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fix: don't loose local mails because of maxage

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Suppose messages A and B were delivered to the remote folder at
"maxage + 1" days ago.

A was downloaded to the local folder "maxage + 1" days ago, but B was only
downloaded "maxage - 1" days ago (contrived scenario to illustrate the two
things that could happen). The behavior was that B gets deleted from the local
folder, but A did not. The expected behavior is that neither is deleted.

Starting where Base.py: __syncmessagesto_delete(self, dstfolder, statusfolder)
is called where:
 - self is the remote folder
and
 - dstfolder is the local folder.

It defines deletelist to be the list of messages in the status folder
messagelist that aren't in the remote folder messagelist with

  not self.uidexists(uid)

A and B are both in the status folder. They're also both *NOT* in the remote
folder messagelist: this list is formed in IMAP.py: cachemessagelist(), which
calls _msgs_to_fetch(), which only asks the IMAP server for messages that are
"< maxage" days old.

Back to Base.py __syncmessagesto_delete(), look at the call
folder.deletemessages(deletelist), where folder is the local folder. This ends
up calling Maildir.py deletemessage() for each message on the deletelist. But we
see that this methods returns (instead of deleting anything) if the message is
in the local folder's messagelist. This messagelist was created by Maildir.py's
cachemessagelist(), which calls _scanfolder(), which tries to exclude messages
based on maxage. So at this point, we *WANT* A and B to be excluded -- then they
will be spared from deletion. This maxage check calls _iswithinmaxage(), and
actually does the date comparison based on the time found at the beginning of
the message's filename. These filenames were originally created in Maildir.py's
new_message_filename(), which calls _gettimeseq() to get the current time (i.e.
the time of retrieval).

Upshot: A's filename has an older timestamp than B's filename. A is excluded
from the local folder messagelist in _scanfolder(), hence spared from deletion
in deletemessage(); B is not excluded, and is deleted.

This patch does not address the timezone issue. As for the IMAP/timezone issue,
a similar issue is discussed in the thunderbird bug tracker here:

https://bugzilla.mozilla.org/show_bug.cgi?id=886534

In the end, they're solving a different problem, but they agree that
there is really no reliable way of guessing the IMAP server's internal
timezone.

Signed-off-by: Janna Martl <janna.martl109@gmail.com>
Signed-off-by: Nicolas Sebrecht <nicolas.s-dev@laposte.net>
This commit is contained in:
Janna Martl 2015-03-07 04:50:33 -05:00 committed by Nicolas Sebrecht
parent 846ebeb2aa
commit 25513e9038
1 changed files with 46 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

