[libvirt] [PATCH] virterror: Don't invoke error callback for ERR_OK

[Cole Robinson]

On 01/13/2010 04:23 AM, Daniel P. Berrange wrote:
> On Tue, Jan 12, 2010 at 03:57:33PM -0500, Cole Robinson wrote:
>> On 01/12/2010 03:48 PM, Daniel P. Berrange wrote:
>>> On Tue, Jan 12, 2010 at 03:26:28PM -0500, Cole Robinson wrote:
>>>> Since virDispatchError is now responsible for invoking the error callback,
>>>> give it the same semantics as ReportError, which will skip VIR_ERR_OK
>>>> (which is encountered when no error was raised).
>>>>
>>>> This fixes invoking the error callback after every non-erroring API call.
>>>>
>>>> Signed-off-by: Cole Robinson <crobinso at redhat.com>
>>>> ---
>>>>  src/util/virterror.c |    6 +++++-
>>>>  1 files changed, 5 insertions(+), 1 deletions(-)
>>>>
>>>> diff --git a/src/util/virterror.c b/src/util/virterror.c
>>>> index e2128b9..78974ee 100644
>>>> --- a/src/util/virterror.c
>>>> +++ b/src/util/virterror.c
>>>> @@ -603,8 +603,12 @@ virDispatchError(virConnectPtr conn)
>>>>      if (!err)
>>>>          return;
>>>>  
>>>> -    /* Set a generic error message if none is already set */
>>>> +    /* We never used to raise ERR_OK, so maintain existing behavior */
>>>>      if (err->code == VIR_ERR_OK)
>>>> +        return;
>>>> +
>>>> +    /* Set a generic error message if none is already set */
>>>> +    if (!err->message)
>>>>          virErrorGenericFailure(err);
>>>>  
>>>>      /* Copy the global error to per-connection error if needed */
>>>
>>> We should only ever be invoking virDispatchError() in error paths, so
>>> if err->code == VIR_ERR_OK, this means we do need set a generic message
>>> because the earlier code indicated an error but forgot to report one.
>>> So I don't think this is correct.
>>>
>>
>> Ah, I think I wanted to check VIR_ERR_NONE here actually.
>> virDispatchError is called regardless of whether an error is actually
>> raised, so it may receive a zero'd out/empty virLastErrorObject, which
>> is what I'm trying to avoid reporting.
> 
> I still don't think you are correct in that. If you run
> 
>   # grep --after 1 virDispatchError libvirt.c
>         virDispatchError(NULL);
>         return (-1);
>   --
>       virDispatchError(net->conn);
>       return -1;
>   --
>           virDispatchError(NULL);
>           return (-1);
>   --
>       virDispatchError(pool->conn);
>       return -1;
> 
> Then all cases where virDispatchError() is called should be followed by the
> return of an error code, 99% of them are -1 or NULL. There are one or two
> where we use '0' for error as a special case. I don't see any places where
> virDispatchError() is called in a successful return path. So we should
> always be invoking the error callback, and ensuring an error is actually 
> set before doing so.
> 

Whoops, sorry for the confusion. I'll investigate more.

Thanks,
Cole