[PATCH 1/3] y2038: linux: Provide __futimes64 implementation

[Vineet Gupta]

Hi Lukasz,

On 2/17/20 5:17 AM, Lukasz Majewski wrote:
> This patch provides new __futimes64 explicit 64 bit function for setting file's
> 64 bit attributes for access and modification time (by specifying file
> descriptor number).
> 
> Internally, the __utimensat64_helper function is used. This patch is necessary
> for having architectures with __WORDSIZE == 32 Y2038 safe.
> 
> Moreover, a 32 bit version - __futimes has been refactored to internally use
> __futimes64.
> 
> The __futimes is now supposed to be used on systems still supporting 32
> bit time (__TIMESIZE != 64) - hence the necessary conversion of struct timeval
> to 64 bit struct __timeval64.
> 
> The check if struct timevals' usec fields are in the range between 0 and 1000000
> has been removed as Linux kernel performs it internally in the implementation
> of utimensat (the conversion between struct __timeval64 and __timespec64 is not
> relevant for this particular check).
> 
> Last but not least, checks for tvp{64} not being NULL have been preserved from
> the original code as some legacy user space programs may rely on it.
> 
> 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 __futimes64 and __futimes.
> ---
>  include/time.h                    |  3 +++
>  sysdeps/unix/sysv/linux/futimes.c | 42 +++++++++++++++++--------------

ARC is 32-bit + TIMESIZE==64 but the new code is not getting built (instead
generic variant is). How do I override the generic fiel to be built instead ?

>  2 files changed, 26 insertions(+), 19 deletions(-)
> 
> diff --git a/include/time.h b/include/time.h
> index b81ecd5e6e..c24066bf3a 100644
> --- a/include/time.h
> +++ b/include/time.h
> @@ -210,8 +210,11 @@ extern int __utimensat64_helper (int fd, const char *file,
>  libc_hidden_proto (__utimensat64_helper);
>  
>  #if __TIMESIZE == 64
> +# define __futimes64 __futimes
>  # define __futimens64 __futimens
>  #else
> +extern int __futimes64 (int fd, const struct __timeval64 tvp64[2]);
> +libc_hidden_proto (__futimes64);
>  extern int __futimens64 (int fd, const struct __timespec64 tsp[2]);
>  libc_hidden_proto (__futimens64);
>  #endif
> diff --git a/sysdeps/unix/sysv/linux/futimes.c b/sysdeps/unix/sysv/linux/futimes.c
> index 4bea864470..21b41e4138 100644
> --- a/sysdeps/unix/sysv/linux/futimes.c
> +++ b/sysdeps/unix/sysv/linux/futimes.c
> @@ -17,35 +17,39 @@
>     <https://www.gnu.org/licenses/>.  */
>  
>  #include <errno.h>
> -#include <sysdep.h>
> -#include <string.h>
>  #include <time.h>
> -#include <utime.h>
> -#include <sys/time.h>
> -#include <_itoa.h>
> -#include <fcntl.h>
> -
>  
>  /* Change the access time of the file associated with FD to TVP[0] and
> -   the modification time of FILE to TVP[1].
> +   the modification time of FILE to TVP[1].  */
> +int
> +__futimes64 (int fd, const struct __timeval64 tvp64[2])
> +{
> +  /* The utimensat system call expects timespec not timeval.  */
> +  struct __timespec64 ts64[2];
> +  if (tvp64 != NULL)
> +    {
> +      ts64[0] = timeval64_to_timespec64 (tvp64[0]);
> +      ts64[1] = timeval64_to_timespec64 (tvp64[1]);
> +    }
> +
> +  return __utimensat64_helper (fd, NULL, tvp64 ? &ts64[0] : NULL, 0);
> +}
> +
> +#if __TIMESIZE != 64
> +libc_hidden_def (__futimes64)
>  
> -   Starting with 2.6.22 the Linux kernel has the utimensat syscall which
> -   can be used to implement futimes.  */
>  int
>  __futimes (int fd, const struct timeval tvp[2])
>  {
> -  /* The utimensat system call expects timespec not timeval.  */
> -  struct timespec ts[2];
> +  struct __timeval64 tv64[2];
> +
>    if (tvp != NULL)
>      {
> -      if (tvp[0].tv_usec < 0 || tvp[0].tv_usec >= 1000000
> -          || tvp[1].tv_usec < 0 || tvp[1].tv_usec >= 1000000)
> -	return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
> -
> -      TIMEVAL_TO_TIMESPEC (&tvp[0], &ts[0]);
> -      TIMEVAL_TO_TIMESPEC (&tvp[1], &ts[1]);
> +      tv64[0] = valid_timeval_to_timeval64 (tvp[0]);
> +      tv64[1] = valid_timeval_to_timeval64 (tvp[1]);
>      }
>  
> -  return INLINE_SYSCALL (utimensat, 4, fd, NULL, tvp ? &ts : NULL, 0);
> +  return __futimes64 (fd, tvp ? &tv64[0] : NULL);
>  }
> +#endif
>  weak_alias (__futimes, futimes)
>