IO#input_pending?

static VALUE
console_input_pending_p(VALUE io)
{
    rb_io_t *fptr;

    GetOpenFile(io, fptr);
    if (rb_io_read_pending(fptr)) return Qtrue;
#ifdef _WIN32
    {
        DWORD mode;
        HANDLE h = (HANDLE)rb_w32_get_osfhandle(GetReadFD(io));

        if (GetConsoleMode(h, &mode)) return _kbhit() ? Qtrue : Qfalse;
    }
#endif
#if defined HAVE_RB_IO_WAIT
    return RTEST(rb_io_wait(io, RB_INT2NUM(RUBY_IO_READABLE), INT2FIX(0))) ? Qtrue : Qfalse;
#else
    {
        struct timeval timeout = {0, 0};
        int result;

        result = rb_wait_for_single_fd(fptr->fd, RB_WAITFD_IN, &timeout);
        if (result < 0) sys_fail(io);
        return (result & RB_WAITFD_IN) ? Qtrue : Qfalse;
    }
#endif
}