C++ 未使用sem_open正确初始化信号量

我正在try 用信号量实现生产者和消费者的问题.我想我的逻辑是正确的，但是我的代码并没有像预期的那样工作.

#include <stdio.h> 
#include <pthread.h> 
#include <semaphore.h> 
#include <unistd.h> 
#include <fcntl.h>
#include <sys/stat.h>
#include <stdlib.h>
 
#define BUFFER_SIZE 10
 
int arr[BUFFER_SIZE];
int position;
 
sem_t *mutex, *empty, *filled;
 
void* producer(void* args){
    printf("Prod starting\n");
    int a,b;
    sem_getvalue(empty, &a);
    sem_getvalue(mutex, &b);

    printf("empty : %d mutex : %d\n", a, b);

    do{
        sem_wait(empty);
        sem_wait(mutex);
         

        int new = rand()%2000;
        printf("Adding %d to buffer\n", new);
        arr[position] = new;
        position++;

        sem_post(mutex);
        sem_post(filled);
    }while(1);
 
}
 
void* consumer(void* arg){printf("Consumer starting\n");
    do{
        sem_wait(filled);
        sem_wait(mutex);
         
        position--;
        printf("Consuming %d from buffer", arr[position]);
        arr[position] = 0; 

        sem_post(mutex);
        sem_post(empty);
    }while(1);
}
 
 
int main() 
{ 
    mutex = sem_open("mutex", O_CREAT, 0644, 1);
    empty = sem_open("empty", O_CREAT, 0644, BUFFER_SIZE);
    filled = sem_open("filled", O_CREAT, 0644, 0);
    pthread_t prod, cons;

    int a, b,c;
    sem_getvalue(empty, &a);
    sem_getvalue(filled, &b);
    sem_getvalue(mutex, &c);
    printf("empty:%d filled:%d mutex:%d\n", a,b,c);

    //printf("Producer = %ld  Consumer = %ld\n", prod, cons);
     
    pthread_create(&prod,NULL,producer,NULL); 
    pthread_create(&cons,NULL,consumer,NULL); 
     
    pthread_join(prod,NULL); 
    pthread_join(cons,NULL); 
     
    sem_close(mutex);
    sem_unlink("mutex");
    sem_close(empty);
    sem_unlink("empty");
    sem_close(filled);
    sem_unlink("filled");
    return 0; 
} 

从以下输出得知，信号量未正确初始化:

empty:0 filled:0 mutex:0
Prod starting
empty : 0 mutex : 0
Consumer starting

我不明白为什么信号量没有正确初始化.从手册页:

Sem_t*sem_open(常量字符*名称，int Omark，模式_t模式，无符号整数值)；

如果在OFLAG中指定了O_CREAT，则有两个附加参数 必须供应.模式参数指定对 被放在新的信号量上，值 参数指定新信号量的初始值.

注意:我不能使用sem_init，因为最后的代码需要在MacOS上完成.我只是在Linux上用sem_getValue()重新创建它，以了解问题.

在@Pilcrow的建议下，我将这个问题重现为:

#include <stdio.h> 
#include <pthread.h> 
#include <semaphore.h> 

sem_t *mutex;

void* thread(void* arg){
    printf("Entered thread\n");
    sem_wait(mutex);
    printf("Hello\n");
    sem_post(mutex);
    pthread_exit(NULL);
}

int main() 
{ 
    mutex = sem_open("mutex", O_CREAT, 0644, 1);

    if(mutex == SEM_FAILED){
        printf("Failed to create semaphore\n");
        return 1;
    }
    
    pthread_t id;
    pthread_create(&id,NULL,thread,NULL); 
    pthread_join(id,NULL); 
    return 0; 
}

输出:

Entered thread

线程继续无限期地等待未正确初始化的mutex信号量.