sysdeps/unix/bsd/bsd4.4/kfreebsd/fbtl/clock_getres.c

   1 /* Copyright (C) 2013 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <stdint.h>
  20 #include <time.h>
  21 #include <sys/time.h>
  22 #include <libc-internal.h>
  23 #include <ldsodefs.h>
  24 #include <sysdep.h>
  25
  26 int __syscall_clock_getres(clockid_t clock_id, struct timespec *tp);
  27 libc_hidden_proto (__syscall_clock_getres)
  28
  29 int __syscall_clock_gettime(clockid_t clock_id, struct timespec *tp);
  30 libc_hidden_proto (__syscall_clock_gettime)
  31
  32 /* Get resolution of clock.  */
  33 int
  34 __clock_getres (clockid_t clock_id, struct timespec *tp)
  35 {
  36   /* we could try to provide fallback
  37      via ??? for CLOCK_REALTIME
  38      via HP_TIMING for CLOCK_PROCESS_CPUTIME_ID,
  39        CLOCK_THREAD_CPUTIME_ID and related timers
  40
  41      for now just pass it to kernel
  42    */
  43   /* the negative clock_id means a CPU-timer, the resolution is same for all of them
  44      the kernel returns resolution regardless whether the timer is accessible,
  45      but POSIX/testsuite expects EINVAL
  46    */
  47
  48   if (clock_id < 0)
  49   {
  50     int rv;
  51     /* we reuse user provided struct timespec */
  52     rv = INLINE_SYSCALL (clock_gettime, 2, clock_id, tp);
  53     if (rv != 0)
  54       return rv;
  55     /* valid, now really get the resolution  */
  56   }
  57
  58   return INLINE_SYSCALL (clock_getres, 2, clock_id, tp);
  59 }
  60 strong_alias (__clock_getres, clock_getres)