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SickGear/lib/feedparser/encodings.py

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# Character encoding routines
# Copyright 2010-2022 Kurt McKee <contactme@kurtmckee.org>
# Copyright 2002-2008 Mark Pilgrim
# All rights reserved.
#
# This file is a part of feedparser.
#
# Redistribution and use in source and binary forms, with or without modification,
# are permitted provided that the following conditions are met:
#
# * Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 'AS IS'
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
import codecs
import re
import typing as t
try:
try:
import cchardet as chardet # type: ignore[import]
except ImportError:
import chardet # type: ignore[no-redef]
except ImportError:
lazy_chardet_encoding = None
else:
def lazy_chardet_encoding(data):
return chardet.detect(data)['encoding'] or ''
from .exceptions import (
CharacterEncodingOverride,
CharacterEncodingUnknown,
NonXMLContentType,
)
# Each marker represents some of the characters of the opening XML
# processing instruction ('<?xm') in the specified encoding.
EBCDIC_MARKER = b'\x4C\x6F\xA7\x94'
UTF16BE_MARKER = b'\x00\x3C\x00\x3F'
UTF16LE_MARKER = b'\x3C\x00\x3F\x00'
UTF32BE_MARKER = b'\x00\x00\x00\x3C'
UTF32LE_MARKER = b'\x3C\x00\x00\x00'
ZERO_BYTES = '\x00\x00'
# Match the opening XML declaration.
# Example: <?xml version="1.0" encoding="utf-8"?>
RE_XML_DECLARATION = re.compile(r'^<\?xml[^>]*?>')
# Capture the value of the XML processing instruction's encoding attribute.
# Example: <?xml version="1.0" encoding="utf-8"?>
RE_XML_PI_ENCODING = re.compile(br'^<\?.*encoding=[\'"](.*?)[\'"].*\?>')
def parse_content_type(line: str) -> t.Tuple[str, str]:
"""Parse an HTTP Content-Type header.
The return value will be a tuple of strings:
the MIME type, and the value of the "charset" (if any).
This is a custom replacement for Python's cgi.parse_header().
The cgi module will be removed in Python 3.13.
"""
chunks = line.split(";")
if not chunks:
return "", ""
mime_type = chunks[0].strip()
charset_value = ""
for chunk in chunks[1:]:
key, _, value = chunk.partition("=")
if key.strip().lower() == "charset":
charset_value = value.strip().strip("\"'")
return mime_type, charset_value
def convert_to_utf8(http_headers, data, result):
"""Detect and convert the character encoding to UTF-8.
http_headers is a dictionary
data is a raw string (not Unicode)"""
# This is so much trickier than it sounds, it's not even funny.
# According to RFC 3023 ('XML Media Types'), if the HTTP Content-Type
# is application/xml, application/*+xml,
# application/xml-external-parsed-entity, or application/xml-dtd,
# the encoding given in the charset parameter of the HTTP Content-Type
# takes precedence over the encoding given in the XML prefix within the
# document, and defaults to 'utf-8' if neither are specified. But, if
# the HTTP Content-Type is text/xml, text/*+xml, or
# text/xml-external-parsed-entity, the encoding given in the XML prefix
# within the document is ALWAYS IGNORED and only the encoding given in
# the charset parameter of the HTTP Content-Type header should be
# respected, and it defaults to 'us-ascii' if not specified.
# Furthermore, discussion on the atom-syntax mailing list with the
# author of RFC 3023 leads me to the conclusion that any document
# served with a Content-Type of text/* and no charset parameter
# must be treated as us-ascii. (We now do this.) And also that it
# must always be flagged as non-well-formed. (We now do this too.)
# If Content-Type is unspecified (input was local file or non-HTTP source)
# or unrecognized (server just got it totally wrong), then go by the
# encoding given in the XML prefix of the document and default to
# 'iso-8859-1' as per the HTTP specification (RFC 2616).
# Then, assuming we didn't find a character encoding in the HTTP headers
# (and the HTTP Content-type allowed us to look in the body), we need
# to sniff the first few bytes of the XML data and try to determine
# whether the encoding is ASCII-compatible. Section F of the XML
# specification shows the way here:
# http://www.w3.org/TR/REC-xml/#sec-guessing-no-ext-info
# If the sniffed encoding is not ASCII-compatible, we need to make it
# ASCII compatible so that we can sniff further into the XML declaration
# to find the encoding attribute, which will tell us the true encoding.
# Of course, none of this guarantees that we will be able to parse the
# feed in the declared character encoding (assuming it was declared
# correctly, which many are not). iconv_codec can help a lot;
# you should definitely install it if you can.
# http://cjkpython.i18n.org/
bom_encoding = ''
xml_encoding = ''
