модуль IO::generic_readable

static VALUE
io_getch(int argc, VALUE *argv, VALUE io)
{
    return rb_funcallv(io, id_getc, argc, argv);
}

static VALUE
io_getpass(int argc, VALUE *argv, VALUE io)
{
    VALUE str;

    rb_check_arity(argc, 0, 1);
    prompt(argc, argv, io);
    rb_check_funcall(io, id_flush, 0, 0);
    str = rb_ensure(gets_call, io, puts_call, io);
    return str_chomp(str);
}

static VALUE
strio_read_nonblock(int argc, VALUE *argv, VALUE self)
{
    VALUE opts = Qnil, val;

    rb_scan_args(argc, argv, "11:", NULL, NULL, &opts);

    if (!NIL_P(opts)) {
        argc--;
    }

    val = strio_read(argc, argv, self);
    if (NIL_P(val)) {
        if (!NIL_P(opts) &&
              rb_hash_lookup2(opts, sym_exception, Qundef) == Qfalse)
            return Qnil;
        else
            rb_eof_error();
    }

    return val;
}

static VALUE
strio_readbyte(VALUE self)
{
    VALUE c = rb_funcallv(self, rb_intern("getbyte"), 0, 0);
    if (NIL_P(c)) rb_eof_error();
    return c;
}

static VALUE
strio_readchar(VALUE self)
{
    VALUE c = rb_funcallv(self, rb_intern("getc"), 0, 0);
    if (NIL_P(c)) rb_eof_error();
    return c;
}

static VALUE
strio_readline(int argc, VALUE *argv, VALUE self)
{
    VALUE line = rb_funcallv_kw(self, rb_intern("gets"), argc, argv, RB_PASS_CALLED_KEYWORDS);
    if (NIL_P(line)) rb_eof_error();
    return line;
}

static VALUE
strio_sysread(int argc, VALUE *argv, VALUE self)
{
    VALUE val = rb_funcallv_kw(self, rb_intern("read"), argc, argv, RB_PASS_CALLED_KEYWORDS);
    if (NIL_P(val)) {
        rb_eof_error();
    }
    return val;
}