sysdeps/pthread/timer_settime.c

   1 /* Copyright (C) 2000-2018 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 (timer_t timerid, int flags, const struct itimerspec *value,
  29                struct itimerspec *ovalue)
  30 {
  31   struct timer_node *timer;
  32   struct thread_node *thread = NULL;
  33   struct timespec now;
  34   int have_now = 0, need_wakeup = 0;
  35   int retval = -1;
  36
  37   timer = timer_id2ptr (timerid);
  38   if (timer == NULL)
  39     {
  40       __set_errno (EINVAL);
  41       goto bail;
  42     }
  43
  44   if (value->it_interval.tv_nsec < 0
  45       || value->it_interval.tv_nsec >= 1000000000
  46       || value->it_value.tv_nsec < 0
  47       || value->it_value.tv_nsec >= 1000000000)
  48     {
  49       __set_errno (EINVAL);
  50       goto bail;
  51     }
  52
  53   /* Will need to know current time since this is a relative timer;
  54      might as well make the system call outside of the lock now! */
  55
  56   if ((flags & TIMER_ABSTIME) == 0)
  57     {
  58       __clock_gettime (timer->clock, &now);
  59       have_now = 1;
  60     }
  61
  62   pthread_mutex_lock (&__timer_mutex);
  63   timer_addref (timer);
  64
  65   /* One final check of timer validity; this one is possible only
  66      until we have the mutex, because it accesses the inuse flag. */
  67
  68   if (! timer_valid(timer))
  69     {
  70       __set_errno (EINVAL);
  71       goto unlock_bail;
  72     }
  73
  74   if (ovalue != NULL)
  75     {
  76       ovalue->it_interval = timer->value.it_interval;
  77
  78       if (timer->armed)
  79         {
  80           if (! have_now)
  81             {
  82               pthread_mutex_unlock (&__timer_mutex);
  83               __clock_gettime (timer->clock, &now);
  84               have_now = 1;
  85               pthread_mutex_lock (&__timer_mutex);
  86               timer_addref (timer);
  87             }
  88
  89           timespec_sub (&ovalue->it_value, &timer->expirytime, &now);
  90         }
  91       else
  92         {
  93           ovalue->it_value.tv_sec = 0;
  94           ovalue->it_value.tv_nsec = 0;
  95         }
  96     }
  97
  98   timer->value = *value;
  99
 100   list_unlink_ip (&timer->links);
 101   timer->armed = 0;
 102
 103   thread = timer->thread;
 104
 105   /* A value of { 0, 0 } causes the timer to be stopped. */
 106   if (value->it_value.tv_sec != 0
 107       || __builtin_expect (value->it_value.tv_nsec != 0, 1))
 108     {
 109       if ((flags & TIMER_ABSTIME) != 0)
 110         /* The user specified the expiration time.  */
 111         timer->expirytime = value->it_value;
 112       else
 113         timespec_add (&timer->expirytime, &now, &value->it_value);
 114
 115       /* Only need to wake up the thread if timer is inserted
 116          at the head of the queue. */
 117       if (thread != NULL)
 118         need_wakeup = __timer_thread_queue_timer (thread, timer);
 119       timer->armed = 1;
 120     }
 121
 122   retval = 0;
 123
 124 unlock_bail:
 125   timer_delref (timer);
 126   pthread_mutex_unlock (&__timer_mutex);
 127
 128 bail:
 129   if (thread != NULL && need_wakeup)
 130     __timer_thread_wakeup (thread);
 131
 132   return retval;
 133 }