bazarr/libs/enzyme/parsers/ebml/readers.py

236 lines
7.2 KiB
Python

# -*- coding: utf-8 -*-
from ...compat import bytes
from ...exceptions import ReadError, SizeError
from datetime import datetime, timedelta
from io import BytesIO
from struct import unpack
__all__ = ['read_element_id', 'read_element_size', 'read_element_integer', 'read_element_uinteger',
'read_element_float', 'read_element_string', 'read_element_unicode', 'read_element_date',
'read_element_binary']
def _read(stream, size):
"""Read the `stream` for *exactly* `size` bytes and raise an exception if
less than `size` bytes are actually read
:param stream: file-like object from which to read
:param int size: number of bytes to read
:raise ReadError: when less than `size` bytes are actually read
:return: read data from the `stream`
:rtype: bytes
"""
data = stream.read(size)
if len(data) < size:
raise ReadError('Less than %d bytes read (%d)' % (size, len(data)))
return data
def read_element_id(stream):
"""Read the Element ID
:param stream: file-like object from which to read
:raise ReadError: when not all the required bytes could be read
:return: the id of the element
:rtype: int
"""
char = _read(stream, 1)
byte = ord(char)
if byte & 0x80:
return byte
elif byte & 0x40:
return unpack('>H', char + _read(stream, 1))[0]
elif byte & 0x20:
b, h = unpack('>BH', char + _read(stream, 2))
return b * 2 ** 16 + h
elif byte & 0x10:
return unpack('>L', char + _read(stream, 3))[0]
else:
ValueError('Not an Element ID')
def read_element_size(stream):
"""Read the Element Size
:param stream: file-like object from which to read
:raise ReadError: when not all the required bytes could be read
:return: the size of element's data
:rtype: int
"""
char = _read(stream, 1)
byte = ord(char)
if byte & 0x80:
return unpack('>B', bytes((byte ^ 0x80,)))[0]
elif byte & 0x40:
return unpack('>H', bytes((byte ^ 0x40,)) + _read(stream, 1))[0]
elif byte & 0x20:
b, h = unpack('>BH', bytes((byte ^ 0x20,)) + _read(stream, 2))
return b * 2 ** 16 + h
elif byte & 0x10:
return unpack('>L', bytes((byte ^ 0x10,)) + _read(stream, 3))[0]
elif byte & 0x08:
b, l = unpack('>BL', bytes((byte ^ 0x08,)) + _read(stream, 4))
return b * 2 ** 32 + l
elif byte & 0x04:
h, l = unpack('>HL', bytes((byte ^ 0x04,)) + _read(stream, 5))
return h * 2 ** 32 + l
elif byte & 0x02:
b, h, l = unpack('>BHL', bytes((byte ^ 0x02,)) + _read(stream, 6))
return b * 2 ** 48 + h * 2 ** 32 + l
elif byte & 0x01:
return unpack('>Q', bytes((byte ^ 0x01,)) + _read(stream, 7))[0]
else:
ValueError('Not an Element Size')
def read_element_integer(stream, size):
"""Read the Element Data of type :data:`INTEGER`
:param stream: file-like object from which to read
:param int size: size of element's data
:raise ReadError: when not all the required bytes could be read
:raise SizeError: if size is incorrect
:return: the read integer
:rtype: int
"""
if size == 1:
return unpack('>b', _read(stream, 1))[0]
elif size == 2:
return unpack('>h', _read(stream, 2))[0]
elif size == 3:
b, h = unpack('>bH', _read(stream, 3))
return b * 2 ** 16 + h
elif size == 4:
return unpack('>l', _read(stream, 4))[0]
elif size == 5:
b, l = unpack('>bL', _read(stream, 5))
return b * 2 ** 32 + l
elif size == 6:
h, l = unpack('>hL', _read(stream, 6))
return h * 2 ** 32 + l
elif size == 7:
b, h, l = unpack('>bHL', _read(stream, 7))
return b * 2 ** 48 + h * 2 ** 32 + l
elif size == 8:
return unpack('>q', _read(stream, 8))[0]
else:
raise SizeError(size)
def read_element_uinteger(stream, size):
"""Read the Element Data of type :data:`UINTEGER`
:param stream: file-like object from which to read
:param int size: size of element's data
:raise ReadError: when not all the required bytes could be read
:raise SizeError: if size is incorrect
:return: the read unsigned integer
:rtype: int
"""
if size == 1:
return unpack('>B', _read(stream, 1))[0]
elif size == 2:
return unpack('>H', _read(stream, 2))[0]
elif size == 3:
b, h = unpack('>BH', _read(stream, 3))
return b * 2 ** 16 + h
elif size == 4:
return unpack('>L', _read(stream, 4))[0]
elif size == 5:
b, l = unpack('>BL', _read(stream, 5))
return b * 2 ** 32 + l
elif size == 6:
h, l = unpack('>HL', _read(stream, 6))
return h * 2 ** 32 + l
elif size == 7:
b, h, l = unpack('>BHL', _read(stream, 7))
return b * 2 ** 48 + h * 2 ** 32 + l
elif size == 8:
return unpack('>Q', _read(stream, 8))[0]
else:
raise SizeError(size)
def read_element_float(stream, size):
"""Read the Element Data of type :data:`FLOAT`
:param stream: file-like object from which to read
:param int size: size of element's data
:raise ReadError: when not all the required bytes could be read
:raise SizeError: if size is incorrect
:return: the read float
:rtype: float
"""
if size == 4:
return unpack('>f', _read(stream, 4))[0]
elif size == 8:
return unpack('>d', _read(stream, 8))[0]
else:
raise SizeError(size)
def read_element_string(stream, size):
"""Read the Element Data of type :data:`STRING`
:param stream: file-like object from which to read
:param int size: size of element's data
:raise ReadError: when not all the required bytes could be read
:raise SizeError: if size is incorrect
:return: the read ascii-decoded string
:rtype: unicode
"""
return _read(stream, size).decode('ascii')
def read_element_unicode(stream, size):
"""Read the Element Data of type :data:`UNICODE`
:param stream: file-like object from which to read
:param int size: size of element's data
:raise ReadError: when not all the required bytes could be read
:raise SizeError: if size is incorrect
:return: the read utf-8-decoded string
:rtype: unicode
"""
return _read(stream, size).decode('utf-8')
def read_element_date(stream, size):
"""Read the Element Data of type :data:`DATE`
:param stream: file-like object from which to read
:param int size: size of element's data
:raise ReadError: when not all the required bytes could be read
:raise SizeError: if size is incorrect
:return: the read date
:rtype: datetime
"""
if size != 8:
raise SizeError(size)
nanoseconds = unpack('>q', _read(stream, 8))[0]
return datetime(2001, 1, 1, 0, 0, 0, 0, None) + timedelta(microseconds=nanoseconds // 1000)
def read_element_binary(stream, size):
"""Read the Element Data of type :data:`BINARY`
:param stream: file-like object from which to read
:param int size: size of element's data
:raise ReadError: when not all the required bytes could be read
:raise SizeError: if size is incorrect
:return: raw binary data
:rtype: bytes
"""
return BytesIO(stream.read(size))