#include <semaphore.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/shm.h>
#include <unistd.h>
#include <iostream>
#include <cstring>
#include <fstream>
#include <stdio.h>
#include <fcntl.h>

using namespace std;

#define MEMORY_ONE "/shm_one"
#define SEMAPHORE_ONE "/sem_one"
#define SIZE 4096

int main() {

	int mc_fd;
	char * ptr;

	// Clean MEMORY and SEMAPHORE
	shm_unlink(MEMORY_ONE);
	sem_unlink(SEMAPHORE_ONE);

	// Create SHARED MEMORY
	mc_fd = shm_open(MEMORY_ONE, O_CREAT | O_RDONLY, 0666);
	if(mc_fd == -1) {
		cerr << "Fallimento nell'apertura della memoria condivisa" << endl;
		exit(-1);
	}

	// Map SHARED MEMORY
	ptr = (char *) mmap(NULL, SIZE, PROT_READ, MAP_SHARED, mc_fd, 0);
	if(ptr == MAP_FAILED) {
		cerr << "Fallimento nella mappatura" << endl;
		exit(-1);
	}

	// Create SEMAPHORE
	sem_t * sem_id = sem_open(SEMAPHORE_ONE,
							  O_CREAT, S_IRUSR | S_IWUSR, 1);

	cout << "SEGMENTATION avviato..." << endl;
	while(true) {
		//sleep(6);
		// -------------------------------------------------------------
		sem_wait(sem_id);
		cout << "Start -> SEZIONE CRITICA!" << endl;

		cout << "BUFFER FOTO: " << ptr;

		sem_post(sem_id);
		cout << "Stop -> SEZIONE CRITICA!" << endl;
		// -------------------------------------------------------------
	}

	return 0;
}