sysdeps/unix/clock_settime.c

   1 /* Copyright (C) 1999-2017 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 <ldsodefs.h>
  22
  23
  24 #if HP_TIMING_AVAIL && !defined HANDLED_CPUTIME
  25 /* Clock frequency of the processor.  We make it a 64-bit variable
  26    because some jokers are already playing with processors with more
  27    than 4GHz.  */
  28 static hp_timing_t freq;
  29
  30
  31 /* This function is defined in the thread library.  */
  32 extern void __pthread_clock_settime (clockid_t clock_id, hp_timing_t offset)
  33      __attribute__ ((__weak__));
  34
  35
  36 static int
  37 hp_timing_settime (clockid_t clock_id, const struct timespec *tp)
  38 {
  39   hp_timing_t tsc;
  40   hp_timing_t usertime;
  41
  42   /* First thing is to get the current time.  */
  43   HP_TIMING_NOW (tsc);
  44
  45   if (__glibc_unlikely (freq == 0))
  46     {
  47       /* This can only happen if we haven't initialized the `freq'
  48          variable yet.  Do this now. We don't have to protect this
  49          code against multiple execution since all of them should lead
  50          to the same result.  */
  51       freq = __get_clockfreq ();
  52       if (__glibc_unlikely (freq == 0))
  53         /* Something went wrong.  */
  54         return -1;
  55     }
  56
  57   /* Convert the user-provided time into CPU ticks.  */
  58   usertime = tp->tv_sec * freq + (tp->tv_nsec * freq) / 1000000000ull;
  59
  60   /* Determine the offset and use it as the new base value.  */
  61   if (clock_id == CLOCK_PROCESS_CPUTIME_ID
  62       || __pthread_clock_settime == NULL)
  63     GL(dl_cpuclock_offset) = tsc - usertime;
  64   else
  65     __pthread_clock_settime (clock_id, tsc - usertime);
  66
  67   return 0;
  68 }
  69 #endif
  70
  71
  72 /* Set CLOCK to value TP.  */
  73 int
  74 __clock_settime (clockid_t clock_id, const struct timespec *tp)
  75 {
  76   int retval;
  77
  78   /* Make sure the time cvalue is OK.  */
  79   if (tp->tv_nsec < 0 || tp->tv_nsec >= 1000000000)
  80     {
  81       __set_errno (EINVAL);
  82       return -1;
  83     }
  84
  85   switch (clock_id)
  86     {
  87 #define HANDLE_REALTIME \
  88       do {                                                                    \
  89         struct timeval tv;                                                    \
  90         TIMESPEC_TO_TIMEVAL (&tv, tp);                                        \
  91                                                                               \
  92         retval = settimeofday (&tv, NULL);                                    \
  93       } while (0)
  94
  95 #ifdef SYSDEP_SETTIME
  96       SYSDEP_SETTIME;
  97 #endif
  98
  99 #ifndef HANDLED_REALTIME
 100     case CLOCK_REALTIME:
 101       HANDLE_REALTIME;
 102       break;
 103 #endif
 104
 105     default:
 106 #ifdef SYSDEP_SETTIME_CPU
 107       SYSDEP_SETTIME_CPU;
 108 #endif
 109 #ifndef HANDLED_CPUTIME
 110 # if HP_TIMING_AVAIL
 111       if (CPUCLOCK_WHICH (clock_id) == CLOCK_PROCESS_CPUTIME_ID
 112           || CPUCLOCK_WHICH (clock_id) == CLOCK_THREAD_CPUTIME_ID)
 113         retval = hp_timing_settime (clock_id, tp);
 114       else
 115 # endif
 116         {
 117           __set_errno (EINVAL);
 118           retval = -1;
 119         }
 120 #endif
 121       break;
 122     }
 123
 124   return retval;
 125 }
 126 weak_alias (__clock_settime, clock_settime)