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Re: Is there a counterpart of curl_multi_fdset to UNset fd's?

From: Federico Vitali <>
Date: Tue, 8 Jul 2014 10:50:13 +0200

Hi Daniel! Thank you so much for your solicit answers!
Reading your answers I'm probably missing some basic concepts from curl
or, even worse, from linux programming! So let me explain what I need to

> I don't get why you want that. You handle your descriptors, and you can
> have libcurl add its descriptors. Why would you remove any?

I'm developing a project for video surveillance based on IP cameras. I'm
using a framework
heavily based on file descriptors and select for timing and scheduling
events and actions.

Let's give an example. I have, among others, a unix socket for IPC with
another process.
Then I have to make a CGI requests to a bunch of IP cameras, 10 in my case,

So I use select to monitor file descriptors (eg my unix socket), with tv
set to next timeout to handle. When I need
to make a bunch of CGI requests like in this example
I set the file descriptors associated with my multi handle via
curl_multi_fdset. Then, after a number
of selects, when curl_multi_perform tells me that there are no more running
requests I would like
to unset the file descriptors associated with curl handles and continue
with my endless select
on my original file descriptors.
You say that I don't need it, so where am I wrong?

Thank you very much!


> I need that because I have to add curl fd's to an already existing set.
> The function was designed to offer that. As the docs says
> "curl_multi_fdset() only adds its own descriptors". So you can set your own
> descriptors first and then ask libcurl to add its descriptors and you can
> then select() on the whole set in a single call.
> And another question: is there a way to get a fd of a specific curl
>> handle of a multi handle set?
> No, but I would be interested in learning why you would want that? When
> you use the multi API you work on all the transfers at once and several
> easy handles can even (at times) share one or more file descriptors.
> --
> /
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Received on 2014-07-08