mirror of
https://github.com/SickGear/SickGear.git
synced 2024-12-21 10:13:39 +00:00
225 lines
8.5 KiB
Python
225 lines
8.5 KiB
Python
######################## BEGIN LICENSE BLOCK ########################
|
|
#
|
|
# Contributor(s):
|
|
# Jason Zavaglia
|
|
#
|
|
# This library is free software; you can redistribute it and/or
|
|
# modify it under the terms of the GNU Lesser General Public
|
|
# License as published by the Free Software Foundation; either
|
|
# version 2.1 of the License, or (at your option) any later version.
|
|
#
|
|
# This library is distributed in the hope that it will be useful,
|
|
# but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
# Lesser General Public License for more details.
|
|
#
|
|
# You should have received a copy of the GNU Lesser General Public
|
|
# License along with this library; if not, write to the Free Software
|
|
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
|
|
# 02110-1301 USA
|
|
######################### END LICENSE BLOCK #########################
|
|
from typing import List, Union
|
|
|
|
from .charsetprober import CharSetProber
|
|
from .enums import ProbingState
|
|
|
|
|
|
class UTF1632Prober(CharSetProber):
|
|
"""
|
|
This class simply looks for occurrences of zero bytes, and infers
|
|
whether the file is UTF16 or UTF32 (low-endian or big-endian)
|
|
For instance, files looking like ( \0 \0 \0 [nonzero] )+
|
|
have a good probability to be UTF32BE. Files looking like ( \0 [nonzero] )+
|
|
may be guessed to be UTF16BE, and inversely for little-endian varieties.
|
|
"""
|
|
|
|
# how many logical characters to scan before feeling confident of prediction
|
|
MIN_CHARS_FOR_DETECTION = 20
|
|
# a fixed constant ratio of expected zeros or non-zeros in modulo-position.
|
|
EXPECTED_RATIO = 0.94
|
|
|
|
def __init__(self) -> None:
|
|
super().__init__()
|
|
self.position = 0
|
|
self.zeros_at_mod = [0] * 4
|
|
self.nonzeros_at_mod = [0] * 4
|
|
self._state = ProbingState.DETECTING
|
|
self.quad = [0, 0, 0, 0]
|
|
self.invalid_utf16be = False
|
|
self.invalid_utf16le = False
|
|
self.invalid_utf32be = False
|
|
self.invalid_utf32le = False
|
|
self.first_half_surrogate_pair_detected_16be = False
|
|
self.first_half_surrogate_pair_detected_16le = False
|
|
self.reset()
|
|
|
|
def reset(self) -> None:
|
|
super().reset()
|
|
self.position = 0
|
|
self.zeros_at_mod = [0] * 4
|
|
self.nonzeros_at_mod = [0] * 4
|
|
self._state = ProbingState.DETECTING
|
|
self.invalid_utf16be = False
|
|
self.invalid_utf16le = False
|
|
self.invalid_utf32be = False
|
|
self.invalid_utf32le = False
|
|
self.first_half_surrogate_pair_detected_16be = False
|
|
self.first_half_surrogate_pair_detected_16le = False
|
|
self.quad = [0, 0, 0, 0]
|
|
|
|
@property
|
|
def charset_name(self) -> str:
|
|
if self.is_likely_utf32be():
|
|
return "utf-32be"
|
|
if self.is_likely_utf32le():
|
|
return "utf-32le"
|
|
if self.is_likely_utf16be():
|
|
return "utf-16be"
|
|
if self.is_likely_utf16le():
|
|
return "utf-16le"
|
|
# default to something valid
|
|
return "utf-16"
|
|
|
|
@property
|
|
def language(self) -> str:
|
|
return ""
|
|
|
|
def approx_32bit_chars(self) -> float:
|
|
return max(1.0, self.position / 4.0)
|
|
|
|
def approx_16bit_chars(self) -> float:
|
|
return max(1.0, self.position / 2.0)
|
|
|
|
def is_likely_utf32be(self) -> bool:
|
|
approx_chars = self.approx_32bit_chars()
|
|
return approx_chars >= self.MIN_CHARS_FOR_DETECTION and (
|
|
self.zeros_at_mod[0] / approx_chars > self.EXPECTED_RATIO
|
|
and self.zeros_at_mod[1] / approx_chars > self.EXPECTED_RATIO
|
|
and self.zeros_at_mod[2] / approx_chars > self.EXPECTED_RATIO
|
|
and self.nonzeros_at_mod[3] / approx_chars > self.EXPECTED_RATIO
|
|
and not self.invalid_utf32be
|
|
)
|
|
|
|
def is_likely_utf32le(self) -> bool:
|
|
approx_chars = self.approx_32bit_chars()
|
|
return approx_chars >= self.MIN_CHARS_FOR_DETECTION and (
|
|
self.nonzeros_at_mod[0] / approx_chars > self.EXPECTED_RATIO
|
|
and self.zeros_at_mod[1] / approx_chars > self.EXPECTED_RATIO
|
|
and self.zeros_at_mod[2] / approx_chars > self.EXPECTED_RATIO
|
|
and self.zeros_at_mod[3] / approx_chars > self.EXPECTED_RATIO
|
|
and not self.invalid_utf32le
|
|
)
|
|
|
|
def is_likely_utf16be(self) -> bool:
|
|
approx_chars = self.approx_16bit_chars()
|
|
return approx_chars >= self.MIN_CHARS_FOR_DETECTION and (
|
|
(self.nonzeros_at_mod[1] + self.nonzeros_at_mod[3]) / approx_chars
|
|
> self.EXPECTED_RATIO
|
|
and (self.zeros_at_mod[0] + self.zeros_at_mod[2]) / approx_chars
|
|
> self.EXPECTED_RATIO
|
|
and not self.invalid_utf16be
|
|
)
|
|
|
|
def is_likely_utf16le(self) -> bool:
|
|
approx_chars = self.approx_16bit_chars()
|
|
return approx_chars >= self.MIN_CHARS_FOR_DETECTION and (
|
|
(self.nonzeros_at_mod[0] + self.nonzeros_at_mod[2]) / approx_chars
|
|
> self.EXPECTED_RATIO
|
|
and (self.zeros_at_mod[1] + self.zeros_at_mod[3]) / approx_chars
|
|
> self.EXPECTED_RATIO
|
|
and not self.invalid_utf16le
|
|
)
|
|
|
|
def validate_utf32_characters(self, quad: List[int]) -> None:
|
|
"""
|
|
Validate if the quad of bytes is valid UTF-32.
