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Add C2X timespec_getres

Message ID alpine.DEB.2.22.394.2105132353340.2102509@digraph.polyomino.org.uk
State Superseded
Headers show
Series Add C2X timespec_getres | expand

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Context Check Description
dj/TryBot-apply_patch success Patch applied to master at the time it was sent

Commit Message

Joseph Myers May 13, 2021, 11:54 p.m. UTC
ISO C2X adds a timespec_getres function alongside the C11
timespec_get, with functionality similar to that of POSIX clock_getres
(including allowing a NULL pointer to be passed to the function).
Implement this function for glibc, similarly to the implementation of
timespec_get.

This includes a basic test like that of timespec_get, but no
documentation in the manual, given that TIME_UTC and timespec_get
aren't documented in the manual at all.  The handling of 64-bit time
follows that in timespec_get; people maintaining patch series for
64-bit time will need to update them accordingly (to export
__timespec_getres64, redirect calls in time.h and run the test for
_TIME_BITS=64).

Tested for x86_64 and x86, and with build-many-glibcs.py.

Comments

Paul Eggert May 14, 2021, 6:32 a.m. UTC | #1
On 5/13/21 4:54 PM, Joseph Myers wrote:
> The handling of 64-bit time
> follows that in timespec_get; people maintaining patch series for
> 64-bit time will need to update them accordingly (to export
> __timespec_getres64, redirect calls in time.h and run the test for
> _TIME_BITS=64).

Would it be simpler if new time_t-related APIs support only 64-bit time_t?
Adhemerval Zanella May 14, 2021, 11:52 a.m. UTC | #2
On 14/05/2021 03:32, Paul Eggert wrote:
> On 5/13/21 4:54 PM, Joseph Myers wrote:
>> The handling of 64-bit time
>> follows that in timespec_get; people maintaining patch series for
>> 64-bit time will need to update them accordingly (to export
>> __timespec_getres64, redirect calls in time.h and run the test for
>> _TIME_BITS=64).
> 
> Would it be simpler if new time_t-related APIs support only 64-bit time_t?
> 

We need first to add such support for all architectures.

[1] https://patchwork.sourceware.org/project/glibc/list/?series=1783
Adhemerval Zanella May 14, 2021, 12:06 p.m. UTC | #3
On 13/05/2021 20:54, Joseph Myers wrote:
> ISO C2X adds a timespec_getres function alongside the C11
> timespec_get, with functionality similar to that of POSIX clock_getres
> (including allowing a NULL pointer to be passed to the function).
> Implement this function for glibc, similarly to the implementation of
> timespec_get.
> 
> This includes a basic test like that of timespec_get, but no
> documentation in the manual, given that TIME_UTC and timespec_get
> aren't documented in the manual at all.  The handling of 64-bit time
> follows that in timespec_get; people maintaining patch series for
> 64-bit time will need to update them accordingly (to export
> __timespec_getres64, redirect calls in time.h and run the test for
> _TIME_BITS=64).

Thanks for heads up, I will update the patch accordingly. 

> 
> Tested for x86_64 and x86, and with build-many-glibcs.py.

LGTM, with a minor suggestion on the test.

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

> 
> diff --git a/NEWS b/NEWS
> index a5631af920..266837bf2d 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -23,6 +23,8 @@ Major new features:
>    /proc to be mounted.  However, different than fexecve, if the syscall is not
>    supported by the kernel an error is returned instead of trying a fallback.
>  
> +* The ISO C2X function timespec_getres has been added.
> +
>  Deprecated and removed features, and other changes affecting compatibility:
>  
>  * The function pthread_mutex_consistent_np has been deprecated; programs

Ok.

> diff --git a/include/time.h b/include/time.h
> index e0636132a6..4372bfbd96 100644
> --- a/include/time.h
> +++ b/include/time.h
> @@ -28,6 +28,9 @@ libc_hidden_proto (__clock_gettime)
>  extern __typeof (clock_settime) __clock_settime;
>  libc_hidden_proto (__clock_settime)
>  
> +extern __typeof (clock_getres) __clock_getres;
> +libc_hidden_proto (__clock_getres)
> +
>  extern __typeof (clock_nanosleep) __clock_nanosleep;
>  libc_hidden_proto (__clock_nanosleep);
>  
> @@ -306,6 +309,7 @@ extern double __difftime (time_t time1, time_t time0);
>  # define __clock_nanosleep_time64 __clock_nanosleep
>  # define __clock_gettime64 __clock_gettime
>  # define __timespec_get64 __timespec_get
> +# define __timespec_getres64 __timespec_getres
>  #else
>  extern int __clock_nanosleep_time64 (clockid_t clock_id,
>                                       int flags, const struct __timespec64 *req,
> @@ -315,6 +319,8 @@ extern int __clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp);
>  libc_hidden_proto (__clock_gettime64)
>  extern int __timespec_get64 (struct __timespec64 *ts, int base);
>  libc_hidden_proto (__timespec_get64)
> +extern int __timespec_getres64 (struct __timespec64 *ts, int base);
> +libc_hidden_proto (__timespec_getres64)
>  #endif
>  
>  #if __TIMESIZE == 64

Ok.

> diff --git a/sysdeps/mach/hurd/i386/libc.abilist b/sysdeps/mach/hurd/i386/libc.abilist
> index fb2683edc2..49aa809366 100644
> --- a/sysdeps/mach/hurd/i386/libc.abilist
> +++ b/sysdeps/mach/hurd/i386/libc.abilist
> @@ -2208,6 +2208,7 @@ GLIBC_2.34 __isnanf128 F
>  GLIBC_2.34 __libc_start_main F
>  GLIBC_2.34 _hurd_libc_proc_init F
>  GLIBC_2.34 execveat F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.4 __confstr_chk F
>  GLIBC_2.4 __fgets_chk F
>  GLIBC_2.4 __fgets_unlocked_chk F
> diff --git a/sysdeps/posix/clock_getres.c b/sysdeps/posix/clock_getres.c
> index 0690ae8fcf..1eb26af6f7 100644
> --- a/sysdeps/posix/clock_getres.c
> +++ b/sysdeps/posix/clock_getres.c
> @@ -62,6 +62,7 @@ __clock_getres (clockid_t clock_id, struct timespec *res)
>  
>    return retval;
>  }
> +libc_hidden_def (__clock_getres)
>  
>  versioned_symbol (libc, __clock_getres, clock_getres, GLIBC_2_17);
>  /* clock_getres moved to libc in version 2.17;

Ok.

