Fix IMAP folder throwing away time zone when parsing email Date headers

Fix imapfolder.getmessageinternaldate misparsing the Date:
header from emails due to a bug or surprising behaviour by
email.utils.parsedate. This is because email.utils.parsedate's
return value contains the unadjusted hour value from the string
parsed but does not include information about the time zone in
which it is specified. For example (Python 2.7.3):

$ python -c "import email.utils;
  print email.utils.parsedate('Mon, 20 Nov 1995 19:12:08 -0500')"
 (1995, 11, 20, 19, 12, 8, 0, 1, -1)

(the -1 is the isdst field); the -0500 time zone is completely
ignored, so e.g. the same input with time "19:12:08 +0300" has
the same result. When passed to time.struct_time as allowed per
the parsedate documentation, this time is interpreted in GMT and
thus deviates from the correct value by the timezone offset
(in this example, -5 hours).

I consider this a bug in email.utils.parsedate: In my opinion,
since the return value of the parsetime doesn't include a timezone,
it should be expressed in terms of UTC rather than in terms of the
time zone from the Date header; the existence of
email.utils.parsedate_tz, to which I've switched, indicates that
maybe the authors were aware of this problem.

Signed-off-by: Sebastian Spaeth <Sebastian@SSpaeth.de>
Make SIGHUP singal handler equivalent to SIGTERM and SIGINT.

offlineimap has several frontends that encourage running it from a
terminal under an X session. When X session closes for a system
shutdown, the terminals exit, after sending SIGHUP to their children.

Previously SIGHUP was treated to be equivalent to SIGUSR1, i.e. wake
up and sync all accounts. This causes delays during shutdown.

According to Wikipedia [0], SIGHUP has been repurposed from a
historical meaning to one of:
 * re-read configuration files, or reinitialize (e.g. Apache, sendmail)
 * controlling pseudo or virtual terminal has been closed

I believe second meaning is more appropriate for offlineimap, and
hence this patch makes SIGHUP to be handled in the same way SIGTERM
and SIGINT are handled.

[0] http://en.wikipedia.org/wiki/SIGHUP

Debian-Bug: http://bugs.debian.org/670120
Reported-By: Steve Langasek <steve.langasek@canonical.com>
Signed-off-by: Dmitrijs Ledkovs <xnox@debian.org>
Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>
Implement stack trace dump for all running threads on SIGQUIT

This is handy when we're debugging the thread locks: we can try to
understand which thread does what and how it was called.

Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>
Add offlineimap.utils to the list of our modules

Forgot to do it while was adding stacktrace support.

Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>
And add forgotten __init__.py for offlineimap.utils

I should learn to check my commits when rebasing and reordering.

Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>
Fix deadlock for IMAP folder synced in singlethreaded mode

The problem lies in the fact that offlineimap.folder.Base's method
syncmessagesto_copy() uses threaded code everytime it is suggested by
the derived class's suggeststhreads() (currently, only IMAP does this
suggestion), but offlineimap/init.py will not spawn the
exitnotifymonitorloop() from offlineimap.threadutil.

The root cause is that ExitNotifyThread-derived threads need
offlineimap.threadutil's exitnotifymonitorloop() to be running the
cleaner for the exitthreads Queue(), because it fills the queue via
the run() method from this class: it wants to put() itself to the
Queue on exit, so when no exitnotifymonitorloop() is running, the
queue will fill up.  And if this thread is an instance of
InstanceLimitedThread that hits the limit on the number of threads,
then it will hold the instancelimitedsems[] semaphore will prevent
other InstanceLimitedThread()s of the same name to pass its start()
method.

The fix is to avoid using threaded code if we're running
single-threaded.

Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>
Obtained-from: X-Ryl669 <boite.pour.spam@gmail.com>
Create global instance of command-line options

This eases testing of option values inside the code.  This instance
is implemented as the read-only copy of the obtained 'options' object,
so callers won't be able to modify its contents.

Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>
IMAP class: don't suggest multithreading in single-threaded mode

Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>
Allow setting IMAP servers' SSL version

We now allow setting the SSL version used when connecting to IMAPS servers, and
do so via the `ssl_version` configuration option. We default to the current
practice (letting python's "ssl" library automatically detect the correct
version). There are however rare cases where one must specify the version to
use.

Signed-off-by: Ryan Kavanagh <rak@debian.org>
Merge pull request #42 from ryanakca/next

Allow setting IMAP servers' SSL version
Rename README to README.md for github
Merge branch 'master' into next
Prune trailing whitespaces from code and documentation

They are redundant in all pruned cases and sometimes even create some
problems, e.g., when one tries to jump through paragraphs in vi.

Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>
IMAP: simplify locking and fix potential lock loss

Run the locked code under 'with': this guarantees that lock
will be released in any case.

This modification also avoids the case when our thread wasn't running
locked when exception was caught, another thread got the lock, our
code checked it via self.connectionlock.locked() and errorneously
released the lock thinking that is was running locked.

Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>
Execute pre/post hooks for IDLE-toggled syncs

Make IDLE syncs be equal to the regular synchronisations
in respect to pre-sync and post-sync hooks.

From: mxgr7 <maxgerer@gmail.com>
Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>
Allow custom sorting of mailboxes for mbnames

mutt-sidebar and, probably, other MUA show mailboxes in the order
they are listed in the file written by mbnames.  Therefore, to allow
customization of the order with which mailboxes are listed, introduce
the new 'sort_keyfunc' directive in the [mbnames] section.

'sort_keyfunc' must be a function that will be called once for each
mailbox.  It must accept the only argument -- a dict with 2 items,
'accountname' and 'foldername', and should return an object that
will be used as the sorting key for each mailbox.

Default key function returns (d['accountname'], d['foldername']),
thus sorting by account name and then by the folder name.

Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>
Typos fixed in config file

Fixed some minor typos in the commented config file.
I think these days Google also uses Gmail in Germany, so also changed
German Google Mail to German Gmail.
make savemessage() handle NO response to APPEND correctly

IMAP servers can return `NO` responses to the `APPEND` command,
e.g. here's an example response from Groupwise's IMAP server:

    NO APPEND The 1500 MB storage limit has been exceeded.

In this case, savemessage() should abort the repository sync rather
than returning UID 0 which would cause the local copy of the message
being saved to get irreversibly deleted.

Signed-off-by: Adam Spiers <offlineimap@adamspiers.org>
Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>
Fix country-specific GMail folder names

 * Germany (and Austria) now use GMail as the base folder names.
 * Suggests users to check their spam and trash folder names
   and set them appropriately.

From: Bart Kerkvliet <bkerkvliet@gmail.com>
Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>
Refactored authentication handling

 - created helper routine that will do authentication;

 - routine tries each method in turn, first successful
   one terminates it: makes things easier to read
   and handle;

 - renamed plainauth() inside offlineimap/imapserver.py
   to loginauth(): the function does IMAP LOGIN authentication
   and there is PLAIN SASL method, so previous name was
   a bit misleading;

 - slightly improved error reporting: all exceptions during
   authentication will be reported at the end of the run;

 - now loginauth() is never called if LOGINDISABLED is advertized
   by the server; it used to be invoked unconditionally when
   CRAM-MD5 fails, but we should respect server's opinion on
   how to handle its users.

Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>