unix_project

user1 #include <signal.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/ipc.h> #include <sys/shm.h> #include <sys/types.h> #include <unistd.h>

#define FILLED 0 #define Ready 1 #define NotReady -1

struct memory { char buff[100]; int status, pid1, pid2; };

struct memory* shmptr;

// handler function to print message received from user2

void handler(int signum) { // if signum is SIGUSR1, then user 1 is receiving a message from user2

if (signum == SIGUSR1) {
	printf("Received User2: ");
	puts(shmptr->buff);
}

}

int main() { // process id of user1

int pid = getpid();

int shmid;

// key value of shared memory
int key = 12345;

// shared memory create
shmid = shmget(key, sizeof(struct memory), IPC_CREAT | 0666);

// attaching the shared memory

shmptr = (struct memory*)shmat(shmid, NULL, 0);

// store the process id of user1 in shared memory
shmptr->pid1 = pid;
shmptr->status = NotReady;

// calling the signal function using signal type SIGUSER1
signal(SIGUSR1, handler);

while (1) {
	while (shmptr->status != Ready)
		continue;
	sleep(1);

	// taking input from user1

	printf("User1: ");
	fgets(shmptr->buff, 100, stdin);

	shmptr->status = FILLED;

	// sending the message to user2 using kill function

	kill(shmptr->pid2, SIGUSR2);
}

shmdt((void*)shmptr);
shmctl(shmid, IPC_RMID, NULL);
return 0;

}

user2 #include <signal.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/ipc.h> #include <sys/shm.h> #include <sys/types.h> #include <unistd.h>

#define FILLED 0 #define Ready 1 #define NotReady -1

struct memory { char buff[100]; int status, pid1, pid2; };

struct memory* shmptr;

// handler function to print message received from user1

void handler(int signum) { // if signum is SIGUSR2, then user 2 is receiving a message from user1

if (signum == SIGUSR2) {
	printf("Received From User1: ");
	puts(shmptr->buff);
}

}

// main function

int main() { // process id of user2 int pid = getpid();

int shmid;

// key value of shared memory
int key = 12345;

// shared memory create

shmid = shmget(key, sizeof(struct memory), IPC_CREAT | 0666);

// attaching the shared memory

shmptr = (struct memory*)shmat(shmid, NULL, 0);

// store the process id of user2 in shared memory
shmptr->pid2 = pid;

shmptr->status = NotReady;

// calling the signal function using signal type SIGUSR2
signal(SIGUSR2, handler);

while (1) {
	sleep(1);

	// taking input from user2

	printf("User2: ");
	fgets(shmptr->buff, 100, stdin);
	shmptr->status = Ready;

	// sending the message to user1 using kill function

	kill(shmptr->pid1, SIGUSR1);

	while (shmptr->status == Ready)
		continue;
}

shmdt((void*)shmptr);
return 0;

}