sysdeps/unix/clock_settime.c

   1 /* Copyright (C) 1999,2000,2001,2002,2003,2004 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, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <errno.h>
  20 #include <time.h>
  21 #include <sys/time.h>
  22 #include <libc-internal.h>
  23 #include <ldsodefs.h>
  24
  25
  26 #if HP_TIMING_AVAIL
  27 /* Clock frequency of the processor.  We make it a 64-bit variable
  28    because some jokers are already playing with processors with more
  29    than 4GHz.  */
  30 static hp_timing_t freq;
  31
  32
  33 /* This function is defined in the thread library.  */
  34 extern void __pthread_clock_settime (clockid_t clock_id, hp_timing_t offset)
  35      __attribute__ ((__weak__));
  36 #endif
  37
  38
  39 /* Set CLOCK to value TP.  */
  40 int
  41 clock_settime (clockid_t clock_id, const struct timespec *tp)
  42 {
  43   int retval;
  44
  45   /* Make sure the time cvalue is OK.  */
  46   if (tp->tv_nsec < 0 || tp->tv_nsec >= 1000000000)
  47     {
  48       __set_errno (EINVAL);
  49       return -1;
  50     }
  51
  52   switch (clock_id)
  53     {
  54 #define HANDLE_REALTIME \
  55       do {                                                                    \
  56         struct timeval tv;                                                    \
  57         TIMESPEC_TO_TIMEVAL (&tv, tp);                                        \
  58                                                                               \
  59         retval = settimeofday (&tv, NULL);                                    \
  60       } while (0)
  61
  62 #ifdef SYSDEP_SETTIME
  63       SYSDEP_SETTIME;
  64 #endif
  65
  66 #ifndef HANDLED_REALTIME
  67     case CLOCK_REALTIME:
  68       HANDLE_REALTIME;
  69       break;
  70 #endif
  71
  72     default:
  73 #if HP_TIMING_AVAIL
  74       if ((clock_id & ((1 << CLOCK_IDFIELD_SIZE) - 1))
  75           != CLOCK_THREAD_CPUTIME_ID)
  76 #endif
  77         {
  78           __set_errno (EINVAL);
  79           retval = -1;
  80           break;
  81         }
  82
  83 #if HP_TIMING_AVAIL
  84       /* FALLTHROUGH.  */
  85     case CLOCK_PROCESS_CPUTIME_ID:
  86       {
  87         hp_timing_t tsc;
  88         hp_timing_t usertime;
  89
  90         /* First thing is to get the current time.  */
  91         HP_TIMING_NOW (tsc);
  92
  93         if (__builtin_expect (freq == 0, 0))
  94           {
  95             /* This can only happen if we haven't initialized the `freq'
  96                variable yet.  Do this now. We don't have to protect this
  97                code against multiple execution since all of them should
  98                lead to the same result.  */
  99             freq = __get_clockfreq ();
 100             if (__builtin_expect (freq == 0, 0))
 101               {
 102                 /* Something went wrong.  */
 103                 retval = -1;
 104                 break;
 105               }
 106           }
 107
 108         /* Convert the user-provided time into CPU ticks.  */
 109         usertime = tp->tv_sec * freq + (tp->tv_nsec * freq) / 1000000000ull;
 110
 111         /* Determine the offset and use it as the new base value.  */
 112         if (clock_id == CLOCK_PROCESS_CPUTIME_ID
 113             || __pthread_clock_settime == NULL)
 114           GL(dl_cpuclock_offset) = tsc - usertime;
 115         else
 116           __pthread_clock_settime (clock_id, tsc - usertime);
 117
 118         retval = 0;
 119       }
 120       break;
 121 #endif
 122     }
 123
 124   return retval;
 125 }