initialize_copy

/* :nodoc: */
static VALUE
rb_struct_init_copy(copy, s)
    VALUE copy, s;
{
    if (copy == s) return copy;
    rb_check_frozen(copy);
    if (!rb_obj_is_instance_of(s, rb_obj_class(copy))) {
        rb_raise(rb_eTypeError, "wrong argument class");
    }
    if (RSTRUCT(copy)->len != RSTRUCT(s)->len) {
        rb_raise(rb_eTypeError, "struct size mismatch");
    }
    MEMCPY(RSTRUCT(copy)->ptr, RSTRUCT(s)->ptr, VALUE, RSTRUCT(copy)->len);

    return copy;
}