This page hosts a formal specification of vfat 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 = Vfat.from_file("path/to/local/file.bin")
Or parse structure from a bytes:
from kaitaistruct import KaitaiStream, BytesIO
raw = b"\x00\x01\x02..."
data = Vfat(KaitaiStream(BytesIO(raw)))
After that, one can get various attributes from the structure by invoking getter methods like:
data.boot_sector # => get boot sector
# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
# type: ignore
import kaitaistruct
from kaitaistruct import KaitaiStruct, KaitaiStream, BytesIO
import dos_datetime
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 Vfat(KaitaiStruct):
"""
.. seealso::
Source - https://download.microsoft.com/download/0/8/4/084c452b-b772-4fe5-89bb-a0cbf082286a/fatgen103.doc
"""
def __init__(self, _io, _parent=None, _root=None):
super(Vfat, self).__init__(_io)
self._parent = _parent
self._root = _root or self
self._read()
def _read(self):
self.boot_sector = Vfat.BootSector(self._io, self, self._root)
def _fetch_instances(self):
pass
self.boot_sector._fetch_instances()
_ = self.fats
if hasattr(self, '_m_fats'):
pass
for i in range(len(self._m_fats)):
pass
_ = self.root_dir
if hasattr(self, '_m_root_dir'):
pass
self._m_root_dir._fetch_instances()
class BiosParamBlock(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
super(Vfat.BiosParamBlock, self).__init__(_io)
self._parent = _parent
self._root = _root
self._read()
def _read(self):
self.bytes_per_ls = self._io.read_u2le()
self.ls_per_clus = self._io.read_u1()
self.num_reserved_ls = self._io.read_u2le()
self.num_fats = self._io.read_u1()
self.max_root_dir_rec = self._io.read_u2le()
self.total_ls_2 = self._io.read_u2le()
self.media_code = self._io.read_u1()
self.ls_per_fat = self._io.read_u2le()
self.ps_per_track = self._io.read_u2le()
self.num_heads = self._io.read_u2le()
self.num_hidden_sectors = self._io.read_u4le()
self.total_ls_4 = self._io.read_u4le()
def _fetch_instances(self):
pass
class BootSector(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
super(Vfat.BootSector, self).__init__(_io)
self._parent = _parent
self._root = _root
self._read()
def _read(self):
self.jmp_instruction = self._io.read_bytes(3)
self.oem_name = (KaitaiStream.bytes_strip_right(self._io.read_bytes(8), 32)).decode(u"ASCII")
self.bpb = Vfat.BiosParamBlock(self._io, self, self._root)
if (not (self.is_fat32)):
pass
self.ebpb_fat16 = Vfat.ExtBiosParamBlockFat16(self._io, self, self._root)
if self.is_fat32:
pass
self.ebpb_fat32 = Vfat.ExtBiosParamBlockFat32(self._io, self, self._root)
def _fetch_instances(self):
pass
self.bpb._fetch_instances()
if (not (self.is_fat32)):
pass
self.ebpb_fat16._fetch_instances()
if self.is_fat32:
pass
self.ebpb_fat32._fetch_instances()
@property
def is_fat32(self):
"""Determines if filesystem is FAT32 (true) or FAT12/16 (false)
by analyzing some preliminary conditions in BPB. Used to
determine whether we should parse post-BPB data as
`ext_bios_param_block_fat16` or `ext_bios_param_block_fat32`.
"""
if hasattr(self, '_m_is_fat32'):
return self._m_is_fat32
self._m_is_fat32 = self.bpb.max_root_dir_rec == 0
return getattr(self, '_m_is_fat32', None)
@property
def ls_per_fat(self):
if hasattr(self, '_m_ls_per_fat'):
return self._m_ls_per_fat
self._m_ls_per_fat = (self.ebpb_fat32.ls_per_fat if self.is_fat32 else self.bpb.ls_per_fat)
return getattr(self, '_m_ls_per_fat', None)
@property
def ls_per_root_dir(self):
"""Size of root directory in logical sectors.
.. seealso::
FAT: General Overview of On-Disk Format, section "FAT Data Structure"
"""
if hasattr(self, '_m_ls_per_root_dir'):
return self._m_ls_per_root_dir
self._m_ls_per_root_dir = ((self.bpb.max_root_dir_rec * 32 + self.bpb.bytes_per_ls) - 1) // self.bpb.bytes_per_ls
return getattr(self, '_m_ls_per_root_dir', None)
@property
def pos_fats(self):
"""Offset of FATs in bytes from start of filesystem."""
if hasattr(self, '_m_pos_fats'):
return self._m_pos_fats
self._m_pos_fats = self.bpb.bytes_per_ls * self.bpb.num_reserved_ls
return getattr(self, '_m_pos_fats', None)
@property
def pos_root_dir(self):
"""Offset of root directory in bytes from start of filesystem."""
if hasattr(self, '_m_pos_root_dir'):
return self._m_pos_root_dir
self._m_pos_root_dir = self.bpb.bytes_per_ls * (self.bpb.num_reserved_ls + self.ls_per_fat * self.bpb.num_fats)
return getattr(self, '_m_pos_root_dir', None)
@property
def size_fat(self):
"""Size of one FAT in bytes."""
if hasattr(self, '_m_size_fat'):
return self._m_size_fat
self._m_size_fat = self.bpb.bytes_per_ls * self.ls_per_fat
return getattr(self, '_m_size_fat', None)
@property
def size_root_dir(self):
"""Size of root directory in bytes."""
if hasattr(self, '_m_size_root_dir'):
return self._m_size_root_dir
self._m_size_root_dir = self.ls_per_root_dir * self.bpb.bytes_per_ls
return getattr(self, '_m_size_root_dir', None)
class ExtBiosParamBlockFat16(KaitaiStruct):
"""Extended BIOS Parameter Block (DOS 4.0+, OS/2 1.0+). Used only
for FAT12 and FAT16.
