/*

* Copyright (c) 2009 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of the License "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description: 

*

*/

#include "sema.h"

// OS specific headers

#ifdef WIN32

#include <windows.h>

#include <tlhelp32.h>

#else

#include <semaphore.h>

#include <sys/types.h>

#include <signal.h>

#include <fcntl.h>

#include <time.h>

#endif

#include <unistd.h>

void sema_create(sbs_semaphore *s)

{

#ifdef WIN32

	s->handle = CreateSemaphore(NULL, 1, 1, s->name);

	if (s->handle)

		CloseHandle(s->handle);

	else

		error("unable to create semaphore %s", s->name);

#else

	s->handle = sem_open(s->name, O_CREAT | O_EXCL, 0644, 1);

  	if (s->handle == SEM_FAILED)

	{

		sem_close(s->handle);

	  	error("unable to create semaphore %s", s->name);

	}

	sem_close(s->handle);

#endif

}

void sema_destroy(sbs_semaphore *s)

{

	#ifdef WIN32

		/* can't destroy a windows semaphore... */

	#else

  		if (sem_unlink(s->name) != 0)

		  	error("unable to unlink semaphore", s->name);

	#endif

}

int sema_wait(sbs_semaphore *s)

{

	/* try and open the semaphore now */

        #ifdef WIN32

		s->handle = CreateSemaphore(NULL, 1, 1, s->name);

		if (!s->handle)

		{

			error("unable to open semaphore %s", s->name);

			return -2;

		}

        #else

		struct timespec tmout;

		s->handle = sem_open(s->name, 0);

	  	if (s->handle == SEM_FAILED)

		{

    			sem_close(s->handle);

      			error("unable to open semaphore %s\n", s->name);

			return -2;

    		}

	#endif

    /* wait for the semaphore to be free [timeout if it takes too long] */

 	int timedOutFlag = 0;

	int semcount = 0;

	#ifdef WIN32

 		timedOutFlag = (WaitForSingleObject(s->handle, s->timeout) != WAIT_OBJECT_0);

	#else

		sem_getvalue(s->handle, &semcount);

      		debug("sema: count before wait: %d\n", semcount);

      		debug("sema: timeout: %d\n", s->timeout);

	        if (clock_gettime(CLOCK_REALTIME, &tmout) == -1)

		{

               		error("sema: clock_gettime failed - can't do timed wait");

			return -1;

		}

		tmout.tv_sec += (s->timeout / 1000);

		tmout.tv_nsec += (s->timeout % 1000) * 1000;

		timedOutFlag = sem_timedwait(s->handle, &tmout); 

		/* roughly speaking the return value indicates timeouts. It also indicated

		 * signals.  We are glossing over this for the moment since it isn't really

		 * interesting in this application 

		 * */

	#endif

	return timedOutFlag;

}

void  sema_release(sbs_semaphore *s)

{

	/* release the semaphore */

	#ifdef WIN32

		ReleaseSemaphore(s->handle, 1, NULL);

	#else

	   	sem_post(s->handle);

	#endif

	   /* clean up */

	#ifdef WIN32

		CloseHandle(s->handle);

	#else

	   	sem_close(s->handle);

	#endif

}