> diff --git a/sysdeps/unix/sysv/linux/aarch64/libc.abilist b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
> index ee5a5523f4..60b69d0546 100644
> --- a/sysdeps/unix/sysv/linux/aarch64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
> @@ -2431,6 +2431,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/alpha/libc.abilist b/sysdeps/unix/sysv/linux/alpha/libc.abilist
> index 387007f7aa..0fb140518c 100644
> --- a/sysdeps/unix/sysv/linux/alpha/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/alpha/libc.abilist
> @@ -2521,6 +2521,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/arc/libc.abilist b/sysdeps/unix/sysv/linux/arc/libc.abilist
> index 2cfd596853..6ce3b1f6d7 100644
> --- a/sysdeps/unix/sysv/linux/arc/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/arc/libc.abilist
> @@ -2190,6 +2190,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/arm/be/libc.abilist b/sysdeps/unix/sysv/linux/arm/be/libc.abilist
> index f7373394fd..6c4a689b18 100644
> --- a/sysdeps/unix/sysv/linux/arm/be/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/arm/be/libc.abilist
> @@ -300,6 +300,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/arm/le/libc.abilist b/sysdeps/unix/sysv/linux/arm/le/libc.abilist
> index cce828e28a..4557f07a92 100644
> --- a/sysdeps/unix/sysv/linux/arm/le/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/arm/le/libc.abilist
> @@ -297,6 +297,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/clock_getres.c b/sysdeps/unix/sysv/linux/clock_getres.c
> index 14e50fbdf2..d560cd7c48 100644
> --- a/sysdeps/unix/sysv/linux/clock_getres.c
> +++ b/sysdeps/unix/sysv/linux/clock_getres.c
> @@ -79,6 +79,7 @@ __clock_getres (clockid_t clock_id, struct timespec *res)
>    return retval;
>  }
>  #endif
> +libc_hidden_def (__clock_getres)
>  
>  versioned_symbol (libc, __clock_getres, clock_getres, GLIBC_2_17);
>  /* clock_getres moved to libc in version 2.17;

Ok.

> diff --git a/sysdeps/unix/sysv/linux/csky/libc.abilist b/sysdeps/unix/sysv/linux/csky/libc.abilist
> index c74d145e6b..255f02da54 100644
> --- a/sysdeps/unix/sysv/linux/csky/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/csky/libc.abilist
> @@ -2374,6 +2374,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/hppa/libc.abilist b/sysdeps/unix/sysv/linux/hppa/libc.abilist
> index 0d5acb6c89..e81d620b03 100644
> --- a/sysdeps/unix/sysv/linux/hppa/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/hppa/libc.abilist
> @@ -2326,6 +2326,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/i386/libc.abilist b/sysdeps/unix/sysv/linux/i386/libc.abilist
> index e739d7788a..ae7d8d43bd 100644
> --- a/sysdeps/unix/sysv/linux/i386/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/i386/libc.abilist
> @@ -2509,6 +2509,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/ia64/libc.abilist b/sysdeps/unix/sysv/linux/ia64/libc.abilist
> index 975d3d3070..fa64dfab7e 100644
> --- a/sysdeps/unix/sysv/linux/ia64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/ia64/libc.abilist
> @@ -2362,6 +2362,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
> index 18f69e5bd3..4979ab38a7 100644
> --- a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
> @@ -301,6 +301,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
> index c04fc80932..8b478b046c 100644
> --- a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
> @@ -2452,6 +2452,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/microblaze/be/libc.abilist b/sysdeps/unix/sysv/linux/microblaze/be/libc.abilist
> index 91676762d1..784109a6d6 100644
> --- a/sysdeps/unix/sysv/linux/microblaze/be/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/microblaze/be/libc.abilist
> @@ -2425,6 +2425,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist b/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist
> index b61b7efc69..3c62d22b61 100644
> --- a/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist
> @@ -2422,6 +2422,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
> index e053d8ad44..e158878805 100644
> --- a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
> @@ -2417,6 +2417,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
> index d17deca37d..76da5e2e75 100644
> --- a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
> @@ -2415,6 +2415,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
> index e1fda2a811..df7e706649 100644
> --- a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
> @@ -2423,6 +2423,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
> index 4d0673d7a9..1d19304f72 100644
> --- a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
> @@ -2417,6 +2417,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/nios2/libc.abilist b/sysdeps/unix/sysv/linux/nios2/libc.abilist
> index f417ac1d6d..6ea829d268 100644
> --- a/sysdeps/unix/sysv/linux/nios2/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/nios2/libc.abilist
> @@ -2464,6 +2464,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
> index c51ae17a5c..685a25f16b 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
> @@ -2479,6 +2479,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
> index de52f0b14f..d10ff1c8a2 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
> @@ -2512,6 +2512,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist
> index 98dc2c37db..e8c6265c09 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist
> @@ -2327,6 +2327,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libc.abilist
> index 8be99e5849..e3114a652f 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libc.abilist
> @@ -2627,6 +2627,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/riscv/rv32/libc.abilist b/sysdeps/unix/sysv/linux/riscv/rv32/libc.abilist
> index aee2f59bb0..b2aa21f9dc 100644
> --- a/sysdeps/unix/sysv/linux/riscv/rv32/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/riscv/rv32/libc.abilist
> @@ -2192,6 +2192,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist b/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist
> index ef4f86b1ce..efda6de7eb 100644
> --- a/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist
> @@ -2392,6 +2392,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
> index 420c5eb1b0..70f7bb13db 100644
> --- a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
> @@ -2477,6 +2477,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
> index e3fd068bf4..813285c91d 100644
> --- a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
> @@ -2364,6 +2364,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/sh/be/libc.abilist b/sysdeps/unix/sysv/linux/sh/be/libc.abilist
> index 7d43481afa..9a692078d3 100644
> --- a/sysdeps/unix/sysv/linux/sh/be/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/sh/be/libc.abilist
> @@ -2333,6 +2333,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/sh/le/libc.abilist b/sysdeps/unix/sysv/linux/sh/le/libc.abilist
> index adc53a4d54..dc801387cb 100644
> --- a/sysdeps/unix/sysv/linux/sh/le/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/sh/le/libc.abilist
> @@ -2330,6 +2330,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
> index abcdb0deec..015a415e68 100644
> --- a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
> @@ -2470,6 +2470,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
> index 2bfe9c786b..a93c45911e 100644
> --- a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
> @@ -2383,6 +2383,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/timespec_getres.c b/sysdeps/unix/sysv/linux/timespec_getres.c
> new file mode 100644
> index 0000000000..9e679146d3
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/timespec_getres.c
> @@ -0,0 +1,50 @@
> +/* Get resolution of a time base.
> +   Copyright (C) 2021 Free Software Foundation, Inc.
> +   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.
> +
> +   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 <time.h>
> +
> +/* Set TS to resolution of time base BASE.  */
> +int
> +__timespec_getres64 (struct __timespec64 *ts, int base)
> +{
> +  if (base == TIME_UTC)
> +    {
> +      __clock_getres64 (CLOCK_REALTIME, ts);
> +      return base;
> +    }
> +  return 0;
> +}
> +
> +#if __TIMESIZE != 64
> +libc_hidden_def (__timespec_getres64)
> +
> +int
> +__timespec_getres (struct timespec *ts, int base)
> +{
> +  int ret;
> +  struct __timespec64 tp64;
> +
> +  ret = __timespec_getres64 (&tp64, base);
> +
> +  if (ret == TIME_UTC && ts != NULL)
> +    *ts = valid_timespec64_to_timespec (tp64);
> +
> +  return ret;
> +}
> +#endif
> +strong_alias (__timespec_getres, timespec_getres);

Ok.

