y2038: linux: Provide __time64 implementation

Message ID 20201015123429.5446-1-lukma@denx.de
State New
Headers show
Series
  • y2038: linux: Provide __time64 implementation
Related show

Commit Message

Lukasz Majewski Oct. 15, 2020, 12:34 p.m.
In the glibc the time function can use vDSO (on power and x86 the
USE_IFUNC_TIME is defined), time syscall or 'default' time() from
./time/time.c (as a fallback).

In this patch the last function (time) has been refactored and moved
to ./sysdeps/unix/sysv/linux/time.c to be Linux specific.

The new __time64 explicit 64 bit function for providing 64 bit value of
seconds after epoch (by internally calling __clock_gettime64) has been
introduced.

Moreover, a 32 bit version - __time has been refactored to internally
use __time64.

The __time is now supposed to be used on systems still supporting 32 bit
time (__TIMESIZE != 64) - hence the necessary check for time_t potential
overflow.

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 __time64 and __time.
---
 include/time.h                 |  7 ++++++
 sysdeps/unix/sysv/linux/time.c | 39 +++++++++++++++++++++++++++++++++-
 2 files changed, 45 insertions(+), 1 deletion(-)

-- 
2.20.1

Comments

H.J. Lu via Libc-alpha Oct. 15, 2020, 1:03 p.m. | #1
On 15/10/2020 09:34, Lukasz Majewski wrote:
> In the glibc the time function can use vDSO (on power and x86 the

> USE_IFUNC_TIME is defined), time syscall or 'default' time() from

> ./time/time.c (as a fallback).

> 

> In this patch the last function (time) has been refactored and moved

> to ./sysdeps/unix/sysv/linux/time.c to be Linux specific.

> 

> The new __time64 explicit 64 bit function for providing 64 bit value of

> seconds after epoch (by internally calling __clock_gettime64) has been

> introduced.

> 

> Moreover, a 32 bit version - __time has been refactored to internally

> use __time64.

> 

> The __time is now supposed to be used on systems still supporting 32 bit

> time (__TIMESIZE != 64) - hence the necessary check for time_t potential

> overflow.

> 

> 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 __time64 and __time.


Looks good in general, some comments below.

> ---

>  include/time.h                 |  7 ++++++

>  sysdeps/unix/sysv/linux/time.c | 39 +++++++++++++++++++++++++++++++++-

>  2 files changed, 45 insertions(+), 1 deletion(-)

> 

> diff --git a/include/time.h b/include/time.h

> index edf6cdf829..caf2af5e74 100644

> --- a/include/time.h

> +++ b/include/time.h

> @@ -317,6 +317,13 @@ extern int __timespec_get64 (struct __timespec64 *ts, int base);

>  libc_hidden_proto (__timespec_get64)

>  #endif

>  

> +#if __TIMESIZE == 64

> +# define __time64 __time

> +#else

> +extern __time64_t __time64 (__time64_t *timer);

> +libc_hidden_proto (__time64)

> +#endif

> +

>  /* Use in the clock_* functions.  Size of the field representing the

>     actual clock ID.  */

>  #define CLOCK_IDFIELD_SIZE	3


Ok.

> diff --git a/sysdeps/unix/sysv/linux/time.c b/sysdeps/unix/sysv/linux/time.c

> index 9d8e573c0a..1a9a7c0413 100644

> --- a/sysdeps/unix/sysv/linux/time.c

> +++ b/sysdeps/unix/sysv/linux/time.c

> @@ -47,5 +47,42 @@ time (time_t *t)

>  }

>  # endif /* !SHARED */

>  #else /* USE_IFUNC_TIME  */


You need to handle USE_IFUNC_TIME, which is still used for powerpc32 and
i686.  I don't think optimizing for vDSO access pay for the complexity in
these cases, so disable it with:

 20 #ifdef USE_IFUNC_TIME && __TIMESIZE == 64
 21 # include <time.h>


> -# include <time/time.c>

> +/* Conversion of time function to support 64 bit time on archs

> +   with __WORDSIZE == 32 and __TIMESIZE == 32/64  */


I think this comment is kinda unnecessary, but if would still want
to add it I would put close to '__time' implementation rather than
the '__time64'.

