cpython/Lib/email/parser.py
Paul Ganssle f69d5c6198 Fix infinite loop in email folding logic (GH-12732)
As far as I can tell, this infinite loop would be triggered if:

1. The value being folded contains a single word (no spaces) longer than
   max_line_length
2. The max_line_length is shorter than the encoding's name + 9
   characters.

bpo-36564: https://bugs.python.org/issue36564
2019-07-16 10:50:01 -07:00

132 lines
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# Copyright (C) 2001-2007 Python Software Foundation
# Author: Barry Warsaw, Thomas Wouters, Anthony Baxter
# Contact: email-sig@python.org
"""A parser of RFC 2822 and MIME email messages."""
__all__ = ['Parser', 'HeaderParser', 'BytesParser', 'BytesHeaderParser',
'FeedParser', 'BytesFeedParser']
from io import StringIO, TextIOWrapper
from email.feedparser import FeedParser, BytesFeedParser
from email._policybase import compat32
class Parser:
def __init__(self, _class=None, *, policy=compat32):
"""Parser of RFC 2822 and MIME email messages.
Creates an in-memory object tree representing the email message, which
can then be manipulated and turned over to a Generator to return the
textual representation of the message.
The string must be formatted as a block of RFC 2822 headers and header
continuation lines, optionally preceded by a `Unix-from' header. The
header block is terminated either by the end of the string or by a
blank line.
_class is the class to instantiate for new message objects when they
must be created. This class must have a constructor that can take
zero arguments. Default is Message.Message.
The policy keyword specifies a policy object that controls a number of
aspects of the parser's operation. The default policy maintains
backward compatibility.
"""
self._class = _class
self.policy = policy
def parse(self, fp, headersonly=False):
"""Create a message structure from the data in a file.
Reads all the data from the file and returns the root of the message
structure. Optional headersonly is a flag specifying whether to stop
parsing after reading the headers or not. The default is False,
meaning it parses the entire contents of the file.
"""
feedparser = FeedParser(self._class, policy=self.policy)
if headersonly:
feedparser._set_headersonly()
while True:
data = fp.read(8192)
if not data:
break
feedparser.feed(data)
return feedparser.close()
def parsestr(self, text, headersonly=False):
"""Create a message structure from a string.
Returns the root of the message structure. Optional headersonly is a
flag specifying whether to stop parsing after reading the headers or
not. The default is False, meaning it parses the entire contents of
the file.
"""
return self.parse(StringIO(text), headersonly=headersonly)
class HeaderParser(Parser):
def parse(self, fp, headersonly=True):
return Parser.parse(self, fp, True)
def parsestr(self, text, headersonly=True):
return Parser.parsestr(self, text, True)
class BytesParser:
def __init__(self, *args, **kw):
"""Parser of binary RFC 2822 and MIME email messages.
Creates an in-memory object tree representing the email message, which
can then be manipulated and turned over to a Generator to return the
textual representation of the message.
The input must be formatted as a block of RFC 2822 headers and header
continuation lines, optionally preceded by a `Unix-from' header. The
header block is terminated either by the end of the input or by a
blank line.
_class is the class to instantiate for new message objects when they
must be created. This class must have a constructor that can take
zero arguments. Default is Message.Message.
"""
self.parser = Parser(*args, **kw)
def parse(self, fp, headersonly=False):
"""Create a message structure from the data in a binary file.
Reads all the data from the file and returns the root of the message
structure. Optional headersonly is a flag specifying whether to stop
parsing after reading the headers or not. The default is False,
meaning it parses the entire contents of the file.
"""
fp = TextIOWrapper(fp, encoding='ascii', errors='surrogateescape')
try:
return self.parser.parse(fp, headersonly)
finally:
fp.detach()
def parsebytes(self, text, headersonly=False):
"""Create a message structure from a byte string.
Returns the root of the message structure. Optional headersonly is a
flag specifying whether to stop parsing after reading the headers or
not. The default is False, meaning it parses the entire contents of
the file.
"""
text = text.decode('ASCII', errors='surrogateescape')
return self.parser.parsestr(text, headersonly)
class BytesHeaderParser(BytesParser):
def parse(self, fp, headersonly=True):
return BytesParser.parse(self, fp, headersonly=True)
def parsebytes(self, text, headersonly=True):
return BytesParser.parsebytes(self, text, headersonly=True)