什麼C＃等價於「mklink/J」？

Question

我知道如何在一個.BAT腳本在Windows中創建符號鏈接：

mklink /J <LinkPath> <OriginalResourcePath> 

如何做同樣的事情在C＃中？

我一直沒有滿意的谷歌搜索，因爲我是C＃初學者，我可能不使用正確的條款。任何人都可以指示API使用嗎？

Answer 1

下面是一個代碼示例：

using System.Runtime.InteropServices; 
using System.IO; 

namespace ConsoleApplication 
{ 
    class Program 
    { 
     [DllImport("kernel32.dll")] 
     static extern bool CreateSymbolicLink(
     string lpSymlinkFileName, string lpTargetFileName, SymbolicLink dwFlags); 

     enum SymbolicLink 
     { 
      File = 0, 
      Directory = 1 
     } 

     static void Main(string[] args) 
     { 
      string symbolicLink = @"c:\bar.txt"; 
      string fileName = @"c:\temp\foo.txt"; 

      using (var writer = File.CreateText(fileName)) 
      { 
       writer.WriteLine("Hello World"); 
      } 

      CreateSymbolicLink(symbolicLink, fileName, SymbolicLink.File); 
     } 
    } 
} 

這將創建一個名爲在C跳回到bar.txt的符號鏈接文件：-drive可鏈接到存儲在C foo.txt的文本文件：\ temp目錄。

Answer 2

這是一個項目，它具有用於創建聯結的PInvoke簽名：http://www.codeproject.com/Articles/15633/Manipulating-NTFS-Junction-Points-in-NET。該代碼被複制如下：

using System; 
using System.IO; 
using System.Runtime.InteropServices; 
using System.Text; 
using Microsoft.Win32.SafeHandles; 

namespace Util { 
    /// <summary> 
    /// Provides access to NTFS junction points in .Net. 
    /// </summary> 
    public static class JunctionPoint { 
     /// <summary> 
     /// The file or directory is not a reparse point. 
     /// </summary> 
     private const int ERROR_NOT_A_REPARSE_POINT = 4390; 

     /// <summary> 
     /// The reparse point attribute cannot be set because it conflicts with an existing attribute. 
     /// </summary> 
     private const int ERROR_REPARSE_ATTRIBUTE_CONFLICT = 4391; 

     /// <summary> 
     /// The data present in the reparse point buffer is invalid. 
     /// </summary> 
     private const int ERROR_INVALID_REPARSE_DATA = 4392; 

     /// <summary> 
     /// The tag present in the reparse point buffer is invalid. 
     /// </summary> 
     private const int ERROR_REPARSE_TAG_INVALID = 4393; 

     /// <summary> 
     /// There is a mismatch between the tag specified in the request and the tag present in the reparse point. 
     /// </summary> 
     private const int ERROR_REPARSE_TAG_MISMATCH = 4394; 

     /// <summary> 
     /// Command to set the reparse point data block. 
     /// </summary> 
     private const int FSCTL_SET_REPARSE_POINT = 0x000900A4; 

     /// <summary> 
     /// Command to get the reparse point data block. 
     /// </summary> 
     private const int FSCTL_GET_REPARSE_POINT = 0x000900A8; 

     /// <summary> 
     /// Command to delete the reparse point data base. 
     /// </summary> 
     private const int FSCTL_DELETE_REPARSE_POINT = 0x000900AC; 

     /// <summary> 
     /// Reparse point tag used to identify mount points and junction points. 
     /// </summary> 
     private const uint IO_REPARSE_TAG_MOUNT_POINT = 0xA0000003; 

     /// <summary> 
     /// This prefix indicates to NTFS that the path is to be treated as a non-interpreted 
     /// path in the virtual file system. 
     /// </summary> 
     private const string NonInterpretedPathPrefix = @"\??\"; 

     [Flags] 
     private enum EFileAccess : uint { 
      GenericRead = 0x80000000, 
      GenericWrite = 0x40000000, 
      GenericExecute = 0x20000000, 
      GenericAll = 0x10000000, 
     } 

