[libvirt] [GSoC] Design ideas for implementing cleanup attribute

[Sukrit Bhatnagar]

On 29 May 2018 at 10:36, Michal Privoznik <mprivozn at redhat.com> wrote:
> On 05/28/2018 09:34 AM, Sukrit Bhatnagar wrote:
>>
>> This is what new macros will look like:
>>
>> # define _VIR_TYPE_PTR(type) type##Ptr
>>
>> # define _VIR_ATTR_AUTOFREE_PTR(type)  __attribute__((cleanup(type##Free)))
>> # define _VIR_ATTR_AUTOCLOSE_PTR(type) __attribute__((cleanup(type##Close)))
>> # define _VIR_ATTR_AUTOCLEAN_PTR(type) __attribute__((cleanup(type##Clean)))
>>
>> # define VIR_AUTOFREE_PTR(type) _VIR_ATTR_AUTOFREE_PTR(type) _VIR_TYPE_PTR(type)
>>
>>
>> The problem is that our vir*Free functions take on vir*Ptr as the
>> parameter and not
>> vir*Ptr * (pointer to it).
>>
>> For example, instead of:
>> void virArpTableFree(virArpTablePtr table);
>>
>> we would need:
>> void virArpTableFree(virArpTablePtr *table);
>>
>> if we declare something like:
>> VIR_AUTOFREE_PTR(virArpTable) table = NULL;
>>
>>
>> Also, I tried to add a new function:
>> void virArpTablePtrFree(virArpTablePtr *table)
>> {
>>     size_t i;
>>
>>     if (!*table)
>>         return;
>>
>>     for (i = 0; i < (*table)->n; i++) {
>>         VIR_FREE((*table)->t[i].ipaddr);
>>         VIR_FREE((*table)->t[i].mac);
>>     }
>>     VIR_FREE((*table)->t);
>>     VIR_FREE((*table));
>>     VIR_FREE(table);
>
> As Erik pointed out, this last VIR_FREE(table) looks fishy. However, do
> you have patch that I can apply and reproduce?

When I was using the above function, even without the last VIR_FREE(table),
I got the same error.
I am now using the original virArpTableFree function, not this.

The error is resolved for now. It seems like some other files I modified were
creating trouble. I reset them.