Re: [PATCH v2 6/7] y2038: linux: Provide __ntp_gettime64 implementation

[Adhemerval Zanella via Libc-alpha <libc-alpha@sourceware.org>]

On 08/05/2020 11:56, Lukasz Majewski wrote:
> This patch provides new __ntp_gettime64 explicit 64 bit function for getting
> time parameters via NTP interface.
> 
> Internally, the __clock_adjtime64 syscall is used instead of __adjtimex. This
> patch is necessary for having architectures with __WORDSIZE == 32 Y2038 safe.
> 
> Moreover, a 32 bit version - __ntp_gettime has been refactored to internally
> use __ntp_gettime64.
> 
> The __ntp_gettime is now supposed to be used on systems still supporting 32
> bit time (__TIMESIZE != 64) - hence the necessary conversions between struct
> ntptimeval and 64 bit struct __ntptimeval64.
> 
> Build tests:
> ./src/scripts/build-many-glibcs.py glibcs
> 
> Run-time tests:
> - Run specific tests on ARM/x86 32bit systems (qemu):
>   https://github.com/lmajewski/meta-y2038 and run tests:
>   https://github.com/lmajewski/y2038-tests/commits/master
> 
> Above tests were performed with Y2038 redirection applied as well as without to
> test the proper usage of both __ntp_gettime64 and __ntp_gettime.

Ok with a doubt below.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

> ---
>  sysdeps/unix/sysv/linux/include/sys/timex.h |  4 ++++
>  sysdeps/unix/sysv/linux/ntp_gettime.c       | 24 ++++++++++++++++++---
>  2 files changed, 25 insertions(+), 3 deletions(-)
> 
> diff --git a/sysdeps/unix/sysv/linux/include/sys/timex.h b/sysdeps/unix/sysv/linux/include/sys/timex.h
> index e762e03230..ef53515803 100644
> --- a/sysdeps/unix/sysv/linux/include/sys/timex.h
> +++ b/sysdeps/unix/sysv/linux/include/sys/timex.h
> @@ -33,6 +33,7 @@ libc_hidden_proto (__adjtimex)
>  #   define __clock_adjtime64 __clock_adjtime
>  #   define ___adjtimex64 ___adjtimex
>  #   define __ntptimeval64 ntptimeval
> +#   define __ntp_gettime64 __ntp_gettime
>  #  else
>  
>  struct __timex64
> @@ -91,6 +92,9 @@ struct __ntptimeval64
>    long int __glibc_reserved3;
>    long int __glibc_reserved4;
>  };
> +extern int __ntp_gettime64 (struct __ntptimeval64 *ntv);
> +libc_hidden_proto (__ntp_gettime64)
> +
>  #  endif
>  
>  /* Convert a known valid struct timex into a struct __timex64.  */

Ok.

> diff --git a/sysdeps/unix/sysv/linux/ntp_gettime.c b/sysdeps/unix/sysv/linux/ntp_gettime.c
> index c8d6a197dc..21aeffadeb 100644
> --- a/sysdeps/unix/sysv/linux/ntp_gettime.c
> +++ b/sysdeps/unix/sysv/linux/ntp_gettime.c
> @@ -17,6 +17,7 @@
>  
>  #define ntp_gettime ntp_gettime_redirect
>  
> +#include <time.h>
>  #include <sys/timex.h>
>  
>  #undef ntp_gettime
> @@ -27,15 +28,32 @@
>  
>  
>  int
> -ntp_gettime (struct ntptimeval *ntv)
> +__ntp_gettime64 (struct __ntptimeval64 *ntv)
>  {
> -  struct timex tntx;
> +  struct __timex64 tntx;
>    int result;
>  
>    tntx.modes = 0;
> -  result = __adjtimex (&tntx);
> +  result = __clock_adjtime64 (CLOCK_REALTIME, &tntx);
>    ntv->time = tntx.time;
>    ntv->maxerror = tntx.maxerror;
>    ntv->esterror = tntx.esterror;
>    return result;
>  }

Ok. Maybe add a comment stating that using CLOCK_REALTIME should
not make the function fail with EINVAL, ENODEV, or EOPNOTSUPP.
I am not sure about EPERM in this situation, should we check for
that and avoid seeting NTV in such situation?

> +
> +#if __TIMESIZE != 64
> +libc_hidden_def (__ntp_gettime64)
> +
> +int
> +__ntp_gettime (struct ntptimeval *ntv)
> +{
> +  struct __ntptimeval64 ntv64;
> +  int result;
> +
> +  result = __ntp_gettime64 (&ntv64);
> +  *ntv = valid_ntptimeval64_to_ntptimeval (ntv64);
> +
> +  return result;
> +}
> +#endif
> +strong_alias (__ntp_gettime, ntp_gettime)
> 

Ok.