S01_PAMIEC_DZIELONA_05

/*
Zademonstruj działanie flagi SHM_RDONLY.
*/

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

#define MESSAGE "Jakas wiadomosc"

int main(void)
{
    int shmid;
    char *shared_memory;

    if((shmid = shmget(IPC_PRIVATE, SHMLBA, 0775 | IPC_CREAT | IPC_EXCL)) == -1){
        perror("shmget");
        return EXIT_FAILURE;
    }

    if((shared_memory = (char *)shmat(shmid, NULL, SHM_RDONLY)) == (void *)-1){
        perror("shmat");
        return EXIT_FAILURE;
    }

    printf("Proba zapisania danych do pamieci dzielonej z flaga SHM_RDONLY\n");
    strncpy(shared_memory, MESSAGE, strlen(MESSAGE));

    printf("W pamieci dzielonej znajduje sie: %s\n", shared_memory);

    if(shmdt(shared_memory) == -1){
        perror("shmdt");
        return EXIT_FAILURE;
    }

    if(shmctl(shmid, IPC_RMID, NULL) == -1){
        perror("shmctl");
        return EXIT_FAILURE;
    }

    return EXIT_SUCCESS;
}