SEHException when calling WTSVirtualChannelClose

SEHException when calling WTSVirtualChannelClose - c#

I'm building application that will communicate with server using Remote Desktop Service API.
I'm building my application using code found here: https://code.google.com/p/tstunnels/ and here: http://www.codeproject.com/Articles/16374/How-to-Write-a-Terminal-Services-Add-in-in-Pure-C
I build client library that is loaded when I do Remote Desktop Connection and I'm able to send and receive messages.
On server side I get SEHException when I'm trying to close my application.
I use this methods using DLLImport:
[DllImport("Wtsapi32.dll", SetLastError = true)]
public static extern IntPtr WTSVirtualChannelOpen(IntPtr server, int sessionId, [MarshalAs(UnmanagedType.LPStr)] string virtualName);
[DllImport("Wtsapi32.dll", SetLastError = true)]
public static extern bool WTSVirtualChannelQuery(IntPtr channelHandle, WtsVirtualClass Class, out IntPtr data, out int bytesReturned);
[DllImport("Wtsapi32.dll")]
public static extern void WTSFreeMemory(IntPtr memory);
[DllImport("Wtsapi32.dll", SetLastError = true)]
public static extern bool WTSVirtualChannelWrite(IntPtr channelHandle, byte[] data, int length, out int bytesWritten);
[DllImport("Wtsapi32.dll")]
public static extern bool WTSVirtualChannelClose(IntPtr channelHandle);
public static Stream WTSVirtualChannelQuery_WTSVirtualFileHandle(IntPtr channelHandle)
{
int len;
IntPtr buffer;
var b = WTSVirtualChannelQuery(channelHandle, WtsVirtualClass.WTSVirtualFileHandle, out buffer, out len);
if (!b) throw new Win32Exception();
var fileHandle = new SafeFileHandle(Marshal.ReadIntPtr(buffer), true);
WTSFreeMemory(buffer);
return new FileStream(fileHandle, FileAccess.ReadWrite, 0x1000, true);
}
Then inside my application I'm doing this:
mHandle = Native.WTSVirtualChannelOpen(IntPtr.Zero, -1, ChannelName);
if (mHandle == IntPtr.Zero)
{
Log("RDP Virtual channel Open Failed: " + new Win32Exception().Message);
return;
}
try
{
var stream = Native.WTSVirtualChannelQuery_WTSVirtualFileHandle(mHandle);
reader = new BinaryReader(new BufferedStream(stream));
}
catch (Win32Exception ex)
{
Log("RDP Virtual channel Query Failed: " + ex.Message);
return;
}
After that I'm able to write and read thru Virtual Channel, but when I try to close using below code I get error.
if (reader != null) reader.Close();
var ret = Native.WTSVirtualChannelClose(mHandle);
Here is error:
System.Runtime.InteropServices.SEHException (0x80004005): External
component has thrown an exception. at
Server.Native.WTSVirtualChannelClose(IntPtr channelHandle) at
Server.Server.Disconnect() in
i:\Tomka\TS\v2\TSAddin\Server\Server.cs:line 73
I tried getting last Win32Error using Marshal.GetLastWin32Error() but it is returning 1008.
Looking in msdn I found that error description:
ERROR_NO_TOKEN 1008 (0x3F0) An attempt was made to reference a token
that does not exist.
I found article on MSDN but code is in C++ so that didn't help, anyway here is the link: http://msdn.microsoft.com/en-us/library/aa383852(v=vs.85).aspx
EDIT 1
I did as #Hans wrote.
Here is first exception I got:
First-chance exception at 0x00000000771105B7 (ntdll.dll) in Server.exe:
0xC0000008: An invalid handle was specified.
EDIT 2
Here are classes I'm using on server:
class Native
{
[DllImport("Wtsapi32.dll", SetLastError = true)]
public static extern IntPtr WTSVirtualChannelOpen(IntPtr server, int sessionId, [MarshalAs(UnmanagedType.LPStr)] string virtualName);
[DllImport("Wtsapi32.dll", SetLastError = true)]
public static extern bool WTSVirtualChannelQuery(IntPtr channelHandle, WtsVirtualClass Class, out IntPtr data, out int bytesReturned);
[DllImport("Wtsapi32.dll")]