65
offlineimap/folder/Maildir.py
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@ -31,7 +31,7 @@ try: # python 2.6 has set() built in
except NameError:
from sets import Set as set
from offlineimap import OfflineImapError
from offlineimap import OfflineImapError, emailutil
# Find the UID in a message filename
re_uidmatch = re.compile(',U=(\d+)')
@ -73,9 +73,9 @@ class MaildirFolder(BaseFolder):
#self.ui is set in BaseFolder.init()
# Everything up to the first comma or colon (or ! if Windows):
self.re_prefixmatch = re.compile('([^'+ self.infosep + ',]*)')
#folder's md, so we can match with recorded file md5 for validity
# folder's md, so we can match with recorded file md5 for validity.
self._foldermd5 = md5(self.getvisiblename()).hexdigest()
# Cache the full folder path, as we use getfullname() very often
# Cache the full folder path, as we use getfullname() very often.
self._fullname = os.path.join(self.getroot(), self.getname())
# Interface from BaseFolder
@ -91,12 +91,12 @@ class MaildirFolder(BaseFolder):
token."""
return 42
#Checks to see if the given message is within the maximum age according
#to the maildir name which should begin with a timestamp
# Checks to see if the given message is within the maximum age according
# to the maildir name which should begin with a timestamp
def _iswithinmaxage(self, messagename, maxage):
#In order to have the same behaviour as SINCE in an IMAP search
#we must convert this to the oldest time and then strip off hrs/mins
#from that day
# In order to have the same behaviour as SINCE in an IMAP search
# we must convert this to the oldest time and then strip off hrs/mins
# from that day.
oldest_time_utc = time.time() - (60*60*24*maxage)
oldest_time_struct = time.gmtime(oldest_time_utc)
oldest_time_today_seconds = ((oldest_time_struct[3] * 3600) \
@ -173,7 +173,7 @@ class MaildirFolder(BaseFolder):
for dirannex, filename in files:
# We store just dirannex and filename, ie 'cur/123...'
filepath = os.path.join(dirannex, filename)
# check maxage/maxsize if this message should be considered
# Check maxage/maxsize if this message should be considered.
if maxage and not self._iswithinmaxage(filename, maxage):
continue
if maxsize and (os.path.getsize(os.path.join(
@ -181,7 +181,7 @@ class MaildirFolder(BaseFolder):
continue
(prefix, uid, fmd5, flags) = self._parse_filename(filename)
if uid is None: # assign negative uid to upload it.
if uid is None: # Assign negative uid to upload it.
uid = nouidcounter
nouidcounter -= 1
else: # It comes from our folder.
@ -202,22 +202,21 @@ class MaildirFolder(BaseFolder):
def quickchanged(self, statusfolder):
"""Returns True if the Maildir has changed"""
self.cachemessagelist()
# Folder has different uids than statusfolder => TRUE
# Folder has different uids than statusfolder => TRUE.
if sorted(self.getmessageuidlist()) != \
sorted(statusfolder.getmessageuidlist()):
return True
# Also check for flag changes, it's quick on a Maildir
# Also check for flag changes, it's quick on a Maildir.
for (uid, message) in self.getmessagelist().iteritems():
if message['flags'] != statusfolder.getmessageflags(uid):
return True
return False #Nope, nothing changed
return False # Nope, nothing changed.
# Interface from BaseFolder
def msglist_item_initializer(self, uid):
return {'flags': set(), 'filename': '/no-dir/no-such-file/'}
# Interface from BaseFolder
def cachemessagelist(self):
if self.ismessagelistempty():
@ -246,16 +245,35 @@ class MaildirFolder(BaseFolder):
filepath = os.path.join(self.getfullname(), filename)
return os.path.getmtime(filepath)
def new_message_filename(self, uid, flags=set()):
def new_message_filename(self, uid, flags=set(), rtime=None):
"""Creates a new unique Maildir filename
:param uid: The UID`None`, or a set of maildir flags
:param flags: A set of maildir flags
:returns: String containing unique message filename"""
# Prefer internal time (rtime) over retrieval time (_gettimeseq()) for
# consistency in the maxage check, which compares times of local mail
# (gotten from the filename) to the internal time of the remote mail.
if rtime is None:
timeval, timeseq = _gettimeseq()
return '%d_%d.%d.%s,U=%d,FMD5=%s%s2,%s'% \
(timeval, timeseq, os.getpid(), socket.gethostname(),
else:
timeval, timeseq = rtime, 0
def build_filename(timeval, timeseq, pid, hostname, uid, folder_id,
infosep, flags):
"""Compute a new filename with 'time sequence' uniqueness in mind."""
filename = '%d_%d.%d.%s,U=%d,FMD5=%s%s2,%s'% (
timeval, timeseq, pid, hostname, uid, folder_id, infosep, flags)
for imap_dir in ['cur', 'new', 'tmp']:
if os.path.exists(os.path.join(self.getfullname(), imap_dir,
filename)):
# Increase timeseq.
return build_filename(timeval, timeseq + 1, pid, hostname,
uid, folder_id, infosep, flags)
return filename
return build_filename(timeval, timeseq, os.getpid(), socket.gethostname(),
uid, self._foldermd5, self.infosep, ''.join(sorted(flags)))
@ -285,14 +303,14 @@ class MaildirFolder(BaseFolder):
time.sleep(0.23)
continue
severity = OfflineImapError.ERROR.MESSAGE
raise OfflineImapError("Unique filename %s already exists." % \
raise OfflineImapError("Unique filename %s already exists."%
filename, severity), None, exc_info()[2]
else:
raise
fd = os.fdopen(fd, 'wt')
fd.write(content)
# Make sure the data hits the disk
# Make sure the data hits the disk.
fd.flush()
if self.dofsync:
os.fsync(fd)
@ -323,7 +341,10 @@ class MaildirFolder(BaseFolder):
# Otherwise, save the message in tmp/ and then call savemessageflags()
# to give it a permanent home.
tmpdir = os.path.join(self.getfullname(), 'tmp')
messagename = self.new_message_filename(uid, flags)
# Make sure rtime is the internal date, so it can be put in the filename
if rtime is None:
rtime = emailutil.get_message_date(content)
messagename = self.new_message_filename(uid, flags, rtime=rtime)
tmpname = self.save_to_tmp_file(messagename, content)
if rtime != None:
os.utime(os.path.join(self.getfullname(), tmpname), (rtime, rtime))
@ -399,8 +420,10 @@ class MaildirFolder(BaseFolder):
oldfilename = self.messagelist[uid]['filename']
dir_prefix, filename = os.path.split(oldfilename)
flags = self.getmessageflags(uid)
content = self.getmessage(uid)
rtime = emailutil.get_message_date(content)
newfilename = os.path.join(dir_prefix,
self.new_message_filename(new_uid, flags))
self.new_message_filename(new_uid, flags, rtime=rtime))
os.rename(os.path.join(self.getfullname(), oldfilename),
os.path.join(self.getfullname(), newfilename))
self.messagelist[new_uid] = self.messagelist[uid]