     [Flags] 
     private enum EFileShare : uint { 
      None = 0x00000000, 
      Read = 0x00000001, 
      Write = 0x00000002, 
      Delete = 0x00000004, 
     } 

     private enum ECreationDisposition : uint { 
      New = 1, 
      CreateAlways = 2, 
      OpenExisting = 3, 
      OpenAlways = 4, 
      TruncateExisting = 5, 
     } 

     [Flags] 
     private enum EFileAttributes : uint { 
      Readonly = 0x00000001, 
      Hidden = 0x00000002, 
      System = 0x00000004, 
      Directory = 0x00000010, 
      Archive = 0x00000020, 
      Device = 0x00000040, 
      Normal = 0x00000080, 
      Temporary = 0x00000100, 
      SparseFile = 0x00000200, 
      ReparsePoint = 0x00000400, 
      Compressed = 0x00000800, 
      Offline = 0x00001000, 
      NotContentIndexed = 0x00002000, 
      Encrypted = 0x00004000, 
      Write_Through = 0x80000000, 
      Overlapped = 0x40000000, 
      NoBuffering = 0x20000000, 
      RandomAccess = 0x10000000, 
      SequentialScan = 0x08000000, 
      DeleteOnClose = 0x04000000, 
      BackupSemantics = 0x02000000, 
      PosixSemantics = 0x01000000, 
      OpenReparsePoint = 0x00200000, 
      OpenNoRecall = 0x00100000, 
      FirstPipeInstance = 0x00080000 
     } 

     [StructLayout(LayoutKind.Sequential)] 
     private struct REPARSE_DATA_BUFFER { 
      /// <summary> 
      /// Reparse point tag. Must be a Microsoft reparse point tag. 
      /// </summary> 
      public uint ReparseTag; 

      /// <summary> 
      /// Size, in bytes, of the data after the Reserved member. This can be calculated by: 
      /// (4 * sizeof(ushort)) + SubstituteNameLength + PrintNameLength + 
      /// (namesAreNullTerminated ? 2 * sizeof(char) : 0); 
      /// </summary> 
      public ushort ReparseDataLength; 

      /// <summary> 
      /// Reserved; do not use. 
      /// </summary> 
      public ushort Reserved; 

      /// <summary> 
      /// Offset, in bytes, of the substitute name string in the PathBuffer array. 
      /// </summary> 
      public ushort SubstituteNameOffset; 

      /// <summary> 
      /// Length, in bytes, of the substitute name string. If this string is null-terminated, 
      /// SubstituteNameLength does not include space for the null character. 
      /// </summary> 
      public ushort SubstituteNameLength; 

      /// <summary> 
      /// Offset, in bytes, of the print name string in the PathBuffer array. 
      /// </summary> 
      public ushort PrintNameOffset; 

      /// <summary> 
      /// Length, in bytes, of the print name string. If this string is null-terminated, 
      /// PrintNameLength does not include space for the null character. 
      /// </summary> 
      public ushort PrintNameLength; 

      /// <summary> 
      /// A buffer containing the unicode-encoded path string. The path string contains 
      /// the substitute name string and print name string. 
      /// </summary> 
      [MarshalAs(UnmanagedType.ByValArray, SizeConst = 0x3FF0)] 
      public byte[] PathBuffer; 
     } 

     [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)] 
     private static extern bool DeviceIoControl(IntPtr hDevice, uint dwIoControlCode, 
      IntPtr InBuffer, int nInBufferSize, 
      IntPtr OutBuffer, int nOutBufferSize, 
      out int pBytesReturned, IntPtr lpOverlapped); 

     [DllImport("kernel32.dll", SetLastError = true)] 
     private static extern IntPtr CreateFile(
      string lpFileName, 
      EFileAccess dwDesiredAccess, 
      EFileShare dwShareMode, 
      IntPtr lpSecurityAttributes, 
      ECreationDisposition dwCreationDisposition, 
      EFileAttributes dwFlagsAndAttributes, 
      IntPtr hTemplateFile); 

