Re: When are these g_io_channel_*() input conditions occurring ?

[tomas tuxteam de]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On Wed, Dec 06, 2006 at 09:16:30AM +0100, Philippe Bertin wrote:
> Hello,
>
> Thanks for specifying this G_IO_NVAL condition.
>
> If I remember correctly, there can be passed an Out-Of-Bound 
> character(/message) on a pipe. It's some kind of priority message, 
> generated for internal pipe management purposes. I *think* that G_IO_PRI 
> condition will be the condition that's fulfilled when receiving such an 
> OOB character (but this is only based on my own -wild- assumption, not 
> on any documentation I found on the subject).

Yep, it's out-of-band data. Sometimes the underlying channel[0] offers a
kind of "fast lane" to transmit urgent signals. The good trusty BSD
socket model has an interface to this: an app reading from a socket
receives a SIGURG signal and can pick up any OOB data from the socket
with the recv() system call[1,2]. See also socket(2) and recv(2).

I haven't my Stevens[3] handy, but this would be the ref I'd turn to to
know more.

- ----------------
[0] TCP, for example does. Telnet makes use of it (I think to signal
    tha app at the other end, if you e.g. do a CTRL-C or CTRL-| or
    whatever key combo is set up to signal the app).
[1] http://en.wikipedia.org/wiki/SIGURG
[2] http://en.wikipedia.org/wiki/Out-of-band
[3] W. Richard Stevens, Unix Netwok Programming

Regards
- -- tomas
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.1 (GNU/Linux)

iD8DBQFFd8wWBcgs9XrR2kYRAjPNAJ9fYXFPwXJX/cFK9C9NYX5dLo9AjQCfXHjA
r8ad+IqGDj2oceVObK0DLl8=
=WhxP
-----END PGP SIGNATURE-----