[PATCH] Convert rfc822 module to email module

[Sebastian Spaeth]

The rfc822 module has been deprecated since python 2.3, and conversion to
the email module is straightforward, so let us do that. rfc822 is
completely gone in python3.

This also fixes a bug that led to offlineimap abortion (but that code path
is apparently usually not exercised so I did not notice:
rfc822|email.utils.parsedate return a tuple which has no named attributes,
but we were using them later in that function. So pass the tuple into a
struct_time() to get named attributes.

While reading the docs, I noticed that email.parsedate returns invalid
daylight savings information (is_dst attribute), and we are using it
anyway. Oh well, the imap server might think the mails are off by an hour
at worst.

Signed-off-by: Sebastian Spaeth <Sebastian at SSpaeth.de>
---
This fixes a bug (this is in no published version yet) that led to
offlineimap abortion at times, but only in the next branch, so this
fix is also on top of current 'next'. At the same time, one more
removal of StringIO where it is not really needed anymore.

 offlineimap/folder/IMAP.py |   14 ++++++++------
 1 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/offlineimap/folder/IMAP.py b/offlineimap/folder/IMAP.py
index a419664..8cf57d4 100644
--- a/offlineimap/folder/IMAP.py
+++ b/offlineimap/folder/IMAP.py
@@ -17,12 +17,11 @@
 #    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 
 import imaplib
-import rfc822
+import email
 import random
 import binascii
 import re
 import time
-from StringIO import StringIO
 from copy import copy
 from Base import BaseFolder
 from offlineimap import imaputil, imaplibutil
@@ -329,16 +328,17 @@ class IMAPFolder(BaseFolder):
                   (including double quotes) or `None` in case of failure
                   (which is fine as value for append)."""
         if rtime is None:
-            message = rfc822.Message(StringIO(content))
+            message = email.message_from_string(content)
             # parsedate returns a 9-tuple that can be passed directly to
             # time.mktime(); Will be None if missing or not in a valid
             # format.  Note that indexes 6, 7, and 8 of the result tuple are
             # not usable.
-            datetuple = rfc822.parsedate(message.getheader('Date'))
-
+            datetuple = email.utils.parsedate(message.get('Date'))
             if datetuple is None:
                 #could not determine the date, use the local time.
                 return None
+            #make it a real struct_time, so we have named attributes
+            datetuple = time.struct_time(datetuple)
         else:
             #rtime is set, use that instead
             datetuple = time.localtime(rtime)
@@ -358,7 +358,8 @@ class IMAPFolder(BaseFolder):
             # or something.  Argh.  It seems that Time2Internaldate
             # will rause a ValueError if the year is 0102 but not 1902,
             # but some IMAP servers nonetheless choke on 1902.
-            self.ui.debug("Message with invalid date %s. Server will use local time." % datetuple)
+            self.ui.debug("Message with invalid date %s. Server will use local time." \
+                              % datetuple)
             return None
 
         #produce a string representation of datetuple that works as
@@ -366,6 +367,7 @@ class IMAPFolder(BaseFolder):
         num2mon = {1:'Jan', 2:'Feb', 3:'Mar', 4:'Apr', 5:'May', 6:'Jun',
                    7:'Jul', 8:'Aug', 9:'Sep', 10:'Oct', 11:'Nov', 12:'Dec'}
 
+        #tm_isdst coming from email.parsedate is not usable, we still use it here, mhh
         if datetuple.tm_isdst == '1':
             zone = -time.altzone
         else:
-- 
1.7.1