public static extern void WTSFreeMemory(IntPtr memory);
[DllImport("Wtsapi32.dll", SetLastError = true)]
public static extern bool WTSVirtualChannelWrite(IntPtr channelHandle, byte[] data, int length, out int bytesWritten);
[DllImport("Wtsapi32.dll", SetLastError = true)]
public static extern bool WTSVirtualChannelRead(IntPtr channelHandle, int timeOut, IntPtr data, int length, out int bytesRead);
[DllImport("Wtsapi32.dll")]
public static extern bool WTSVirtualChannelClose(IntPtr channelHandle);
public static Stream WTSVirtualChannelQuery_WTSVirtualFileHandle(IntPtr channelHandle)
{
int len;
IntPtr buffer;
var b = WTSVirtualChannelQuery(channelHandle, WtsVirtualClass.WTSVirtualFileHandle, out buffer, out len);
if (!b) throw new Win32Exception();
var fileHandle = new SafeFileHandle(Marshal.ReadIntPtr(buffer), true);
WTSFreeMemory(buffer);
return new FileStream(fileHandle, FileAccess.ReadWrite, 0x1000, true);
}
public enum WtsVirtualClass
{
WTSVirtualClient = 0,
WTSVirtualFileHandle = 1
}
}
and Server.cs:
public class Server
{
private IntPtr mHandle;
private BinaryReader reader;
public bool IsConnected { get; private set; }
private bool SeenHello;
public const string ChannelName = "TEST";
private delegate void Action();
public void Connect()
{
mHandle = Native.WTSVirtualChannelOpen(IntPtr.Zero, -1, ChannelName);
if (mHandle == IntPtr.Zero)
{
Log("RDP Virtual channel Open Failed: " + new Win32Exception().Message);
return;
}
try
{
var stream = Native.WTSVirtualChannelQuery_WTSVirtualFileHandle(mHandle);
reader = new BinaryReader(new BufferedStream(stream));
}
catch (Win32Exception ex)
{
Log("RDP Virtual channel Query Failed: " + ex.Message);
return;
}
IsConnected = true;
Log("Connected");
Action process = Process;
process.BeginInvoke(process.EndInvoke, null);
Action hello = () =>
{
while (!SeenHello && IsConnected)
{
WriteMessage("HELLO");
Log("Sending HELLO");
Thread.Sleep(200);
}
};
hello.BeginInvoke(hello.EndInvoke, null);
}
public void Disconnect()
{
IsConnected = false;
if (reader != null) reader.Close();
var ret = Native.WTSVirtualChannelClose(mHandle);
}
private void Process()
{
while (IsConnected)
{
try
{
var len = reader.ReadInt32();
Log(len.ToString());
byte[] buff = reader.ReadBytes(len);
Log(Encoding.UTF8.GetString(buff));
MessageReceived(Encoding.UTF8.GetString(buff));
}
catch (OperationCanceledException ex)
{
Log(ex);
return;
}
catch (Exception ex)
{
Log(ex);
}
}
}
public bool WriteMessage(string msg)
{
byte[] data = Encoding.UTF8.GetBytes(msg);
int written;
var ret = Native.WTSVirtualChannelWrite(mHandle, data, data.Length, out written);
if (ret) return true;
var ex = new Win32Exception();
if (!SeenHello && ex.NativeErrorCode == 1 /* Incorrect Function */) return false;
Log("RDP Virtual channel Write Failed: " + ex.Message);
return false;
}
public void MessageReceived(string msg)
{
Log(msg);
if (msg.ToUpper() == "HELLO:RESPONSE")
{
if (!SeenHello)
{
SeenHello = true;
OnConnected(msg);
}
}
OnMessage(msg);
}
public EventHandler<MessageEventArgs> Connected;
protected void OnConnected(string msg)
{
if (Connected != null)
Connected(this, new MessageEventArgs(msg));
}
public EventHandler<MessageEventArgs> Message;
protected void OnMessage(string msg)
{
if (Message != null)
Message(this, new MessageEventArgs(msg));
}
public void Log(object message)
{
OnMessageLogged(message.ToString());
}
public EventHandler<MessageEventArgs> MessageLogged;
protected void OnMessageLogged(string message)
{
if (MessageLogged != null)
MessageLogged(this, new MessageEventArgs(message));
}
}
and usage looks like this:
In main form constructor I'm creating server object, in Load I'm calling Server.Connect() and in FormClosed Server.Disconnect().

