Elaborato_SO/src/custom_sem.c

#include <sys/sem.h>
#include <sys/stat.h>
#include <errno.h>
#include <stdio.h>

#include <custom_sem.h>
#include <structures.h>
#include <errExit.h>

int _SEMID;

void resetServerSem(int semid);

void setupServerSem() {
    key_t semKey = ftok(KEYFILE, SEMKEY);
    _SEMID = semget(semKey, 3, IPC_CREAT | S_IRUSR | S_IWUSR);
    if (_SEMID == -1) {
        errExit("getsem", "F4Server");
    }
    
    resetServerSem(_SEMID);
}


void setupClientSem() {
    key_t semKey = ftok(KEYFILE, SEMKEY);
    _SEMID = semget(semKey, 3, IPC_CREAT | S_IRUSR | S_IWUSR);
    if (_SEMID == -1) {
        errExit("getsem", "F4Client");
    }
}

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

    int res;
    do {
        res = semop(semid, &sop, 1);
    } while ((errno == EINTR));
    
    if (res == -1) {
        errExitMsg("semOp");
    }
}

int getSemid(key_t key, int size){
    int semid = semget(key, size, S_IRUSR | S_IWUSR | IPC_CREAT);
    if (semid == -1) {
        errExit("semget", "getSemid");
    }

    return semid;
}

// mette i semafori a 0 e 2
void resetServerSem(int semid){
    unsigned short val[3] = {0, 0, 0};      // player1, player2, server
    union semun arg;
    arg.array = val;

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