> diff --git a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
> index b6f9385076..a44b3f33b8 100644
> --- a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
> @@ -2342,6 +2342,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
> index 61ae4b65f4..507de90caf 100644
> --- a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
> @@ -2446,6 +2446,7 @@ GLIBC_2.34 sem_wait F
>  GLIBC_2.34 thrd_detach F
>  GLIBC_2.34 thrd_exit F
>  GLIBC_2.34 thrd_join F
> +GLIBC_2.34 timespec_getres F
>  GLIBC_2.34 tss_create F
>  GLIBC_2.34 tss_delete F
>  GLIBC_2.34 tss_get F
> diff --git a/time/Makefile b/time/Makefile
> index e1faeb3921..805c79c4d0 100644
> --- a/time/Makefile
> +++ b/time/Makefile
> @@ -36,7 +36,7 @@ routines := offtime asctime clock ctime ctime_r difftime \
>  	    stime dysize timegm ftime			 \
>  	    getdate strptime strptime_l			 \
>  	    strftime wcsftime strftime_l wcsftime_l	 \
> -	    timespec_get				 \
> +	    timespec_get timespec_getres		 \
>  	    clock_getcpuclockid clock_getres		 \
>  	    clock_gettime clock_settime clock_nanosleep
>  
> @@ -50,7 +50,7 @@ tests	:= test_time clocktest tst-posixtz tst-strptime tst_wcsftime \
>  	   tst-clock tst-clock2 tst-clock_nanosleep tst-cpuclock1 \
>  	   tst-adjtime tst-ctime tst-difftime tst-mktime4 tst-clock_settime \
>  	   tst-settimeofday tst-itimer tst-gmtime tst-timegm \
> -	   tst-timespec_get
> +	   tst-timespec_get tst-timespec_getres
>  
>  include ../Rules
>  

Ok.

> diff --git a/time/Versions b/time/Versions
> index df22ac7f6a..69dad1e7b0 100644
> --- a/time/Versions
> +++ b/time/Versions
> @@ -74,6 +74,9 @@ libc {
>      clock_getres; clock_gettime; clock_settime; clock_getcpuclockid;
>      clock_nanosleep;
>    }
> +  GLIBC_2.34 {
> +    timespec_getres;
> +  }
>    GLIBC_PRIVATE {
>      # same as clock_gettime; used in other libraries
>      __clock_gettime;

Ok.

> diff --git a/time/clock_getres.c b/time/clock_getres.c
> index 9099b62672..69d2446504 100644
> --- a/time/clock_getres.c
> +++ b/time/clock_getres.c
> @@ -27,6 +27,7 @@ __clock_getres (clockid_t clock_id, struct timespec *res)
>    __set_errno (ENOSYS);
>    return -1;
>  }
> +libc_hidden_def (__clock_getres)
>  
>  versioned_symbol (libc, __clock_getres, clock_getres, GLIBC_2_17);
>  /* clock_getres moved to libc in version 2.17;

Ok.

> diff --git a/time/time.h b/time/time.h
> index 3bf206be0b..5a7f419905 100644
> --- a/time/time.h
> +++ b/time/time.h
> @@ -259,6 +259,13 @@ extern int timespec_get (struct timespec *__ts, int __base)
>  #endif
>  
>  
> +#if __GLIBC_USE (ISOC2X)
> +/* Set TS to resolution of time base BASE.  */
> +extern int timespec_getres (struct timespec *__ts, int __base)
> +     __THROW;
> +#endif
> +
> +
>  #ifdef __USE_XOPEN_EXTENDED
>  /* Set to one of the following values to indicate an error.
>       1  the DATEMSK environment variable is null or undefined,

Ok.

> diff --git a/time/timespec_getres.c b/time/timespec_getres.c
> new file mode 100644
> index 0000000000..2a5f6ede76
> --- /dev/null
> +++ b/time/timespec_getres.c
> @@ -0,0 +1,32 @@
> +/* Get resolution of a time base.
> +   Copyright (C) 2021 Free Software Foundation, Inc.
> +   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.
> +
> +   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 <time.h>
> +
> +
> +/* Set TS to resolution of time base BASE.  */
> +int
> +timespec_getres (struct timespec *ts, int base)
> +{
> +  if (base == TIME_UTC)
> +    {
> +      __clock_getres (CLOCK_REALTIME, ts);
> +      return base;
> +    }
> +  return 0;
> +}

Ok.

> diff --git a/time/tst-timespec_getres.c b/time/tst-timespec_getres.c
> new file mode 100644
> index 0000000000..086f27f6dc
> --- /dev/null
> +++ b/time/tst-timespec_getres.c
> @@ -0,0 +1,45 @@
> +/* Basic tests for timespec_getres.
> +   Copyright (C) 2021 Free Software Foundation, Inc.
> +   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 <time.h>
> +#include <support/check.h>
> +
> +static int
> +do_test (void)
> +{
> +  {
> +    struct timespec ts;
> +    TEST_COMPARE (timespec_getres (&ts, 0), 0);
> +    TEST_COMPARE (timespec_getres (NULL, 0), 0);
> +  }
> +
> +  {
> +    struct timespec ts;
> +    TEST_COMPARE (timespec_getres (&ts, TIME_UTC), TIME_UTC);
> +    /* Expect all supported systems to support TIME_UTC with
> +       resolution better than one second.  */
> +    TEST_VERIFY (ts.tv_sec == 0);
> +    TEST_VERIFY (ts.tv_nsec > 0);
> +    TEST_VERIFY (ts.tv_nsec < 1000000000);
> +    TEST_COMPARE (timespec_getres (NULL, TIME_UTC), TIME_UTC);
> +  }

Maybe also check if timespec_getres and clock_getres (CLOCK_REALTIME) are
similar?

> +
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>
> 

Ok.
Joseph Myers May 17, 2021, 7:54 p.m. UTC | #4
On Thu, 13 May 2021, Paul Eggert wrote:

> On 5/13/21 4:54 PM, Joseph Myers wrote:
> > The handling of 64-bit time
> > follows that in timespec_get; people maintaining patch series for
> > 64-bit time will need to update them accordingly (to export
> > __timespec_getres64, redirect calls in time.h and run the test for
> > _TIME_BITS=64).
> 
> Would it be simpler if new time_t-related APIs support only 64-bit time_t?

