fget_procdesc
error = fget_procdesc(td, fd, &cap_pdwait_rights, &fp, &pd, NULL);
error = fget_procdesc(td, uap->fd, &cap_pdkill_rights, &fp, NULL, &p);
error = fget_procdesc(td, fd, rightsp, &fp, NULL, NULL);
error = fget_procdesc(td, pdfd, &cap_pddupfd_rights, &pfp, NULL, &p);
int fget_procdesc(struct thread *td, int pfd,