librt/clock_gettime.c

   1 /* clock_gettime -- Get current time from a POSIX clockid_t.  Linux version.
   2    Copyright (C) 2003, 2004 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    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <sysdep.h>
  21 #include <time.h>
  22 #include <sys/time.h>
  23 #include "kernel-posix-cpu-timers.h"
  24
  25
  26 #define SYSCALL_GETTIME \
  27   retval = INLINE_SYSCALL (clock_gettime, 2, clock_id, tp); \
  28   break
  29
  30 /* The REALTIME and MONOTONIC clock are definitely supported in the kernel.  */
  31 #define SYSDEP_GETTIME                                                        \
  32   SYSDEP_GETTIME_CPUTIME                                                      \
  33   case CLOCK_REALTIME:                                                        \
  34   case CLOCK_MONOTONIC:                                                       \
  35     SYSCALL_GETTIME
  36
  37 /* We handled the REALTIME clock here.  */
  38 #define HANDLED_REALTIME        1
  39 #define HANDLED_CPUTIME 1
  40
  41 #define SYSDEP_GETTIME_CPU SYSCALL_GETTIME
  42 #define SYSDEP_GETTIME_CPUTIME  /* Default catches them too.  */
  43
  44 static inline int
  45 realtime_gettime (struct timespec *tp)
  46 {
  47   struct timeval tv;
  48   int retval = gettimeofday (&tv, NULL);
  49   if (retval == 0)
  50     /* Convert into `timespec'.  */
  51     TIMEVAL_TO_TIMESPEC (&tv, tp);
  52   return retval;
  53 }
  54
  55 /* Get current value of CLOCK and store it in TP.  */
  56 int
  57 clock_gettime (clockid_t clock_id, struct timespec *tp)
  58 {
  59   int retval = -1;
  60 #ifndef HANDLED_REALTIME
  61   struct timeval tv;
  62 #endif
  63
  64   switch (clock_id)
  65     {
  66 #ifdef SYSDEP_GETTIME
  67       SYSDEP_GETTIME;
  68 #endif
  69
  70 #ifndef HANDLED_REALTIME
  71     case CLOCK_REALTIME:
  72       retval = gettimeofday (&tv, NULL);
  73       if (retval == 0)
  74         TIMEVAL_TO_TIMESPEC (&tv, tp);
  75       break;
  76 #endif
  77
  78     default:
  79 #ifdef SYSDEP_GETTIME_CPU
  80       SYSDEP_GETTIME_CPU;
  81 #endif
  82         __set_errno (EINVAL);
  83       break;
  84     }
  85
  86   return retval;
  87 }