Related

Extract .cab file in C#

I am developing a c# application and I a need to extract a cab file.
I couldn't find a library that does that in C# ) I cannot use Microsoft.Deployment.Compression.Cab.dll because of a licensing issue.
I found this code, but the problem is that when I use it I am able to find and extract only the first file in the cabinet.
OutputFileClose is called only if OutputFileOpen returns something either then IntPtr.Zero.
but if OutputFileClose is calles, then the enumeration is stopped.
So for this code OutputFileClose can be called only for one file
Can someone please help me figuring out how to write a code that will extract all the files?

I found out that Microsoft.Deployment.Compression.cab DLL can also be obtained from here
if you look at previous versions such as version 3.5 you will see that they were licensed with Common Public License Version 1.0 (CPL).
It seems that only in later versions the license was changes to MS-RL.
I was also able to create a solution of my own, but it is not optimal( I stopped working on it since I found that I can use Microsoft.Deployment.Compression.cab).
This is the code:
public class CabExtractor : IDisposable
{
private static class NativeMethods
{
[StructLayout(LayoutKind.Sequential)]
internal class CabError //Cabinet API: "ERF"
{
public int erfOper;
public int erfType;
public int fError;
}
[StructLayout(LayoutKind.Sequential)]
internal class FdiNotification //Cabinet API: "FDINOTIFICATION"
{
internal int cb;
//not sure if this should be a IntPtr or a strong
internal IntPtr psz1;
internal IntPtr psz2;
internal IntPtr psz3;
internal IntPtr pv;
internal IntPtr hf;
internal short date;
internal short time;
internal short attribs;
internal short setID;
internal short iCabinet;
internal short iFolder;
internal int fdie;
}
internal enum FdiNotificationType
{
CabinetInfo,
PartialFile,
CopyFile,
CloseFileInfo,
NextCabinet,
Enumerate
}
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
internal delegate IntPtr FdiMemAllocDelegate(int numBytes);
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
internal delegate void FdiMemFreeDelegate(IntPtr mem);
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
internal delegate IntPtr FdiFileOpenDelegate(string fileName, int oflag, int pmode);
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
internal delegate Int32 FdiFileReadDelegate(IntPtr hf,
[In, Out] [MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 2,
ArraySubType = UnmanagedType.U1)] byte[] buffer, int cb);
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
internal delegate Int32 FdiFileWriteDelegate(IntPtr hf,
[In] [MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 2,
ArraySubType = UnmanagedType.U1)] byte[] buffer, int cb);
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
internal delegate Int32 FdiFileCloseDelegate(IntPtr hf);
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
internal delegate Int32 FdiFileSeekDelegate(IntPtr hf, int dist, int seektype);
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
internal delegate IntPtr FdiNotifyDelegate(
FdiNotificationType fdint, [In] [MarshalAs(UnmanagedType.LPStruct)] FdiNotification fdin);
[DllImport("cabinet.dll", CallingConvention = CallingConvention.Cdecl, EntryPoint = "FDICreate", CharSet = CharSet.Ansi)]
internal static extern IntPtr FdiCreate(
FdiMemAllocDelegate fnMemAlloc,
FdiMemFreeDelegate fnMemFree,
FdiFileOpenDelegate fnFileOpen,
FdiFileReadDelegate fnFileRead,
FdiFileWriteDelegate fnFileWrite,
FdiFileCloseDelegate fnFileClose,
FdiFileSeekDelegate fnFileSeek,
int cpuType,
[MarshalAs(UnmanagedType.LPStruct)] CabError erf);
[DllImport("cabinet.dll", CallingConvention = CallingConvention.Cdecl, EntryPoint = "FDIDestroy", CharSet = CharSet.Ansi)]
internal static extern bool FdiDestroy(IntPtr hfdi);
[DllImport("cabinet.dll", CallingConvention = CallingConvention.Cdecl, EntryPoint = "FDICopy", CharSet = CharSet.Ansi)]
internal static extern bool FdiCopy(
IntPtr hfdi,
string cabinetName,
string cabinetPath,
int flags,
FdiNotifyDelegate fnNotify,
IntPtr fnDecrypt,
IntPtr userData);
}
internal class ArchiveFile
{
public IntPtr Handle { get; set; }
public string Name { get; set; }
public bool Found { get; set; }
public int Length { get; set; }
public byte[] Data { get; set; }
}
#region fields and properties
/// Very important!
/// Do not try to call directly to this methods, instead use the delegates. if you use them directly it may cause application crashes, corruption and data loss.
