1  /* clock_getres -- Get the resolution of a POSIX clockid_t.  Linux version.
       2     Copyright (C) 2003-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <sysdep.h>
      20  #include <errno.h>
      21  #include <time.h>
      22  
      23  #include <sysdep-vdso.h>
      24  #include <shlib-compat.h>
      25  #include <kernel-features.h>
      26  
      27  /* Get resolution of clock.  */
      28  int
      29  __clock_getres64 (clockid_t clock_id, struct __timespec64 *res)
      30  {
      31    int r;
      32  
      33  #ifndef __NR_clock_getres_time64
      34  # define __NR_clock_getres_time64 __NR_clock_getres
      35  #endif
      36  
      37  #ifdef HAVE_CLOCK_GETRES64_VSYSCALL
      38    r = INLINE_VSYSCALL (clock_getres_time64, 2, clock_id, res);
      39  #else
      40    r = INLINE_SYSCALL_CALL (clock_getres_time64, clock_id, res);
      41  #endif
      42    if (r == 0 || errno != ENOSYS)
      43      return r;
      44  
      45  #ifndef __ASSUME_TIME64_SYSCALLS
      46    /* Fallback code that uses 32-bit support.  */
      47    struct timespec ts32;
      48  # ifdef HAVE_CLOCK_GETRES_VSYSCALL
      49    r = INLINE_VSYSCALL (clock_getres, 2, clock_id, &ts32);
      50  # else
      51    r = INLINE_SYSCALL_CALL (clock_getres, clock_id, &ts32);
      52  # endif
      53    if (r == 0 && res != NULL)
      54      *res = valid_timespec_to_timespec64 (ts32);
      55  #endif
      56  
      57    return r;
      58  }
      59  
      60  #if __TIMESIZE != 64
      61  libc_hidden_def (__clock_getres64)
      62  
      63  int
      64  __clock_getres (clockid_t clock_id, struct timespec *res)
      65  {
      66    struct __timespec64 ts64;
      67    int retval;
      68  
      69    retval = __clock_getres64 (clock_id, &ts64);
      70    if (retval == 0 && res != NULL)
      71      *res = valid_timespec64_to_timespec (ts64);
      72  
      73    return retval;
      74  }
      75  #endif
      76  libc_hidden_def (__clock_getres)
      77  
      78  versioned_symbol (libc, __clock_getres, clock_getres, GLIBC_2_17);
      79  /* clock_getres moved to libc in version 2.17;
      80     old binaries may expect the symbol version it had in librt.  */
      81  #if SHLIB_COMPAT (libc, GLIBC_2_2, GLIBC_2_17)
      82  strong_alias (__clock_getres, __clock_getres_2);
      83  compat_symbol (libc, __clock_getres_2, clock_getres, GLIBC_2_2);
      84  #endif