No.  It would be more complicated to have a mixture of APIs that are 
supported unconditionally and APIs that are only supported for 
_TIME_BITS=64 and on architectures where time_t defaults to 64-bit.
Joseph Myers May 17, 2021, 8:56 p.m. UTC | #5
On Fri, 14 May 2021, Adhemerval Zanella via Libc-alpha wrote:

> Maybe also check if timespec_getres and clock_getres (CLOCK_REALTIME) are
> similar?

I've committed this version of the patch, with that change.

Add C2X timespec_getres

ISO C2X adds a timespec_getres function alongside the C11
timespec_get, with functionality similar to that of POSIX clock_getres
(including allowing a NULL pointer to be passed to the function).
Implement this function for glibc, similarly to the implementation of
timespec_get.

This includes a basic test like that of timespec_get, but no
documentation in the manual, given that TIME_UTC and timespec_get
aren't documented in the manual at all.  The handling of 64-bit time
follows that in timespec_get; people maintaining patch series for
64-bit time will need to update them accordingly (to export
__timespec_getres64, redirect calls in time.h and run the test for
_TIME_BITS=64).

Tested for x86_64 and x86, and (previous version; only testcase
differs) with build-many-glibcs.py.

diff --git a/NEWS b/NEWS
index a5631af920..266837bf2d 100644
--- a/NEWS
+++ b/NEWS
@@ -23,6 +23,8 @@ Major new features:
   /proc to be mounted.  However, different than fexecve, if the syscall is not
   supported by the kernel an error is returned instead of trying a fallback.
 
+* The ISO C2X function timespec_getres has been added.
+
 Deprecated and removed features, and other changes affecting compatibility:
 
 * The function pthread_mutex_consistent_np has been deprecated; programs
diff --git a/include/time.h b/include/time.h
index e0636132a6..4372bfbd96 100644
--- a/include/time.h
+++ b/include/time.h
@@ -28,6 +28,9 @@ libc_hidden_proto (__clock_gettime)
 extern __typeof (clock_settime) __clock_settime;
 libc_hidden_proto (__clock_settime)
 
+extern __typeof (clock_getres) __clock_getres;
+libc_hidden_proto (__clock_getres)
+
 extern __typeof (clock_nanosleep) __clock_nanosleep;
 libc_hidden_proto (__clock_nanosleep);
 
@@ -306,6 +309,7 @@ extern double __difftime (time_t time1, time_t time0);
 # define __clock_nanosleep_time64 __clock_nanosleep
 # define __clock_gettime64 __clock_gettime
 # define __timespec_get64 __timespec_get
+# define __timespec_getres64 __timespec_getres
 #else
 extern int __clock_nanosleep_time64 (clockid_t clock_id,
                                      int flags, const struct __timespec64 *req,
@@ -315,6 +319,8 @@ extern int __clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp);
 libc_hidden_proto (__clock_gettime64)
 extern int __timespec_get64 (struct __timespec64 *ts, int base);
 libc_hidden_proto (__timespec_get64)
+extern int __timespec_getres64 (struct __timespec64 *ts, int base);
+libc_hidden_proto (__timespec_getres64)
 #endif
 
 #if __TIMESIZE == 64
diff --git a/sysdeps/mach/hurd/i386/libc.abilist b/sysdeps/mach/hurd/i386/libc.abilist
index fb2683edc2..49aa809366 100644
--- a/sysdeps/mach/hurd/i386/libc.abilist
+++ b/sysdeps/mach/hurd/i386/libc.abilist
@@ -2208,6 +2208,7 @@ GLIBC_2.34 __isnanf128 F
 GLIBC_2.34 __libc_start_main F
 GLIBC_2.34 _hurd_libc_proc_init F
 GLIBC_2.34 execveat F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.4 __confstr_chk F
 GLIBC_2.4 __fgets_chk F
 GLIBC_2.4 __fgets_unlocked_chk F
diff --git a/sysdeps/posix/clock_getres.c b/sysdeps/posix/clock_getres.c
index 0690ae8fcf..1eb26af6f7 100644
--- a/sysdeps/posix/clock_getres.c
+++ b/sysdeps/posix/clock_getres.c
@@ -62,6 +62,7 @@ __clock_getres (clockid_t clock_id, struct timespec *res)
 
   return retval;
 }
+libc_hidden_def (__clock_getres)
 
 versioned_symbol (libc, __clock_getres, clock_getres, GLIBC_2_17);
 /* clock_getres moved to libc in version 2.17;
diff --git a/sysdeps/unix/sysv/linux/aarch64/libc.abilist b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
index c8920ed79b..bc051ba9f5 100644
--- a/sysdeps/unix/sysv/linux/aarch64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
@@ -2445,6 +2445,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/alpha/libc.abilist b/sysdeps/unix/sysv/linux/alpha/libc.abilist
index dbc4a25aa3..3bea473d00 100644
--- a/sysdeps/unix/sysv/linux/alpha/libc.abilist
+++ b/sysdeps/unix/sysv/linux/alpha/libc.abilist
@@ -2536,6 +2536,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/arc/libc.abilist b/sysdeps/unix/sysv/linux/arc/libc.abilist
index de790e8ecf..3461527c5a 100644
--- a/sysdeps/unix/sysv/linux/arc/libc.abilist
+++ b/sysdeps/unix/sysv/linux/arc/libc.abilist
@@ -2204,6 +2204,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/arm/be/libc.abilist b/sysdeps/unix/sysv/linux/arm/be/libc.abilist
index 93ca2a5b28..7c3029a7e5 100644
--- a/sysdeps/unix/sysv/linux/arm/be/libc.abilist
+++ b/sysdeps/unix/sysv/linux/arm/be/libc.abilist
@@ -311,6 +311,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/arm/le/libc.abilist b/sysdeps/unix/sysv/linux/arm/le/libc.abilist
index 935b2f99bb..24f5b202e8 100644
--- a/sysdeps/unix/sysv/linux/arm/le/libc.abilist
+++ b/sysdeps/unix/sysv/linux/arm/le/libc.abilist
@@ -308,6 +308,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/clock_getres.c b/sysdeps/unix/sysv/linux/clock_getres.c
index 14e50fbdf2..d560cd7c48 100644
--- a/sysdeps/unix/sysv/linux/clock_getres.c
+++ b/sysdeps/unix/sysv/linux/clock_getres.c
@@ -79,6 +79,7 @@ __clock_getres (clockid_t clock_id, struct timespec *res)
   return retval;
 }
 #endif
+libc_hidden_def (__clock_getres)
 
