st_space
error = st_space(st, number - nmarks,
error = st_space(st, number, SP_BLKS, flags);
error = st_space(st, 1, SP_EOM, flags);
error = st_space(st, 0, SP_FILEMARKS,
error = st_space(st, -*nmarks, SP_FILEMARKS, flags);
int st_space(struct st_softc *, int, u_int, int);
if (st_space(st, 0, SP_FILEMARKS, 0)) {