[PATCH 2/6] time: Add a timeval with a long tv_sec and tv_usec

[Alistair Francis]

On Tue, Feb 4, 2020 at 6:24 AM Lukasz Majewski <lukma@denx.de> wrote:
>
> Hi Alistair,
>
> > On y2038 safe 32-bit systems the Linux kernel expects itimerval to
> > use a 32-bit time_t, even though the other time_t's are 64-bit. To
> > address this let's add a timeval_long struct to be used internally.
>                            ^^^^^^^^^^ - I think that this shall be
>                            updated.

I'm not clear what you mean here, what should be changed?

>
> > ---
> >  include/time.h | 43 +++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 43 insertions(+)
> >
> > diff --git a/include/time.h b/include/time.h
> > index d425c69ede..c2c05bb671 100644
> > --- a/include/time.h
> > +++ b/include/time.h
> > @@ -388,6 +388,49 @@ timespec64_to_timeval64 (const struct
> > __timespec64 ts64) return tv64;
> >  }
> >
> > +/* A version of 'struct timeval' with `long` time_t
> > +   and suseconds_t.  */
> > +struct __timeval32
> > +{
> > +  long tv_sec;         /* Seconds.  */
>
> As __timeval32 will be used in e.g __setitimer64 (which in turn will be
> aliased to setitimer on archs with __WORDSIZE==64 && __TIMESIZE==64)
> long seems to be the best option as it will be 64 bits for those
> machines.

Yep, that's the plan :)

>
> For ones with __WORDSIZE==32 it will be 32 bits instead. Am I correct?

Yes.

>
> > +  long tv_usec;        /* Microseconds.  */
> > +};
> > +
> > +/* Conversion functions for converting to/from __timeval32
> > +.  If the seconds field of a __timeval32 would
> > +   overflow, they write { INT32_MAX, 999999 } to the output.  */
> > +static inline struct __timeval64
> > +valid_timeval32_to_timeval64 (const struct __timeval32 tv)
> > +{
> > +  return (struct __timeval64) { tv.tv_sec, tv.tv_usec };
> > +}
> > +
> > +static inline struct __timeval32
> > +valid_timeval64_to_timeval32 (const struct __timeval64 tv64)
> > +{
> > +  if (__glibc_unlikely (tv64.tv_sec > (time_t) 2147483647))
> > +    return (struct __timeval32) { 2147483647, 999999};
>
> What is the purpose of this code?
>
> The valid_* prefix shall indicate that the timeval64 will fit the
> timeval32 and there is no need for any explicit check.

Ah ok. I'll remove the check from here.

>
> I would expect usage of this function as presented here:
> https://patchwork.ozlabs.org/patch/1230884/
>
> if (! in_time_t_range (tv64.tv_sec))
>   {
>     __set_errno (EOVERFLOW);
>     return -1;
>   }
>
>   if (tv)
>     *tv = valid_timeval64_to_timeval (tv64);

and I have added the check to here.

Alistair

>
>
> > +  return (struct __timeval32) { tv64.tv_sec, tv64.tv_usec };
> > +}
> > +
> > +static inline struct timeval
> > +valid_timeval32_to_timeval (const struct __timeval32 tv)
> > +{
> > +  return (struct timeval) { tv.tv_sec, tv.tv_usec };
> > +}
> > +
> > +static inline struct timespec
> > +valid_timeval32_to_timespec (const struct __timeval32 tv)
> > +{
> > +  return (struct timespec) { tv.tv_sec, tv.tv_usec * 1000 };
> > +}
> > +
> > +static inline struct __timeval32
> > +valid_timespec_to_timeval32 (const struct timespec ts)
> > +{
> > +  return (struct __timeval32) { (time_t) ts.tv_sec, ts.tv_nsec /
> > 1000 }; +}
> > +
> >  /* Check if a value is in the valid nanoseconds range. Return true if
> >     it is, false otherwise.  */
> >  static inline bool
>
>
>
>
> Best regards,
>
> Lukasz Majewski
>
> --
>
> DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de