Question

我正在使用旧文件格式。

该文件是使用非托管C ++创建的，该C ++使用WinBase.h CreateFile（）＆amp; WriteFile（）函数（在kernel32.dll中找到）。

我一直在使用P / Invoke互操作来访问这些本机函数，如下所示：

    [DllImport("kernel32.dll")]
    public static extern bool WriteFile(
        IntPtr hFile,
        byte[] lpBuffer,
        uint nNumberOfBytesToWrite,
        out uint lpNumberOfBytesWritten,
        [In] ref NativeOverlapped lpOverlapped);

    [DllImport("kernel32.dll", SetLastError = true)]
    public static extern bool WriteFileEx(
        IntPtr hFile,
        byte[] lpBuffer,
        uint nNumberOfBytesToWrite,
        [In] ref NativeOverlapped lpOverlapped,
        WriteFileCompletionDelegate lpCompletionRoutine);

    [DllImport("kernel32.dll", SetLastError = true)]
    public static extern IntPtr CreateFile(
        string lpFileName, uint dwDesiredAccess,
        uint dwShareMode, IntPtr lpSecurityAttributes,
        uint dwCreationDisposition,
        uint dwFlagsAndAttributes, IntPtr hTemplateFile);

    [DllImport("kernel32.dll", SetLastError = true)]
    public static extern bool CloseHandle(IntPtr hObject);

    public delegate void WriteFileCompletionDelegate(
        UInt32 dwErrorCode,
        UInt32 dwNumberOfBytesTransfered,
        ref NativeOverlapped lpOverlapped);

这个问题是当我调用WriteFile（）时，文件总是被正在进行的调用覆盖。

首选我想使用兼容的.NET等价物，这样我就可以生成完全相同的输出格式。

C ++代码如下所示:(工作）

HANDLE hFile = CreateFile(sFileName, GENERIC_WRITE, FILE_SHARE_WRITE, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
WriteFile(hFile, &someVar1, sizeof(bool), &dwWritten, NULL);
WriteFile(hFile, &someVar1, sizeof(long), &dwWritten, NULL);
WriteFile(hFile, &someVar2, sizeof(bool), &dwWritten, NULL);
WriteFile(hFile, sStr.GetBuffer(0), dwStrLen*sizeof(TCHAR), &dwWritten, NULL);
CloseHandle(hFile);

C＃如下:( OVERWRITES PREVIOUS WRITE，即输出文件只包含'T'）

{   
    var hFile = COMFileOps2.CreateFile(FILE_NAME, (uint) COMFileOps2.FILE_GENERIC_WRITE,
                                       COMFileOps2.FILE_SHARE_WRITE, IntPtr.Zero, COMFileOps2.CREATE_ALWAYS,
                                       COMFileOps2.FILE_ATTRIBUTE_NORMAL, IntPtr.Zero);

    var natOverlap = new NativeOverlapped();

    COMFileOps2.WriteFileEx(hFile, new byte[] {(byte) 't'}, 1, ref natOverlap, Callback);
    COMFileOps2.WriteFileEx(hFile, new byte[] { (byte)'e' }, 1, ref natOverlap, Callback);
    COMFileOps2.WriteFileEx(hFile, new byte[] { (byte)'s' }, 1, ref natOverlap, Callback);
    COMFileOps2.WriteFileEx(hFile, new byte[] { (byte)'T' }, 1, ref natOverlap, Callback);

    COMFileOps2.CloseHandle(hFile);

}

private static void Callback(uint dwerrorcode, uint dwnumberofbytestransfered, ref NativeOverlapped lpoverlapped)
{
    throw new NotImplementedException();
}

更新：以下C＃代码会写出“测试”：

uint written;
uint position = 0;

var natOverlap0 = new NativeOverlapped();
COMFileOps.WriteFile(hFile, new byte[] {(byte) 'T'}, 1, out written, ref natOverlap0);

position += written;
var natOverlap1 = new NativeOverlapped {OffsetLow = (int) position};
COMFileOps.WriteFile(hFile, new byte[] { (byte)'e' }, 1, out written, ref natOverlap1);

position += written;
var natOverlap2 = new NativeOverlapped { OffsetLow = (int)position };
COMFileOps.WriteFile(hFile, new byte[] { (byte)'s' }, 1, out written, ref natOverlap2);

position += written;
var natOverlap3 = new NativeOverlapped { OffsetLow = (int)position };
COMFileOps.WriteFile(hFile, new byte[] { (byte)'t' }, 1, out written, ref natOverlap3);

COMFileOps.CloseHandle(hFile);

感谢。

Answer 1

您没有解释您尝试处理的格式，但File.WriteAllText是否足够？

File.WriteAllText("someFile.txt", "some format");

对于二进制文件，您可以使用File.WriteAllBytes：

File.WriteAllBytes("someFile.bin", new byte[] { 0x1, 0x2, 0x3 });

Answer 2

WriteFileEx只能异步运行，您必须为每个挂起的调用提供OVERLAPPED的SEPARATE实例，并且必须设置OVERLAPPED成员，例如文件偏移量。然后，在完成所有操作之前，您无法调用CloseHandle。并使用局部变量OVERLAPPED并让它超出范围？被覆盖的数据是您显示的代码可能出错的最少。

这就是为什么你的代码不起作用的原因。我不知道为什么你首先从WriteFile切换到WriteFileEx。此外，从C＃调用Win32 API非常不方便，尽管偶尔需要。但首先要看看.NET File API是否能满足您的需求。

由于.NET文件API倾向于使用字符串（在textmode中，注意换行符等）或字节数组，因此需要将其他变量转换为byte []。 BitConverter课程是你的朋友。

Answer 3

查看他们提供您正在寻找的方法的System.IO.File和System.IO.FileInfo类。

Answer 4

原始API调用没有什么特别之处。只需获得System.IO.FileStream并在其上调用Write。（获取FileStream的一种方法是首先获取System.IO.File。

托管.NET等同于CreateFile＆amp;来自WinBase的WriteFile（kernel32.dll）

4 个答案: