Transmitting BREAK

[swatt at ittvax.UUCP]

Guy Harris writes:

	Berkeley UNIX is the only "major" version which puts "file
	descriptor must be open for reading/writing" restrictions on
	"ioctl"s.  S3/S5 don't, but then again, neither did V7.

This is not true for 4.1; I haven't seen 4.2.  The code in "tty.c"
for the "ttioctl" function has a comment to the effect that if the
ioctl function changes the behavior of the device, insist on write
permission and suspend background processes.  However, the code to
enforce the write permission requirement is commented out.  The
manual page for ioctl(2) incorrectly claims the behavior Guy noted.

Has this changed in 4.2?

	- Alan S. "always insist on sources!" Watt