t_header
error = ioctlf(fp, CDIOREADTOCHEADER, &t_header);
l_tochdr.cdth_trk0 = t_header.starting_track;
l_tochdr.cdth_trk1 = t_header.ending_track;
error = ioctlf(fp, CDIOREADTOCHEADER, &t_header);
t_header.starting_track != t_header.ending_track;