sysdeps/unix/clock_settime.c

   1 /* Copyright (C) 1999-2015 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 <time.h>
  20 #include <sys/time.h>
  21 #include <libc-internal.h>
  22 #include <ldsodefs.h>
  23
  24
  25 #if HP_TIMING_AVAIL && !defined HANDLED_CPUTIME
  26 /* Clock frequency of the processor.  We make it a 64-bit variable
  27    because some jokers are already playing with processors with more
  28    than 4GHz.  */
  29 static hp_timing_t freq;
  30
  31
  32 /* This function is defined in the thread library.  */
  33 extern void __pthread_clock_settime (clockid_t clock_id, hp_timing_t offset)
  34      __attribute__ ((__weak__));
  35
  36
  37 static int
  38 hp_timing_settime (clockid_t clock_id, const struct timespec *tp)
  39 {
  40   hp_timing_t tsc;
  41   hp_timing_t usertime;
  42
  43   /* First thing is to get the current time.  */
  44   HP_TIMING_NOW (tsc);
  45
  46   if (__glibc_unlikely (freq == 0))
  47     {
  48       /* This can only happen if we haven't initialized the `freq'
  49          variable yet.  Do this now. We don't have to protect this
  50          code against multiple execution since all of them should lead
  51          to the same result.  */
  52       freq = __get_clockfreq ();
  53       if (__glibc_unlikely (freq == 0))
  54         /* Something went wrong.  */
  55         return -1;
  56     }
  57
  58   /* Convert the user-provided time into CPU ticks.  */
  59   usertime = tp->tv_sec * freq + (tp->tv_nsec * freq) / 1000000000ull;
  60
  61   /* Determine the offset and use it as the new base value.  */
  62   if (clock_id == CLOCK_PROCESS_CPUTIME_ID
  63       || __pthread_clock_settime == NULL)
  64     GL(dl_cpuclock_offset) = tsc - usertime;
  65   else
  66     __pthread_clock_settime (clock_id, tsc - usertime);
  67
  68   return 0;
  69 }
  70 #endif
  71
  72
  73 /* Set CLOCK to value TP.  */
  74 int
  75 __clock_settime (clockid_t clock_id, const struct timespec *tp)
  76 {
  77   int retval;
  78
  79   /* Make sure the time cvalue is OK.  */
  80   if (tp->tv_nsec < 0 || tp->tv_nsec >= 1000000000)
  81     {
  82       __set_errno (EINVAL);
  83       return -1;
  84     }
  85
  86   switch (clock_id)
  87     {
  88 #define HANDLE_REALTIME \
  89       do {                                                                    \
  90         struct timeval tv;                                                    \
  91         TIMESPEC_TO_TIMEVAL (&tv, tp);                                        \
  92                                                                               \
  93         retval = settimeofday (&tv, NULL);                                    \
  94       } while (0)
  95
  96 #ifdef SYSDEP_SETTIME
  97       SYSDEP_SETTIME;
  98 #endif
  99
 100 #ifndef HANDLED_REALTIME
 101     case CLOCK_REALTIME:
 102       HANDLE_REALTIME;
 103       break;
 104 #endif
 105
 106     default:
 107 #ifdef SYSDEP_SETTIME_CPU
 108       SYSDEP_SETTIME_CPU;
 109 #endif
 110 #ifndef HANDLED_CPUTIME
 111 # if HP_TIMING_AVAIL
 112       if (CPUCLOCK_WHICH (clock_id) == CLOCK_PROCESS_CPUTIME_ID
 113           || CPUCLOCK_WHICH (clock_id) == CLOCK_THREAD_CPUTIME_ID)
 114         retval = hp_timing_settime (clock_id, tp);
 115       else
 116 # endif
 117         {
 118           __set_errno (EINVAL);
 119           retval = -1;
 120         }
 121 #endif
 122       break;
 123     }
 124
 125   return retval;
 126 }
 127 weak_alias (__clock_settime, clock_settime)