File: timer_create.c

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/* Copyright (C) 2003,2004, 2007, 2009, 2012 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@redhat.com>, 2003.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public License as
   published by the Free Software Foundation; either version 2.1 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <errno.h>
#include <pthread.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <sysdep.h>
#include <kernel-features.h>
#include <internaltypes.h>
#include <fbtl/pthreadP.h>
#include "kernel-posix-timers.h"
#include "kernel-posix-cpu-timers.h"


int
timer_create (clockid_t clock_id, struct sigevent *evp, timer_t *timerid)
{
    {
      /* If the user wants notification via a thread we need to handle
	 this special.  */
      if (evp == NULL
	  || __builtin_expect (evp->sigev_notify != SIGEV_THREAD, 1))
	{
	  struct sigevent local_evp;

	  struct timer *newp = __kfreebsd_timer_alloc ();

	  if (newp == NULL)
	    /* No more memory.  */
	    return -1;

	  if (evp == NULL)
	    {
	      /* The kernel has to pass up the timer ID which is a
		 userlevel object.  Therefore we cannot leave it up to
		 the kernel to determine it.  */
	      local_evp.sigev_notify = SIGEV_SIGNAL;
	      local_evp.sigev_signo = SIGALRM;
	      local_evp.sigev_value.sival_int = __kfreebsd_timer_ptr2id (newp);

	      evp = &local_evp;
	    }

	  kernel_timer_t ktimerid;
	  int retval = INLINE_SYSCALL (ktimer_create, 3, clock_id, evp,
				       &ktimerid);

	    {

	      if (retval != -1)
		{
		  newp->sigev_notify = (evp != NULL
					? evp->sigev_notify : SIGEV_SIGNAL);
		  newp->ktimerid = ktimerid;

		  *timerid = __kfreebsd_timer_ptr2id (newp);
		}
	      else
		{
		  /* Cannot allocate the timer, fail.  */
		  __kfreebsd_timer_free (newp);
		  retval = -1;
		}

	      return retval;
	    }
	}
      else
	{
	    {
	      /* Create the helper thread.  */
	      pthread_once (&__helper_once, __start_helper_thread);
	      if (__helper_tid == 0)
		{
		  /* No resources to start the helper thread.  */
		  __set_errno (EAGAIN);
		  return -1;
		}

	      struct timer *newp;
	      newp = __kfreebsd_timer_alloc ();
	      if (newp == NULL)
		return -1;

	      /* Copy the thread parameters the user provided.  */
	      newp->sival = evp->sigev_value;
	      newp->thrfunc = evp->sigev_notify_function;
	      newp->sigev_notify = SIGEV_THREAD;

	      /* We cannot simply copy the thread attributes since the
		 implementation might keep internal information for
		 each instance.  */
	      (void) pthread_attr_init (&newp->attr);
	      if (evp->sigev_notify_attributes != NULL)
		{
		  struct pthread_attr *nattr;
		  struct pthread_attr *oattr;

		  nattr = (struct pthread_attr *) &newp->attr;
		  oattr = (struct pthread_attr *) evp->sigev_notify_attributes;

		  nattr->schedparam = oattr->schedparam;
		  nattr->schedpolicy = oattr->schedpolicy;
		  nattr->flags = oattr->flags;
		  nattr->guardsize = oattr->guardsize;
		  nattr->stackaddr = oattr->stackaddr;
		  nattr->stacksize = oattr->stacksize;
		}

	      /* In any case set the detach flag.  */
	      (void) pthread_attr_setdetachstate (&newp->attr,
						  PTHREAD_CREATE_DETACHED);

	      /* Create the event structure for the kernel timer.  */
	      struct sigevent sev =
		{ .sigev_value.sival_ptr = newp,
		  .sigev_signo = SIGTIMER,
		  .sigev_notify = SIGEV_THREAD_ID,
		  .sigev_notify_thread_id = __helper_tid,
		};

	      /* Create the timer.  */
	      int res;
	      res = INLINE_SYSCALL (ktimer_create, 3,
				      clock_id, &sev, &newp->ktimerid);
	      if (res != -1)
		{
		  /* Add to the queue of active timers with thread
		     delivery.  */
		  pthread_mutex_lock (&__active_timer_sigev_thread_lock);
		  newp->next = __active_timer_sigev_thread;
		  __active_timer_sigev_thread = newp;
		  pthread_mutex_unlock (&__active_timer_sigev_thread_lock);

		  *timerid = __kfreebsd_timer_ptr2id (newp);
		  return 0;
		}

	      /* Free the resources.  */
	      __kfreebsd_timer_free (newp);

	      return -1;
	    }
	}
    }
}