don't retry dead Stores for every Channel.
this also introduces a state for transient errors (specifically, connect
failures), but this is currently unused.
a directory is no mailbox unless it contains a cur/ subdir.
but if that one is present, create new/ and tmp/ if they are missing.
this makes it possible to resume interrupted maildir creations.
the seznam.cz IMAP server seems very eager to send UIDNEXT responses
despite not supporting UIDPLUS. this doesn't appear to be a particularly
sensible combination, but it's valid nonetheless.
however, that means that we need to save the UIDNEXT value before we
start storing messages, lest imap_find_new_msgs() will simply overlook
them. we do that outside the driver, in an already present field - this
actually makes the main path more consistent with the journal recovery
path.
analysis by Tomas Tintera <trosos@seznam.cz>.
REFMAIL: 20141220215032.GA10115@kyvadlo.trosos.seznam.cz
... for windows fs compatibility.
the maildir-specific InfoDelimiter inherits the global FieldDelimiter
(which affects SyncState), based on the assumption that if the sync
state is on a windows FS, the mailboxes certainly will be as well, while
the inverse is not necessarily true (when running on unix, anyway).
REFMAIL: <CA+m_8J1ynqAjHRJagvKt9sb31yz047Q7NH-ODRmHOKyfru8vtA@mail.gmail.com>
memcmp() is unfortunately not guaranteed to read forward byte-by-byte,
which means that the clever use as a strncmp() without the pointless
strlen()s is not permitted, and can actually misbehave with
SSE-optimized string functions.
so implement proper equals() and starts_with() functions. as a bonus,
the calls are less cryptic.
the highest assigned UID must always be at least as high as the highest
actually found UID, as otherwise we'd hand out duplicate UIDs at some
point. also, getting into such a state in the first place indicates some
potentially serious trouble, or at least external interference (e.g.,
moving/copying a message from another folder without giving it a
pristine filename).
REFMAIL: 20140626211831.GA11590@sie.protva.ru
if something managed to make the maildir .uidvalidity files big enough
(possible only by appending garbage or scrambling them alltogether), we
would overflow the read buffer by one when appending the terminating
null.
this is not expected to have any real-world impact.
found by coverity.
we would see the recent timestamp of the creation and conclude that
something is going on, so we'd wait. this is obviously nonsense.
as we know that a freshly created mailbox is empty, simply skip the
message scan alltogether.
time_t may be long long. to keep the sprintf format strings simple, just
downcast - this is not going to be a problem for the next 30 years, and
until then long will be 64-bit everywhere anyway.
suggested 3.5 years ago by Antoine Reilles <tonio@NetBSD.org>.
this fixes two possible failure scenarios:
- if the journal is committed but the mails are not, the missing files
would be erroneously interpreted as deletions which would be
propagated
- less seriously, if the mail files' meta data was committed but the
file contents were not, we would end up with empty files, which would
have to be re-fetched "behind mbsync's back" (just deleting the files
would not work - see above)