/// Using fields to save the delegate so that the delegate won't be garbage collected !
/// When passing delegates to unmanaged code, they must be kept alive by the managed application until it is guaranteed that they will never be called.
private readonly NativeMethods.FdiMemAllocDelegate _fdiAllocMemHandler;
private readonly NativeMethods.FdiMemFreeDelegate _fdiFreeMemHandler;
private readonly NativeMethods.FdiFileOpenDelegate _fdiOpenStreamHandler;
private readonly NativeMethods.FdiFileReadDelegate _fdiReadStreamHandler;
private readonly NativeMethods.FdiFileWriteDelegate _fdiWriteStreamHandler;
private readonly NativeMethods.FdiFileCloseDelegate _fdiCloseStreamHandler;
private readonly NativeMethods.FdiFileSeekDelegate _fdiSeekStreamHandler;
private ArchiveFile _currentFileToDecompress;
readonly List<string> _fileNames = new List<string>();
private readonly NativeMethods.CabError _erf;
private const int CpuTypeUnknown = -1;
private readonly byte[] _inputData;
private bool _disposed;
/// <summary>
///
/// </summary>
private readonly List<string> _subDirectoryToIgnore = new List<string>();
/// <summary>
/// Path to the folder where the files will be extracted to
/// </summary>
private readonly string _extractionFolderPath;
/// <summary>
/// The name of the folder where the files will be extracted to
/// </summary>
public const string ExtractedFolderName = "ExtractedFiles";
public const string CabFileName = "setup.cab";
#endregion
public CabExtractor(string cabFilePath, IEnumerable<string> subDirectoryToUnpack)
: this(cabFilePath)
{
if (subDirectoryToUnpack != null)
_subDirectoryToIgnore.AddRange(subDirectoryToUnpack);
}
public CabExtractor(string cabFilePath)
{
var cabBytes =
File.ReadAllBytes(cabFilePath);
_inputData = cabBytes;
var cabFileLocation = Path.GetDirectoryName(cabFilePath) ?? "";
_extractionFolderPath = Path.Combine(cabFileLocation, ExtractedFolderName);
_erf = new NativeMethods.CabError();
FdiContext = IntPtr.Zero;
_fdiAllocMemHandler = MemAlloc;
_fdiFreeMemHandler = MemFree;
_fdiOpenStreamHandler = InputFileOpen;
_fdiReadStreamHandler = FileRead;
_fdiWriteStreamHandler = FileWrite;
_fdiCloseStreamHandler = InputFileClose;
_fdiSeekStreamHandler = FileSeek;
FdiContext = FdiCreate(_fdiAllocMemHandler, _fdiFreeMemHandler, _fdiOpenStreamHandler, _fdiReadStreamHandler, _fdiWriteStreamHandler, _fdiCloseStreamHandler, _fdiSeekStreamHandler, _erf);
}
public bool ExtractCabFiles()
{
if (!FdiIterate())
{
throw new Exception("Failed to iterate cab files");
}
foreach (var file in _fileNames)
{
ExtractFile(file);
}
return true;
}
private void ExtractFile(string fileName)
{
try
{
_currentFileToDecompress = new ArchiveFile { Name = fileName };
FdiCopy();
CreateAllRelevantDirectories(fileName);
if (_currentFileToDecompress.Data != null)
{
File.WriteAllBytes(Path.Combine(_extractionFolderPath, _currentFileToDecompress.Name), _currentFileToDecompress.Data);
}
}
catch (Exception ex)
{
SbaLogger.Instance.Error(ex);
SbaLogger.Instance.Error(string.Format("Failed to cextract file file {0}", fileName));
}
}
private void CreateAllRelevantDirectories(string filePath)
{
try
{
if (!Directory.Exists(_extractionFolderPath))
{
Directory.CreateDirectory(_extractionFolderPath);
}
var fullPathToFile = Path.GetDirectoryName(filePath);
if (fullPathToFile != null &&
!Directory.Exists(Path.Combine(_extractionFolderPath, fullPathToFile)))
{
Directory.CreateDirectory(Path.Combine(_extractionFolderPath, fullPathToFile));
}
}
catch (Exception ex)
{
SbaLogger.Instance.Error(ex);
SbaLogger.Instance.Error(string.Format("Failed to create directories for the file {0}",filePath));
}
}
private static string GetFileName(NativeMethods.FdiNotification notification)
{
var encoding = ((int)notification.attribs & 128) != 0 ? Encoding.UTF8 : Encoding.Default;
int length = 0;
while (Marshal.ReadByte(notification.psz1, length) != 0)
checked { ++length; }
var numArray = new byte[length];
Marshal.Copy(notification.psz1, numArray, 0, length);
string path = encoding.GetString(numArray);
if (Path.IsPathRooted(path))
path = path.Replace(String.Concat(Path.VolumeSeparatorChar), "");
return path;
}
private IntPtr ExtractCallback(NativeMethods.FdiNotificationType fdint, NativeMethods.FdiNotification fdin)
{
switch (fdint)
{
case NativeMethods.FdiNotificationType.CopyFile:
return CopyFiles(fdin);
case NativeMethods.FdiNotificationType.CloseFileInfo:
return OutputFileClose(fdin);
default:
return IntPtr.Zero;
}
}
private IntPtr IterateCallback(NativeMethods.FdiNotificationType fdint, NativeMethods.FdiNotification fdin)
