semop 错误File too large

[xunyingren]

void up(int sem_id, int sem_num)
{
struct sembuf xx;
xx.sem_num = sem_num;
xx.sem_op = 1;
xx.sem_flg = 0;
if(semop(sem_id, &xx, 1)== -1)
{
fprintf(stderr,"Fail in upsemop:%s\n",strerror(errno));
//exit(1);
}
}
是不是删除了信号量之后会出现错误Invalid argument
那什么时候会出现错误File too large
还有改为sem_flg=SEM_UNDO有什么区别，up操作时信号量是不是立即加1

[xunyingren]

补充：


我查到

27
EFBIG
File too large
The value for sem_num is < 0 or >= to the number of semaphores in the set.
可我不知道那里出错？
#define SEM_EMPTY 0
#define SEM_FULL 4
#define SEM_MUTEX 1
#define SEM_NUMBER 2
#define SEM_LETTER 3


//down操作
void down(int sem_id, int sem_num)
{
/*
struct sembuf {
ushort sem_num ; //member # in set (0, 1,, nsems-1
short sem_op ; //operation(negative, 0,or pasitive)
short sem_flg ; // IPC_NOWAIT, SEM_UNDO
} ;
*/
struct sembuf xx;
xx.sem_num = sem_num;
xx.sem_op = -1;
xx.sem_flg = 0;
/*int semop(int semid, struct sembuf semoparray[], size_t nops) ;
semoparray是一个指针，它指向一个信号量操作数组。
nops规定该数组中操作的数量（元素数）。
*/
if(semop(sem_id, &xx, 1)== -1)
{
fprintf(stderr,"Fail in downsemop:%s\n",strerror(errno));
//exit(1);
}
}

//up操作
void up(int sem_id, int sem_num)
{
struct sembuf xx;
xx.sem_num = sem_num;
xx.sem_op = 1;
xx.sem_flg = 0;
if(semop(sem_id, &xx, 1)== -1)
{
fprintf(stderr,"Fail in upsemop:%s\n",strerror(errno));
//exit(1);
}
}
down(sem_id,SEM_EMPTY);
down(sem_id,SEM_MUTEX);

up(sem_id,SEM_MUTEX);
up(sem_id,SEM_NUMBER);

[cceczjxy]

File too large
应该不是 if(semop(sem_id, &xx, 1)== -1)
的错误,如果想知道某个操作的失败原因,最好在其之前,使errno=0;