libifconfig: Initial code available, looking for feedback

[Kristof Provost]

> On 09 Apr 2016, at 15:59, Marie Helene Kvello-Aune <marieheleneka at gmail.com> wrote:
> I've just pushed an initial version of libifconfig to the github
> repository[2]. I would appreciate feedback, in particular on the API design
> and usage, and especially on how it communicates error state to the
> application.
> 
Awesome. This is important work. I can’t be the only one who’s tired of writing
ioctl() calls to set an IP address.

Is it still your intention to re-implement/refactor/re-whatever ifconfig to use this
library? It seems like it’d be both a good test-case and a good way to ensure
the library stays up to date, and grows new capabilities as features are added
to the network stack.

> Expect the API to break frequently/often for the time being, as it is still
> in very early stages of development.

I’ve had a quick look at the library so far, and have a few remarks.

It might be better to have an explicit (opaque to the library user) handle
to contain both the error state (libifconfig_errstate) and the open sockets (sdkeys).
This would go a long way in making the library thread-safe (because users can now
rely on their error state not getting clobbered by another thread).

Bikeshedding:
 - libifconfig_ seems quite long for a prefix. Perhaps libifc_ or lifc_ ?
 - if (foo != NULL) free(foo); can be safely written as free(foo);

Regards,
Kristof