 versioned_symbol (libc, __clock_getres, clock_getres, GLIBC_2_17);
 /* clock_getres moved to libc in version 2.17;
diff --git a/sysdeps/unix/sysv/linux/csky/libc.abilist b/sysdeps/unix/sysv/linux/csky/libc.abilist
index 32f14e48f6..85851c5fca 100644
--- a/sysdeps/unix/sysv/linux/csky/libc.abilist
+++ b/sysdeps/unix/sysv/linux/csky/libc.abilist
@@ -2388,6 +2388,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/hppa/libc.abilist b/sysdeps/unix/sysv/linux/hppa/libc.abilist
index 4264754c4d..ede69c7ed5 100644
--- a/sysdeps/unix/sysv/linux/hppa/libc.abilist
+++ b/sysdeps/unix/sysv/linux/hppa/libc.abilist
@@ -2341,6 +2341,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/i386/libc.abilist b/sysdeps/unix/sysv/linux/i386/libc.abilist
index 519a060643..c883dc08bc 100644
--- a/sysdeps/unix/sysv/linux/i386/libc.abilist
+++ b/sysdeps/unix/sysv/linux/i386/libc.abilist
@@ -2524,6 +2524,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/ia64/libc.abilist b/sysdeps/unix/sysv/linux/ia64/libc.abilist
index 7a13ab08f6..38fb02e32b 100644
--- a/sysdeps/unix/sysv/linux/ia64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/ia64/libc.abilist
@@ -2377,6 +2377,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
index 9b378e4447..8ee9648828 100644
--- a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
@@ -312,6 +312,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
index b6d0f57e9d..1c51cb41ec 100644
--- a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
@@ -2467,6 +2467,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/microblaze/be/libc.abilist b/sysdeps/unix/sysv/linux/microblaze/be/libc.abilist
index ac5d3656c7..f8b67cd170 100644
--- a/sysdeps/unix/sysv/linux/microblaze/be/libc.abilist
+++ b/sysdeps/unix/sysv/linux/microblaze/be/libc.abilist
@@ -2439,6 +2439,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist b/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist
index 3c47c1c907..edac4a1bb4 100644
--- a/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist
+++ b/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist
@@ -2436,6 +2436,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
index f9b4a578a9..db900c89ab 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
@@ -2432,6 +2432,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
index 9e6c0e1c57..4e15f48b6c 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
@@ -2430,6 +2430,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
index d52f480650..616a6076f1 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
@@ -2438,6 +2438,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
index 86727e2e50..59a353d306 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
@@ -2432,6 +2432,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/nios2/libc.abilist b/sysdeps/unix/sysv/linux/nios2/libc.abilist
index af7e10feb6..0fc42897aa 100644
--- a/sysdeps/unix/sysv/linux/nios2/libc.abilist
+++ b/sysdeps/unix/sysv/linux/nios2/libc.abilist
@@ -2478,6 +2478,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
index 9591c4b782..553ecdabc9 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
@@ -2494,6 +2494,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
index f539198508..7ec438f7b4 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
@@ -2527,6 +2527,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist
index f4d4d39e38..f382e3e296 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist
@@ -2342,6 +2342,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libc.abilist
index 632acd4d74..97ff951418 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libc.abilist
@@ -2641,6 +2641,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/riscv/rv32/libc.abilist b/sysdeps/unix/sysv/linux/riscv/rv32/libc.abilist
index 7080ea1119..5bde5bb508 100644
--- a/sysdeps/unix/sysv/linux/riscv/rv32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/riscv/rv32/libc.abilist
@@ -2206,6 +2206,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist b/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist
index dbdf580afc..42f6d52e13 100644
--- a/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist
@@ -2406,6 +2406,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
index ba6f93488f..2274342208 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
@@ -2492,6 +2492,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
index 4e814da843..14d1c5e7f8 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
@@ -2379,6 +2379,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/sh/be/libc.abilist b/sysdeps/unix/sysv/linux/sh/be/libc.abilist
index ed0575e545..97942ff01a 100644
--- a/sysdeps/unix/sysv/linux/sh/be/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sh/be/libc.abilist
@@ -2348,6 +2348,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/sh/le/libc.abilist b/sysdeps/unix/sysv/linux/sh/le/libc.abilist
index 23c356ea4d..617b673620 100644
--- a/sysdeps/unix/sysv/linux/sh/le/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sh/le/libc.abilist
@@ -2345,6 +2345,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
index dd24236ad8..3c6559bb4f 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
@@ -2485,6 +2485,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
index b3fcaadd70..77f54bb23b 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
@@ -2398,6 +2398,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/timespec_getres.c b/sysdeps/unix/sysv/linux/timespec_getres.c
new file mode 100644
index 0000000000..9e679146d3
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/timespec_getres.c
@@ -0,0 +1,50 @@
+/* Get resolution of a time base.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   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.
+
+   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 <time.h>
+
+/* Set TS to resolution of time base BASE.  */
+int
+__timespec_getres64 (struct __timespec64 *ts, int base)
+{
+  if (base == TIME_UTC)
+    {
+      __clock_getres64 (CLOCK_REALTIME, ts);
+      return base;
+    }
+  return 0;
+}
+
+#if __TIMESIZE != 64
+libc_hidden_def (__timespec_getres64)
+
+int
+__timespec_getres (struct timespec *ts, int base)
+{
+  int ret;
+  struct __timespec64 tp64;
+
+  ret = __timespec_getres64 (&tp64, base);
+
+  if (ret == TIME_UTC && ts != NULL)
+    *ts = valid_timespec64_to_timespec (tp64);
+
+  return ret;
+}
+#endif
+strong_alias (__timespec_getres, timespec_getres);
diff --git a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
index ea61127067..4035841a1e 100644
--- a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
@@ -2357,6 +2357,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
index 8425366915..61ac187db9 100644
--- a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
@@ -2460,6 +2460,7 @@ GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/time/Makefile b/time/Makefile
index e1faeb3921..805c79c4d0 100644
--- a/time/Makefile
+++ b/time/Makefile
@@ -36,7 +36,7 @@ routines := offtime asctime clock ctime ctime_r difftime \
 	    stime dysize timegm ftime			 \
 	    getdate strptime strptime_l			 \
 	    strftime wcsftime strftime_l wcsftime_l	 \
-	    timespec_get				 \
+	    timespec_get timespec_getres		 \
 	    clock_getcpuclockid clock_getres		 \
 	    clock_gettime clock_settime clock_nanosleep
 
