?? sem_trywait.c
字號:
/* include sem_trywait */
#include "unpipc.h"
#include "semaphore.h"
int
mysem_trywait(mysem_t *sem)
{
struct sembuf op;
if (sem->sem_magic != SEM_MAGIC) {
errno = EINVAL;
return(-1);
}
op.sem_num = 0;
op.sem_op = -1;
op.sem_flg = IPC_NOWAIT;
if (semop(sem->sem_semid, &op, 1) < 0)
return(-1);
return(0);
}
/* end sem_trywait */
int
Mysem_trywait(mysem_t *sem)
{
int rc;
if ( (rc = mysem_trywait(sem)) == -1 && errno != EAGAIN)
err_sys("mysem_trywait error");
return(rc);
}
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