IO#cursor

static VALUE
console_cursor_pos(VALUE io)
{
#ifdef _WIN32
    rb_console_size_t ws;
    int fd = GetWriteFD(io);
    if (!GetConsoleScreenBufferInfo((HANDLE)rb_w32_get_osfhandle(fd), &ws)) {
        rb_syserr_fail(LAST_ERROR, 0);
    }
    return rb_assoc_new(UINT2NUM(ws.dwCursorPosition.Y), UINT2NUM(ws.dwCursorPosition.X));
#else
    static const struct query_args query = {"\033[6n", 0};
    VALUE resp = console_vt_response(0, 0, io, &query);
    VALUE row, column, term;
    unsigned int r, c;
    if (!RB_TYPE_P(resp, T_ARRAY) || RARRAY_LEN(resp) != 3) return Qnil;
    term = RARRAY_AREF(resp, 2);
    if (!RB_TYPE_P(term, T_STRING) || RSTRING_LEN(term) != 1) return Qnil;
    if (RSTRING_PTR(term)[0] != 'R') return Qnil;
    row = RARRAY_AREF(resp, 0);
    column = RARRAY_AREF(resp, 1);
    rb_ary_resize(resp, 2);
    r = NUM2UINT(row) - 1;
    c = NUM2UINT(column) - 1;
    RARRAY_ASET(resp, 0, INT2NUM(r));
    RARRAY_ASET(resp, 1, INT2NUM(c));
    return resp;
#endif
}