rt/timer_settime.c

   1 /* Copyright (C) 2000-2022 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 License as
   6    published by the Free Software Foundation; either version 2.1 of the
   7    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; see the file COPYING.LIB.  If
  16    not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <pthread.h>
  20 #include <time.h>
  21
  22 #include "posix-timer.h"
  23
  24
  25 /* Set timer TIMERID to VALUE, returning old value in OVLAUE.  */
  26 int
  27 timer_settime (timer_t timerid, int flags, const struct itimerspec *value,
  28                struct itimerspec *ovalue)
  29 {
  30   struct timer_node *timer;
  31   struct thread_node *thread = NULL;
  32   struct timespec now;
  33   int have_now = 0, need_wakeup = 0;
  34   int retval = -1;
  35
  36   timer = timer_id2ptr (timerid);
  37   if (timer == NULL)
  38     {
  39       __set_errno (EINVAL);
  40       goto bail;
  41     }
  42
  43   if (! valid_nanoseconds (value->it_interval.tv_nsec)
  44       || ! valid_nanoseconds (value->it_value.tv_nsec))
  45     {
  46       __set_errno (EINVAL);
  47       goto bail;
  48     }
  49
  50   /* Will need to know current time since this is a relative timer;
  51      might as well make the system call outside of the lock now! */
  52
  53   if ((flags & TIMER_ABSTIME) == 0)
  54     {
  55       __clock_gettime (timer->clock, &now);
  56       have_now = 1;
  57     }
  58
  59   pthread_mutex_lock (&__timer_mutex);
  60   timer_addref (timer);
  61
  62   /* One final check of timer validity; this one is possible only
  63      until we have the mutex, because it accesses the inuse flag. */
  64
  65   if (! timer_valid(timer))
  66     {
  67       __set_errno (EINVAL);
  68       goto unlock_bail;
  69     }
  70
  71   if (ovalue != NULL)
  72     {
  73       ovalue->it_interval = timer->value.it_interval;
  74
  75       if (timer->armed)
  76         {
  77           if (! have_now)
  78             {
  79               pthread_mutex_unlock (&__timer_mutex);
  80               __clock_gettime (timer->clock, &now);
  81               have_now = 1;
  82               pthread_mutex_lock (&__timer_mutex);
  83               timer_addref (timer);
  84             }
  85
  86           timespec_sub (&ovalue->it_value, &timer->expirytime, &now);
  87         }
  88       else
  89         {
  90           ovalue->it_value.tv_sec = 0;
  91           ovalue->it_value.tv_nsec = 0;
  92         }
  93     }
  94
  95   timer->value = *value;
  96
  97   list_unlink_ip (&timer->links);
  98   timer->armed = 0;
  99
 100   thread = timer->thread;
 101
 102   /* A value of { 0, 0 } causes the timer to be stopped. */
 103   if (value->it_value.tv_sec != 0
 104       || __builtin_expect (value->it_value.tv_nsec != 0, 1))
 105     {
 106       if ((flags & TIMER_ABSTIME) != 0)
 107         /* The user specified the expiration time.  */
 108         timer->expirytime = value->it_value;
 109       else
 110         timespec_add (&timer->expirytime, &now, &value->it_value);
 111
 112       /* Only need to wake up the thread if timer is inserted
 113          at the head of the queue. */
 114       if (thread != NULL)
 115         need_wakeup = __timer_thread_queue_timer (thread, timer);
 116       timer->armed = 1;
 117     }
 118
 119   retval = 0;
 120
 121 unlock_bail:
 122   timer_delref (timer);
 123   pthread_mutex_unlock (&__timer_mutex);
 124
 125 bail:
 126   if (thread != NULL && need_wakeup)
 127     __timer_thread_wakeup (thread);
 128
 129   return retval;
 130 }