> +# include <time.h>

> +# include <time-clockid.h>

> +# include <errno.h>

> +/* Return the time now, and store it in *TIMER if not NULL.  */


Space after the include.

> +

> +__time64_t

> +__time64 (__time64_t *timer)

> +{

> +  struct __timespec64 ts;

> +  __clock_gettime64 (TIME_CLOCK_GETTIME_CLOCKID, &ts);

> +

> +  if (timer)


No implicit checks, use 'if (timer != NULL)'.

> +    *timer = ts.tv_sec;

> +  return ts.tv_sec;

> +}

> +

> +# if __TIMESIZE != 64

> +libc_hidden_def (__time64)


Ok.

> +

> +time_t

> +__time (time_t *timer)

> +{

> +  __time64_t t = __time64 (NULL);

> +

> +  if (! in_time_t_range (t))

> +    {

> +      __set_errno (EOVERFLOW);

> +      return -1;

> +    }

> +

> +  if (timer)


No implicit checks, use 'if (timer != NULL)'.

> +    *timer = t;

> +  return t;

> +}

> +# endif

> +weak_alias (__time, time)

>  #endif

>
Lukasz Majewski Oct. 16, 2020, 10:18 a.m. | #2
Hi Adhemerval,

> On 15/10/2020 09:34, Lukasz Majewski wrote:

> > In the glibc the time function can use vDSO (on power and x86 the

> > USE_IFUNC_TIME is defined), time syscall or 'default' time() from

> > ./time/time.c (as a fallback).

> > 

> > In this patch the last function (time) has been refactored and moved

> > to ./sysdeps/unix/sysv/linux/time.c to be Linux specific.

> > 

> > The new __time64 explicit 64 bit function for providing 64 bit

> > value of seconds after epoch (by internally calling

> > __clock_gettime64) has been introduced.

> > 

> > Moreover, a 32 bit version - __time has been refactored to

> > internally use __time64.

> > 

> > The __time is now supposed to be used on systems still supporting

> > 32 bit time (__TIMESIZE != 64) - hence the necessary check for

> > time_t potential overflow.

> > 

> > 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 __time64 and __time.  

> 

> Looks good in general, some comments below.


I'm going to send v2 of this patch.

> 

> > ---

> >  include/time.h                 |  7 ++++++

> >  sysdeps/unix/sysv/linux/time.c | 39

> > +++++++++++++++++++++++++++++++++- 2 files changed, 45

> > insertions(+), 1 deletion(-)

> > 

> > diff --git a/include/time.h b/include/time.h

> > index edf6cdf829..caf2af5e74 100644

> > --- a/include/time.h

> > +++ b/include/time.h

> > @@ -317,6 +317,13 @@ extern int __timespec_get64 (struct

> > __timespec64 *ts, int base); libc_hidden_proto (__timespec_get64)

> >  #endif

> >  

> > +#if __TIMESIZE == 64

> > +# define __time64 __time

> > +#else

> > +extern __time64_t __time64 (__time64_t *timer);

> > +libc_hidden_proto (__time64)

> > +#endif

> > +

> >  /* Use in the clock_* functions.  Size of the field representing

> > the actual clock ID.  */

> >  #define CLOCK_IDFIELD_SIZE	3  

> 

> Ok.

> 

> > diff --git a/sysdeps/unix/sysv/linux/time.c

> > b/sysdeps/unix/sysv/linux/time.c index 9d8e573c0a..1a9a7c0413 100644

> > --- a/sysdeps/unix/sysv/linux/time.c

> > +++ b/sysdeps/unix/sysv/linux/time.c

> > @@ -47,5 +47,42 @@ time (time_t *t)

> >  }

> >  # endif /* !SHARED */

> >  #else /* USE_IFUNC_TIME  */  

> 

> You need to handle USE_IFUNC_TIME, which is still used for powerpc32

> and i686.  I don't think optimizing for vDSO access pay for the

> complexity in these cases, so disable it with:

> 

>  20 #ifdef USE_IFUNC_TIME && __TIMESIZE == 64

>  21 # include <time.h>

> 


In the gettimeofday() conversion patch it was enough to use 
#ifdef __x86_64__ and #ifdef __powerpc64__ in arch specific time.c so

(SHA1: 7455b700279ec8baccf8dd7b119648f8b3e34eec)

> 

> > -# include <time/time.c>

> > +/* Conversion of time function to support 64 bit time on archs

> > +   with __WORDSIZE == 32 and __TIMESIZE == 32/64  */  

> 

> I think this comment is kinda unnecessary, but if would still want

> to add it I would put close to '__time' implementation rather than

> the '__time64'.


