Elaborato_SO/src/custom_sem.c

#include <sys/sem.h>
#include <sys/stat.h>
#include <custom_sem.h>
#include <structures.h>
#include <errExit.h>

void semOp(int semid, short sem_num, short sem_op) {
    struct sembuf sop = {.sem_num = sem_num, .sem_op = sem_op, .sem_flg = 0};

    if (semop(semid, &sop, 1) == -1) {
        errExit("semop", "semOp");
    }
}

int getSemid(){
    int semid = semget(IPC_PRIVATE, 2, S_IRUSR | S_IWUSR);
    if (semid == -1) {
        errExit("semget", "getSemid");
    }

    unsigned short val[] = {0, 0};
    union semun arg;
    arg.array = val;

    if (semctl(semid, 0 , SETALL, arg) == -1) {
        errExit("semctl", "getSemid");
    }

    return semid;
}