fdatasync() the journal after creating the pair record and recording
the TUID, but before the message propagation actually starts.
all other writes to the journal are not flushed, as they will at worst
cause some unnecessary network traffic without visible effect.
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)
make sure that the new state is committed to disk before overwriting the
old version - by default meta data is committed first, so we may end up
with no valid state at all otherwise.
this removes the pathological O(<number of sync records> * <number of
new messages>) case at the cost of being a bit more cpu-intensive (but
O(<number of all messages>)) for old messages.
when we find that the store is incompatible with in-store sync state,
we want to fail the whole channel. however, we must not claim that the
store died, otherwise it won't be disposed of properly.
pass DB_TRUNCATE when creating databases. otherwise bdb will complain
about the empty file we pass it (we have to create it upfront to
implement our locking).
in fact, UIDNEXT (and UIDVALIDITY) null is *not* allowed (see RFC3501
section 9). them popping up nonetheless was a dovecot bug (which would
also confuse dovecot itself).
having it in as a workaround was no good either, as quite some other
code in mbsync assumes that UIDs are not null.
This reverts commit e1fa867 and most of 39006d7.
-REFMAIL: 4CA62BA1.4020104@lemma.co.uk
files may be renamed (due to new -> cur transition or flag changes),
which may lead to two effects if ignored:
- we see both the old and the new name, so we report a spurious
duplicate UID
- we see neither name, so we report a spurious deletion
as countermeasure, record and compare directory modification times. upon
mismatch, we just start over - as usual.
don't try to unlock and close databases and files - this will happen a
moment later anyway, through cancelation or re-selection.
ironically, this plugs a memory leak, because an open main database is
used as a signal to close a temporary db in maildir_scan().
instead of SEARCHing every single message (which is slow and happens to
be unreliabe with M$ Exchange 2010), just FETCH the new messages from
the mailbox - the ones we just appended will be amongst them.
unless an info message is explictly marked as a continuation, it must
terminate any pending line (typically the progress information) first.
debug output is not affected, as it is mutually exclusive with info
output, and no debug lines are left unterminated outside clear scopes.
- introduce sys_error() and use it instead of perror() and
error(strerror()) in all expected error conditions
- perror() is used only for "something's really wrong with the system"
kind of errors
- file names, etc. are quoted if they are not validated yet, so e.g. an
empty string becomes immediately obvious
- improve and unify language
- add missing newlines
- asynchronous sockets using an event loop
- connect & starttls have completion callback parameters
- callbacks for notification about filled input buffer and emptied
output buffer
- unsent imap command queue
- used when
- socket output buffer is non-empty
- number of commands in flight exceeds limit
- last sent command requires round-trip
- command has a dependency on completion of previous command
- trashnc is tri-state so only a single "scout" trash APPEND/COPY is
sent at first. a possibly resulting CREATE is injected in front of
the remaining trash commands, so they can succeed (or be cancel()d
if it fails).
- queue's presence necessitates imap_cancel implementation
this prepares the code for being called from a callback.
notably, this makes the imap list parser have a "soft stack", so the
recursion can be suspended at any time.
instead of returning a write()-like result, return only a binary status
code - write errors are handled internally anyway, so user code doesn't
have to check the write length.
this makes the IMAP command submission interface asynchronous.
the functions still have synchronous return codes as well - this enables
clean error return paths. only when we invoke callbacks we resort to
refcounting.
as a "side effect", properly sequence commands after CREATE resulting
from [TRYCREATE].
synchronous error codes which are passed through callbacks aren't a
particularly good idea, after all: latest when the callback does stuff
which does not concern the caller, the return code becomes ambiguous.
instead, protect the sync_vars object with a refcount when invoking
driver functions from loops, as the callbacks they call could invalidate
the object and we would have no way of knowing that the loop should be
aborted prematurely. the upcoming async imap driver will also need a
refcount to protect the cancelation marker of the imap socket dispatcher
loop.
that way we don't have to piggy-back (possibly asynchronous) fatal
errors to particular commands.
internally, the drivers still use synchronous return values as well,
so they don't try to access the invalidated store after calling back.
just use the presence of an SSL object as an indicator. if something
goes wrong during the ssl handshake or certificate validation, the
socket must be immediately closed anyway.
don't pretend that the server has no literal+ for the time of the
first relevant command's synchronous execution. instead, enable the
lower layer to do the processing by telling it for which commands
trashnc ("trash's existence not confirmed") is relevant.
we always actually open the mailbox before appending to it, so we
obviously know that it exists - that's why the code was already
commented out. changing this assumption would significantly complicate
matters for little gain, so let's just assume it won't happen.
consequently, also don't set param.create when appending to regular
mailboxes.
- don't silently fail in release mode (expression with side effects
inside assert())
- save some redundand strlen()s by not throwing away known lengths
- reorganize the code for legibility
if the header contained no CRs but the body (or the post-TUID part of
the header) did, the TUID insertion would add an excess CR, thus
overflowing the buffer by one byte.
we'd send a LOGOUT command in plain text while the server was already
expecting an encrypted command, which would typically lead to waiting
for more data and thus an indefinite hang.
so close the socket immediately instead of letting the normal shutdown
path take care of it.
inspired by a patch by Steven Flintham.
-REFMAIL: 4C9AB98E.3000400@lemma.co.uk
