🚀 go-pugleaf

>The problem is that under HPUX 7.0 you can't do TIOCGPGRP on the
>master side of a pty (don't ask me why not -- it worked under 6.2).

I don't know whether HP-UX supports BSD-style "asynchronous I/O", but
perhaps they decided to implement it on pseudo-tty masters?  In order to
make it work, you have to provide some way of setting the process or
process group to which the SIGIO should be sent; SunOS 4.x does so by
supporting *only* the F_GETOWN and F_SETOWN BSD "fcntl"s for
manipulating the master's process group, so that old programs that do
TIOCGPGRP or TIOCSPGRP on the master side of a pty still work. 

>I don't know how widespread TIOCSIGSEND is (CMU's BSD 4.3 machines
>don't seem to have it);

It's not in vanilla 4.3BSD or 4.3-tahoe.

It *is* in SunOS 3.2 and later, as I remember, and I think it's in
System V Release 4 as well - except that it's called "TIOCSIGNAL"
instead, and takes a pointer to an "int" containing the signal number
rather than, as I infer from your code TIOCSIGSEND does, taking the
signal number as an argument.

I hope to browbeat Berkeley into providing TIOCSIGNAL in 4.4BSD (Dave
Borman's patches for his new "telnet" add something called TIOCSIG -
just what we need, a *third* name for this function! - that's TIOCSIGNAL
with a different name). 

HP might want to consider offering TIOCSIGNAL as well as TIOCSIGSEND in
a future release.