Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!columbia!rutgers!caip!clyde!cuae2!ltuxa!we53!sw013b!dj3b1!killer!ndmce!pollux!bobkat!m5
From: m5@bobkat.UUCP (Mr Mike McNally)
Newsgroups: net.unix-wizards
Subject: SIGTTOU
Message-ID: <163@bobkat.UUCP>
Date: Wed, 15-Oct-86 09:44:55 EDT
Article-I.D.: bobkat.163
Posted: Wed Oct 15 09:44:55 1986
Date-Received: Fri, 17-Oct-86 03:36:53 EDT
Reply-To: m5@bobkat.UUCP (Mr Mike McNally)
Distribution: na
Organization: Digital Lynx; Dallas, TX
Lines: 33
Keywords: SIGTTOU LTOSTOP TIOCPGRP ioctl setpgrp

I have recently discovered a feature of the 4.2 tty driver which seems
contrary to the documentation.  The code to produce the effect is as
follows:

/*
    variable "new_pgrp_id" contains a valid process group identifier
    which is different from the distinguished process group for the
    terminal open on channel "tty_fd".
*/

    setpgrp(0, new_pgrp_id);
    ioctl(tty_fd, TIOCSPGRP, &new_pgrp_id);

Regardless of the setting of the LTOSTOP bit in the local modes, the
driver sends SIGTTOU upon the call to "ioctl".  I suppose I can agree
with the signal being sent if LTOSTOP were set (although I have not
seen any documentation indicating that the signal should be sent).
However, my notion of the purpose of LTOSTOP is that it prevents the
driver from EVER sending a SIGTTOU.

Am I just a babe-in-the-UNIX-woods for believing the tty(4)
documentation?  Is there a good reason for SIGTTOU to be sent
unconditionally upon ioctl calls from non-distinguished process group
processes which change the settings of the tty?

-- 
****                                                         ****
**** At Digital Lynx, we're almost in Garland, but not quite ****
****                                                         ****

Mike McNally                                    Digital Lynx Inc.
Software (not hardware) Person                  Dallas  TX  75243
uucp: ...convex!ctvax!bobkat!m5                 (214) 238-7474