[PATCH v2 1/2] python: open messages in binary mode

[Florian Klink]

currently, notmuch's get_message_parts() opens the file in text mode and passes
the file object to email.message_from_file(fp). In case the email contains
UTF-8 characters, reading might fail inside email.parser with the following exception:

  File "/usr/lib/python3.6/site-packages/notmuch/message.py", line 591, in get_message_parts
    email_msg = email.message_from_binary_file(fp)
  File "/usr/lib/python3.6/email/__init__.py", line 62, in message_from_binary_file
    return BytesParser(*args, **kws).parse(fp)
  File "/usr/lib/python3.6/email/parser.py", line 110, in parse
    return self.parser.parse(fp, headersonly)
  File "/usr/lib/python3.6/email/parser.py", line 54, in parse
    data = fp.read(8192)
  File "/usr/lib/python3.6/codecs.py", line 321, in decode
    (result, consumed) = self._buffer_decode(data, self.errors, final)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe4 in position 1865: invalid continuation byte

To fix this, read file in binary mode and pass to
email.message_from_binary_file(fp).

Unfortunately, Python 2 doesn't support
email.message_from_binary_file(fp), so keep using
email.message_from_file(fp) there.

Signed-off-by: Florian Klink <flokli at flokli.de>
---
 bindings/python/notmuch/message.py | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/bindings/python/notmuch/message.py b/bindings/python/notmuch/message.py
index cce377d0..d5b98e4f 100644
--- a/bindings/python/notmuch/message.py
+++ b/bindings/python/notmuch/message.py
@@ -41,6 +41,7 @@ from .tag import Tags
 from .filenames import Filenames
 
 import email
+import sys
 
 
 class Message(Python3StringMixIn):
@@ -587,8 +588,11 @@ class Message(Python3StringMixIn):
 
     def get_message_parts(self):
         """Output like notmuch show"""
-        fp = open(self.get_filename())
-        email_msg = email.message_from_file(fp)
+        fp = open(self.get_filename(), 'rb')
+        if sys.version_info[0] < 3:
+            email_msg = email.message_from_file(fp)
+        else:
+            email_msg = email.message_from_binary_file(fp)
         fp.close()
 
         out = []
-- 
2.14.1