readlines

static VALUE
strio_readlines(int argc, VALUE *argv, VALUE self)
{
    struct StringIO *ptr = StringIO(self);
    VALUE ary = rb_ary_new(), line;
    while (!NIL_P(line = strio_getline(argc, argv, readable(ptr)))) {
        rb_ary_push(ary, line);
    }
    return ary;
}