#include "sys/mman.h"
#include "stdio.h"
#include "assert.h"
#include "unistd.h"
#include "fcntl.h"
#define NAME "/shm"
#define SIZE 1024

void getSHM(int* fd, int** shm_object, int size)
{
    if((*fd = shm_open(NAME, O_CREAT, 0)) == -1)
    {
        assert(0 && "Opening object failed!");
    }

    if((*shm_object = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, *fd, 0)) == NULL)
    {
        assert(0 && "Mapping failed");
    }
}

int main ()
{
    int* shm_object;
    int fd;

    pid_t pid = fork();

    if(pid)
    {
        getSHM(&fd, &shm_object, sizeof(int) * SIZE);
        int my_pid = (int)getpid();
        printf("Writing to SHM, my PID is : %d\n", my_pid);

        for(int i = 0; i < SIZE; i++)
        {

            shm_object[i] = i;
        }
        printf("Finished writing\n");
    }
    else
    {
        getSHM(&fd, &shm_object, sizeof(int) * SIZE);
        sleep(10);
        printf("Reading from SHM,\n");
        for(int i = 0; i < SIZE; i++)
        {
            if(shm_object[i] != i)
            {
                printf("Found %d, expected %d\n", shm_object[i], i);
                assert(0);
            }
        }
        printf("All good!\n");
    }

    return 0;
}