On 03/16/2012 11:26 AM, Eric Blake wrote:
>
>> +
>> + if (!nparams) {
>> + if ((cpu = PyDict_New()) == NULL) {
>> + error = NULL;
>
> Initialize error to NULL at the front, and you won't have to set it here.
>
>> + goto failed;
>> + }
>> +
>> + if (PyList_Append(ret, cpu) < 0) {
>> + Py_DECREF(cpu);
>> + error = NULL;
>> + goto failed;
>> + }
>> +
>> + Py_DECREF(cpu);
>> + return ret;
>
> So why are we populating the list with a single empty dictionary?
> Shouldn't we instead be populating it with one empty dictionary per cpu?
> That is, this code returns [{}], but if ncpus is 4, it should return
> [{},{},{},{}].
In fact, instead of returning early here, you can just say:
if (nparams) {
// get parameters, via for loop over...
>
>> + }
>> + sumparams = nparams * ncpus;
>> +
>> + if (VIR_ALLOC_N(params, sumparams) < 0) {
>> + error = PyErr_NoMemory();
>> + goto failed;
>> + }
>> +
>> + LIBVIRT_BEGIN_ALLOW_THREADS;
>> + i_retval = virDomainGetCPUStats(domain, params, nparams, 0, ncpus, flags);
>
> This will fail if ncpus > 128. You have to do this in a for loop,
> grabbing only 128 cpus per iteration.
>
>> + LIBVIRT_END_ALLOW_THREADS;
>> +
>> + if (i_retval < 0) {
>> + error = VIR_PY_NONE;
>> + goto cleanup;
>> + }
} else {
i_retval = 0;
}
>> +
>> + for (i = 0; i < ncpus; i++) {
>> + if (params[i * nparams].type == 0)
>> + continue;
>
> Technically, this is only possible if you called virDomainGetCPUStats
> with ncpus larger than what the hypervisor already told you to use. But
> I guess it doesn't hurt to leave these two lines in.
then drop these two lines after all (since in the i_retval==0 case,
params might be NULL and this would be a NULL deref),
>
>> +
>> + cpuparams = ¶ms[i * nparams];
This is just an address computation, so it doesn't matter if params is NULL.
>> + if ((cpu = getPyVirTypedParameter(cpuparams, nparams)) == NULL) {
>
> Here, you want to iterate over the number of returned parameters, not
> the number of array slots you passed in. s/nparams/i_retval/
and this will properly create your empty dictionary, since
getPyVirTypedParameter does the right thing if i_retval is 0. That way,
your PyList_Append() code can be reused to populate the correct return
value for ncpus regardless of whether nparams was 0.
--
Eric Blake eblake@xxxxxxxxxx +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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