如何使用 C# 同步一致地删除 NTFS 上的文件夹

Question

这个：

Directory.Delete(dir, true);

不是同步的。

在接下来的行中，您仍然可以操作/读取目录。

例如，这个：

Directory.Delete(destinationDir, true);
Directory.CreateDirectory(destinationDir);
Thread.Sleep(1000);

导致文件夹不存在。删除运行异步，CreateDirectory 不创建，因为它已经存在，然后删除实际触发并删除目录。

是否有可以让我保持一致性的 IO API？

涉及Thread.Sleep 的答案将调用 Zalgo。我想要一个真正的解决方案。

Answer 1

正如其他人所提到的，.net 框架似乎没有同步运行。在 PowerShell 中对其进行测试表明 .Net 调用不会等待，因此这样的事情会产生类似的结果：

Remove-Item -Recurse -Force "C:\tempfolder"
New-Item -ItemType Directory "C:\tempfolder"

使用文件观察器（前面也提到过）将确保目录删除在创建完成之前完成：

var path = @"C:\tempfolder";
var watcher = new FileSystemWatcher(path);
watcher.Deleted += (sender, args) => Directory.CreateDirectory(args.FullPath);
Directory.Delete(path, true);

没有真正的惊喜，但至少它是一个有效的解决方案，不涉及从托管代码调用 C++ API。

Answer 2

在 C++ 中进行一些测试后，用于删除文件/目录的本机 Windows 函数似乎确实阻塞了。当涉及到删除功能未被阻止时，问题似乎出在 .NET 方面，因为 Directory.CreateDirectory() 似乎在 Directory.Delete() 完成之前被调用。

这是我在 Win32 控制台应用程序中尝试的：

printf("Press enter to begin...");
while(getchar() != '\n');

LPCSTR DeletePath = "C:\\test\\DeleteMe"; //The directory to delete.
_SHFILEOPSTRUCTA* fileopt = new _SHFILEOPSTRUCTA();

fileopt->hwnd = NULL;        //No window handle.
fileopt->wFunc = FO_DELETE;  //Delete mode.
fileopt->pFrom = DeletePath; //The directory to delete.
fileopt->pTo = NULL;         //No target directory (this is only used when moving, copying, etc.).
fileopt->fFlags = FOF_NO_UI; //Display no UI dialogs.

int Success = SHFileOperationA(fileopt); //Remove the entire directory and all it's contents.
bool Success2 = CreateDirectoryA(DeletePath, NULL); //Create a new directory.

LPCSTR ReturnedValue = "False"; //I'm no C++ guru, so please don't hate. :)
LPCSTR ReturnedValue2 = "False";
if(Success == 0) { ReturnedValue = "True"; } //The SHFileOperation() returns 0 if it succeeds.
if(Success2 == true) { ReturnedValue2 = "True"; }

//Print the result of SHFileOperation().
printf("Returned value: ");
printf(ReturnedValue);
printf("\n");

//Print the result of CreateDirectory().
printf("Returned value 2: ");
printf(ReturnedValue2);
printf("\n");

//Continue.
printf("Press enter to exit...");
while(getchar() != '\n');

第一次按 ENTER 后，在显示结果之前会有一小段延迟，之后查看文件夹时它是空的，有一个新的创建和最后修改的日期 - 这意味着它已被删除并以正确的顺序重新创建.

因此，为了实现您想要的，我想您可以尝试创建自己的方法来调用 SHFileOperation()，因为问题似乎是 Directory.Delete() 方法在 .NET 代码中执行迭代本身（请参阅Reference Source)。

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--- 编辑 ---

在 C# 中测试后，这似乎有效！唯一的问题是第一次（自应用程序启动后）调用 P/Invoked SHFileOperation() 函数时，它将返回值 2，相当于 ERROR_FILE_NOT_FOUND。但是如果你再次执行它会返回 0（成功）。

NativeMethods.cs：

需要进口：

using System;
using System.Runtime.InteropServices;

其余代码：

[DllImport("shell32.dll", CharSet = CharSet.Unicode)]
public static extern int SHFileOperation([In] ref SHFILEOPSTRUCT lpFileOp);

