glibc/sysdeps/unix/sysv/linux/timespec_getres.c
Joseph Myers e5ac7bd679 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.
2021-05-17 20:55:21 +00:00

51 lines
1.3 KiB
C

/* 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);