{
switch (fdint)
{
case NativeMethods.FdiNotificationType.CopyFile:
return OutputFileOpen(fdin);
default:
return IntPtr.Zero;
}
}
private IntPtr InputFileOpen(string fileName, int oflag, int pmode)
{
var stream = new MemoryStream(_inputData);
GCHandle gch = GCHandle.Alloc(stream);
return (IntPtr)gch;
}
private int InputFileClose(IntPtr hf)
{
var stream = StreamFromHandle(hf);
stream.Close();
((GCHandle)(hf)).Free();
return 0;
}
/// <summary>
/// Copies the contents of input to output. Doesn't close either stream.
/// </summary>
public static void CopyStream(Stream input, Stream output)
{
var buffer = new byte[8 * 1024];
int len;
while ((len = input.Read(buffer, 0, buffer.Length)) > 0)
{
output.Write(buffer, 0, len);
}
}
private IntPtr CopyFiles(NativeMethods.FdiNotification fdin)
{
var fileName = GetFileName(fdin);
var extractFile = _currentFileToDecompress.Name == fileName ? _currentFileToDecompress : null;
if (extractFile != null)
{
var stream = new MemoryStream();
GCHandle gch = GCHandle.Alloc(stream);
extractFile.Handle = (IntPtr)gch;
return extractFile.Handle;
}
//Do not extract this file
return IntPtr.Zero;
}
private IntPtr OutputFileOpen(NativeMethods.FdiNotification fdin)
{
try
{
var extractFile = new ArchiveFile { Name = GetFileName(fdin) };
if (ShouldIgnoreFile(extractFile))
{
//ignore this file.
return IntPtr.Zero;
}
var stream = new MemoryStream();
GCHandle gch = GCHandle.Alloc(stream);
extractFile.Handle = (IntPtr)gch;
AddToListOfFiles(extractFile);
}
catch (Exception ex)
{
SbaLogger.Instance.Verbose(ex);
}
//return IntPtr.Zero so that the iteration will keep on going
return IntPtr.Zero;
}
private bool ShouldIgnoreFile(ArchiveFile extractFile)
{
var rootFolder = GetFileRootFolder(extractFile.Name);
return _subDirectoryToIgnore.Any(dir => dir.Equals(rootFolder, StringComparison.InvariantCultureIgnoreCase));
}
private string GetFileRootFolder(string path)
{
try
{
return path.Split(new[] { Path.DirectorySeparatorChar }, StringSplitOptions.RemoveEmptyEntries).FirstOrDefault();
}
catch (Exception)
{
return string.Empty;
}
}
private void AddToListOfFiles(ArchiveFile extractFile)
{
if (!_fileNames.Any(file => file.Equals(extractFile.Name)))
{
_fileNames.Add(extractFile.Name);
}
}
private IntPtr OutputFileClose(NativeMethods.FdiNotification fdin)
{
var extractFile = _currentFileToDecompress.Handle == fdin.hf ? _currentFileToDecompress : null;
var stream = StreamFromHandle(fdin.hf);
if (extractFile != null)
{
extractFile.Found = true;
extractFile.Length = (int)stream.Length;
if (stream.Length > 0)
{
extractFile.Data = new byte[stream.Length];
stream.Position = 0;
stream.Read(extractFile.Data, 0, (int)stream.Length);
}
}
stream.Close();
return IntPtr.Zero;
}
private static IntPtr FdiCreate(
NativeMethods.FdiMemAllocDelegate fnMemAlloc,
NativeMethods.FdiMemFreeDelegate fnMemFree,
NativeMethods.FdiFileOpenDelegate fnFileOpen,
NativeMethods.FdiFileReadDelegate fnFileRead,
NativeMethods.FdiFileWriteDelegate fnFileWrite,
NativeMethods.FdiFileCloseDelegate fnFileClose,
NativeMethods.FdiFileSeekDelegate fnFileSeek,
NativeMethods.CabError erf)
{
return NativeMethods.FdiCreate(fnMemAlloc, fnMemFree, fnFileOpen, fnFileRead, fnFileWrite,
fnFileClose, fnFileSeek, CpuTypeUnknown, erf);
}
private static int FileRead(IntPtr hf, byte[] buffer, int cb)
{
var stream = StreamFromHandle(hf);
return stream.Read(buffer, 0, cb);
}
private static int FileWrite(IntPtr hf, byte[] buffer, int cb)
{
var stream = StreamFromHandle(hf);
stream.Write(buffer, 0, cb);
return cb;
}
private static Stream StreamFromHandle(IntPtr hf)
{
return (Stream)((GCHandle)hf).Target;
}
private IntPtr MemAlloc(int cb)
{
return Marshal.AllocHGlobal(cb);
}
private void MemFree(IntPtr mem)
{
Marshal.FreeHGlobal(mem);
}
private int FileSeek(IntPtr hf, int dist, int seektype)
{
var stream = StreamFromHandle(hf);
return (int)stream.Seek(dist, (SeekOrigin)seektype);
}
private bool FdiCopy()
{
try
{
return NativeMethods.FdiCopy(FdiContext, "<notused>", "<notused>", 0, ExtractCallback, IntPtr.Zero, IntPtr.Zero);
}
catch (Exception)
{
return false;
}
}
private bool FdiIterate()
{
return NativeMethods.FdiCopy(FdiContext, "<notused>", "<notused>", 0, IterateCallback, IntPtr.Zero, IntPtr.Zero);
}
private IntPtr FdiContext { get; set; }
public void Dispose()
{
Dispose(true);
}
private void Dispose(bool disposing)
{
if (disposing)
{
if (!_disposed)
{
if (FdiContext != IntPtr.Zero)
{
NativeMethods.FdiDestroy(FdiContext);
FdiContext = IntPtr.Zero;
}
_disposed = true;
}
}
}
}