"""
def __init__(self, _io, _parent=None, _root=None):
super(Vfat.ExtBiosParamBlockFat16, self).__init__(_io)
self._parent = _parent
self._root = _root
self._read()
def _read(self):
self.phys_drive_num = self._io.read_u1()
self.reserved1 = self._io.read_u1()
self.ext_boot_sign = self._io.read_u1()
self.volume_id = self._io.read_bytes(4)
self.partition_volume_label = (KaitaiStream.bytes_strip_right(self._io.read_bytes(11), 32)).decode(u"ASCII")
self.fs_type_str = (KaitaiStream.bytes_strip_right(self._io.read_bytes(8), 32)).decode(u"ASCII")
def _fetch_instances(self):
pass
class ExtBiosParamBlockFat32(KaitaiStruct):
"""Extended BIOS Parameter Block for FAT32."""
def __init__(self, _io, _parent=None, _root=None):
super(Vfat.ExtBiosParamBlockFat32, self).__init__(_io)
self._parent = _parent
self._root = _root
self._read()
def _read(self):
self.ls_per_fat = self._io.read_u4le()
self.has_active_fat = self._io.read_bits_int_le(1) != 0
self.reserved1 = self._io.read_bits_int_le(3)
self.active_fat_id = self._io.read_bits_int_le(4)
self.reserved2 = self._io.read_bytes(1)
if not self.reserved2 == b"\x00":
raise kaitaistruct.ValidationNotEqualError(b"\x00", self.reserved2, self._io, u"/types/ext_bios_param_block_fat32/seq/4")
self.fat_version = self._io.read_u2le()
self.root_dir_start_clus = self._io.read_u4le()
self.ls_fs_info = self._io.read_u2le()
self.boot_sectors_copy_start_ls = self._io.read_u2le()
self.reserved3 = self._io.read_bytes(12)
self.phys_drive_num = self._io.read_u1()
self.reserved4 = self._io.read_u1()
self.ext_boot_sign = self._io.read_u1()
self.volume_id = self._io.read_bytes(4)
self.partition_volume_label = (KaitaiStream.bytes_strip_right(self._io.read_bytes(11), 32)).decode(u"ASCII")
self.fs_type_str = (KaitaiStream.bytes_strip_right(self._io.read_bytes(8), 32)).decode(u"ASCII")
def _fetch_instances(self):
pass
class RootDirectory(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
super(Vfat.RootDirectory, self).__init__(_io)
self._parent = _parent
self._root = _root
self._read()
def _read(self):
self.records = []
for i in range(self._root.boot_sector.bpb.max_root_dir_rec):
self.records.append(Vfat.RootDirectoryRec(self._io, self, self._root))
def _fetch_instances(self):
pass
for i in range(len(self.records)):
pass
self.records[i]._fetch_instances()
class RootDirectoryRec(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
super(Vfat.RootDirectoryRec, self).__init__(_io)
self._parent = _parent
self._root = _root
self._read()
def _read(self):
self.file_name = self._io.read_bytes(11)
self._raw_attrs = self._io.read_bytes(1)
_io__raw_attrs = KaitaiStream(BytesIO(self._raw_attrs))
self.attrs = Vfat.RootDirectoryRec.AttrFlags(_io__raw_attrs, self, self._root)
self.reserved = self._io.read_bytes(10)
self._raw_last_write_time = self._io.read_bytes(4)
_io__raw_last_write_time = KaitaiStream(BytesIO(self._raw_last_write_time))
self.last_write_time = dos_datetime.DosDatetime(_io__raw_last_write_time)
self.start_clus = self._io.read_u2le()
self.file_size = self._io.read_u4le()
def _fetch_instances(self):
pass
self.attrs._fetch_instances()
self.last_write_time._fetch_instances()
class AttrFlags(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
super(Vfat.RootDirectoryRec.AttrFlags, self).__init__(_io)
self._parent = _parent
self._root = _root
self._read()
def _read(self):
self.read_only = self._io.read_bits_int_le(1) != 0
self.hidden = self._io.read_bits_int_le(1) != 0
self.system = self._io.read_bits_int_le(1) != 0
self.volume_id = self._io.read_bits_int_le(1) != 0
self.is_directory = self._io.read_bits_int_le(1) != 0
self.archive = self._io.read_bits_int_le(1) != 0
self.reserved = self._io.read_bits_int_le(2)
def _fetch_instances(self):
pass
@property
def long_name(self):
if hasattr(self, '_m_long_name'):
return self._m_long_name
self._m_long_name = ((self.read_only) and (self.hidden) and (self.system) and (self.volume_id))
return getattr(self, '_m_long_name', None)
@property
def fats(self):
if hasattr(self, '_m_fats'):
return self._m_fats
_pos = self._io.pos()
self._io.seek(self.boot_sector.pos_fats)
self._m_fats = []
for i in range(self.boot_sector.bpb.num_fats):
self._m_fats.append(self._io.read_bytes(self.boot_sector.size_fat))
self._io.seek(_pos)
return getattr(self, '_m_fats', None)
@property
def root_dir(self):
if hasattr(self, '_m_root_dir'):
return self._m_root_dir
_pos = self._io.pos()
self._io.seek(self.boot_sector.pos_root_dir)
self._raw__m_root_dir = self._io.read_bytes(self.boot_sector.size_root_dir)
_io__raw__m_root_dir = KaitaiStream(BytesIO(self._raw__m_root_dir))
self._m_root_dir = Vfat.RootDirectory(_io__raw__m_root_dir, self, self._root)
self._io.seek(_pos)
return getattr(self, '_m_root_dir', None)