使用重叠 IO 进行控制台输入？

Question

我正在尝试使用重叠 IO 从控制台读取输入，方法是使用 FILE_FLAG_OVERLAPPED 标志打开 CONIN$。但是，当我使用 ReadFile 时，它​​会阻塞，即使使用 OVERLAPPED 参数也是如此。

我已经阅读了一些报告这是 Windows 7 错误的帖子。我正在使用 7，所以这可能是可能的。

这是我正在使用的代码：

// Create a console window
AllocConsole();
AttachConsole(GetProcessId(GetModuleHandle(NULL)));

HANDLE overlappedConsoleIn = CreateFile(L"CONIN$",
                              GENERIC_READ,
                              FILE_SHARE_READ,
                              NULL,
                              OPEN_EXISTING,
                              FILE_FLAG_OVERLAPPED | FILE_FLAG_NO_BUFFERING,
                              NULL);

// Set up the console to work with stdio
FILE *consoleOut = _fdopen(_open_osfhandle((long)GetStdHandle(STD_OUTPUT_HANDLE), _O_TEXT), "w");
FILE *consoleIn = _fdopen(_open_osfhandle((long)overlappedConsoleIn, _O_TEXT), "r");

*stdout = *consoleOut;
*stdin = *consoleIn;

setvbuf(consoleOut, NULL, _IONBF, 0);
setvbuf(consoleIn, NULL, _IONBF, 0);

std::ios::sync_with_stdio();

// Create a completion event
HANDLE inputEvent = CreateEvent(NULL, true, false, NULL);

BYTE inputBuffer[128];

OVERLAPPED overlappedData;
overlappedData.Offset = 0;
overlappedData.OffsetHigh = 0;
overlappedData.hEvent = inputEvent;

DWORD numBytesRead = 0;

// Asynchronously read from console
ReadFile(overlappedConsoleIn, inputBuffer, 128, &numBytesRead, &overlappedData);

while(true)
{
    if(WaitForSingleObject(inputEvent, 0) == WAIT_OBJECT_0)
    {
        std::cout << "input has been received" << std::endl;
    }
    std::cout << "doing something" << std::endl;
}

Answer 1

当您打开CONIN$ 或CONOUT$ 时，参数dwFlagsAndAttributes 将被忽略（在CreateFile 函数的文档中完整描述了如何打开控制台）。如果您喜欢异步读取控制台，您可以将CreateFile 返回的句柄直接传递给WaitForSingleObject 函数，如果有任何控制台事件未决，则会发出此句柄的信号，使用函数ReadConsoleInput 你是否读取了未决的事件。 Here 是关于如何在 windows 中使用控制台的完整文档。