S01_LAB03_02

/*
Zmodyfikuj zadanie pierwsze, tak aby proces tworzył potomka
i komunikował się z nim przy użyciu kolejki.
*/

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

#define MESSAGE_TO_SEND "Jakas inna wiadomosc"
#define BUFFER_SIZE 128

struct msgbuf {
    long mtype;
    char mtext[BUFFER_SIZE];
};

void send_message(int id)
{
    struct msgbuf send_buffer;

    send_buffer.mtype = 1;
    memset(send_buffer.mtext, '\0', BUFFER_SIZE-1);
    strncpy(send_buffer.mtext, MESSAGE_TO_SEND, BUFFER_SIZE-1);

    if(msgsnd(id, &send_buffer, strlen(send_buffer.mtext), 0) == -1){
        perror("msgsnd");
        exit(EXIT_FAILURE);
    }
}

void recv_message(int id)
{
    struct msgbuf recv_buffer;
    memset(recv_buffer.mtext, '\0', BUFFER_SIZE-1);
    if(msgrcv(id, &recv_buffer, sizeof(recv_buffer.mtext), 1, 0) == -1){
        perror("msgrecv");
        exit(EXIT_FAILURE);
    }

    printf("Przeslana wiadomosc: %s\n", recv_buffer.mtext);
}

int main(void)
{
    int id;
    pid_t pid;
    if((id = msgget(IPC_PRIVATE, 0600 | IPC_CREAT)) == -1){
        perror("msgget");
        return EXIT_FAILURE;
    }

    pid = fork();
    if(pid == -1){
        perror("fork");
        return EXIT_FAILURE;
    }
    else if(pid == 0){
        send_message(id);
    }
    else{
        wait(NULL);
        recv_message(id);
        if(msgctl(id, IPC_RMID, 0) == -1){
            perror("msgctl");
            return EXIT_FAILURE;
        }


    }

    return EXIT_SUCCESS;
}