Messages in this thread |  | | From | Willem de Bruijn <> | Date | Sun, 6 Aug 2017 17:24:20 -0400 | Subject | Re: [PATCH v06 18/36] uapi linux/errqueue.h: include linux/time.h in user space |
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>> > +#ifdef __KERNEL__ >> > +#include <linux/time.h> >> > +#else >> > +#include <time.h> >> > +#endif /* __KERNEL__ */ >> >> This will break applications that include <linux/time.h> manually. >> I previously sent a patch to use libc-compat to make compilation succeed >> when both are included in the case where <linux/time.h> is included after >> <time.h>. >> >> https://lkml.org/lkml/2016/9/12/872 >> >> The inverse will require changes to the libc header to avoid redefining >> symbols already defined by <linux/time.h> >> >> The second patch in that 2-patch set included <linux/time.h> >> unconditionally after the fix. This broke builds that also included >> <time.h> in the wrong order. I did not resubmit the first patch as a >> stand-alone, as it is not sufficient to avoid breakage. > > I wasn't aware of your change, but I was about to send this to fix the > case when glibc <time.h> is included before <linux/time.h>: > > https://github.com/mcfrisk/linux/commit/f3952a27b8a21c6478d26e6246055383483f6a66
There are a few differences between the two. Including <time.h> does not unconditionally define all the symbols. Some are conditional on additional state, such as __timespec_defined.
> but you also ran into problems where <linux/time.h> is included before > <time.h> which need fixes in libc header side. > > So how to proceed with these?
The libc-compat change is a good fix that can be submitted on its own.
> I don't like leaving a few dozen non-compiling header files into uapi.
I agree, but I do not see a simple solution.
Unless libc has the analogous change, including either <time.h> or <linux/time.h> in userspace can unfortunately cause breakage.
The added include if __KERNEL__ is defined should be safe, though.
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