     /// <summary> 
     /// Creates a junction point from the specified directory to the specified target directory. 
     /// </summary> 
     /// <remarks> 
     /// Only works on NTFS. 
     /// </remarks> 
     /// <param name="targetDir">The target directory to create</param> 
     /// <param name="sourceDir">The source directory to alias</param> 
     /// <param name="overwrite">If true overwrites an existing reparse point or empty directory</param> 
     /// <exception cref="IOException">Thrown when the junction point could not be created or when 
     /// an existing directory was found and <paramref name="overwrite" /> if false</exception> 
     public static void Create(string sourceDir, string targetDir, bool overwrite) { 
      sourceDir = Path.GetFullPath(sourceDir); 

      if (!Directory.Exists(sourceDir)) 
       throw new IOException($"Source path does not exist or is not a directory."); 

      if (Directory.Exists(targetDir)) 
       throw new IOException($"Directory '{targetDir}' already exists."); 

      Directory.CreateDirectory(targetDir); 

      using (SafeFileHandle handle = OpenReparsePoint(targetDir, EFileAccess.GenericWrite)) { 
       byte[] sourceDirBytes = Encoding.Unicode.GetBytes(NonInterpretedPathPrefix + Path.GetFullPath(sourceDir)); 

       REPARSE_DATA_BUFFER reparseDataBuffer = new REPARSE_DATA_BUFFER(); 

       reparseDataBuffer.ReparseTag = IO_REPARSE_TAG_MOUNT_POINT; 
       reparseDataBuffer.ReparseDataLength = (ushort)(sourceDirBytes.Length + 12); 
       reparseDataBuffer.SubstituteNameOffset = 0; 
       reparseDataBuffer.SubstituteNameLength = (ushort)sourceDirBytes.Length; 
       reparseDataBuffer.PrintNameOffset = (ushort)(sourceDirBytes.Length + 2); 
       reparseDataBuffer.PrintNameLength = 0; 
       reparseDataBuffer.PathBuffer = new byte[0x3ff0]; 
       Array.Copy(sourceDirBytes, reparseDataBuffer.PathBuffer, sourceDirBytes.Length); 

       int inBufferSize = Marshal.SizeOf(reparseDataBuffer); 
       IntPtr inBuffer = Marshal.AllocHGlobal(inBufferSize); 

       try { 
        Marshal.StructureToPtr(reparseDataBuffer, inBuffer, false); 

        int bytesReturned; 
        bool result = DeviceIoControl(handle.DangerousGetHandle(), FSCTL_SET_REPARSE_POINT, 
         inBuffer, sourceDirBytes.Length + 20, IntPtr.Zero, 0, out bytesReturned, IntPtr.Zero); 

        if (!result) 
         ThrowLastWin32Error($"Unable to create junction point '{sourceDir}' -> '{targetDir}'."); 
       } finally { 
        Marshal.FreeHGlobal(inBuffer); 
       } 
      } 
     } 

     /// <summary> 
     /// Deletes a junction point at the specified source directory along with the directory itself. 
     /// Does nothing if the junction point does not exist. 
     /// </summary> 
     /// <remarks> 
     /// Only works on NTFS. 
     /// </remarks> 
     /// <param name="junctionPoint">The junction point path</param> 
     public static void Delete(string junctionPoint) { 
      if (!Directory.Exists(junctionPoint)) { 
       if (File.Exists(junctionPoint)) 
        throw new IOException("Path is not a junction point."); 

       return; 
      } 

      using (SafeFileHandle handle = OpenReparsePoint(junctionPoint, EFileAccess.GenericWrite)) { 
       REPARSE_DATA_BUFFER reparseDataBuffer = new REPARSE_DATA_BUFFER(); 

       reparseDataBuffer.ReparseTag = IO_REPARSE_TAG_MOUNT_POINT; 
       reparseDataBuffer.ReparseDataLength = 0; 
       reparseDataBuffer.PathBuffer = new byte[0x3ff0]; 

       int inBufferSize = Marshal.SizeOf(reparseDataBuffer); 
       IntPtr inBuffer = Marshal.AllocHGlobal(inBufferSize); 
       try { 
        Marshal.StructureToPtr(reparseDataBuffer, inBuffer, false); 

        int bytesReturned; 
        bool result = DeviceIoControl(handle.DangerousGetHandle(), FSCTL_DELETE_REPARSE_POINT, 
         inBuffer, 8, IntPtr.Zero, 0, out bytesReturned, IntPtr.Zero); 

        if (!result) 
         ThrowLastWin32Error("Unable to delete junction point."); 
       } finally { 
        Marshal.FreeHGlobal(inBuffer); 
       } 

       try { 
        Directory.Delete(junctionPoint); 
       } catch (IOException ex) { 
        throw new IOException("Unable to delete junction point.", ex); 
       } 
      } 
     } 

