seek(_pos)

            return self._m_child if hasattr(self, '_m_child') else None

        @property
        def left_sibling(self):
            if hasattr(self, '_m_left_sibling'):
                return self._m_left_sibling if hasattr(self, '_m_left_sibling') else None

            if self.left_sibling_id != -1:
                io = self._root._io
                _pos = io.pos()
                io.seek((((self._root.header.ofs_dir + 1) * self._root.sector_size) + (self.left_sibling_id * 128)))
                self._m_left_sibling = MicrosoftCfb.DirEntry(io, self, self._root)
                io.seek(_pos)

            return self._m_left_sibling if hasattr(self, '_m_left_sibling') else None

        @property
        def right_sibling(self):
            if hasattr(self, '_m_right_sibling'):
                return self._m_right_sibling if hasattr(self, '_m_right_sibling') else None

            if self.right_sibling_id != -1:
                io = self._root._io
                _pos = io.pos()
                io.seek((((self._root.header.ofs_dir + 1) * self._root.sector_size) + (self.right_sibling_id * 128)))
                self._m_right_sibling = MicrosoftCfb.DirEntry(io, self, self._root)
                io.seek(_pos)

            return self._m_right_sibling if hasattr(self, '_m_right_sibling') else None


    @property
    def sector_size(self):
        if hasattr(self, '_m_sector_size'):
            return self._m_sector_size if hasattr(self, '_m_sector_size') else None

        self._m_sector_size = (1 << self.header.sector_shift)
        return self._m_sector_size if hasattr(self, '_m_sector_size') else None

    @property
    def fat(self):
        if hasattr(self, '_m_fat'):
            return self._m_fat if hasattr(self, '_m_fat') else None

        _pos = self._io.pos()
        self._io.seek(self.sector_size)
        self._raw__m_fat = self._io.read_bytes((self.header.size_fat * self.sector_size))
        _io__raw__m_fat = KaitaiStream(BytesIO(self._raw__m_fat))
        self._m_fat = MicrosoftCfb.FatEntries(_io__raw__m_fat, self, self._root)
        self._io.seek(_pos)
        return self._m_fat if hasattr(self, '_m_fat') else None

    @property
    def dir(self):
        if hasattr(self, '_m_dir'):
            return self._m_dir if hasattr(self, '_m_dir') else None

        _pos = self._io.pos()
        self._io.seek(((self.header.ofs_dir + 1) * self.sector_size))
        self._m_dir = MicrosoftCfb.DirEntry(self._io, self, self._root)
        self._io.seek(_pos)
        return self._m_dir if hasattr(self, '_m_dir') else None