From 905c8c3d8dfe081d91e399aa5fd93d1659655264 Mon Sep 17 00:00:00 2001 From: R David Murray Date: Sat, 8 Feb 2014 11:48:20 -0500 Subject: #19772: Do not mutate message when downcoding to 7bit. This is a bit of an ugly hack because of the way generator pieces together the output message. The deepcopys aren't too expensive, though, because we know it is only called on messages that are not multiparts, and the payload (the thing that could be large) is an immutable object. Test and preliminary work on patch by Vajrasky Kok. --- Lib/email/generator.py | 14 ++++++++++++++ Lib/test/test_email/test_email.py | 12 +++++++++++- Misc/NEWS | 3 +++ 3 files changed, 28 insertions(+), 1 deletion(-) diff --git a/Lib/email/generator.py b/Lib/email/generator.py index 4ea0b55..07a97c7 100644 --- a/Lib/email/generator.py +++ b/Lib/email/generator.py @@ -12,6 +12,7 @@ import time import random import warnings +from copy import deepcopy from io import StringIO, BytesIO from email._policybase import compat32 from email.header import Header @@ -173,10 +174,18 @@ class Generator: # necessary. oldfp = self._fp try: + self._munge_cte = None self._fp = sfp = self._new_buffer() self._dispatch(msg) finally: self._fp = oldfp + munge_cte = self._munge_cte + del self._munge_cte + # If we munged the cte, copy the message again and re-fix the CTE. + if munge_cte: + msg = deepcopy(msg) + msg.replace_header('content-transfer-encoding', munge_cte[0]) + msg.replace_header('content-type', munge_cte[1]) # Write the headers. First we see if the message object wants to # handle that itself. If not, we'll do it generically. meth = getattr(msg, '_write_headers', None) @@ -225,9 +234,14 @@ class Generator: if _has_surrogates(msg._payload): charset = msg.get_param('charset') if charset is not None: + # XXX: This copy stuff is an ugly hack to avoid modifying the + # existing message. + msg = deepcopy(msg) del msg['content-transfer-encoding'] msg.set_payload(payload, charset) payload = msg.get_payload() + self._munge_cte = (msg['content-transfer-encoding'], + msg['content-type']) if self._mangle_from_: payload = fcre.sub('>From ', payload) self._write_lines(payload) diff --git a/Lib/test/test_email/test_email.py b/Lib/test/test_email/test_email.py index 4157a06..73ec2a6 100644 --- a/Lib/test/test_email/test_email.py +++ b/Lib/test/test_email/test_email.py @@ -3495,7 +3495,7 @@ Here's the message body self.assertTrue(msg.get_payload(0).get_payload().endswith('\r\n')) -class Test8BitBytesHandling(unittest.TestCase): +class Test8BitBytesHandling(TestEmailBase): # In Python3 all input is string, but that doesn't work if the actual input # uses an 8bit transfer encoding. To hack around that, in email 5.1 we # decode byte streams using the surrogateescape error handler, and @@ -3748,6 +3748,16 @@ class Test8BitBytesHandling(unittest.TestCase): email.generator.Generator(out).flatten(msg) self.assertEqual(out.getvalue(), self.non_latin_bin_msg_as7bit_wrapped) + def test_str_generator_should_not_mutate_msg_when_handling_8bit(self): + msg = email.message_from_bytes(self.non_latin_bin_msg) + out = BytesIO() + BytesGenerator(out).flatten(msg) + orig_value = out.getvalue() + Generator(StringIO()).flatten(msg) # Should not mutate msg! + out = BytesIO() + BytesGenerator(out).flatten(msg) + self.assertEqual(out.getvalue(), orig_value) + def test_bytes_generator_with_unix_from(self): # The unixfrom contains a current date, so we can't check it # literally. Just make sure the first word is 'From' and the diff --git a/Misc/NEWS b/Misc/NEWS index ae5f83a..cedd4e5 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -48,6 +48,9 @@ Core and Builtins Library ------- +- Issue #19772: email.generator no longer mutates the message object when + doing a down-transform from 8bit to 7bit CTEs. + - Issue #18805: the netmask/hostmask parsing in ipaddress now more reliably filters out illegal values and correctly allows any valid prefix length. -- cgit v0.12