@@ -50,7 +50,7 @@ tests	:= test_time clocktest tst-posixtz tst-strptime tst_wcsftime \
 	   tst-clock tst-clock2 tst-clock_nanosleep tst-cpuclock1 \
 	   tst-adjtime tst-ctime tst-difftime tst-mktime4 tst-clock_settime \
 	   tst-settimeofday tst-itimer tst-gmtime tst-timegm \
-	   tst-timespec_get
+	   tst-timespec_get tst-timespec_getres
 
 include ../Rules
 
diff --git a/time/Versions b/time/Versions
index df22ac7f6a..69dad1e7b0 100644
--- a/time/Versions
+++ b/time/Versions
@@ -74,6 +74,9 @@ libc {
     clock_getres; clock_gettime; clock_settime; clock_getcpuclockid;
     clock_nanosleep;
   }
+  GLIBC_2.34 {
+    timespec_getres;
+  }
   GLIBC_PRIVATE {
     # same as clock_gettime; used in other libraries
     __clock_gettime;
diff --git a/time/clock_getres.c b/time/clock_getres.c
index 9099b62672..69d2446504 100644
--- a/time/clock_getres.c
+++ b/time/clock_getres.c
@@ -27,6 +27,7 @@ __clock_getres (clockid_t clock_id, struct timespec *res)
   __set_errno (ENOSYS);
   return -1;
 }
+libc_hidden_def (__clock_getres)
 
 versioned_symbol (libc, __clock_getres, clock_getres, GLIBC_2_17);
 /* clock_getres moved to libc in version 2.17;
diff --git a/time/time.h b/time/time.h
index 3bf206be0b..5a7f419905 100644
--- a/time/time.h
+++ b/time/time.h
@@ -259,6 +259,13 @@ extern int timespec_get (struct timespec *__ts, int __base)
 #endif
 
 
+#if __GLIBC_USE (ISOC2X)
+/* Set TS to resolution of time base BASE.  */
+extern int timespec_getres (struct timespec *__ts, int __base)
+     __THROW;
+#endif
+
+
 #ifdef __USE_XOPEN_EXTENDED
 /* Set to one of the following values to indicate an error.
      1  the DATEMSK environment variable is null or undefined,
diff --git a/time/timespec_getres.c b/time/timespec_getres.c
new file mode 100644
index 0000000000..2a5f6ede76
--- /dev/null
+++ b/time/timespec_getres.c
@@ -0,0 +1,32 @@
+/* Get resolution of a time base.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   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.
+
+   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 <time.h>
+
+
+/* Set TS to resolution of time base BASE.  */
+int
+timespec_getres (struct timespec *ts, int base)
+{
+  if (base == TIME_UTC)
+    {
+      __clock_getres (CLOCK_REALTIME, ts);
+      return base;
+    }
+  return 0;
+}
diff --git a/time/tst-timespec_getres.c b/time/tst-timespec_getres.c
new file mode 100644
index 0000000000..e15824c0ed
--- /dev/null
+++ b/time/tst-timespec_getres.c
@@ -0,0 +1,51 @@
+/* Basic tests for timespec_getres.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   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 <time.h>
+#include <support/check.h>
+
+static int
+do_test (void)
+{
+  {
+    struct timespec ts;
+    TEST_COMPARE (timespec_getres (&ts, 0), 0);
+    TEST_COMPARE (timespec_getres (NULL, 0), 0);
+  }
+
+  {
+    struct timespec ts;
+    TEST_COMPARE (timespec_getres (&ts, TIME_UTC), TIME_UTC);
+    /* Expect all supported systems to support TIME_UTC with
+       resolution better than one second.  */
+    TEST_VERIFY (ts.tv_sec == 0);
+    TEST_VERIFY (ts.tv_nsec > 0);
+    TEST_VERIFY (ts.tv_nsec < 1000000000);
+    TEST_COMPARE (timespec_getres (NULL, TIME_UTC), TIME_UTC);
+    /* Expect the resolution to be the same as that reported for
+       CLOCK_REALTIME with clock_getres.  */
+    struct timespec cts;
+    TEST_COMPARE (clock_getres (CLOCK_REALTIME, &cts), 0);
+    TEST_COMPARE (ts.tv_sec, cts.tv_sec);
+    TEST_COMPARE (ts.tv_nsec, cts.tv_nsec);
+  }
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff mbox series

Patch

diff --git a/NEWS b/NEWS
index a5631af920..266837bf2d 100644
--- a/NEWS
+++ b/NEWS
@@ -23,6 +23,8 @@  Major new features:
   /proc to be mounted.  However, different than fexecve, if the syscall is not
   supported by the kernel an error is returned instead of trying a fallback.
 
+* The ISO C2X function timespec_getres has been added.
+
 Deprecated and removed features, and other changes affecting compatibility:
 
 * The function pthread_mutex_consistent_np has been deprecated; programs
diff --git a/include/time.h b/include/time.h
index e0636132a6..4372bfbd96 100644
--- a/include/time.h
+++ b/include/time.h
@@ -28,6 +28,9 @@  libc_hidden_proto (__clock_gettime)
 extern __typeof (clock_settime) __clock_settime;
 libc_hidden_proto (__clock_settime)
 
+extern __typeof (clock_getres) __clock_getres;
+libc_hidden_proto (__clock_getres)
+
 extern __typeof (clock_nanosleep) __clock_nanosleep;
 libc_hidden_proto (__clock_nanosleep);
 
@@ -306,6 +309,7 @@  extern double __difftime (time_t time1, time_t time0);
 # define __clock_nanosleep_time64 __clock_nanosleep
 # define __clock_gettime64 __clock_gettime
 # define __timespec_get64 __timespec_get
+# define __timespec_getres64 __timespec_getres
 #else
 extern int __clock_nanosleep_time64 (clockid_t clock_id,
                                      int flags, const struct __timespec64 *req,
@@ -315,6 +319,8 @@  extern int __clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp);
 libc_hidden_proto (__clock_gettime64)
 extern int __timespec_get64 (struct __timespec64 *ts, int base);
 libc_hidden_proto (__timespec_get64)
+extern int __timespec_getres64 (struct __timespec64 *ts, int base);
+libc_hidden_proto (__timespec_getres64)
 #endif
 
