/* 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
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