[PATCH] libc: add issetugid()

[Rich Felker]

On Sun, Jul 27, 2014 at 01:20:46PM -0400, Anthony G. Basile wrote:
> >I don't think removing the guard would be correct at all; that would
> >expose it even in profiles where the namespace is supposed to conform
> >to POSIX/XSI. If __USE_MISC is inappropriate, the solution would be to
> >move it to a more-inclusive featureset, not a less-inclusive one.
> 
> Yeah since unistd.h is POSIX/XSI and issetugid is not, I guess you
> really do need *some* guard.  As I see it, we have only two
> possibilities (from include/features.h):
> 
>    __USE_BSD            Define 4.3BSD things.
>    __USE_MISC           Define things common to BSD and System V Unix.
> 
> The other choices _USE_POSIX* _USE_XOPEN* _USE_GNU etc are clearly wrong.
> 
> issetugid is not in 4.3BSD, and MISC is more inclusive, hence my
> original choice.
> 
> So now I'm leaning back using __USE_MISC.

Note that uclibc's strlcpy is under __USE_BSD. It's an analogous
function (adopted from later BSD, but not in 4.3BSD) so I think
__USE_BSD might be the right place for issetugid.

Rich