内存映射

首先，进程A 创建一个命名内存映射对象

其次，进程B 通过名称来访问进程A创建的内存映射对象

上面操作都成功后就可以进行通信，通信的同步处理可以用命名的事件、信号量等内核对象来实现

 

    //创建内存映射对象
    static HANDLE hFileMap = CreateFileMapping(INVALID_HANDLE_VALUE
                                                , NULL
                                                , PAGE_READWRITE|SEC_COMMIT
                                                , 0,sizeof(DWORD)
                                                ,L"FileMapLink");

    if (NULL == hFileMap)
    {
        switch(GetLastError())
        {
        case ERROR_FILE_INVALID:
            TRACE("CreateFileMapping Error:企图创建一个零长度的文件映射\r\n");
            break;

        case ERROR_INVALID_HANDLE:
            TRACE("CreateFileMapping Error:ERROR_INVALID_HANDLE\r\n");
            break;

        case ERROR_ALREADY_EXISTS:
            TRACE("CreateFileMapping Error:已有一个同名内存映射存在.\r\n");
            break;
        }
        return;
    }

    //访问内存映射对象
    static VOID* pViewMap = MapViewOfFile( hFileMap
                                            , FILE_MAP_WRITE //访问方式
                                            , 0, 0, 0);
    if (NULL == pViewMap)
    {
        TRACE("MapViewOfFile Error:访问内存映射对象失败.\r\n");
        return;
    }

    //向映射内存写入数据
    *((DWORD*)pViewMap) = GetCurrentProcessId();

    //创建一个通知事件
    static HANDLE hEvent = CreateEvent(NULL, FALSE, FALSE, L"EventLink");
    if (NULL == hEvent)
    {
        TRACE("CreateEvent Error:创建失败.\r\n");
        return;
    }
    
    //通知对方，内存中已有数据，可以进行读取
    SetEvent(hEvent); 

    //不使用是，释放资源
    UnmapViewOfFile(pViewMap);
    CloseHandle(hFileMap);
    CloseHandle(hEvent);

下面展示，进程B如何来访问进程A的数据

   

    static HANDLE hFileMap = OpenFileMapping(FILE_MAP_READ, FALSE, L"FileMapLink");
    if (NULL == hFileMap)
    {
        TRACE("OpenFileMapping Error:打开内存映射对象失败.\r\n");
    }
    else
    {
        static HANDLE hEvent = OpenEvent(SYNCHRONIZE, FALSE, L"EventLink");
        if (NULL == hEvent)
        {
            TRACE("OpenEvent Error:访问事件失败.\r\n");
        }
        else
        {
            if (WAIT_OBJECT_0 == WaitForSingleObject(hEvent, 5000))
            {
                static void* pBuf = MapViewOfFile(hFileMap, FILE_MAP_READ, 0, 0, 0);
                if (pBuf)
                {
                    DWORD   dwCurrProcessID = *((DWORD*)pBuf);
                    TRACE("CMockShim>> OXProvider ProcessID =  %d", dwCurrProcessID);
                    //LOGON_INFO* pstLogonInfo = (LOGON_INFO*)pBuf;
                    //TRACE("pstLogonInfo->szUserName = %s\r\n", pstLogonInfo->szUserName);
                    //TRACE("pstLogonInfo->szUserPwd = %s\r\n", pstLogonInfo->szUserPwd);
                }

                UnmapViewOfFile(pBuf);
            }
        }
    }

    CloseHandle(hFileMap);

    CloseHandle(hEvent);