c - Share pthread semaphore between processes -

i'm trying create shared semaphore class in c , share between 2 processes via shared memory.

sharedmemory.h (shared across processes)

typedef struct semaphore {     int value;              //- semaphore's value     int wakeups;            //- number of pending signals                             //      avoid thread starvation     pthread_mutex_t *mutex;  //- used protect value , wakeups     pthread_cond_t *cond;    //- waiting on semaphore } semaphore;  semaphore *sem; //- semaphore 1: free | 0: in use 

sharedmemory.c (shared across processes)

//- initialize semaphore object semaphore *semaphore_init(int value) {     semaphore *semaphore = (semaphore*) malloc(sizeof(semaphore));     semaphore->value = value;     semaphore->wakeups = 0;      //- mutex init     pthread_mutexattr_init(&attrmutex);     pthread_mutexattr_setpshared(&attrmutex, pthread_process_shared);     semaphore->mutex = (pthread_mutex_t *)malloc(sizeof(pthread_mutex_t));     pthread_mutex_init(semaphore->mutex, &attrmutex);      //- condition init     pthread_condattr_init(&attrcond);     pthread_condattr_setpshared(&attrcond, pthread_process_shared);     semaphore->cond = (pthread_cond_t*)malloc(sizeof(pthread_cond_t));     pthread_cond_init(semaphore->cond, &attrcond);      return semaphore; }  int signalsemaphore(semaphore* sem) {     pthread_mutex_lock(sem->mutex);     /* todo illustrative example: don't worry overflow */     sem->value++;     pthread_cond_signal(sem->cond);     pthread_mutex_unlock(sem->mutex);     return 0; }  //- wait semaphore int waitsemaphore(semaphore* sem) {     pthread_mutex_lock(sem->mutex);      while(sem->value == 0) {         pthread_cond_wait(sem->cond, sem->mutex);     }     sem->value--;      pthread_mutex_unlock(sem->mutex);     return 0; } 

my server calls sem = semaphore_init(1);

theory 1

should client call semaphore_init well?

or should different function using pthread_mutexattr_getshared , pthread_condattr_getshared?

what's best way set up? right now, when client calls waitsemaphore(sem) throws segmentation fault.