sysdeps/unix/sysv/linux/clock_getres.c

   1 /* clock_getres -- Get the resolution of a POSIX clockid_t.  Linux version.
   2    Copyright (C) 2003-2021 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 <time64-support.h>
  25 #include <shlib-compat.h>
  26 #include <kernel-features.h>
  27
  28 /* Get resolution of clock.  */
  29 int
  30 __clock_getres64 (clockid_t clock_id, struct __timespec64 *res)
  31 {
  32   int r;
  33
  34 #ifndef __NR_clock_getres_time64
  35 # define __NR_clock_getres_time64 __NR_clock_getres
  36 #endif
  37   if (supports_time64 ())
  38     {
  39 #ifdef HAVE_CLOCK_GETRES64_VSYSCALL
  40       r = INLINE_VSYSCALL (clock_getres_time64, 2, clock_id, res);
  41 #else
  42       r = INLINE_SYSCALL_CALL (clock_getres_time64, clock_id, res);
  43 #endif
  44
  45       if (r == 0 || errno != ENOSYS)
  46         return r;
  47
  48       mark_time64_unsupported ();
  49     }
  50
  51 #ifndef __ASSUME_TIME64_SYSCALLS
  52   /* Fallback code that uses 32-bit support.  */
  53   struct timespec ts32;
  54 # ifdef HAVE_CLOCK_GETRES_VSYSCALL
  55   r = INLINE_VSYSCALL (clock_getres, 2, clock_id, &ts32);
  56 # else
  57   r = INLINE_SYSCALL_CALL (clock_getres, clock_id, &ts32);
  58 # endif
  59   if (r == 0)
  60     *res = valid_timespec_to_timespec64 (ts32);
  61 #endif
  62
  63   return r;
  64 }
  65
  66 #if __TIMESIZE != 64
  67 libc_hidden_def (__clock_getres64)
  68
  69 int
  70 __clock_getres (clockid_t clock_id, struct timespec *res)
  71 {
  72   struct __timespec64 ts64;
  73   int retval;
  74
  75   retval = __clock_getres64 (clock_id, &ts64);
  76   if (retval == 0 && res != NULL)
  77     *res = valid_timespec64_to_timespec (ts64);
  78
  79   return retval;
  80 }
  81 #endif
  82
  83 versioned_symbol (libc, __clock_getres, clock_getres, GLIBC_2_17);
  84 /* clock_getres moved to libc in version 2.17;
  85    old binaries may expect the symbol version it had in librt.  */
  86 #if SHLIB_COMPAT (libc, GLIBC_2_2, GLIBC_2_17)
  87 strong_alias (__clock_getres, __clock_getres_2);
  88 compat_symbol (libc, __clock_getres_2, clock_getres, GLIBC_2_2);
  89 #endif