On 05/05/2015 10:26 AM, Ján Tomko wrote:
> On Tue, May 05, 2015 at 10:14:18AM -0600, Eric Blake wrote:
>> On 05/05/2015 10:05 AM, Ján Tomko wrote:
>>> For some reason, we allow a bridge name with %d in it, which we replace
>>> with an unsigned integer to form a bridge name that does not yet exist
>>> on the host.
>>>
>>> + if (def->bridge &&
>>> + (p = strchr(def->bridge, '%')) == strrchr(def->bridge, '%') &&
>>> + strstr(def->bridge, "%d"))
>>
>> Simpler as:
>>
>> if (def->bridge &&
>> strstr(def->bridge, "%d") == strrchr(def->bridge, '%'))
>
> I still don't see it.
>
> [A] strchr(def->bridge, '%')
> [B] strrchr(def->bridge, '%')
> [C] strstr(def->bridge, "%d"))
>
> When def->bridge is '%s%s%s%d', [A] points to the first %s, [B] points
> to the %d and so does [C]
>
> This string would pass the simplified condition (B == C), but not the
> full one (A != C)
Okay, I see your counterargument. Still, strstr() is pretty expensive
compared to just:
if (def->bridge &&
(p = strchr(def->bridge, '%')) == strrchr(def->bridge, '%') &&
p[1] == 'd')
>
> Jan
>>
>> ACK with that simplification.
at which point p is no longer a dead variable, but I've still reduced
the code complexity.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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