Question

我正在尝试在Linux（Ubuntu16）中从生产者进程到消费者进程共享一些内存。

只有一个通用的标头定义了这个小结构

struct my_small_pod_structure {
    void *handle;
    int width;
    int height;
};

生产者流程正在做

// Create a semaphore to synchronize
psem = sem_open ("producerSem", O_CREAT | O_EXCL, 0644, 0);
sem_unlink ("producerSem"); // Avoid persisting after the process closed

shmkey = ftok("/dev/null", 5);

int shmid = shmget(shmkey, sizeof(my_small_pod_structure), 0644 | IPC_CREAT);
if (shmid < 0) {
    error("shmget failed");
    exit(1);
}


my_small_pod_structure *shared_ptr = (my_small_pod_structure*) shmat (shmid, NULL, 0);
// populate shared_ptr with the producer data here..
...

sem_post (psem); // data is ready

sleep(1000000); // very long value, assured that the producer isn't exiting before the consumer pulls it

消费者：

sem_t *psem = sem_open ("producerSem", O_CREAT | O_EXCL, 0644, 0);
sem_unlink ("producerSem");

key_t shmkey = ftok("/dev/null", 5);
int shmid = shmget(shmkey, sizeof(my_small_pod_structure), 0644 | IPC_CREAT);
if (shmid < 0) {
    int error = errno;
    printf("shmget failed %d\n", error);
    exit(1);
}

sem_wait (psem); // wait for data to be ready

// DATA IS READY!

my_small_pod_structure *shared_ptr = (my_small_pod_structure*) shmat (shmid, NULL, 0);

// use shared_ptr..
...

但是，即使生产者在消费者之前就开始了（尽管我认为由于信号量这没关系），我还是从消费者那里得到的。

shmget failed 13

生产者似乎正在工作并到达睡眠点，等待消费者拿起它。

我在做什么错？为什么13-权限被拒绝？

Linux共享内存-shmget失败

0 个答案: