jaildesc_find
error = jaildesc_find(td, jfd_in, &jdpr, NULL);
error = jaildesc_find(td, jfd_in, &pr, &jdcred);
error = jaildesc_find(td, jfd_in, &pr, NULL);
error = jaildesc_find(td, jfd_in, &jdpr, NULL);
error = jaildesc_find(td, uap->fd, &pr, &jdcred);
error = jaildesc_find(td, uap->fd, &pr, &jdcred);
int jaildesc_find(struct thread *td, int fd, struct prison **prp,