Re: [Qemu-devel] [PATCH v6 06/12] nbd/server: Refactor zero-length option check

[Eric Blake]

On 10/30/2017 09:11 PM, Eric Blake wrote:
> On 10/30/2017 06:22 PM, Vladimir Sementsov-Ogievskiy wrote:
>> 27.10.2017 13:40, Eric Blake wrote:
>>> Consolidate the response for a non-zero-length option payload
>>> into a new function, nbd_reject_length().  This check will
>>> also be used when introducing support for structured replies.
>>>

>>> +                if (length) {
>>> +                    /* Unconditionally drop the connection if the client
>>> +                     * can't start a TLS negotiation correctly */
>>> +                    nbd_reject_length(client, length, option, true,
>>> errp);
>>> +                    return -EINVAL;
>>
>> why not to return nbd_reject_length's result? this EINVAL may not
>> correspond to errp (about EIO for example)..
> 
> Somewhat true, if nbd_reject_length() fails. But nbd_reject_length() may
> also return 0 without setting errp, in which case, maybe this code
> should set errp rather than just blindly returning -EINVAL.
> 
>>
>> with or without this fixed:
>>
>> Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>
>>
> 
> Okay, I'll squash this in, and include it in my pull request to be sent
> shortly.

D'oh. Long week for me. The whole reason I added a 'bool fatal'
parameter was so that I don't have to worry about nbd_reject_length()
returning 0.  So it is instead better to just do:

> --- i/nbd/server.c
> +++ w/nbd/server.c
> @@ -684,8 +684,13 @@ static int nbd_negotiate_options(NBDClient *client,
> uint16_t myflags,
>                  if (length) {
>                      /* Unconditionally drop the connection if the client
>                       * can't start a TLS negotiation correctly */
> -                    nbd_reject_length(client, length, option, true, errp);
> -                    return -EINVAL;
> +                    return nbd_reject_length(client, length, option, true,
> +                                             errp);

rather than repeating an error message.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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