nptl/sysdeps/pthread/timer_settime.c

   1 /* Copyright (C) 2000-2014 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Kaz Kylheku <kaz@ashi.footprints.net>.
   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 License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    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; see the file COPYING.LIB.  If
  17    not, see <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <pthread.h>
  21 #include <time.h>
  22
  23 #include "posix-timer.h"
  24
  25
  26 /* Set timer TIMERID to VALUE, returning old value in OVLAUE.  */
  27 int
  28 timer_settime (timerid, flags, value, ovalue)
  29      timer_t timerid;
  30      int flags;
  31      const struct itimerspec *value;
  32      struct itimerspec *ovalue;
  33 {
  34   struct timer_node *timer;
  35   struct thread_node *thread = NULL;
  36   struct timespec now;
  37   int have_now = 0, need_wakeup = 0;
  38   int retval = -1;
  39
  40   timer = timer_id2ptr (timerid);
  41   if (timer == NULL)
  42     {
  43       __set_errno (EINVAL);
  44       goto bail;
  45     }
  46
  47   if (value->it_interval.tv_nsec < 0
  48       || value->it_interval.tv_nsec >= 1000000000
  49       || value->it_value.tv_nsec < 0
  50       || value->it_value.tv_nsec >= 1000000000)
  51     {
  52       __set_errno (EINVAL);
  53       goto bail;
  54     }
  55
  56   /* Will need to know current time since this is a relative timer;
  57      might as well make the system call outside of the lock now! */
  58
  59   if ((flags & TIMER_ABSTIME) == 0)
  60     {
  61       clock_gettime (timer->clock, &now);
  62       have_now = 1;
  63     }
  64
  65   pthread_mutex_lock (&__timer_mutex);
  66   timer_addref (timer);
  67
  68   /* One final check of timer validity; this one is possible only
  69      until we have the mutex, because it accesses the inuse flag. */
  70
  71   if (! timer_valid(timer))
  72     {
  73       __set_errno (EINVAL);
  74       goto unlock_bail;
  75     }
  76
  77   if (ovalue != NULL)
  78     {
  79       ovalue->it_interval = timer->value.it_interval;
  80
  81       if (timer->armed)
  82         {
  83           if (! have_now)
  84             {
  85               pthread_mutex_unlock (&__timer_mutex);
  86               clock_gettime (timer->clock, &now);
  87               have_now = 1;
  88               pthread_mutex_lock (&__timer_mutex);
  89               timer_addref (timer);
  90             }
  91
  92           timespec_sub (&ovalue->it_value, &timer->expirytime, &now);
  93         }
  94       else
  95         {
  96           ovalue->it_value.tv_sec = 0;
  97           ovalue->it_value.tv_nsec = 0;
  98         }
  99     }
 100
 101   timer->value = *value;
 102
 103   list_unlink_ip (&timer->links);
 104   timer->armed = 0;
 105
 106   thread = timer->thread;
 107
 108   /* A value of { 0, 0 } causes the timer to be stopped. */
 109   if (value->it_value.tv_sec != 0
 110       || __builtin_expect (value->it_value.tv_nsec != 0, 1))
 111     {
 112       if ((flags & TIMER_ABSTIME) != 0)
 113         /* The user specified the expiration time.  */
 114         timer->expirytime = value->it_value;
 115       else
 116         timespec_add (&timer->expirytime, &now, &value->it_value);
 117
 118       /* Only need to wake up the thread if timer is inserted
 119          at the head of the queue. */
 120       if (thread != NULL)
 121         need_wakeup = __timer_thread_queue_timer (thread, timer);
 122       timer->armed = 1;
 123     }
 124
 125   retval = 0;
 126
 127 unlock_bail:
 128   timer_delref (timer);
 129   pthread_mutex_unlock (&__timer_mutex);
 130
 131 bail:
 132   if (thread != NULL && need_wakeup)
 133     __timer_thread_wakeup (thread);
 134
 135   return retval;
 136 }