some brave soul should look at it.

device is opened by default).
Don't open the file w/o adding a /dev/ prefix unless the file has
a '/' in it.  This prevents problems where someone says "disklabel
sd0" with a file called "sd0" in the cwd.
The OPENDEV_DRCT flag has been deprecated as it is the the default
behavior and always has been.
Add checks for >= MAXPATHLEN and return ENAMETOOLONG in that case.

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

others.  This is a generic version of the code used by mt(1).