Which events to poll in session_startup when non-blocking ?

[Rodolphe Rocca]

Hi,

first of all, thank you for this good SSH library. That's a pretty good 
piece of software :-)

Now I have a question.

In the libssh2 examples I can see this :

while ((rc = libssh2_session_startup(session, sock)) ==
           LIBSSH2_ERROR_EAGAIN);
if (rc) {
     fprintf(stderr, "Failure establishing SSH session: %d\n", rc);
     return -1;
}

That's fine for an example, but in some real cases it's going to consume 
lots of CPU cycles for nothing.

So what I want to do is to poll for new data in the loop instead of 
immediately returning, something like :

while ((rc = libssh2_session_startup(session, sock)) ==
           LIBSSH2_ERROR_EAGAIN)
{       
        ps = poll(&fds, 1, timeout);

        if (ps == -1)
        {
                // handle error
        }
        else if (ps == 0)
        {
                // handle timeout
        }
}

The problem with this is that I do not know if I have to POLLIN or POLLOUT.

What should I do ? Poll for both ?

NB : OpenSSL solved this by having two return codes : 
SSL_ERROR_WANT_READ and SSL_ERROR_WANT_WRITE

--
Rodolphe
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