.dat file format of Fallout: Python parsing library

Application

Fallout

File extension

dat

KS implementation details

License: CC0-1.0

References

This page hosts a formal specification of .dat file format of Fallout 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 = FalloutDat.from_file("path/to/local/file.dat")

Or parse structure from a bytes:

from kaitaistruct import KaitaiStream, BytesIO

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

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

data.folder_count # => get folder count

Python source code to parse .dat file format of Fallout

fallout_dat.py

# 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 FalloutDat(KaitaiStruct):

    class Compression(Enum):
        none = 32
        lzss = 64
    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.folder_count = self._io.read_u4be()
        self.unknown1 = self._io.read_u4be()
        self.unknown2 = self._io.read_u4be()
        self.timestamp = self._io.read_u4be()
        self.folder_names = []
        for i in range(self.folder_count):
            self.folder_names.append(FalloutDat.Pstr(self._io, self, self._root))

        self.folders = []
        for i in range(self.folder_count):
            self.folders.append(FalloutDat.Folder(self._io, self, self._root))


    class Pstr(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.size = self._io.read_u1()
            self.str = (self._io.read_bytes(self.size)).decode(u"ASCII")


    class Folder(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.file_count = self._io.read_u4be()
            self.unknown = self._io.read_u4be()
            self.flags = self._io.read_u4be()
            self.timestamp = self._io.read_u4be()
            self.files = []
            for i in range(self.file_count):
                self.files.append(FalloutDat.File(self._io, self, self._root))



    class File(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.name = FalloutDat.Pstr(self._io, self, self._root)
            self.flags = KaitaiStream.resolve_enum(FalloutDat.Compression, self._io.read_u4be())
            self.offset = self._io.read_u4be()
            self.size_unpacked = self._io.read_u4be()
            self.size_packed = self._io.read_u4be()

        @property
        def contents(self):
            if hasattr(self, '_m_contents'):
                return self._m_contents

            io = self._root._io
            _pos = io.pos()
            io.seek(self.offset)
            self._m_contents = io.read_bytes((self.size_unpacked if self.flags == FalloutDat.Compression.none else self.size_packed))
            io.seek(_pos)
            return getattr(self, '_m_contents', None)