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/* clock_getres -- Get the resolution of a POSIX clockid_t. Linux version.
Copyright (C) 2003-2020 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 <sysdep.h>
#include <errno.h>
#include <time.h>
#include <sysdep-vdso.h>
#include <shlib-compat.h>
#include <kernel-features.h>
/* Get resolution of clock. */
int
__clock_getres64 (clockid_t clock_id, struct __timespec64 *res)
{
#ifdef __ASSUME_TIME64_SYSCALLS
/* 64 bit ABIs or Newer 32-bit ABIs that only support 64-bit time_t. */
# ifndef __NR_clock_getres_time64
# define __NR_clock_getres_time64 __NR_clock_getres
# endif
# ifdef HAVE_CLOCK_GETRES64_VSYSCALL
return INLINE_VSYSCALL (clock_getres_time64, 2, clock_id, res);
# else
return INLINE_SYSCALL_CALL (clock_getres_time64, clock_id, res);
# endif
#else
int r;
/* Old 32-bit ABI with possible 64-bit time_t support. */
# ifdef __NR_clock_getres_time64
/* Avoid issue a __NR_clock_getres_time64 syscall on kernels that do not
support 64-bit time_t. */
static int time64_support = 1;
if (atomic_load_relaxed (&time64_support) != 0)
{
# ifdef HAVE_CLOCK_GETRES64_VSYSCALL
r = INLINE_VSYSCALL (clock_getres_time64, 2, clock_id, res);
# else
r = INLINE_SYSCALL_CALL (clock_getres_time64, clock_id, res);
# endif
if (r == 0 || errno != ENOSYS)
return r;
atomic_store_relaxed (&time64_support, 0);
}
# endif
/* Fallback code that uses 32-bit support. */
struct timespec ts32;
# ifdef HAVE_CLOCK_GETRES_VSYSCALL
r = INLINE_VSYSCALL (clock_getres, 2, clock_id, &ts32);
# else
r = INLINE_SYSCALL_CALL (clock_getres, clock_id, &ts32);
# endif
if (r == 0)
*res = valid_timespec_to_timespec64 (ts32);
return r;
#endif
}
#if __TIMESIZE != 64
libc_hidden_def (__clock_getres64)
int
__clock_getres (clockid_t clock_id, struct timespec *res)
{
struct __timespec64 ts64;
int retval;
retval = __clock_getres64 (clock_id, &ts64);
if (retval == 0 && res != NULL)
*res = valid_timespec64_to_timespec (ts64);
return retval;
}
#endif
versioned_symbol (libc, __clock_getres, clock_getres, GLIBC_2_17);
/* clock_getres moved to libc in version 2.17;
old binaries may expect the symbol version it had in librt. */
#if SHLIB_COMPAT (libc, GLIBC_2_2, GLIBC_2_17)
strong_alias (__clock_getres, __clock_getres_2);
compat_symbol (libc, __clock_getres_2, clock_getres, GLIBC_2_2);
#endif
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