stty bug + effects

[Guy Harris]

> One short correction.  On 4.1 and 4.2 you CANNOT force data on
> someone else's tty line via the TIOCSTI call.  I am not sure
> how this is checked for (possibly both read and write permission
> are required on the descriptor), but I tried it, and it does
> not work!

TIOCSTI is only allowed 1) if the terminal in question is the control terminal
of the process trying to do the TIOCSTI (to be technical, it's if the
u.u_ttyp in the process' U page is the tty structure pointer for that terminal;
u.u_ttyp gets set to the ttyp for the first terminal that the process
opens if the process is not in any process group and the terminal doesn't
belong to any process group) or 2) if you're the super-user.

	Guy Harris
	{seismo,ihnp4,allegra}!rlgvax!guy