amends 9c86ec344.
S_FIND was for the sync record status field. it has no business in the
sync vars status fields. its value coincided with ST_SELECTED, which
luckily only means that we always tried to match up TUIDs even if there
was nothing to do.
the need for TUID matching arises in two mostly independent
circumstances, so add two separate flags ST_FIND_{OLD,NEW}.
this value is only ever used to find just pushed messages by TUID, so we
can simply use the UIDNEXT value from before we started pushing - and of
course, we need to record that in the journal. it makes no sense to log
the new value after completing a search, as there won't be a next search
before we push the next messages.
the purpose of this variable is to hold the UIDNEXT value from before
we started pushing new messages, i.e., the minimal uid we can expect
them to have.
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.
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.
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
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.
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.
imap may very well store messages with LF line endings. only RFC2822
requires CRLF.
consequently, preserve the line endings as much as possible unless the
mailbox format does not support it (this would be the case for unix mbox
- i actually have no idea about maildir).
