Readline.input=

static VALUE
readline_s_set_input(VALUE self, VALUE input)
{
    rb_io_t *ifp;
    int fd;
    FILE *f;

    if (NIL_P(input)) {
        clear_rl_instream();
    }
    else {
        Check_Type(input, T_FILE);
        GetOpenFile(input, ifp);
        clear_rl_instream();
        fd = rb_cloexec_dup(ifp->fd);
        if (fd == -1)
            rb_sys_fail("dup");
        f = fdopen(fd, "r");
        if (f == NULL) {
            int save_errno = errno;
            close(fd);
            rb_syserr_fail(save_errno, "fdopen");
        }
        rl_instream = readline_rl_instream = f;
        readline_instream = input;
    }
    return input;
}