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From: brnstnd@kramden.acf.nyu.edu (Dan Bernstein)
Newsgroups: comp.unix.internals
Subject: Re: Device Emulation with a pty?
Message-ID: <4670:Oct902:04:3890@kramden.acf.nyu.edu>
Date: 9 Oct 90 02:04:38 GMT
References: <6372@emory.mathcs.emory.edu> <1978:Oct803:29:0790@kramden.acf.nyu.edu> <4166@auspex.auspex.com>
Organization: IR
Lines: 21

In article <4166@auspex.auspex.com> guy@auspex.auspex.com (Guy Harris) writes:
> >>  * detect device specific slave side ioctls and reply to them from
> >>    the master side.
> >Look up TIOCPKT and TIOCREMOTE.
> Which will tell you that you can only detect *some* effects from
> slave-side "ioctl"s

Well, yes, but it's also the spot where vendors put in their more
advanced pseudo-tty controls. TIOCUCNTL, for example.

> (I'm not sure what "reply to them from the master
> side" means, but if it means that the process on the master side is to
> be responsible for providing the return code for "ioctl"s or providing
> the return data from "ioctl"s such as TIOCGETP that return data, you
> can't do that, either).

On some systems (such as HP-UX) you can do exactly that. There isn't
much standardization beyond TIOCPKT, but the features do exist. Which is
why I recommended looking them up...

---Dan