ct_enc_width
if (len < ct_enc_width(c))
libedit_private size_t ct_enc_width(wchar_t);
offset += ct_enc_width(*p);
offset += ct_enc_width(*p);
nwread += ct_enc_width(tmp[i]);
w += ct_enc_width(buf[i]);
w += ct_enc_width(end[1]);