Re: [PATCH] do not export kernel's NULL #define to userspace

From: Arnd Bergmann
Date: Wed Mar 21 2012 - 10:17:50 EST


On Wednesday 21 March 2012, Lubos Lunak wrote:
> > If so, we might have to replace it with a __KERNEL_NULL constant
> > or something, like we do for the stuff in linux/types.h, so we
> > don't accidentally break user applications that rely on the
> > header files to be self-contained.
> >
> > I think there is at least a NULL usage in linux/wireless.h and some
> > netfilter headers.
>
> I see. How about the attached patch then?

Strictly speaking, you should not include standard headers from kernel
provided headers, and the problems would be similar to those before
your patch: anyone who currently doesn't include <stddef.h> but has
their own definition of NULL will still get a conflict from including
a kernel header that includes <linux/stddef.h>.

Arnd
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