LPOVERLAPPED_COMPLETION_ROUTINE与功能不兼容 [英] LPOVERLAPPED_COMPLETION_ROUTINE is incompatible with function

问题描述

我想使用 winapi 中的 WriteFileEx 将数据异步写入文件，但是我对回调有疑问。

I want to asynchronously write data to file using WriteFileEx from winapi, but I have a problem with callback.

我正在跟踪错误：
类型为 void（*）（DWORD dwErrorCode，DWORD dwNumberOfBytesTransfered，LPOVERLAPPED lpOverlapped）的参数不兼容参数类型为 LPOVERLAPPED_COMPLETION_ROUTINE

I'm getting follow error: an argument of type "void (*) (DWORD dwErrorCode, DWORD dwNumberOfBytesTransfered, LPOVERLAPPED lpOverlapped)" is incompatible with parameter of type "LPOVERLAPPED_COMPLETION_ROUTINE"

我在做什么错了？

这是代码：

// Callback
void onWriteComplete(
        DWORD dwErrorCode,
        DWORD dwNumberOfBytesTransfered,
        LPOVERLAPPED lpOverlapped) {
    return;
}

BOOL writeToOutputFile(String ^outFileName, List<String ^> ^fileNames) {
    HANDLE hFile;
    char DataBuffer[] = "This is some test data to write to the file.";
    DWORD dwBytesToWrite = (DWORD) strlen(DataBuffer);
    DWORD dwBytesWritten = 0;
    BOOL bErrorFlag = FALSE;

    pin_ptr<const wchar_t> wFileName = PtrToStringChars(outFileName);

    hFile = CreateFile(
        wFileName,              // name of the write
        GENERIC_WRITE,          // open for writing
        0,                      // do not share
        NULL,                   // default security
        CREATE_NEW,             // create new file only
        FILE_FLAG_OVERLAPPED, 
        NULL);                  // no attr. template

    if (hFile == INVALID_HANDLE_VALUE) {
        return FALSE;
    }

    OVERLAPPED oOverlap;
    bErrorFlag = WriteFileEx(
        hFile,           // open file handle
        DataBuffer,      // start of data to write
        dwBytesToWrite,  // number of bytes to write
        &oOverlap,      // overlapped structure
        onWriteComplete),

    CloseHandle(hFile);
}

推荐答案

您应该先阅读仔细文档。这部分尤其重要：

You should start by reading the documentation carefully. This part is of particular import:

在写操作期间，OVERLAPPED数据结构必须保持有效。它不应是在写操作待完成时可以超出范围的变量。

The OVERLAPPED data structure must remain valid for the duration of the write operation. It should not be a variable that can go out of scope while the write operation is pending completion.

您不满足该要求，并且您需要紧急解决该问题。

You are not meeting that requirement, and you need to tackle that issue urgently.

对于编译器错误，这很简单。您的回调不符合要求。再次查阅文档，其签名为：

As for the compiler error, that's simple enough. Your callback does not meet the requirements. Again consult the documentation where its signature is given as:

VOID CALLBACK FileIOCompletionRoutine(
  _In_     DWORD dwErrorCode,
  _In_     DWORD dwNumberOfBytesTransfered,
  _Inout_  LPOVERLAPPED lpOverlapped
);

您已省略 CALLBACK 约定。

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