Re: Why does fhandler_tty_slave::open call attach_tty?

[Christopher Faylor <cgf at redhat dot com>]

On Tue, Oct 09, 2001 at 12:32:34AM -0500, Jon Cast wrote:
>
>cgf told me to submit patches here, since I'm not planning on becoming
>a major contributor to Cygwin.  However, I'm not sure if this is the
>correct place to submit questions about the Cygwin code to.  Hoping it
>is, here's my question.
>
>fhandler_tty_slave::open begins with the following code:
>
>-- 461 --
>>  tcinit (cygwin_shared->tty[ttynum]);
>>
>>  attach_tty (ttynum);
>>  tc->set_ctty (ttynum, flags);
>
>attach_tty just calls tty_list::connect_tty, which in turn just
>verifies the tty number and returns it if it's meaningful.
>
>However, that return code isn't used by fhandler_tty_slave::open.
>What is attach_tty supposed to do, and why is it called here?

I think your analysis is correct.  This could be an artifact of an
earlier attach_tty implementation.  It's probably ok to just remove
the attach_tty if you want to try it and see if it works.
>
>Also, what does tty_min::set_ctty do?  I have a feeling one or both of
>these is intended to set the controlling tty of the process.  If so,
>what is the recommended way to get around this code in
>fhandler_tty_slave::open (as openpty needs to do)?

set_ctty sets the controlling terminal for the process if there is not
one assigned.  If you inspect the code you should be able to see how
to avoid doing this.  You set the standard UNIX flags.

>Finally, are there any design documents I'm missing?

Any available information is talked about here:
http://cygwin.com/contrib.html

cgf

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