private NativeMethods.ReparseDataBuffer GetReparsePointInfo()
{
const uint fileOpenReparsePoint = 0x00200000;
const uint fileFlagBackupSemantics = 0x02000000;
const FileOptions flags = (FileOptions)(fileOpenReparsePoint | fileFlagBackupSemantics);
using (var handle = NativeMethods.CreateFile(LinkName, NativeMethods.FileAccessEx.None, FileShare.Read, IntPtr.Zero, FileMode.Open, flags, IntPtr.Zero))
{
if (handle.IsInvalid)
{
throw Win32Utils.GetExceptionForLastError();
}
var reparseDataBuffer = new NativeMethods.ReparseDataBuffer();
const int fsctlGetReparsePoint = 0x000900A8;
var bytesReturned = 0;
var success = NativeMethods.DeviceIoControl(handle, fsctlGetReparsePoint,
IntPtr.Zero, 0,
reparseDataBuffer, Marshal.SizeOf(typeof(NativeMethods.ReparseDataBuffer)),
ref bytesReturned, IntPtr.Zero);
if (!success)
{
const uint pathNotAReparsePointError = 0x80071126;
if ((uint)Marshal.GetHRForLastWin32Error() == pathNotAReparsePointError)
{
return(null);
}
throw Win32Utils.GetExceptionForLastError();
}
return(reparseDataBuffer);
}
}
/// <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))
{
if (!overwrite)
{
throw new IOException("Directory '{targetDir}' already exists.");
}
}
else
{
Directory.CreateDirectory(targetDir);
}
using (SafeFileHandle handle = OpenReparsePoint(targetDir, NativeMethods.FileAccess.GenericWrite))
{
byte[] sourceDirBytes = Encoding.Unicode.GetBytes(NativeMethods.NonInterpretedPathPrefix + Path.GetFullPath(sourceDir));
NativeMethods.ReparseDataBuffer reparseDataBuffer = new NativeMethods.ReparseDataBuffer();
reparseDataBuffer.ReparseTag = NativeMethods.IoReparseTagMountPoint;
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 = NativeMethods.DeviceIoControl(handle.DangerousGetHandle(), NativeMethods.FsctlSetReparsePoint,
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, NativeMethods.FileAccess.GenericWrite))
{
NativeMethods.ReparseDataBuffer reparseDataBuffer = new NativeMethods.ReparseDataBuffer();
reparseDataBuffer.ReparseTag = NativeMethods.IoReparseTagMountPoint;
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 = NativeMethods.DeviceIoControl(handle.DangerousGetHandle(), NativeMethods.FsctlDeleteReparsePoint,
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>
///
/// </summary>
/// <param name="handle"></param>
/// <returns></returns>
private static string InternalGetTarget(SafeFileHandle handle)
{
int outBufferSize = Marshal.SizeOf(typeof(NativeMethods.ReparseDataBuffer));
IntPtr outBuffer = Marshal.AllocHGlobal(outBufferSize);
try
{
int bytesReturned;
bool result = NativeMethods.DeviceIoControl(handle.DangerousGetHandle(), NativeMethods.FsctlGetReparsePoint,
IntPtr.Zero, 0, outBuffer, outBufferSize, out bytesReturned, IntPtr.Zero);
if (!result)
{
int error = Marshal.GetLastWin32Error();
if (error == NativeMethods.ErrorNotAReparsePoint)
{
return(null);
}
ThrowLastWin32Error("Unable to get information about junction point.");
}
NativeMethods.ReparseDataBuffer reparseDataBuffer = (NativeMethods.ReparseDataBuffer)
Marshal.PtrToStructure(outBuffer, typeof(NativeMethods.ReparseDataBuffer));
if (reparseDataBuffer.ReparseTag != NativeMethods.IoReparseTagMountPoint)
{
return(null);
}
string targetDir = Encoding.Unicode.GetString(reparseDataBuffer.PathBuffer,
reparseDataBuffer.SubstituteNameOffset, reparseDataBuffer.SubstituteNameLength);
if (targetDir.StartsWith(NativeMethods.NonInterpretedPathPrefix))
{
targetDir = targetDir.Substring(NativeMethods.NonInterpretedPathPrefix.Length);
}
return(targetDir);
}
finally
{
Marshal.FreeHGlobal(outBuffer);
}
}
