unionfs_copyfile
int unionfs_copyfile(struct unionfs_node *unp, int docopy, kauth_cred_t cred);
error = unionfs_copyfile(unp, 1, fcnp->cn_cred);
error = unionfs_copyfile(unp, 1, cred);
error = unionfs_copyfile(unp,
error = unionfs_copyfile(unp, (vap->va_size != 0),
error = unionfs_copyfile(unp, 1, cnp->cn_cred);