Have you tried exploring the 7zip sdk http://www.7-zip.org/sdk.html
Try this codeproject article - http://www.codeproject.com/Articles/15397/Cabinet-File-CAB-Compression-and-Extraction

Memory leak in the accepted answer.
method:
private IntPtr OutputFileClose(NativeMethods.FdiNotification fdin)
should call:
GCHandle.FromIntPtr(fdin.hf).Free();

Shared Memory, write to file

I have TXT file in shard memory.
The code is at the end. I've been attempting to get it out of the memory and write to a file in the C:\ drive.
But i get a error:
Type 'SharedMemSaveToFile.SharedMemSaver+Data' cannot be marshaled as an
unmanaged structure; no meaningful size or offset can be computed.
If i change the code to write the Memory the CMD, it works, so i know the memory is there. I've also tried using these to write the TXT:
System.IO.StreamWriter file = new System.IO.StreamWriter("c:\\file.txt");
file.WriteLine(d);
and:
using (StreamWriter outfile = new StreamWriter(d + #"C:\\file.txt"))
{
outfile.Write(sb.ToString());
}
and:
StreamWriter sw = new StreamWriter("file.txt");
sw.Write(d);
sw.Close();
Thanks!
public class Data
{
static void Main(string[] args)
{
SharedMemSaver sf = new SharedMemSaver();
sf.OpenView();
String d = sf.GetData();
System.IO.File.WriteAllText(#"C:\file.txt", d);
}
}
#region Win32 API stuff
public const int FILE_MAP_READ = 0x0004;
[DllImport("Kernel32", CharSet = CharSet.Auto, SetLastError = true)]
internal static extern IntPtr OpenFileMapping(int dwDesiredAccess,
bool bInheritHandle, StringBuilder lpName);
[DllImport("Kernel32", CharSet = CharSet.Auto, SetLastError = true)]
internal static extern IntPtr MapViewOfFile(IntPtr hFileMapping,
int dwDesiredAccess, int dwFileOffsetHigh, int dwFileOffsetLow,
int dwNumberOfBytesToMap);
[DllImport("Kernel32.dll")]
internal static extern bool UnmapViewOfFile(IntPtr map);
[DllImport("kernel32.dll")]
internal static extern bool CloseHandle(IntPtr hObject);
#endregion
private bool fileOpen = false;
private IntPtr map;
private IntPtr handle;
~SharedMemSaver()
{
CloseView();
}
public bool OpenView()
{
if (!fileOpen)
{
StringBuilder sharedMemFile = new StringBuilder("Mem_Values");
handle = OpenFileMapping(FILE_MAP_READ, false, sharedMemFile);
if (handle == IntPtr.Zero)
{
throw new Exception("Unable to open file mapping.");
}
map = MapViewOfFile(handle, FILE_MAP_READ, 0, 0, Marshal.SizeOf((Type)typeof(Data)));
if (map == IntPtr.Zero)
{
throw new Exception("Unable to read shared memory.");
}
fileOpen = true;
}
return fileOpen;
}
public void CloseView()
{
if (fileOpen)
{
UnmapViewOfFile(map);
CloseHandle(handle);
}
}
public String GetData()
{
if (fileOpen)
{
String data = (String)Marshal.PtrToStringAuto(map);
return data;
}
else
{
return null;
}
}
}
}

I would strongly recommend to use the built-in MemoryMappedFile class (new in .NET 4).

See Yahia's answer for the solution.
But trying to fix your code, the error message says all:
What are you trying to get with Marshal.SizeOf((Type)typeof(Data))?
It has no size, because it holds not data.
Looking at the MSDN doc. of MapViewOfFile's last parameter, "If this parameter is 0 (zero), the mapping extends from the specified offset to the end of the file mapping."