|
|
|
|
UTF-32 is valid in the range 0x00000000 - 0x0010FFFF
|
|
excluding 0x0000D800 - 0x0000DFFF
|
|
|
|
https://en.wikipedia.org/wiki/UTF-32
|
|
"""
|
|
if (
|
|
quad[0] != 0
|
|
or quad[1] > 0x10
|
|
or (quad[0] == 0 and quad[1] == 0 and 0xD8 <= quad[2] <= 0xDF)
|
|
):
|
|
self.invalid_utf32be = True
|
|
if (
|
|
quad[3] != 0
|
|
or quad[2] > 0x10
|
|
or (quad[3] == 0 and quad[2] == 0 and 0xD8 <= quad[1] <= 0xDF)
|
|
):
|
|
self.invalid_utf32le = True
|
|
|
|
def validate_utf16_characters(self, pair: List[int]) -> None:
|
|
"""
|
|
Validate if the pair of bytes is valid UTF-16.
|
|
|
|
UTF-16 is valid in the range 0x0000 - 0xFFFF excluding 0xD800 - 0xFFFF
|
|
with an exception for surrogate pairs, which must be in the range
|
|
0xD800-0xDBFF followed by 0xDC00-0xDFFF
|
|
|
|
https://en.wikipedia.org/wiki/UTF-16
|
|
"""
|
|
if not self.first_half_surrogate_pair_detected_16be:
|
|
if 0xD8 <= pair[0] <= 0xDB:
|
|
self.first_half_surrogate_pair_detected_16be = True
|
|
elif 0xDC <= pair[0] <= 0xDF:
|
|
self.invalid_utf16be = True
|
|
else:
|
|
if 0xDC <= pair[0] <= 0xDF:
|
|
self.first_half_surrogate_pair_detected_16be = False
|
|
else:
|
|
self.invalid_utf16be = True
|
|
|
|
if not self.first_half_surrogate_pair_detected_16le:
|
|
if 0xD8 <= pair[1] <= 0xDB:
|
|
self.first_half_surrogate_pair_detected_16le = True
|
|
elif 0xDC <= pair[1] <= 0xDF:
|
|
self.invalid_utf16le = True
|
|
else:
|
|
if 0xDC <= pair[1] <= 0xDF:
|
|
self.first_half_surrogate_pair_detected_16le = False
|
|
else:
|
|
self.invalid_utf16le = True
|
|
|
|
def feed(self, byte_str: Union[bytes, bytearray]) -> ProbingState:
|
|
for c in byte_str:
|
|
mod4 = self.position % 4
|
|
self.quad[mod4] = c
|
|
if mod4 == 3:
|
|
self.validate_utf32_characters(self.quad)
|
|
self.validate_utf16_characters(self.quad[0:2])
|
|
self.validate_utf16_characters(self.quad[2:4])
|
|
if c == 0:
|
|
self.zeros_at_mod[mod4] += 1
|
|
else:
|
|
self.nonzeros_at_mod[mod4] += 1
|
|
self.position += 1
|
|
return self.state
|
|
|
|
@property
|
|
def state(self) -> ProbingState:
|
|
if self._state in {ProbingState.NOT_ME, ProbingState.FOUND_IT}:
|
|
# terminal, decided states
|
|
return self._state
|
|
if self.get_confidence() > 0.80:
|
|
self._state = ProbingState.FOUND_IT
|
|
elif self.position > 4 * 1024:
|
|
# if we get to 4kb into the file, and we can't conclude it's UTF,
|
|
# let's give up
|
|
self._state = ProbingState.NOT_ME
|
|
return self._state
|
|
|
|
def get_confidence(self) -> float:
|
|
return (
|
|
0.85
|
|
if (
|
|
self.is_likely_utf16le()
|
|
or self.is_likely_utf16be()
|
|
or self.is_likely_utf32le()
|
|
or self.is_likely_utf32be()
|
|
)
|
|
else 0.00
|
|
)
|