to separate the open(/dev/ptm) from the ioctl(PTMGET) for privilege
separation or pledge().
Based on a diff from reyk@.
ok deraadt millert

ok jca@ krw@

ok millert

ok guenther millert kettenis

util.h.
ok guenther

/dev/ptm.  Users are strongly encouraged to upgrade to a more recent
release if they haven't already.
ok deraadt

okay deraadt@, millert@, krw@

instead of 16.  E.g. it is now /dev/{p,t}typ[0-9a-zA-z] instead of just
/dev/{p,t}typ[0-9a-f].  This requires that you update MAKEDEV and run:
# cd /dev && ./MAKEDEV pty0 && rm -f [pt]ty[rq]*

ioctl(2), an unprivileged process may allocate a pty and have its owner
and mode set appropriately.  This means that programs such as xterm and
screen no longer need to be setuid.  Programs using the openpty()
function require zero changes and will "just work".
Designed by beck@ and deraadt@; changes by beck@ with cleanup (and
a rewrite of the vnode bits) by art@ and tweaks/bugfixes by me.
Tested by many.

rescinded 22 July 1999.  Proofed by myself and Theo.

some brave soul should look at it.

opendev.h: ok, so I merged it with util.h
opendev.h: use util.h
everything else: use "util.h"