Re: [PATCH 3/3] y2038: linux: Provide __utime64 implementation

[Lukasz Majewski <lukma at denx dot de>]

Hi Adhemerval,

> On 07/02/2020 10:00, Lukasz Majewski wrote:
> > This patch replaces auto generated wrapper (as described in
> > sysdeps/unix/sysv/linux/syscalls.list) for utime with one which
> > adds extra support for setting file's access and modification 64
> > bit time on machines with __TIMESIZE != 64.
> > 
> > Internally, the __utimensat_time64 helper function is used. This
> > patch is necessary for having architectures with __WORDSIZE == 32
> > && __TIMESIZE != 64 Y2038 safe.
> > 
> > Moreover, a 32 bit version - __utime has been refactored to
> > internally use __utime64.
> > The __utime is now supposed to be used on systems still supporting
> > 32 bit time (__TIMESIZE != 64) - hence the necessary conversion
> > between struct utimbuf and struct __utimbuf64.
> > 
> > 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 proper usage of both __utime64 and __utime.  
> 
> LGTM with some smalls changes below.
> 
> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> 
> > ---
> >  include/time.h                        |  3 ++
> >  sysdeps/unix/sysv/linux/syscalls.list |  1 -
> >  sysdeps/unix/sysv/linux/utime.c       | 56
> > +++++++++++++++++++++++++++ 3 files changed, 59 insertions(+), 1
> > deletion(-) create mode 100644 sysdeps/unix/sysv/linux/utime.c
> > 
> > diff --git a/include/time.h b/include/time.h
> > index b04747889a..c0d1ea3315 100644
> > --- a/include/time.h
> > +++ b/include/time.h
> > @@ -211,9 +211,12 @@ libc_hidden_proto (__clock_getres64);
> >  #endif
> >  
> >  #if __TIMESIZE == 64
> > +# define __utime64 __utime
> >  # define __utimes64 __utimes
> >  # define __utimensat64 __utimensat
> >  #else
> > +extern int __utime64 (const char *file, const struct __utimbuf64
> > *times); +libc_hidden_proto (__utime64)
> >  extern int __utimes64 (const char *file, const struct __timeval64
> > tvp[2]); libc_hidden_proto (__utimes64)
> >  extern int __utimensat64 (int fd, const char *file,  
> 
> Ok.
> 
> > diff --git a/sysdeps/unix/sysv/linux/syscalls.list
> > b/sysdeps/unix/sysv/linux/syscalls.list index
> > 5d65ed23e0..e40f993495 100644 ---
> > a/sysdeps/unix/sysv/linux/syscalls.list +++
> > b/sysdeps/unix/sysv/linux/syscalls.list @@ -65,7 +65,6 @@
> > swapon		-	swapon		i:si
> > __swapon	swapon swapoff		-
> > swapoff		i:s	__swapoff	swapoff
> > unshare		EXTRA	unshare
> > i:i	unshare uselib		EXTRA	uselib
> > 	i:s	__compat_uselib
> > uselib@GLIBC_2.0:GLIBC_2.23 -utime		-
> > utime		i:sP	utime chown
> > -	chown		i:sii	__libc_chown
> > __chown chown 
> 
> Ok.
> 
> > diff --git a/sysdeps/unix/sysv/linux/utime.c
> > b/sysdeps/unix/sysv/linux/utime.c new file mode 100644
> > index 0000000000..75ee0745ec
> > --- /dev/null
> > +++ b/sysdeps/unix/sysv/linux/utime.c
> > @@ -0,0 +1,56 @@
> > +/* utime -- Change access and modification times of file.  Linux
> > version.
> > +   Copyright (C) 1991-2020 Free Software Foundation, Inc.  
> 
> I think it should be only 2020, since it is a new implementation.

Ok.

> 
> > +   This file is part of the GNU C Library.
> > +
> > +   The GNU C Library is free software; you can redistribute it
> > and/or
> > +   modify it under the terms of the GNU Lesser General Public
> > +   License as published by the Free Software Foundation; either
> > +   version 2.1 of the License, or (at your option) any later
> > version. +
> > +   The GNU C Library is distributed in the hope that it will be
> > useful,
> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > GNU
> > +   Lesser General Public License for more details.
> > +
> > +   You should have received a copy of the GNU Lesser General Public
> > +   License along with the GNU C Library; if not, see
> > +   <https://www.gnu.org/licenses/>.  */
> > +
> > +#include <utime.h>
> > +#include <time.h>
> > +
> > +int
> > +__utime64 (const char *file, const struct __utimbuf64 *times)
> > +{
> > +  struct __timespec64 ts64[2];
> > +
> > +  if (times)  
> 
> No implicit checks.

Please consider my reply to __utimes64 patch.

> 
> > +    {
> > +      ts64[0].tv_sec = times->actime;
> > +      ts64[0].tv_nsec = 0LL;
> > +      ts64[1].tv_sec = times->modtime;
> > +      ts64[1].tv_nsec = 0LL;
> > +    }  
> 
> Should we use type modifiers here?

the __utime64 has following parameters: (const char *file, const struct
__utimbuf64 *times)

Hence, the times has __time64_t actime and modtime members and casting
them to __time64_t tv.sec shall be safe.

> 
> > +
> > +  return __utimensat64_helper (0, file, times ? ts64 : NULL, 0);
> > +}  
> 
> Ok.
> 
> > +
> > +#if __TIMESIZE != 64
> > +libc_hidden_def (__utime64)
> > +
> > +int
> > +__utime (const char *file, const struct utimbuf *times)
> > +{
> > +  struct __utimbuf64 utb64;
> > +
> > +  if (times)  
> 
> No implicit checks.
> 
> > +    {
> > +      utb64.actime = (__time64_t) times->actime;
> > +      utb64.modtime = (__time64_t) times->modtime;  
> 
> Do we need to explicit cast here?

We could get away with not having them (as we cast from smaller range
integer to larger one).

However, the __utime's *times parameter points to struct utimbuf, which
atime and modtime fields are __time_t (32 bit on ARM32).
I've add those casts to emphasize that we do convert to 64 bit types.

> 
> > +    }
> > +
> > +  return __utime64 (file, times ? &utb64 : NULL);
> > +}
> > +#endif
> > +strong_alias (__utime, utime)
> > +libc_hidden_def (utime)
> >   
> 
> Ok.




Best regards,

Lukasz Majewski

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