Question

有人能帮帮我吗？

我尝试从托管的.net代码P/Invoke获取WINAPI方法。 CreateFile()方法始终返回false。如果我使给定的路径小于256，它就可以正常工作，但如果大于256则不行。我可能做错了。根据这个link，我应该能够使用长度大于256的长路径文件。

以下是我尝试过的代码：

static void Main(string[] args)
        {
        string path =            @"c:\tttttttttttaaaaaaaaaaaaaaatttttttttttttttaaaaaaaaaaaaaaatttttttttttttttttttttttttttttttaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaattttttttttttttttttaaaaaaaaaaaaaaaaatttttttttttaaaaaaaaaaatttttttaaaaaaaaaaaaaaaaattttttttttttttttttaaaaaaaaaaaaaaaaattttttttttttttaaaaaaaaaaaaaaaaatttttt";

        LongPath.TestCreateAndWrite(path);

        }


    // This code snippet is provided under the Microsoft Permissive License.
    [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
    internal static extern SafeFileHandle CreateFile(
    string lpFileName,
    EFileAccess dwDesiredAccess,
    EFileShare dwShareMode,
    IntPtr lpSecurityAttributes,
    ECreationDisposition dwCreationDisposition,
    EFileAttributes dwFlagsAndAttributes,
    IntPtr hTemplateFile);




public static void TestCreateAndWrite(string fileName) {

    string formattedName = @"\\?\" + fileName;
    //string formattedName = @"\\?\UNC" + fileName;
    // Create a file with generic write access
    SafeFileHandle fileHandle = CreateFile(formattedName, EFileAccess.GenericWrite, 
       EFileShare.None, IntPtr.Zero,  ECreationDisposition.CreateAlways, 0, IntPtr.Zero);

    // Check for errors
    int lastWin32Error = Marshal.GetLastWin32Error();
    if (fileHandle.IsInvalid) {
        throw new System.ComponentModel.Win32Exception(lastWin32Error);
    }

    // Pass the file handle to FileStream. FileStream will close the
    // handle
    using (FileStream fs = new FileStream(fileHandle,
                                    FileAccess.Write)) {
        fs.WriteByte(80);
        fs.WriteByte(81);
        fs.WriteByte(83);
        fs.WriteByte(84);
    }
}

此方法抛出错误代码3，这是根据系统错误代码（0-499）（Windows）未指定的文件路径。

任何帮助都会非常明显。

Answer 1

虽然\\?\表示法允许您使用总长度超过MAX_PATH的路径，但您仍必须遵守GetVolumeInformation报告的每个组件限制。对于NTFS，每个组件的限制为255，这意味着如果没有反斜杠，则不允许超过255个字符。

使用长路径时调用WinApi

1 个答案: