Path: utzoo!utgpu!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!tut.cis.ohio-state.edu!ucbvax!hplabs!hp-pcd!hpfcso!hpfcdc!rml
From: rml@hpfcdc.HP.COM (Bob Lenk)
Newsgroups: comp.sys.hp
Subject: Re: Device drivers for Hewlet Packard HP-UX version 7
Message-ID: <5570392@hpfcdc.HP.COM>
Date: 28 Mar 90 03:15:40 GMT
References: <1054@vision.UUCP>
Organization: HP Ft. Collins, Co.
Lines: 38

In message <1054@vision.UUCP> chas@vision.UUCP (Charles Hirst) writes:

> I traced the problem to the failure of the TIOCSPGRP ioctl issued by the
> csh.
> ...
> However if I pass the TIOCSPGRP ioctl down it fails with error 25,
> ENOTTY.  As a fix I trap it myself and simply fill the tty t_pgrp field
> in with the supplied argument ( the requested pid to set process group
> to ).
> 
> Can anybody tell me what fields need filling in, in a tty structure
> during the open routine.  Looking at the tty struct does not help as HP
> have played with it a lot to get POSIX compatibility.  I currently treat
> it like a BSD structure.
> 
> The driver used to work with version 3 of HP-UX, if that helps.

Most likely the problem is due to POSIX security requirements on the
ioctl call (actually the POSIX tcsetpgrp() call, which is the same
thing).  POSIX requires that the tty be the controlling tty of the
calling process and that the tty be associated with the session of
the calling process.  Your solution is essentially defeating these checks;
note that it could cause security problems in some environments.  Earlier
versions of HP-UX used different checks based on uids instead.

The check probably is based on fields in the proc or user structure, as
well as the tty structure that point to or otherwise identify each
other.  If I understand your "driver" to be a user process at the master
end of a pty, it shouldn't be handling these directly.  The best way to
handle this is probably to make sure that the session in the window is
initialized properly to create the affiliations.  This requires that the
session leader (probably whatever exec's csh) be the first to open the
slave, and that it call setsid(2) or setpgrp(2) before opening the slave
(details on termio(7)).

		Bob Lenk
		rml@hpfcla.hp.com
		hplabs!hpfcla!rml