Re: [Qemu-devel] [PATCH v2 1/4] qmp-event: Avoid qobject_from_jsonf("%"PRId64)

[Eric Blake <eblake@redhat.com>]

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On 11/24/2016 05:00 AM, Markus Armbruster wrote:
> Eric Blake <eblake@redhat.com> writes:
> 

>> +    /* Put -1 to indicate failure of getting host time */
>> +    obj = qobject_from_jsonf("{ 'seconds': %lld, 'microseconds': %lld }",
>> +                             err < 0 ? -1LL : tv.tv_sec,
>> +                             err < 0 ? -1LL : tv.tv_usec);
>>      qdict_put_obj(qdict, "timestamp", obj);
>>  }
> 
> The ternaries must both yield long long for this to work.  They will,
> unless their last operand's rank is greater than long long's, or their
> last operand is unsigned long long.  The latter case should be harmless
> in practice.  The former case would be weird.  Hmm.
> 
> I think it's best to be a bit more explicit here.  Let's cast the last
> operands to long long, or use long long variables.  Your choice.

I think I favor the cast, as in:

err < 0 ? -1LL : (long long) tv.tv_sec

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


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