NFDBYTES
vec_ri = ev_realloc (vec_ri, new_max * NFDBYTES);
vec_ro = ev_realloc (vec_ro, new_max * NFDBYTES); /* could free/malloc */
vec_wi = ev_realloc (vec_wi, new_max * NFDBYTES);
vec_wo = ev_realloc (vec_wo, new_max * NFDBYTES); /* could free/malloc */
vec_eo = ev_realloc (vec_eo, new_max * NFDBYTES); /* could free/malloc */
fd_setsize = vec_max * NFDBYTES;