New submission from radical164 <tpt...@tuta.io>:
I just reported a bug about email folding at issue 33524, but this issue is
more fatal in some languages like Chinese or Japanese, which does not insert
spaces between each words.
Python 3.6.5 has this issue, while 3.6.4 does not.
Create an email with longer header than max_line_length set by its policy. And
the header contains non-ascii characters but no white spaces.
When try to fold it, python gets stuck and finally system hangs. There are no
output unless I stop it with Ctrl-C.
^CTraceback (most recent call last):
File "emailtest.py", line 7, in <module>
policy.fold("Subject", msg["Subject"])
File "/usr/lib/python3.6/email/policy.py", line 183, in fold
return self._fold(name, value, refold_binary=True)
File "/usr/lib/python3.6/email/policy.py", line 205, in _fold
return value.fold(policy=self)
File "/usr/lib/python3.6/email/headerregistry.py", line 258, in fold
return header.fold(policy=policy)
File "/usr/lib/python3.6/email/_header_value_parser.py", line 144, in fold
return _refold_parse_tree(self, policy=policy)
File "/usr/lib/python3.6/email/_header_value_parser.py", line 2651, in
_refold_parse_tree
part.ew_combine_allowed, charset)
File "/usr/lib/python3.6/email/_header_value_parser.py", line 2735, in
_fold_as_ew
ew = _ew.encode(first_part)
File "/usr/lib/python3.6/email/_encoded_words.py", line 215, in encode
blen = _cte_encode_length['b'](bstring)
File "/usr/lib/python3.6/email/_encoded_words.py", line 130, in len_b
groups_of_3, leftover = divmod(len(bstring), 3)
KeyboardInterrupt
Code to reproduce:
from email.message import EmailMessage
from email.policy import default
policy = default # max_line_length = 78
msg = EmailMessage()
msg["Subject"] = "รก"*100
policy.fold("Subject", msg["Subject"])
No problems in following cases:
1. If the header is shorter than max_line_length.
2. If the header can be split with spaces and the all chunk is shorter than
max_line_length.
3. If the header is fully composed with ascii characters. In this case, there
is no problem even if it is very long without spaces.
----------
components: email
messages: 316747
nosy: barry, r.david.murray, radical164
priority: normal
severity: normal
status: open
title: Infinite loop on folding email if headers has no spaces
type: behavior
versions: Python 3.6
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue33529>
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