C SHMGET在失败时返回-1以外的值

Question

我正在尝试使用Unix共享内存创建与此Windows代码等效的内容，但是当文档说并设置-1值时，而不是返回errno，而不是共享内存已创建，它返回65537。

我只是想让它循环，直到在另一个进程中创建了内存，然后返回id并'连接到它'。

Windows代码：

    HANDLE hClientSlot = NULL;
    unsigned long long* clientSlot;

    while(hClientSlot == NULL)
    {
        hClientSlot = OpenFileMapping(FILE_MAP_ALL_ACCESS, FALSE, CLIENTSLOTNAME);

        if(hClientSlot == NULL)
        {
            std::cout << "Could not open Client Slot file mapping object:" << GetLastError() << std::endl;
        }
    }

    clientSlot = reinterpret_cast<unsigned long long*>( MapViewOfFile(hClientSlot, FILE_MAP_ALL_ACCESS, 0, 0, 1 * sizeof(unsigned long long)) );
    if(!clientSlot)
    {
        std::cout << "Error: Failed to map Client Slot!" << std::endl;
    }

Unix代码：编辑：根据@Zack的反馈添加了Key_T内容

    unsigned long long* clientSlot;
    int clientSlotID = -1;

    key_t slotKey;
    slotKey = ftok(CLIENTSLOTNAME, ID);

    while(clientSlotID == -1)
    {
        clientSlotID = shmget(slotKey, sizeof(unsigned long long), 0666);
    }

    clientSlot = (unsigned long long*) shmat(clientSlotID, NULL, 0);

    if(!clientSlot)
    {
        std::cout << "Error: Failed to map client slot!" << std::endl;
    }