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

#define errExit(msg)        \
    do                      \
    {                       \
        perror(msg);        \
        exit(EXIT_FAILURE); \
    } while (0)

union semun
{ /* Used in calls to semctl() */
    int val;
    struct semid_ds *buf;
    unsigned short *array;
#if defined(__linux__)
    struct seminfo *__buf;
#endif
};

#define MEM_SIZE 4096