Re: [RFC 1/7] y2038: Introduce struct __timespec64

[Lukasz Majewski <lukma at denx dot de>]

Hi Paul,

> >> However, as long as __time64_t and __time_t are not visible to user
> >> code when _TIME_BITS=64, this will address most of my own practical
> >> concerns and should be OK as a compromise.  
> > 
> > To sum up:
> > ----------
> > 
> > 1. __time64_t and __time_t are "exported" (visible
> > in /usr/include/*) always (similar to __off_t and __off64_t).  
> 
> No, the compromise is that these types are "exported" only when
> _TIME_BITS<64. Exporting them when _TIME_BITS==64 is unnecessary and
> confusing. (It's also unnecessary and confusing when _TIME_BITS<64,
> but I'm willing to compromise there because the _TIME_BITS<64 case is
> obsolescent and will eventually go away.)

Ok. As __time64_t has been "hidden" in your previous mktime patch set,
I suppose that this would be changed in the next version?

> 
> > 2. The "exported" struct timespec would look like:
> > 
> > struct timespec
> > {
> > /* Use the original definition for 64-bit arches
> >     or when 64-bit-time by default has *not* been requested */
> > #if __WORDSIZE > 32 || ! defined(__USE_TIME_BITS64)
> >    __time_t tv_sec; /* Seconds. */
> > #else
> >    __time64_t tv_sec;
> > #end
> >    __syscall_slong_t tv_nsec;
> > };  
> 
> Sorry, I'm not following this. Why can't this be the natural 'struct
> timespec { time_t tv_sec; ...; }'? The two forms are equivalent,
> regardless of whether __WORDSIZE > 32 || ! defined(__USE_TIME_BITS64)
> and regardless of what we do about (1), so why use the
> more-complicated and more-confusing definition?

Currently there is __time_t tv_sec, so I've followed the pattern.

I don't mind to change it to time_t tv_sec.

> 
> As Joseph mentioned, there may need to be ifdeffery around tv_nsec
> due to the issue of endian-dependent padding around tv_nsec. 

I thought that we may only be concerned about endiannes on the
"internal" (i.e. struct __timespec64) representation, which would be
passed as the argument to Linux syscalls.

> However,
> there does not need to be ifdeffery around tv_sec. Just use time_t
> there; problem solved.

Ok.

> 
> > 3. Put the internal struct __timespec64 ...
> > into include/time.h and don't introduce separate
> > include/bits/types/struct___timespec64.h
> > 
> > The same idea would be applied to struct timeval  
> 
> Yes.


Best regards,

Lukasz Majewski

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