 #if __TIMESIZE == 64
diff --git a/sysdeps/mach/hurd/i386/libc.abilist b/sysdeps/mach/hurd/i386/libc.abilist
index fb2683edc2..49aa809366 100644
--- a/sysdeps/mach/hurd/i386/libc.abilist
+++ b/sysdeps/mach/hurd/i386/libc.abilist
@@ -2208,6 +2208,7 @@  GLIBC_2.34 __isnanf128 F
 GLIBC_2.34 __libc_start_main F
 GLIBC_2.34 _hurd_libc_proc_init F
 GLIBC_2.34 execveat F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.4 __confstr_chk F
 GLIBC_2.4 __fgets_chk F
 GLIBC_2.4 __fgets_unlocked_chk F
diff --git a/sysdeps/posix/clock_getres.c b/sysdeps/posix/clock_getres.c
index 0690ae8fcf..1eb26af6f7 100644
--- a/sysdeps/posix/clock_getres.c
+++ b/sysdeps/posix/clock_getres.c
@@ -62,6 +62,7 @@  __clock_getres (clockid_t clock_id, struct timespec *res)
 
   return retval;
 }
+libc_hidden_def (__clock_getres)
 
 versioned_symbol (libc, __clock_getres, clock_getres, GLIBC_2_17);
 /* clock_getres moved to libc in version 2.17;
diff --git a/sysdeps/unix/sysv/linux/aarch64/libc.abilist b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
index ee5a5523f4..60b69d0546 100644
--- a/sysdeps/unix/sysv/linux/aarch64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
@@ -2431,6 +2431,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/alpha/libc.abilist b/sysdeps/unix/sysv/linux/alpha/libc.abilist
index 387007f7aa..0fb140518c 100644
--- a/sysdeps/unix/sysv/linux/alpha/libc.abilist
+++ b/sysdeps/unix/sysv/linux/alpha/libc.abilist
@@ -2521,6 +2521,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/arc/libc.abilist b/sysdeps/unix/sysv/linux/arc/libc.abilist
index 2cfd596853..6ce3b1f6d7 100644
--- a/sysdeps/unix/sysv/linux/arc/libc.abilist
+++ b/sysdeps/unix/sysv/linux/arc/libc.abilist
@@ -2190,6 +2190,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/arm/be/libc.abilist b/sysdeps/unix/sysv/linux/arm/be/libc.abilist
index f7373394fd..6c4a689b18 100644
--- a/sysdeps/unix/sysv/linux/arm/be/libc.abilist
+++ b/sysdeps/unix/sysv/linux/arm/be/libc.abilist
@@ -300,6 +300,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/arm/le/libc.abilist b/sysdeps/unix/sysv/linux/arm/le/libc.abilist
index cce828e28a..4557f07a92 100644
--- a/sysdeps/unix/sysv/linux/arm/le/libc.abilist
+++ b/sysdeps/unix/sysv/linux/arm/le/libc.abilist
@@ -297,6 +297,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/clock_getres.c b/sysdeps/unix/sysv/linux/clock_getres.c
index 14e50fbdf2..d560cd7c48 100644
--- a/sysdeps/unix/sysv/linux/clock_getres.c
+++ b/sysdeps/unix/sysv/linux/clock_getres.c
@@ -79,6 +79,7 @@  __clock_getres (clockid_t clock_id, struct timespec *res)
   return retval;
 }
 #endif
+libc_hidden_def (__clock_getres)
 
 versioned_symbol (libc, __clock_getres, clock_getres, GLIBC_2_17);
 /* clock_getres moved to libc in version 2.17;
diff --git a/sysdeps/unix/sysv/linux/csky/libc.abilist b/sysdeps/unix/sysv/linux/csky/libc.abilist
index c74d145e6b..255f02da54 100644
--- a/sysdeps/unix/sysv/linux/csky/libc.abilist
+++ b/sysdeps/unix/sysv/linux/csky/libc.abilist
@@ -2374,6 +2374,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/hppa/libc.abilist b/sysdeps/unix/sysv/linux/hppa/libc.abilist
index 0d5acb6c89..e81d620b03 100644
--- a/sysdeps/unix/sysv/linux/hppa/libc.abilist
+++ b/sysdeps/unix/sysv/linux/hppa/libc.abilist
@@ -2326,6 +2326,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/i386/libc.abilist b/sysdeps/unix/sysv/linux/i386/libc.abilist
index e739d7788a..ae7d8d43bd 100644
--- a/sysdeps/unix/sysv/linux/i386/libc.abilist
+++ b/sysdeps/unix/sysv/linux/i386/libc.abilist
@@ -2509,6 +2509,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/ia64/libc.abilist b/sysdeps/unix/sysv/linux/ia64/libc.abilist
index 975d3d3070..fa64dfab7e 100644
--- a/sysdeps/unix/sysv/linux/ia64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/ia64/libc.abilist
@@ -2362,6 +2362,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
index 18f69e5bd3..4979ab38a7 100644
--- a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
@@ -301,6 +301,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
index c04fc80932..8b478b046c 100644
--- a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
@@ -2452,6 +2452,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/microblaze/be/libc.abilist b/sysdeps/unix/sysv/linux/microblaze/be/libc.abilist
index 91676762d1..784109a6d6 100644
--- a/sysdeps/unix/sysv/linux/microblaze/be/libc.abilist
+++ b/sysdeps/unix/sysv/linux/microblaze/be/libc.abilist
@@ -2425,6 +2425,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist b/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist
index b61b7efc69..3c62d22b61 100644
--- a/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist
+++ b/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist
@@ -2422,6 +2422,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
index e053d8ad44..e158878805 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
@@ -2417,6 +2417,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
index d17deca37d..76da5e2e75 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
@@ -2415,6 +2415,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
index e1fda2a811..df7e706649 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
@@ -2423,6 +2423,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
index 4d0673d7a9..1d19304f72 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
@@ -2417,6 +2417,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/nios2/libc.abilist b/sysdeps/unix/sysv/linux/nios2/libc.abilist
index f417ac1d6d..6ea829d268 100644
--- a/sysdeps/unix/sysv/linux/nios2/libc.abilist
+++ b/sysdeps/unix/sysv/linux/nios2/libc.abilist
@@ -2464,6 +2464,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
index c51ae17a5c..685a25f16b 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
@@ -2479,6 +2479,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
index de52f0b14f..d10ff1c8a2 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
@@ -2512,6 +2512,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist
index 98dc2c37db..e8c6265c09 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist
@@ -2327,6 +2327,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libc.abilist
index 8be99e5849..e3114a652f 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libc.abilist
@@ -2627,6 +2627,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/riscv/rv32/libc.abilist b/sysdeps/unix/sysv/linux/riscv/rv32/libc.abilist
index aee2f59bb0..b2aa21f9dc 100644
--- a/sysdeps/unix/sysv/linux/riscv/rv32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/riscv/rv32/libc.abilist
@@ -2192,6 +2192,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist b/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist
index ef4f86b1ce..efda6de7eb 100644
--- a/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist
@@ -2392,6 +2392,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
index 420c5eb1b0..70f7bb13db 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
@@ -2477,6 +2477,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
index e3fd068bf4..813285c91d 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
@@ -2364,6 +2364,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/sh/be/libc.abilist b/sysdeps/unix/sysv/linux/sh/be/libc.abilist
index 7d43481afa..9a692078d3 100644
--- a/sysdeps/unix/sysv/linux/sh/be/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sh/be/libc.abilist
@@ -2333,6 +2333,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/sh/le/libc.abilist b/sysdeps/unix/sysv/linux/sh/le/libc.abilist
index adc53a4d54..dc801387cb 100644
--- a/sysdeps/unix/sysv/linux/sh/le/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sh/le/libc.abilist
@@ -2330,6 +2330,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
index abcdb0deec..015a415e68 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
@@ -2470,6 +2470,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
index 2bfe9c786b..a93c45911e 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
@@ -2383,6 +2383,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/timespec_getres.c b/sysdeps/unix/sysv/linux/timespec_getres.c
new file mode 100644
index 0000000000..9e679146d3
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/timespec_getres.c
@@ -0,0 +1,50 @@ 
+/* Get resolution of a time base.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   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.
+
+   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 <time.h>
+
+/* Set TS to resolution of time base BASE.  */
+int
+__timespec_getres64 (struct __timespec64 *ts, int base)
+{
+  if (base == TIME_UTC)
+    {
+      __clock_getres64 (CLOCK_REALTIME, ts);
+      return base;
+    }
+  return 0;
+}
+
+#if __TIMESIZE != 64
+libc_hidden_def (__timespec_getres64)
+
+int
+__timespec_getres (struct timespec *ts, int base)
+{
+  int ret;
+  struct __timespec64 tp64;
+
+  ret = __timespec_getres64 (&tp64, base);
+
+  if (ret == TIME_UTC && ts != NULL)
+    *ts = valid_timespec64_to_timespec (tp64);
+
+  return ret;
+}
+#endif
+strong_alias (__timespec_getres, timespec_getres);
diff --git a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
index b6f9385076..a44b3f33b8 100644
--- a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
@@ -2342,6 +2342,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
index 61ae4b65f4..507de90caf 100644
--- a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
@@ -2446,6 +2446,7 @@  GLIBC_2.34 sem_wait F
 GLIBC_2.34 thrd_detach F
 GLIBC_2.34 thrd_exit F
 GLIBC_2.34 thrd_join F
+GLIBC_2.34 timespec_getres F
 GLIBC_2.34 tss_create F
 GLIBC_2.34 tss_delete F
 GLIBC_2.34 tss_get F
diff --git a/time/Makefile b/time/Makefile
index e1faeb3921..805c79c4d0 100644
--- a/time/Makefile
+++ b/time/Makefile
@@ -36,7 +36,7 @@  routines := offtime asctime clock ctime ctime_r difftime \
 	    stime dysize timegm ftime			 \
 	    getdate strptime strptime_l			 \
 	    strftime wcsftime strftime_l wcsftime_l	 \
-	    timespec_get				 \
+	    timespec_get timespec_getres		 \
 	    clock_getcpuclockid clock_getres		 \
 	    clock_gettime clock_settime clock_nanosleep
 
