A minimal patch against current which implements openat(2) is
available at:

http://www.pvv.ntnu.no/~steinarh/diff.openat

The patch extends the use of ni_startdir in struct nameidata, so the
starting point for namei(9) on relative pathnames can be specified in
the same fashion as for individual lookup(9)s. NDINIT(9) initializes
ni_startdir with NULL which by namei(9) is taken as the normal
behavior; the process current working directory.

I'd like som feedback on this approach before continuing with
fstatat(2) and opendir(3).

        Steinar