Ok. I will remove it.

> 

> > +# include <time.h>

> > +# include <time-clockid.h>

> > +# include <errno.h>

> > +/* Return the time now, and store it in *TIMER if not NULL.  */  

> 

> Space after the include.


Those #includes are following the 
#else /* USE_IFUNC_TIME  */
and the same indentation is used in other places in this file. I've
just followed it.

> 

> > +

> > +__time64_t

> > +__time64 (__time64_t *timer)

> > +{

> > +  struct __timespec64 ts;

> > +  __clock_gettime64 (TIME_CLOCK_GETTIME_CLOCKID, &ts);

> > +

> > +  if (timer)  

> 

> No implicit checks, use 'if (timer != NULL)'.


Ok.

> 

> > +    *timer = ts.tv_sec;

> > +  return ts.tv_sec;

> > +}

> > +

> > +# if __TIMESIZE != 64

> > +libc_hidden_def (__time64)  

> 

> Ok.

> 

> > +

> > +time_t

> > +__time (time_t *timer)

> > +{

> > +  __time64_t t = __time64 (NULL);

> > +

> > +  if (! in_time_t_range (t))

> > +    {

> > +      __set_errno (EOVERFLOW);

> > +      return -1;

> > +    }

> > +

> > +  if (timer)  

> 

> No implicit checks, use 'if (timer != NULL)'.


Ok.

> 

> > +    *timer = t;

> > +  return t;

> > +}

> > +# endif

> > +weak_alias (__time, time)

> >  #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

Patch

diff --git a/include/time.h b/include/time.h
index edf6cdf829..caf2af5e74 100644
--- a/include/time.h
+++ b/include/time.h
@@ -317,6 +317,13 @@  extern int __timespec_get64 (struct __timespec64 *ts, int base);
 libc_hidden_proto (__timespec_get64)
 #endif
 
+#if __TIMESIZE == 64
+# define __time64 __time
+#else
+extern __time64_t __time64 (__time64_t *timer);
+libc_hidden_proto (__time64)
+#endif
+
 /* Use in the clock_* functions.  Size of the field representing the
    actual clock ID.  */
 #define CLOCK_IDFIELD_SIZE	3
diff --git a/sysdeps/unix/sysv/linux/time.c b/sysdeps/unix/sysv/linux/time.c
index 9d8e573c0a..1a9a7c0413 100644
--- a/sysdeps/unix/sysv/linux/time.c
+++ b/sysdeps/unix/sysv/linux/time.c
@@ -47,5 +47,42 @@  time (time_t *t)
 }
 # endif /* !SHARED */
 #else /* USE_IFUNC_TIME  */
-# include <time/time.c>
+/* Conversion of time function to support 64 bit time on archs
+   with __WORDSIZE == 32 and __TIMESIZE == 32/64  */
+# include <time.h>
+# include <time-clockid.h>
+# include <errno.h>
+/* Return the time now, and store it in *TIMER if not NULL.  */
+
+__time64_t
+__time64 (__time64_t *timer)
+{
+  struct __timespec64 ts;
+  __clock_gettime64 (TIME_CLOCK_GETTIME_CLOCKID, &ts);
+
+  if (timer)
+    *timer = ts.tv_sec;
+  return ts.tv_sec;
+}
+
+# if __TIMESIZE != 64
+libc_hidden_def (__time64)
+
+time_t
+__time (time_t *timer)
+{
+  __time64_t t = __time64 (NULL);
+
+  if (! in_time_t_range (t))
+    {
+      __set_errno (EOVERFLOW);
+      return -1;
+    }
+
+  if (timer)
+    *timer = t;
+  return t;
+}
+# endif
+weak_alias (__time, time)
 #endif