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glibc  2.9
Functions
timer_settime.c File Reference
#include <errno.h>
#include <pthread.h>
#include <time.h>
#include "posix-timer.h"

Go to the source code of this file.

Functions

int timer_settime (timer_t timerid, int flags, const struct itimerspec *value, struct itimerspec *ovalue)

Function Documentation

int timer_settime ( timer_t  timerid,
int  flags,
const struct itimerspec *  value,
struct itimerspec *  ovalue 
)

Definition at line 29 of file timer_settime.c.

{
  struct timer_node *timer;
  struct thread_node *thread = NULL;
  struct timespec now;
  int have_now = 0, need_wakeup = 0;
  int retval = -1;

  timer = timer_id2ptr (timerid);
  if (timer == NULL)
    {
      __set_errno (EINVAL);
      goto bail;
    }

  if (value->it_interval.tv_nsec < 0
      || value->it_interval.tv_nsec >= 1000000000
      || value->it_value.tv_nsec < 0
      || value->it_value.tv_nsec >= 1000000000)
    {
      __set_errno (EINVAL);
      goto bail;
    }

  /* Will need to know current time since this is a relative timer;
     might as well make the system call outside of the lock now! */

  if ((flags & TIMER_ABSTIME) == 0)
    {
      clock_gettime (timer->clock, &now);
      have_now = 1;
    }

  pthread_mutex_lock (&__timer_mutex);
  timer_addref (timer);

  /* One final check of timer validity; this one is possible only
     until we have the mutex, because it accesses the inuse flag. */

  if (! timer_valid(timer))
    {
      __set_errno (EINVAL);
      goto unlock_bail;
    }

  if (ovalue != NULL)
    {
      ovalue->it_interval = timer->value.it_interval;

      if (timer->armed)
       {
         if (! have_now)
           {
             pthread_mutex_unlock (&__timer_mutex);
             clock_gettime (timer->clock, &now);
             have_now = 1;
             pthread_mutex_lock (&__timer_mutex);
             timer_addref (timer);
           }

         timespec_sub (&ovalue->it_value, &timer->expirytime, &now);
       }
      else
       {
         ovalue->it_value.tv_sec = 0;
         ovalue->it_value.tv_nsec = 0;
       }
    }

  timer->value = *value;

  list_unlink_ip (&timer->links);
  timer->armed = 0;

  thread = timer->thread;

  /* A value of { 0, 0 } causes the timer to be stopped. */
  if (value->it_value.tv_sec != 0
      || __builtin_expect (value->it_value.tv_nsec != 0, 1))
    {
      if ((flags & TIMER_ABSTIME) != 0)
       /* The user specified the expiration time.  */
       timer->expirytime = value->it_value;
      else
       timespec_add (&timer->expirytime, &now, &value->it_value);

      /* Only need to wake up the thread if timer is inserted
        at the head of the queue. */
      if (thread != NULL)
       need_wakeup = __timer_thread_queue_timer (thread, timer);
      timer->armed = 1;
    }

  retval = 0;

unlock_bail:
  timer_delref (timer);
  pthread_mutex_unlock (&__timer_mutex);

bail:
  if (thread != NULL && need_wakeup)
    __timer_thread_wakeup (thread);

  return retval;
}

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