Re: [9front] upas/fs: handle outlook's quirks

[Risto Salminen <risto.salminen@gmx.com>]

ori wrote:
> Give me a couple of days.

Sure, there is no hurry.

> Yes, though I'm probably going to see if I can
> make sense of some other imap implementations and
> see how fetching is handled differently there before
> I commit this.

I took a quick look at isync and mutt, and both seem to
fetch either the header section or the whole body of
the message at once, without relying on the rfc822.size
attribute that Gmail and Outlook apparently do not tell
correctly.  Therefore they work correctly with any kind
of an IMAP server.

On the other hand, upas/fs fetches the message in
multiple substrings, whose sizes are calculated based
on the rfc822.size attribute, which means that there has
to be special handling for quirky servers that return
incorrect rfc822.size.

The message is fetched in substrings apparently because
then it is possible to fetch only the headers if the
body is not yet needed, which saves bandwidth and memory
and consequently also time.  The same effect should be
achievable by fetching only the header section as the
IMAP specification allows.  Of course, then one would
have to rely on the server implementing that correctly.
In any case, at least fetching the whole message, without
specifying substring limits, at once should work properly
with any IMAP server and indeed return the whole message.

In my opinion, the correct solution for making upas/fs
work with any IMAP server without any special quirks
would be to convert it from the current substring
strategy to fetch either the header section or the whole
body of the message at once.  This would however seem to
require quite extensive changes.  I could try to work on
that in some timeframe though, if that is deemed
appropriate.

Thanks,
Risto