Update if.h to match Linux kernel headers?

[Florian Weimer]

On 06/23/2016 06:21 PM, Szabolcs Nagy wrote:
> On 23/06/16 17:06, Florian Weimer wrote:
>> On 06/23/2016 05:57 PM, David Miller wrote:
>>> From: Florian Weimer <fweimer@redhat.com>
>>> Date: Thu, 23 Jun 2016 17:10:54 +0200
>>>
>>>> On 06/17/2016 11:12 AM, Joseph Myers wrote:
>>>>> On Thu, 16 Jun 2016, Carlos O'Donell wrote:
>>>>>
>>>>>> I'm not entirely sure if userspace can make use of these flags, but
>>>>>> one
>>>>>> could conceivably write userspace tools and drivers that would.
>>>>>
>>>>> In <https://sourceware.org/ml/libc-alpha/2014-06/msg00413.html> I
>>>>> noted
>>>>> that I presumed the exclusion of IFF_* values not fitting in a "short"
>>>>> flags field was deliberate.
>>>>
>>>> Can you elaborate way?  Do you fear that we might end up with an ABI
>>>> change if the enum promotes to int, not short?  But doesn't do it that
>>>> already, due to the value IFF_DYNAMIC = 0x8000?
>>>
>>> Because ifr_flags in struct ifreq is 16-bit.
>>
>> But these flags are also used for ifr_flags?

Sorry, I meant ‘ifa_flags’, an important difference.  Sorry.

>> So maybe we should put them into a separate enum block and point to struct ifaddrs and getifaddrs?
>>
>
> i don't see how the enum matters.

I meant that for documentation purposes.

> and ifr_flags is not the only way to use these
> so that should not limit the definitions either.

Yes, ifa_flags uses them (but it's defined in another header files), 
which is why I suggested adding a comment explaining the difference.

Thanks,
Florian