How does 'mv' rename directories?

[Doug Gwyn]

In article <4195 at buengc.BU.EDU> bph at buengc.bu.edu (Blair P. Houghton) writes:
-I've been told that mv(1) may call mv_dir(?) (which doesn't exist
-on this machine... Encore's Umax is a vanilla BSD...) which is
-setuid-root (it is claimed).  If this is how it's done, then the
-reason for the setuid-root could be to allow the moving of a
-directory across partition boundaries when the directory may
-contain files with an owner different from the directory-owner.

No, the setUID-0 is because linking to directories requires privilege.