@@ -50,7 +50,7 @@  tests	:= test_time clocktest tst-posixtz tst-strptime tst_wcsftime \
 	   tst-clock tst-clock2 tst-clock_nanosleep tst-cpuclock1 \
 	   tst-adjtime tst-ctime tst-difftime tst-mktime4 tst-clock_settime \
 	   tst-settimeofday tst-itimer tst-gmtime tst-timegm \
-	   tst-timespec_get
+	   tst-timespec_get tst-timespec_getres
 
 include ../Rules
 
diff --git a/time/Versions b/time/Versions
index df22ac7f6a..69dad1e7b0 100644
--- a/time/Versions
+++ b/time/Versions
@@ -74,6 +74,9 @@  libc {
     clock_getres; clock_gettime; clock_settime; clock_getcpuclockid;
     clock_nanosleep;
   }
+  GLIBC_2.34 {
+    timespec_getres;
+  }
   GLIBC_PRIVATE {
     # same as clock_gettime; used in other libraries
     __clock_gettime;
diff --git a/time/clock_getres.c b/time/clock_getres.c
index 9099b62672..69d2446504 100644
--- a/time/clock_getres.c
+++ b/time/clock_getres.c
@@ -27,6 +27,7 @@  __clock_getres (clockid_t clock_id, struct timespec *res)
   __set_errno (ENOSYS);
   return -1;
 }
+libc_hidden_def (__clock_getres)
 
 versioned_symbol (libc, __clock_getres, clock_getres, GLIBC_2_17);
 /* clock_getres moved to libc in version 2.17;
diff --git a/time/time.h b/time/time.h
index 3bf206be0b..5a7f419905 100644
--- a/time/time.h
+++ b/time/time.h
@@ -259,6 +259,13 @@  extern int timespec_get (struct timespec *__ts, int __base)
 #endif
 
 
+#if __GLIBC_USE (ISOC2X)
+/* Set TS to resolution of time base BASE.  */
+extern int timespec_getres (struct timespec *__ts, int __base)
+     __THROW;
+#endif
+
+
 #ifdef __USE_XOPEN_EXTENDED
 /* Set to one of the following values to indicate an error.
      1  the DATEMSK environment variable is null or undefined,
diff --git a/time/timespec_getres.c b/time/timespec_getres.c
new file mode 100644
index 0000000000..2a5f6ede76
--- /dev/null
+++ b/time/timespec_getres.c
@@ -0,0 +1,32 @@ 
+/* Get resolution of a time base.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   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.
+
+   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 <time.h>
+
+
+/* Set TS to resolution of time base BASE.  */
+int
+timespec_getres (struct timespec *ts, int base)
+{
+  if (base == TIME_UTC)
+    {
+      __clock_getres (CLOCK_REALTIME, ts);
+      return base;
+    }
+  return 0;
+}
diff --git a/time/tst-timespec_getres.c b/time/tst-timespec_getres.c
new file mode 100644
index 0000000000..086f27f6dc
--- /dev/null
+++ b/time/tst-timespec_getres.c
@@ -0,0 +1,45 @@ 
+/* Basic tests for timespec_getres.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   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 <time.h>
+#include <support/check.h>
+
+static int
+do_test (void)
+{
+  {
+    struct timespec ts;
+    TEST_COMPARE (timespec_getres (&ts, 0), 0);
+    TEST_COMPARE (timespec_getres (NULL, 0), 0);
+  }
+
+  {
+    struct timespec ts;
+    TEST_COMPARE (timespec_getres (&ts, TIME_UTC), TIME_UTC);
+    /* Expect all supported systems to support TIME_UTC with
+       resolution better than one second.  */
+    TEST_VERIFY (ts.tv_sec == 0);
+    TEST_VERIFY (ts.tv_nsec > 0);
+    TEST_VERIFY (ts.tv_nsec < 1000000000);
+    TEST_COMPARE (timespec_getres (NULL, TIME_UTC), TIME_UTC);
+  }
+
+  return 0;
+}
+
+#include <support/test-driver.c>