TIOCCDTR (bug|feature)

[acg at pur-ee.UUCP]

	We have a local mod on the PUCC systems that only permit an
	ioctl to proceed if the process has IREAD permission on the
	inode or if the device is the process's controlling tty.
	We have yet to see anything that this breaks.

	Philosophically, this is justifyable if one considers executing
	an ioctl on a terminal in the same class as forcing characters
	to the terminal's input stream.  Permission to execute an ioctl
	on a terminal should be bound to input (read) permission not
	write (output) permission.

			- Jeff Schwab
			  Purdue University Computing Center
			  <pur-ee!pucc-h:acg>
			  <jrs at purdue>