Forcing closed an open file by C# [duplicate]

I've seen several of answers about using Handle or Process Monitor, but I would like to be able to find out in my own code (C#)
which process is locking a file.
I have a nasty feeling that I'm going to have to spelunk around in the win32 API, but if anyone has already done this and can put me on the right track, I'd really appreciate the help.
Update
Links to similar questions
How does one figure out what process locked a file using c#?
Command line tool
Across a Network
Locking a USB device
Unit test fails with locked file
deleting locked file

Long ago it was impossible to reliably get the list of processes locking a file because Windows simply did not track that information. To support the Restart Manager API, that information is now tracked.
I put together code that takes the path of a file and returns a List<Process> of all processes that are locking that file.
using System.Runtime.InteropServices;
using System.Diagnostics;
using System;
using System.Collections.Generic;
static public class FileUtil
{
[StructLayout(LayoutKind.Sequential)]
struct RM_UNIQUE_PROCESS
{
public int dwProcessId;
public System.Runtime.InteropServices.ComTypes.FILETIME ProcessStartTime;
}
const int RmRebootReasonNone = 0;
const int CCH_RM_MAX_APP_NAME = 255;
const int CCH_RM_MAX_SVC_NAME = 63;
enum RM_APP_TYPE
{
RmUnknownApp = 0,
RmMainWindow = 1,
RmOtherWindow = 2,
RmService = 3,
RmExplorer = 4,
RmConsole = 5,
RmCritical = 1000
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
struct RM_PROCESS_INFO
{
public RM_UNIQUE_PROCESS Process;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = CCH_RM_MAX_APP_NAME + 1)]
public string strAppName;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = CCH_RM_MAX_SVC_NAME + 1)]
public string strServiceShortName;
public RM_APP_TYPE ApplicationType;
public uint AppStatus;
public uint TSSessionId;
[MarshalAs(UnmanagedType.Bool)]
public bool bRestartable;
}
[DllImport("rstrtmgr.dll", CharSet = CharSet.Unicode)]
static extern int RmRegisterResources(uint pSessionHandle,
UInt32 nFiles,
string[] rgsFilenames,
UInt32 nApplications,
[In] RM_UNIQUE_PROCESS[] rgApplications,
UInt32 nServices,
string[] rgsServiceNames);
[DllImport("rstrtmgr.dll", CharSet = CharSet.Auto)]
static extern int RmStartSession(out uint pSessionHandle, int dwSessionFlags, string strSessionKey);
[DllImport("rstrtmgr.dll")]
static extern int RmEndSession(uint pSessionHandle);
[DllImport("rstrtmgr.dll")]
static extern int RmGetList(uint dwSessionHandle,
out uint pnProcInfoNeeded,
ref uint pnProcInfo,
[In, Out] RM_PROCESS_INFO[] rgAffectedApps,
ref uint lpdwRebootReasons);
/// <summary>
/// Find out what process(es) have a lock on the specified file.
/// </summary>
/// <param name="path">Path of the file.</param>
/// <returns>Processes locking the file</returns>
/// <remarks>See also:
/// http://msdn.microsoft.com/en-us/library/windows/desktop/aa373661(v=vs.85).aspx
/// http://wyupdate.googlecode.com/svn-history/r401/trunk/frmFilesInUse.cs (no copyright in code at time of viewing)
///
/// </remarks>
static public List<Process> WhoIsLocking(string path)
{
uint handle;
string key = Guid.NewGuid().ToString();
List<Process> processes = new List<Process>();
int res = RmStartSession(out handle, 0, key);
if (res != 0) throw new Exception("Could not begin restart session. Unable to determine file locker.");
try
{
const int ERROR_MORE_DATA = 234;
uint pnProcInfoNeeded = 0,
pnProcInfo = 0,
lpdwRebootReasons = RmRebootReasonNone;
string[] resources = new string[] { path }; // Just checking on one resource.
res = RmRegisterResources(handle, (uint)resources.Length, resources, 0, null, 0, null);
if (res != 0) throw new Exception("Could not register resource.");
//Note: there's a race condition here -- the first call to RmGetList() returns
// the total number of process. However, when we call RmGetList() again to get
// the actual processes this number may have increased.
res = RmGetList(handle, out pnProcInfoNeeded, ref pnProcInfo, null, ref lpdwRebootReasons);
if (res == ERROR_MORE_DATA)
{
// Create an array to store the process results
RM_PROCESS_INFO[] processInfo = new RM_PROCESS_INFO[pnProcInfoNeeded];
pnProcInfo = pnProcInfoNeeded;
// Get the list
res = RmGetList(handle, out pnProcInfoNeeded, ref pnProcInfo, processInfo, ref lpdwRebootReasons);
if (res == 0)
{
processes = new List<Process>((int)pnProcInfo);
// Enumerate all of the results and add them to the
// list to be returned
for (int i = 0; i < pnProcInfo; i++)
{
try
{
processes.Add(Process.GetProcessById(processInfo[i].Process.dwProcessId));
}
// catch the error -- in case the process is no longer running
catch (ArgumentException) { }
}
}
else throw new Exception("Could not list processes locking resource.");
}
else if (res != 0) throw new Exception("Could not list processes locking resource. Failed to get size of result.");
}
finally
{
RmEndSession(handle);
}
return processes;
}
}
Using from Limited Permission (e.g. IIS)
This call accesses the registry. If the process does not have permission to do so, you will get ERROR_WRITE_FAULT, meaning An operation was unable to read or write to the registry. You could selectively grant permission to your restricted account to the necessary part of the registry. It is more secure though to have your limited access process set a flag (e.g. in the database or the file system, or by using an interprocess communication mechanism such as queue or named pipe) and have a second process call the Restart Manager API.
Granting other-than-minimal permissions to the IIS user is a security risk.

