#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/mman.h>
#include <sys/stat.h>        /* mnemonici in mode */
#include <fcntl.h>           /* mnemonici in oflag */
#include <semaphore.h>


void main ()
{ 	
	int fd, i, j, pid, size=sizeof(int); 
	int* buffer;
	sem_t* mutex1; 
	sem_t* barbiere;
	sem_t* cliente; 
	int* nr_clienti;

	mutex1=sem_open("mutex1", O_CREAT, S_IRUSR | S_IWUSR, 1);	/* creo i semafori */
	barbiere=sem_open("barb", O_CREAT, S_IRUSR | S_IWUSR, 0);
	cliente=sem_open("clien", O_CREAT, S_IRUSR | S_IWUSR, 0);

	fd = shm_open("mymem1",  O_CREAT | O_EXCL |O_RDWR, S_IRUSR | S_IWUSR); /*creo la SHM */
 	ftruncate(fd,size);
 	buffer = mmap(NULL ,size,PROT_READ | PROT_WRITE, MAP_SHARED ,fd, 0);

	nr_clienti=buffer;
	//*nr_clienti=0;

	while(1){
		sem_wait(cliente); 
		sem_post(barbiere);		
		sleep(1);
		printf("barbiere: ho servito il cliente %d\n",*nr_clienti);
		sem_wait(mutex1);
		*nr_clienti=*nr_clienti-1; 		
		sem_post(mutex1); 						
	}
}