/*

 * ex9a.c
 *
 *  Created on: Jun 17, 2018



 Authors: joshuaad N yisraelwa

 DESCRIPTION:

 The prog' has three processes:
 1) process father that creates a shared memory
 2) child proces a
 3) child process b
 the two of the children has to get a random numbers in a loop
 the frist that get a prime number is the winner.

 1st  the winner blocks the other brother from accessing to the shaed memory
 2nd  has to kill his brother
 3rd  to store the prime num in the shared memory
 4th uses the SIGUSR1 signal. once the father get the SIGUSR1 he prints
 the prime number and quit.

 races cases are impossible due to semaphoresem_t method being  used.


 */
//============================//
//        ---INCLUDE---       //
//============================//
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/wait.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <time.h>
#include <semaphore.h>
#include <fcntl.h>

//----------------------------//
//       ---GLOBALS---        //
//----------------------------//
int shm_id ;
int *shm_ptr;
sem_t* mutex;
//============================//
//       ---PROTOTYPES---     //
//============================//
void runProcess();
void runSonA(int *shm_ptr);
void runSonB(int *shm_ptr);
void sigHandler();
int isPrime(int num);
//=========================================//
//              --MAIN FUNCTION--          //
//=========================================//
int main()
{

	signal(SIGUSR1,sigHandler);
	runProcess();

return 0;
}
//================================================//
//               ---PROCESS---                    //
//================================================//
void runProcess()
{
	key_t key ;
	if ((key = ftok("/tmp", 'x')) == -1)
	{
		perror("ftok() failed") ;
		exit(EXIT_FAILURE) ;
	}
	//-------------------------------------//

	shm_id = shmget ( key, sizeof(int)*3, IPC_CREAT |IPC_EXCL | 0600 ) ;
	if (shm_id == -1)
	{
		printf("%d",key);
		perror("shmget() failed\n") ;
		exit(EXIT_FAILURE) ;
	}


	mutex=sem_open("/mymutex",O_CREAT,0644,1);
	if(mutex==SEM_FAILED)
	{
		perror("sem_open() failed\n") ;
	}


	shm_ptr = (int *) shmat ( shm_id, NULL, 0);
	if (shm_ptr == (int *)-1)
	{
		perror( "shmat failed" ) ;
		exit( EXIT_FAILURE ) ;
	}
		//-------------------------------------//
		srand(time(NULL));

	    pid_t sonB;
	    pid_t sonA;



	//-------------------------------------------------//

		sonA=fork();
		if(sonA)//the father iteration
		{
			sonB=fork();
		}


		if(!sonA)
		{
			shm_ptr[1]=(int)getpid();
			runSonA(shm_ptr);

		}
		if(!sonB)
		{
			shm_ptr[2]=(int)getpid();
			runSonB(shm_ptr);
		}

		wait(NULL);
		wait(NULL);

}
//================================================//
//                ---SON A---                     //
//================================================//
void runSonA(int *shm_ptr)
 {
	sem_t* s;
	s =sem_open("/mymutex", 0);
	sem_post(s);
	 int num=2;

	 pid_t pidbrother;


	 while(1)
	 {

	  num=rand();

	  if(isPrime(num))
	  {



		  sem_wait(s);
		  shm_ptr[0]=num;

		   printf("Hey there I won, I'm son a\n");//test
		   sem_close(s);
		   pidbrother=(pid_t)shm_ptr[2];
		   kill(pidbrother,SIGUSR1);
		   sem_unlink("/mutex" );



		  // kill(getpid(),0);

		   exit(EXIT_SUCCESS);
	  }

	 }

 }
//================================================//
//                ---SON B---                     //
//================================================//
void runSonB(int *shm_ptr)
{
	sem_t* s;
	s =sem_open("/mymutex", 0);
	sem_post(s);

 int num=2;
 pid_t pidbrother=(pid_t)shm_ptr[1];

 while(1)
 {
  num=rand();
  if(isPrime(num))
  {
	  sem_wait(s);
	  shm_ptr[0]=num;
	  printf("%s","Hey there I won, I'm son b\n");//test

	  sem_close(s);
	  kill(pidbrother,SIGUSR1);
	  sem_unlink("/mutex" );




	   exit(EXIT_SUCCESS);
  }

 }



}
//=========================================//
//             --SIGNAL HANDLER--          //
//=========================================//
void sigHandler()
{
	printf("%d is a prime\n",shm_ptr[0]);
	shmdt(shm_ptr) ;

	if (shmctl(shm_id,IPC_RMID, NULL) == -1)
	{
		perror( "shmctl failed" ) ;
		exit( EXIT_FAILURE ) ;
	}

	exit( EXIT_SUCCESS) ;
}
//=========================================//
//               ---IS PRIME---            //
//=========================================//
int isPrime(int num)
{

	int i=0;
	int flag=1;
	  for(i=2; i<=num/2; ++i)
	    {
	        // condition for nonprime number
	        if(num%i==0)
	        {
	            flag=0;
	            return flag;
	        }
	    }
	  return flag;
}