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct SHFILEOPSTRUCT
{
    public IntPtr hwnd;
    public FileFuncFlags wFunc;

    [MarshalAs(UnmanagedType.LPWStr)]
    public string pFrom;

    [MarshalAs(UnmanagedType.LPWStr)]
    public string pTo;
    public FILEOP_FLAGS fFlags;

    [MarshalAs(UnmanagedType.Bool)]
    public bool fAnyOperationsAborted;
    public IntPtr hNameMappings;

    [MarshalAs(UnmanagedType.LPWStr)]
    public string lpszProgressTitle;
}

public enum FileFuncFlags : uint
{
    FO_MOVE = 0x1,
    FO_COPY = 0x2,
    FO_DELETE = 0x3,
    FO_RENAME = 0x4
}

[Flags]
public enum FILEOP_FLAGS : ushort
{
    FOF_MULTIDESTFILES = 0x1,
    FOF_CONFIRMMOUSE = 0x2,
    /// <summary>
    /// Don't create progress/report
    /// </summary>
    FOF_SILENT = 0x4,
    FOF_RENAMEONCOLLISION = 0x8,
    /// <summary>
    /// Don't prompt the user.
    /// </summary>
    FOF_NOCONFIRMATION = 0x10,
    /// <summary>
    /// Fill in SHFILEOPSTRUCT.hNameMappings.
    /// Must be freed using SHFreeNameMappings
    /// </summary>
    FOF_WANTMAPPINGHANDLE = 0x20,
    FOF_ALLOWUNDO = 0x40,
    /// <summary>
    /// On *.*, do only files
    /// </summary>
    FOF_FILESONLY = 0x80,
    /// <summary>
    /// Don't show names of files
    /// </summary>
    FOF_SIMPLEPROGRESS = 0x100,
    /// <summary>
    /// Don't confirm making any needed dirs
    /// </summary>
    FOF_NOCONFIRMMKDIR = 0x200,
    /// <summary>
    /// Don't put up error UI
    /// </summary>
    FOF_NOERRORUI = 0x400,
    /// <summary>
    /// Dont copy NT file Security Attributes
    /// </summary>
    FOF_NOCOPYSECURITYATTRIBS = 0x800,
    /// <summary>
    /// Don't recurse into directories.
    /// </summary>
    FOF_NORECURSION = 0x1000,
    /// <summary>
    /// Don't operate on connected elements.
    /// </summary>
    FOF_NO_CONNECTED_ELEMENTS = 0x2000,
    /// <summary>
    /// During delete operation, 
    /// warn if nuking instead of recycling (partially overrides FOF_NOCONFIRMATION)
    /// </summary>
    FOF_WANTNUKEWARNING = 0x4000,
    /// <summary>
    /// Treat reparse points as objects, not containers
    /// </summary>
    FOF_NORECURSEREPARSE = 0x8000
}

其他地方：

string DeletePath = "C:\\test\\DeleteMe";
NativeMethods.SHFILEOPSTRUCT fileopt = new NativeMethods.SHFILEOPSTRUCT();

fileopt.hwnd = IntPtr.Zero;
fileopt.wFunc = NativeMethods.FileFuncFlags.FO_DELETE;
fileopt.pFrom = DeletePath;
fileopt.pTo = null;
fileopt.fFlags = NativeMethods.FILEOP_FLAGS.FOF_SILENT | NativeMethods.FILEOP_FLAGS.FOF_NOCONFIRMATION |
                 NativeMethods.FILEOP_FLAGS.FOF_NOERRORUI | NativeMethods.FILEOP_FLAGS.FOF_NOCONFIRMMKDIR; //Equivalent of FOF_NO_UI.

int Success = NativeMethods.SHFileOperation(ref fileopt);
Directory.CreateDirectory(DeletePath);

MessageBox.Show("Operation returned value: " + Success.ToString(), "Test", MessageBoxButtons.OK, MessageBoxIcon.Information);

希望这会有所帮助！

Answer 3

这是一个有同样问题的人的link，首先重命名/移动目录的解决方案可能对你有用。

否则您可以使用 FileWatcher 对目录删除做出反应，但这感觉有点矫枉过正。