# Look at the first few bytes of the document to guess what
# its encoding may be. We only need to decode enough of the
# document that we can use an ASCII-compatible regular
# expression to search for an XML encoding declaration.
# The heuristic follows the XML specification, section F:
# http://www.w3.org/TR/REC-xml/#sec-guessing-no-ext-info
# Check for BOMs first.
if data[:4] == codecs.BOM_UTF32_BE:
bom_encoding = 'utf-32be'
data = data[4:]
elif data[:4] == codecs.BOM_UTF32_LE:
bom_encoding = 'utf-32le'
data = data[4:]
elif data[:2] == codecs.BOM_UTF16_BE and data[2:4] != ZERO_BYTES:
bom_encoding = 'utf-16be'
data = data[2:]
elif data[:2] == codecs.BOM_UTF16_LE and data[2:4] != ZERO_BYTES:
bom_encoding = 'utf-16le'
data = data[2:]
elif data[:3] == codecs.BOM_UTF8:
bom_encoding = 'utf-8'
data = data[3:]
# Check for the characters '<?xm' in several encodings.
elif data[:4] == EBCDIC_MARKER:
bom_encoding = 'cp037'
elif data[:4] == UTF16BE_MARKER:
bom_encoding = 'utf-16be'
elif data[:4] == UTF16LE_MARKER:
bom_encoding = 'utf-16le'
elif data[:4] == UTF32BE_MARKER:
bom_encoding = 'utf-32be'
elif data[:4] == UTF32LE_MARKER:
bom_encoding = 'utf-32le'
tempdata = data
try:
if bom_encoding:
tempdata = data.decode(bom_encoding).encode('utf-8')
except UnicodeDecodeError:
xml_encoding_match = None
else:
xml_encoding_match = RE_XML_PI_ENCODING.match(tempdata)
if xml_encoding_match:
xml_encoding = xml_encoding_match.groups()[0].decode('utf-8').lower()
# Normalize the xml_encoding if necessary.
if bom_encoding and (xml_encoding in (
'u16', 'utf-16', 'utf16', 'utf_16',
'u32', 'utf-32', 'utf32', 'utf_32',
'iso-10646-ucs-2', 'iso-10646-ucs-4',
'csucs4', 'csunicode', 'ucs-2', 'ucs-4'
)):
xml_encoding = bom_encoding
# Find the HTTP Content-Type and, hopefully, a character
# encoding provided by the server. The Content-Type is used
# to choose the "correct" encoding among the BOM encoding,
# XML declaration encoding, and HTTP encoding, following the
# heuristic defined in RFC 3023.
http_content_type = http_headers.get('content-type') or ''
http_content_type, http_encoding = parse_content_type(http_content_type)
acceptable_content_type = 0
application_content_types = ('application/xml', 'application/xml-dtd',
'application/xml-external-parsed-entity')
text_content_types = ('text/xml', 'text/xml-external-parsed-entity')
json_content_types = ('application/feed+json', 'application/json')
json = False
if (
http_content_type in application_content_types
or (
http_content_type.startswith('application/')
and http_content_type.endswith('+xml')
)
):
acceptable_content_type = 1
rfc3023_encoding = http_encoding or xml_encoding or 'utf-8'
elif (
http_content_type in text_content_types
or (
http_content_type.startswith('text/')
and http_content_type.endswith('+xml')
)
):
acceptable_content_type = 1
rfc3023_encoding = http_encoding or 'us-ascii'
elif (
http_content_type in json_content_types
or (
not http_content_type
and data and data.lstrip()[0] == '{'
)
):
http_content_type = json_content_types[0]
acceptable_content_type = 1
json = True
rfc3023_encoding = http_encoding or 'utf-8' # RFC 7159, 8.1.
elif http_content_type.startswith('text/'):
rfc3023_encoding = http_encoding or 'us-ascii'
elif http_headers and 'content-type' not in http_headers:
rfc3023_encoding = xml_encoding or 'iso-8859-1'
else:
rfc3023_encoding = xml_encoding or 'utf-8'
# gb18030 is a superset of gb2312, so always replace gb2312
# with gb18030 for greater compatibility.
if rfc3023_encoding.lower() == 'gb2312':
rfc3023_encoding = 'gb18030'
if xml_encoding.lower() == 'gb2312':
xml_encoding = 'gb18030'
# there are four encodings to keep track of:
# - http_encoding is the encoding declared in the Content-Type HTTP header
# - xml_encoding is the encoding declared in the <?xml declaration
# - bom_encoding is the encoding sniffed from the first 4 bytes of the XML data
# - rfc3023_encoding is the actual encoding, as per RFC 3023 and a variety of other conflicting specifications
error = None
if http_headers and (not acceptable_content_type):
if 'content-type' in http_headers:
msg = '%s is not an accepted media type' % http_headers['content-type']
else:
msg = 'no Content-type specified'
error = NonXMLContentType(msg)
# determine character encoding
known_encoding = 0
tried_encodings = []
# try: HTTP encoding, declared XML encoding, encoding sniffed from BOM
for proposed_encoding in (rfc3023_encoding, xml_encoding, bom_encoding,
lazy_chardet_encoding, 'utf-8', 'windows-1252', 'iso-8859-2'):
if callable(proposed_encoding):
proposed_encoding = proposed_encoding(data)
if not proposed_encoding:
continue
if proposed_encoding in tried_encodings:
continue
tried_encodings.append(proposed_encoding)
try:
data = data.decode(proposed_encoding)
except (UnicodeDecodeError, LookupError):
pass
else:
known_encoding = 1
if not json:
# Update the encoding in the opening XML processing instruction.
new_declaration = '''<?xml version='1.0' encoding='utf-8'?>'''
if RE_XML_DECLARATION.search(data):
data = RE_XML_DECLARATION.sub(new_declaration, data)
else:
data = new_declaration + '\n' + data
data = data.encode('utf-8')
break
# if still no luck, give up
if not known_encoding:
error = CharacterEncodingUnknown(
'document encoding unknown, I tried ' +
'%s, %s, utf-8, windows-1252, and iso-8859-2 but nothing worked' %
(rfc3023_encoding, xml_encoding))
rfc3023_encoding = ''
elif proposed_encoding != rfc3023_encoding:
error = CharacterEncodingOverride(
'document declared as %s, but parsed as %s' %
(rfc3023_encoding, proposed_encoding))
rfc3023_encoding = proposed_encoding
result['content-type'] = http_content_type # for selecting the parser
result['encoding'] = rfc3023_encoding
if error:
result['bozo'] = True
result['bozo_exception'] = error
return data
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