Re: [Qemu-devel] [PATCH 1/3] qmp/hmp: Add QMP getfd command that returns fd

[Corey Bryant <coreyb@linux.vnet.ibm.com>]

On 06/08/2012 06:46 AM, Daniel P. Berrange wrote:
> On Wed, Jun 06, 2012 at 10:04:23AM -0400, Corey Bryant wrote:
>>
>>
>> On 06/05/2012 02:30 PM, Luiz Capitulino wrote:
>>> On Mon,  4 Jun 2012 09:10:08 -0400
>>> Corey Bryant<coreyb@linux.vnet.ibm.com>   wrote:
>>>
>>>> This patch adds QMP support for the getfd command using the QAPI framework.
>>>> Like the HMP getfd command, it is used to pass a file descriptor via
>>>> SCM_RIGHTS.  However, the QMP getfd command also returns the received file
>>>> descriptor, which is a difference in behavior from the HMP getfd command,
>>>> which returns nothing.
>>>
>>> I have a few comments regarding the qapi conversion below, but something
>>> important to discuss is that returning an int the way you're doing it is
>>> certainly incompatible.
>>
>> Thanks for your feedback.
>>
>>>
>>> Today, we return a dict on success:
>>>
>>>   { "return": {} }
>>>
>>> But this patch changes it to:
>>>
>>>   { "return": 42 }
>>>
>>> There are two ways to do this without breaking compatibility:
>>>
>>>   1. Add a new command (say get-file-descriptor)
>>
>> What do you think about using getfd2 for the command name?  I'm
>> thinking getfd2 may be more obvious that it corresponds to closefd.
>> That assumes we'll use the same array internally to store fds and
>> closefd can be used to close the fd opened by
>> get-file-descriptor/getfd2.
>
> How about calling it 'passfd' instead ?  I have always thought
> the name 'getfd' to be a little wierd really, since we're not
> getting an FD from QEMU, we're passing it one that we have.

I agree, thanks for the suggestion.  I know Luiz suggested detailed 
command names, and I think this will be ok and self documents itself 
fairly well with the compact 'passfd'.

I have v2 patches that are just about ready, so I'll update them to use 
'passfd'.

-- 
Regards,
Corey