     /// <summary> 
     /// Determines whether the specified path exists and refers to a junction point. 
     /// </summary> 
     /// <param name="path">The junction point path</param> 
     /// <returns>True if the specified path represents a junction point</returns> 
     /// <exception cref="IOException">Thrown if the specified path is invalid 
     /// or some other error occurs</exception> 
     public static bool Exists(string path) { 
      if (!Directory.Exists(path)) 
       return false; 

      using (SafeFileHandle handle = OpenReparsePoint(path, EFileAccess.GenericRead)) { 
       string target = InternalGetTarget(handle); 
       return target != null; 
      } 
     } 

     /// <summary> 
     /// Gets the target of the specified junction point. 
     /// </summary> 
     /// <remarks> 
     /// Only works on NTFS. 
     /// </remarks> 
     /// <param name="junctionPoint">The junction point path</param> 
     /// <returns>The target of the junction point</returns> 
     /// <exception cref="IOException">Thrown when the specified path does not 
     /// exist, is invalid, is not a junction point, or some other error occurs</exception> 
     public static string GetTarget(string junctionPoint) { 
      using (SafeFileHandle handle = OpenReparsePoint(junctionPoint, EFileAccess.GenericRead)) { 
       string target = InternalGetTarget(handle); 
       if (target == null) 
        throw new IOException("Path is not a junction point."); 

       return target; 
      } 
     } 

     private static string InternalGetTarget(SafeFileHandle handle) { 
      int outBufferSize = Marshal.SizeOf(typeof(REPARSE_DATA_BUFFER)); 
      IntPtr outBuffer = Marshal.AllocHGlobal(outBufferSize); 

      try { 
       int bytesReturned; 
       bool result = DeviceIoControl(handle.DangerousGetHandle(), FSCTL_GET_REPARSE_POINT, 
        IntPtr.Zero, 0, outBuffer, outBufferSize, out bytesReturned, IntPtr.Zero); 

       if (!result) { 
        int error = Marshal.GetLastWin32Error(); 
        if (error == ERROR_NOT_A_REPARSE_POINT) 
         return null; 

        ThrowLastWin32Error("Unable to get information about junction point."); 
       } 

       REPARSE_DATA_BUFFER reparseDataBuffer = (REPARSE_DATA_BUFFER) 
        Marshal.PtrToStructure(outBuffer, typeof(REPARSE_DATA_BUFFER)); 

       if (reparseDataBuffer.ReparseTag != IO_REPARSE_TAG_MOUNT_POINT) 
        return null; 

       string targetDir = Encoding.Unicode.GetString(reparseDataBuffer.PathBuffer, 
        reparseDataBuffer.SubstituteNameOffset, reparseDataBuffer.SubstituteNameLength); 

       if (targetDir.StartsWith(NonInterpretedPathPrefix)) 
        targetDir = targetDir.Substring(NonInterpretedPathPrefix.Length); 

       return targetDir; 
      } finally { 
       Marshal.FreeHGlobal(outBuffer); 
      } 
     } 

     private static SafeFileHandle OpenReparsePoint(string reparsePoint, EFileAccess accessMode) { 
      SafeFileHandle reparsePointHandle = new SafeFileHandle(CreateFile(reparsePoint, accessMode, 
       EFileShare.Read | EFileShare.Write | EFileShare.Delete, 
       IntPtr.Zero, ECreationDisposition.OpenExisting, 
       EFileAttributes.BackupSemantics | EFileAttributes.OpenReparsePoint, IntPtr.Zero), true); 

      if (Marshal.GetLastWin32Error() != 0) 
       ThrowLastWin32Error("Unable to open reparse point."); 

      return reparsePointHandle; 
     } 

     private static void ThrowLastWin32Error(string message) { 
      throw new IOException(message, Marshal.GetExceptionForHR(Marshal.GetHRForLastWin32Error())); 
     } 
    } 
}