#define _GNU_SOURCE

#include <unistd.h>
#include <sys/types.h>
#include <stdio.h>
#include <sys/shm.h>
#include <fcntl.h>
#include <sys/mman.h>

#define SIZE 1024

char* sharedMem;

int parent()
{
    sleep(1);

    printf("Parent: Writing...\n");
    strcpy(sharedMem, "Bla bla bla\n");

    munmap(sharedMem, SIZE);
    return 0;
}

int child()
{
    sleep(3);
    
    printf("Child: Reading: ");
    char buffer[100];
    strcpy(buffer, sharedMem);
    puts(buffer);

    munmap(sharedMem, SIZE);
    return 0;
}


int main()
{
    sharedMem = (char*)mmap(NULL, SIZE, 
	PROT_READ|PROT_WRITE, 
	MAP_SHARED|MAP_ANONYMOUS, -1, 0);

    pid_t res = fork();
    
    if (res < 0) return 1;

    if (res > 0) return parent();
    else return child();

    return 0;
}