Листинг 10.43. Функция sem_trywait
//my_pxsem_svsem/sem_trywait.c
1 #include "unpipc.h"
2 #include "semaphore.h"
3 int
4 mysem_trywait(mysem_t *sem)
5 {
6 struct sembuf op;
7 if (sem->sem_magic != SEM_MAGIC) {
8 errno = EINVAL;
9 return(-1);
10 }
11 op.sem_num = 0;
12 op.sem_op = –1;
13 op.sem_flg = IPC_NOWAIT;
14 if (semop(sem->sem_semid, &op, 1) < 0)
15 return(-1);
16 return(0);
17 }