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#include <stdlib.h>
#include <stdio.h>
#include <sys/wait.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/types.h>
#include <unistd.h> 

int i;

int main(){
	int id,tmp;
	int *buf;

	id = shmget(IPC_PRIVATE,SHMLBA, IPC_CREAT|0600);
	if (id == -1){
		perror("Utworzenie segmentu pamieci wspoldzielonej");
		exit(1);
	}

	buf = shmat(id, NULL, 0);

	if (buf == NULL){
		perror("Przylaczenie segmentu pamieci wspoldzielonej");
		exit(1);
	}
	buf[0]=0;
	tmp=buf[0];
	//proces 1
	if(fork() == 0) {
		while(tmp!=0) tmp=buf[0];
		
		buf[1]=1;
		buf[0]++;
		printf("Proces1: buf[1]=%d (buf[0]=%d)\n",buf[1],buf[0]);
		exit(0);
	}
	else {
		//proces 2
		if(fork() == 0) {
			while(tmp!=1) tmp=buf[0];
			buf[2]=2;
			buf[0]++;
			printf("Proces2: buf[2]=%d (buf[0]=%d)\n",buf[2],buf[0]);
			exit(0);
		}
		else wait(NULL);

		//proces 3
		if(fork() == 0) {
			while(tmp!=2) tmp=buf[0];
			buf[3]=3;
			buf[0]++;
			printf("Proces2: buf[3]=%d (buf[0]=%d)\n",buf[3],buf[0]);
			exit(0);
		}	else wait(NULL);

		wait(NULL);
		for (i=0; i<4; i++){ 
			printf("buf[%d]=%d\n", i, buf[i]); 
		}
		shmctl(id,IPC_RMID,NULL);
	}


	return(0);
}