Re: [Qemu-devel] [PATCH 1/3] qapi: Allow QMP/QAPI commands to have array inputs

[Anthony Liguori <anthony@codemonkey.ws>]

On 02/22/2012 02:25 PM, Luiz Capitulino wrote:
> On Wed, 22 Feb 2012 11:35:26 -0600
> Anthony Liguori<anthony@codemonkey.ws>  wrote:
>
>> On 02/22/2012 10:12 AM, Jeff Cody wrote:
>>> On 02/22/2012 09:53 AM, Anthony Liguori wrote:
>>>> On 02/20/2012 11:31 AM, Jeff Cody wrote:
>>>>> The QAPI scripts allow for generating commands that receive parameter
>>>>> input consisting of a list of custom structs, but the QMP input paramter
>>>>> checking did not support receiving a qlist as opposed to a qdict for
>>>>> input.
>>>>
>>>> What are you trying to send on the wire? Something like
>>>>
>>>> {"execute": "foo", "arguments": [ "a", "b", "c" ]}
>>>>
>>>> ?
>>>>
>>>> That's not valid per the QMP protocol. "arguments" must always be a QMP
>>>> dictionary.
>>>>
>>>
>>> Not a bare list like that (perhaps my wording was poor), but rather an array of
>>> custom structs, that contain QMP dicts. In this particular case:
>>>
>>> {"execute": "blockdev-group-snapshot-sync", "arguments": [{ "device":
>>> "ide-hd0","snapshot-file":"/some/place/my-image","format": "qcow2" }]}
>>>
>>> When specifying this in the schema JSON file as shown below[1], the QAPI scripts
>>> generate the marshaller&  visitor functions that handle everything correctly.
>>> The monitor code, however, could not deal with the QList container for the input
>>> parameters, prior to passing the data to the generated functions.
>>>
>>>
>>> [1] JSON schema definition:
>>>
>>> { 'type': 'SnapshotDev',
>>> 'data': {'device': 'str', 'snapshot-file': 'str', '*format': 'str' } }
>>>
>>> { 'command': 'blockdev-group-snapshot-sync',
>>> 'data': { 'dev': [ 'SnapshotDev' ] } }
>>
>>
>> This will end up looking like:
>>
>> { "execute": "blockdev-group-snapshot-sync",
>>     "arguments": { "dev": [{"device": "ide-hd0"....}] } }
>>
>> Which should work as expected in QMP.  HMP argument validation doesn't handle
>> arguments of lists but IMHO, it's time to kill that code.
>>
>> Luiz, what do you think?
>
> I don't think the code can just be dropped (if that's what you meant), as there
> are some features on top of it, like auto-completion, suffix support (G, M, k, etc),
> but it certainly can be improved.
>
> Also note that QMP does argument validation too, which is unfortunate enough to
> be based on HMP's,

Once everything is converted to middle mode, this validation can be dropped for 
QMP.  The generated code should do thorough checking of arguments and can handle 
complex types.

Regards,

Anthony Liguori