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Re: RFC: More imap patch.

From: Daniel Stenberg <>
Date: Tue, 6 Apr 2010 20:33:08 +0200 (CEST)

On Mon, 5 Apr 2010, Ben Greear wrote:

>> Easy: libcurl only gets one resource per request, so you'd call it three
>> times to get three mails.
> Ahh, so you don't want to support something like this?
> imap://;uid=1:3

I didn't say that.

If that is a valid URL then I think it is worth doing an effort to make that
URL supported. However, everything is a ballance and features come at a price.
I'm not prepared to sacrifise everything just to do more protocol features.

If the above URL can be supported without the source becoming a maze, then I'm
all for it.

>> Considering more than one file then enters the "FTP wildcard" concept area,
>> but it would still technically be made by doing multiple individual
>> requests internally even if you can hide that as looking like one big
>> request from the outside the way the FTP wildcard patch does.
> I don't think I'll be writing such logic, but I will remove the current
> support in my patch for multiple email if you prefer that.

The thing is, your current logic is twisted and isn't following the curl ways
so we cannot have it that way. If you're not prepared to take a step back and
redo the functionality in a way that is more curlish, then yes I believe
removing the support for that feature is the only option.

> Ok, so after we either download the complete thing in pp->cache OR set up
> the transfer with Curl_setup_transfer, we always call: state(conn,
> IMAP_STOP) in the fetch_body response, and then some part of the pingpong
> statemachine (or something else?) will cause the Transfer to happen?

pp->cache is only for keeping headers, and headers are only headers. I think
we should strive to minimize abusing the header buffers to get data with.

Content that is downloaded or uploaded is meant to be done in the TRANSFER
phase, and it is not supposed to be limited to fixed sizes like header lengths
or similar.

Downloads are started in the current code by the imap_state_fetch_resp()
function. It calls Curl_setup_transfer() and then ends the state machine, and
as that is part of the DO phase state-machine, the next logical step within
libcurl after DO is: TRANSFER.

>>> * SEARCH [25k of data]

>> Since pingpong won't deal with that, I can only imagine that we need to
>> consider the search results to be the transfer here, so DO would issue the
>> search command and the TRANSFER would receive the results.
> We need to watch for the response result line (first line that doesn't start
> with "* SEARCH"

However hideous that is, I can't see how we can avoid it. But we already do a
similar thing for POP3 which always scans for \r\n.\r\n to signal end of
transfer, so it should be fairly easy to make a similar thing for IMAP SEARCH.
See Curl_pop3_write().

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Received on 2010-04-06