[PATCH] Y2038: add struct __timespec64

[Albert ARIBAUD]

Hi Joseph,

On Wed, 26 Sep 2018 16:28:21 +0000, Joseph Myers
<joseph@codesourcery.com> wrote :

> On Wed, 26 Sep 2018, Albert ARIBAUD wrote:
> 
> > I have just checked the Y2038 syscalls branch I am using currently, and
> > it seems to clear the 32 upper bits of tv_nsec when receiving it from
> > the userland, so yes, we actually don't need to clear it ourselves
> > (I'll have to update the design document, which still assumes
> > otherwise).  
> 
> In that case, is there any reason for the contents of the internal type to 
> differ at all from the contents of the public type?  Or would it be best 
> for both to use the anonymous padding when building for 32-bit long?

The only reason for a difference between an internal (64-bit tv_nsec)
and public (32-bit tv_nsec) type is that we want application source code
to build and run the same for 32-bit and 64-bit time, and Posix defines
tv_nsec as a long (for 32-bit time), so application source code /might/
expect it to be a long for 64-bit time too. However, the worse I can
foresee if we make tv_nsec 64-bit is that some application source code
might copy it into a long, which /may/ trigger gcc to warn if the
compiler options include -Wconversion.

If we consider this not to be a problem, then we can keep the 32-bit
tv_nsec plus anonymous padding in both the public and private struct
__timespec64 types.

Cordialement,
Albert ARIBAUD
3ADEV