l_tochdr
memset(&l_tochdr, 0, sizeof(l_tochdr));
l_tochdr.cdth_trk0 = t_header.starting_track;
l_tochdr.cdth_trk1 = t_header.ending_track;
error = copyout(&l_tochdr, SCARG(uap, data), sizeof l_tochdr);