Re: [RFC v6 03/23] time: Add a timeval with a long tv_sec and tv_usec

[Lukasz Majewski <lukma at denx dot de>]

Hi Alistair,

> On Tue, Jan 14, 2020 at 8:17 PM 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  
> >                            ^^^^^^^^^^^^^ - I'm not so seasoned glibc
> >                            developer, but I think that the _long
> > suffix is a bit misleading.
> >
> >         Maybe it would be more readable to name it as struct
> >         __timeval32 ? In that way one can see from the outset that
> > we operate on 32 bit values.  
> 
> It isn't explicitly 32-bit, it's just always a long which is why I
> went with long in the name instead.
> 
> I'm happy to change the name, it doesn't really matter too much as
> it's only user internally.
> 
> I'll wait to see what others think before changing it.

Yes, I also think that it would be best to wait for more input from the
community.

> 
> 
> Alistair
> 
> >
> >         Community feedback is welcome :-)
> >  
> > > struct to be used internally.
> > > ---
> > >  include/time.h                   | 29
> > > +++++++++++++++++++++++++++++ time/bits/types/struct_timeval.h |
> > > 8 ++++++++ 2 files changed, 37 insertions(+)
> > >
> > > diff --git a/include/time.h b/include/time.h
> > > index e5e8246eac..201342d1ca 100644
> > > --- a/include/time.h
> > > +++ b/include/time.h
> > > @@ -310,6 +310,35 @@ valid_timespec64_to_timeval (const struct
> > > __timespec64 ts64) return tv;
> > >  }
> > >
> > > +/* Conversion functions for converting to/from __timeval_long
> > > +.  If the seconds field of a __timeval_long would
> > > +   overflow, they write { INT32_MAX, 999999 } to the output.  */
> > > +static inline struct timeval
> > > +valid_timeval_long_to_timeval64 (const struct __timeval_long tv)
> > > +{
> > > +  return (struct timeval) { tv.tv_sec, tv.tv_usec };
> > > +}
> > > +
> > > +static inline struct __timeval_long
> > > +valid_timeval64_to_timeval_long (const struct timeval tv64)
> > > +{
> > > +  if (__glibc_unlikely (tv64.tv_sec > (time_t) 2147483647))
> > > +    return (struct __timeval_long) { 2147483647, 999999};
> > > +  return (struct __timeval_long) { tv64.tv_sec, tv64.tv_usec };
> > > +}
> > > +
> > > +static inline struct timespec
> > > +valid_timeval_long_to_timespec (const struct __timeval_long tv)
> > > +{
> > > +  return (struct timespec) { tv.tv_sec, tv.tv_usec * 1000 };
> > > +}
> > > +
> > > +static inline struct __timeval_long
> > > +valid_timespec_to_timeval_long (const struct timespec ts)
> > > +{
> > > +  return (struct __timeval_long) { (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
> > > diff --git a/time/bits/types/struct_timeval.h
> > > b/time/bits/types/struct_timeval.h index 70394ce886..73697689cc
> > > 100644 --- a/time/bits/types/struct_timeval.h
> > > +++ b/time/bits/types/struct_timeval.h
> > > @@ -10,4 +10,12 @@ struct timeval
> > >    __time_t tv_sec;           /* Seconds.  */
> > >    __suseconds_t tv_usec;     /* Microseconds.  */
> > >  };
> > > +
> > > +/* A version of 'struct timeval' with `long` time_t
> > > +   and suseconds_t.  */
> > > +struct __timeval_long
> > > +{
> > > +  long tv_sec;               /* Seconds.  */
> > > +  long tv_usec;              /* Microseconds.  */
> > > +};
> > >  #endif  
> >
> > 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  




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

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