/usr/lib/python3/dist-packages/kaitaistruct.py is in python3-kaitaistruct 0.7-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import sys
from struct import unpack
try:
import cStringIO
BytesIO = cStringIO.StringIO
except ImportError:
from io import BytesIO # noqa
PY2 = sys.version_info[0] == 2
# Kaitai Struct runtime streaming API version, defined as per PEP-0396
# standard. Used for two purposes:
#
# * .py files generated by ksc from .ksy check that they import proper
# KS runtime library by this version number;
# * distribution utils (setup.py) use this when packaging for PyPI
#
__version__ = '0.7'
class KaitaiStruct(object):
def __init__(self, stream):
self._io = stream
def __enter__(self):
return self
def __exit__(self, *args, **kwargs):
self.close()
@classmethod
def from_file(cls, filename):
f = open(filename, 'rb')
try:
return cls(KaitaiStream(f))
except Exception:
# close file descriptor, then reraise the exception
f.close()
raise
def close(self):
self._io.close()
class KaitaiStream(object):
def __init__(self, io):
self._io = io
self.align_to_byte()
def __enter__(self):
return self
def __exit__(self, *args, **kwargs):
self.close()
def close(self):
self._io.close()
# ========================================================================
# Stream positioning
# ========================================================================
def is_eof(self):
io = self._io
t = io.read(1)
if t == b'':
return True
else:
io.seek(io.tell() - 1)
return False
def seek(self, n):
self._io.seek(n)
def pos(self):
return self._io.tell()
def size(self):
# Python has no internal File object API function to get
# current file / StringIO size, thus we use the following
# trick.
io = self._io
# Remember our current position
cur_pos = io.tell()
# Seek to the end of the File object
io.seek(0, 2)
# Remember position, which is equal to the full length
full_size = io.tell()
# Seek back to the current position
io.seek(cur_pos)
return full_size
# ========================================================================
# Integer numbers
# ========================================================================
# ------------------------------------------------------------------------
# Signed
# ------------------------------------------------------------------------
def read_s1(self):
return unpack('b', self.read_bytes(1))[0]
# ........................................................................
# Big-endian
# ........................................................................
def read_s2be(self):
return unpack('>h', self.read_bytes(2))[0]
def read_s4be(self):
return unpack('>i', self.read_bytes(4))[0]
def read_s8be(self):
return unpack('>q', self.read_bytes(8))[0]
# ........................................................................
# Little-endian
# ........................................................................
def read_s2le(self):
return unpack('<h', self.read_bytes(2))[0]
def read_s4le(self):
return unpack('<i', self.read_bytes(4))[0]
def read_s8le(self):
return unpack('<q', self.read_bytes(8))[0]
# ------------------------------------------------------------------------
# Unsigned
# ------------------------------------------------------------------------
def read_u1(self):
return unpack('B', self.read_bytes(1))[0]
# ........................................................................
# Big-endian
# ........................................................................
def read_u2be(self):
return unpack('>H', self.read_bytes(2))[0]
def read_u4be(self):
return unpack('>I', self.read_bytes(4))[0]
def read_u8be(self):
return unpack('>Q', self.read_bytes(8))[0]
# ........................................................................
# Little-endian
# ........................................................................
def read_u2le(self):
return unpack('<H', self.read_bytes(2))[0]
def read_u4le(self):
return unpack('<I', self.read_bytes(4))[0]
def read_u8le(self):
return unpack('<Q', self.read_bytes(8))[0]
# ========================================================================
# Floating point numbers
# ========================================================================
# ........................................................................
# Big-endian
# ........................................................................
def read_f4be(self):
return unpack('>f', self.read_bytes(4))[0]
def read_f8be(self):
return unpack('>d', self.read_bytes(8))[0]
# ........................................................................
# Little-endian
# ........................................................................
def read_f4le(self):
return unpack('<f', self.read_bytes(4))[0]
def read_f8le(self):
return unpack('<d', self.read_bytes(8))[0]
# ========================================================================
# Unaligned bit values
# ========================================================================
def align_to_byte(self):
self.bits = 0
self.bits_left = 0
def read_bits_int(self, n):
bits_needed = n - self.bits_left
if bits_needed > 0:
# 1 bit => 1 byte
# 8 bits => 1 byte
# 9 bits => 2 bytes
bytes_needed = ((bits_needed - 1) // 8) + 1
buf = self.read_bytes(bytes_needed)
for byte in buf:
# Python 2 will get "byte" as one-character str, thus
# we need to convert it to integer manually; Python 3
# is fine as is.
if isinstance(byte, str):
byte = ord(byte)
self.bits <<= 8
self.bits |= byte
self.bits_left += 8
# raw mask with required number of 1s, starting from lowest bit
mask = (1 << n) - 1
# shift mask to align with highest bits available in self.bits
shift_bits = self.bits_left - n
mask <<= shift_bits
# derive reading result
res = (self.bits & mask) >> shift_bits
# clear top bits that we've just read => AND with 1s
self.bits_left -= n
mask = (1 << self.bits_left) - 1
self.bits &= mask
return res
# ========================================================================
# Byte arrays
# ========================================================================
def read_bytes(self, n):
r = self._io.read(n)
if len(r) < n:
raise EOFError(
"requested %d bytes, but got only %d bytes" % (n, len(r))
)
return r
def read_bytes_full(self):
return self._io.read()
def read_bytes_term(self, term, include_term, consume_term, eos_error):
r = b''
while True:
c = self._io.read(1)
if c == b'':
if eos_error:
raise Exception(
"End of stream reached, but no terminator %d found" %
(term,)
)
else:
return r
elif ord(c) == term:
if include_term:
r += c
if not consume_term:
self._io.seek(self._io.tell() - 1)
return r
else:
r += c
def ensure_fixed_contents(self, expected):
actual = self._io.read(len(expected))
if actual != expected:
raise Exception(
"Unexpected fixed contents: got %s, was waiting for %s" %
(str(actual), str(expected))
)
return actual
@staticmethod
def bytes_strip_right(src, pad_byte):
new_len = len(src)
if PY2:
data = bytearray(src)
else:
data = src
while data[new_len - 1] == pad_byte:
new_len -= 1
return data[:new_len]
@staticmethod
def bytes_terminate(src, term, include_term):
new_len = 0
max_len = len(src)
if PY2:
data = bytearray(src)
else:
data = src
while new_len < max_len and data[new_len] != term:
new_len += 1
if include_term and new_len < max_len:
new_len += 1
return data[:new_len]
# ========================================================================
# Byte array processing
# ========================================================================
@staticmethod
def process_xor_one(data, key):
if PY2:
r = bytearray(data)
for i in range(len(r)):
r[i] ^= key
return bytes(r)
else:
return bytes(v ^ key for v in data)
@staticmethod
def process_xor_many(data, key):
if PY2:
r = bytearray(data)
k = bytearray(key)
ki = 0
kl = len(k)
for i in range(len(r)):
r[i] ^= k[ki]
ki += 1
if ki >= kl:
ki = 0
return bytes(r)
else:
return bytes(a ^ b for a, b in zip(data, itertools.cycle(key)))
@staticmethod
def process_rotate_left(data, amount, group_size):
if group_size != 1:
raise Exception(
"unable to rotate group of %d bytes yet" %
(group_size,)
)
mask = group_size * 8 - 1
anti_amount = -amount & mask
r = bytearray(data)
for i in range(len(r)):
r[i] = (r[i] << amount) & 0xff | (r[i] >> anti_amount)
return bytes(r)
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