Re: [Qemu-devel] [PATCH 5/5] block: extend block-commit to accept a string for the backing file

[Eric Blake <eblake@redhat.com>]

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On 05/15/2014 06:26 AM, Benoît Canet wrote:
> The Wednesday 14 May 2014 à 23:20:19 (-0400), Jeff Cody wrote :
>> On some image chains, QEMU may not always be able to resolve the
>> filenames properly, when updating the backing file of an image
>> after a block commit.
>>

>>      } else {
>>          commit_start(bs, base_bs, top_bs, speed, on_error, block_job_cb, bs,
>> -                    &local_err);
>> +                     backing_file, &local_err);
> 
> I don't know QAPI well enough to be sure but are we certain that if 
> has_backing_file == false then backing_file == NULL and not some
> random pointer ?
> 
> If am thinking to add has_backing_file ? backing_file : NULL here.

We are moving towards having qapi guarantee sane defaults for FOO when
has_FOO is false; but aren't there yet.  You are correct that this needs
to guarantee that we aren't passing random memory.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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