This question had an original answer that is now over 7 years old. That code is preserved at https://gist.github.com/i-e-b/2290426
This old version might work for you if you need to use Windows XP for some reason.
A much better answer is at How to check for file lock?
I've replicated Eric J's answer below (with using statements added, and class & method names to match the old code that was here) Please note that the comments to this answer may be out-of-date.
Research by user 'Walkman' is ongoing to improve the older code, as there are some conditions where the Restart Manager does not list all locks. See Github repo: https://github.com/Walkman100/FileLocks
Use like:
List<Process> locks = Win32Processes.GetProcessesLockingFile(#"C:\Hello.docx");
Code:
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Runtime.InteropServices;
namespace FileLockInfo
{
public static class Win32Processes
{
/// <summary>
/// Find out what process(es) have a lock on the specified file.
/// </summary>
/// <param name="path">Path of the file.</param>
/// <returns>Processes locking the file</returns>
/// <remarks>See also:
/// http://msdn.microsoft.com/en-us/library/windows/desktop/aa373661(v=vs.85).aspx
/// http://wyupdate.googlecode.com/svn-history/r401/trunk/frmFilesInUse.cs (no copyright in code at time of viewing)
/// </remarks>
public static List<Process> GetProcessesLockingFile(string path)
{
uint handle;
string key = Guid.NewGuid().ToString();
int res = RmStartSession(out handle, 0, key);
if (res != 0) throw new Exception("Could not begin restart session. Unable to determine file locker.");
try
{
const int MORE_DATA = 234;
uint pnProcInfoNeeded, pnProcInfo = 0, lpdwRebootReasons = RmRebootReasonNone;
string[] resources = {path}; // Just checking on one resource.
res = RmRegisterResources(handle, (uint) resources.Length, resources, 0, null, 0, null);
if (res != 0) throw new Exception("Could not register resource.");
//Note: there's a race condition here -- the first call to RmGetList() returns
// the total number of process. However, when we call RmGetList() again to get
// the actual processes this number may have increased.
res = RmGetList(handle, out pnProcInfoNeeded, ref pnProcInfo, null, ref lpdwRebootReasons);
if (res == MORE_DATA)
{
return EnumerateProcesses(pnProcInfoNeeded, handle, lpdwRebootReasons);
}
else if (res != 0) throw new Exception("Could not list processes locking resource. Failed to get size of result.");
}
finally
{
RmEndSession(handle);
}
return new List<Process>();
}
[StructLayout(LayoutKind.Sequential)]
public struct RM_UNIQUE_PROCESS
{
public int dwProcessId;
public System.Runtime.InteropServices.ComTypes.FILETIME ProcessStartTime;
}
const int RmRebootReasonNone = 0;
const int CCH_RM_MAX_APP_NAME = 255;
const int CCH_RM_MAX_SVC_NAME = 63;
public enum RM_APP_TYPE
{
RmUnknownApp = 0,
RmMainWindow = 1,
RmOtherWindow = 2,
RmService = 3,
RmExplorer = 4,
RmConsole = 5,
RmCritical = 1000
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct RM_PROCESS_INFO
{
public RM_UNIQUE_PROCESS Process;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = CCH_RM_MAX_APP_NAME + 1)] public string strAppName;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = CCH_RM_MAX_SVC_NAME + 1)] public string strServiceShortName;
public RM_APP_TYPE ApplicationType;
public uint AppStatus;
public uint TSSessionId;
[MarshalAs(UnmanagedType.Bool)] public bool bRestartable;
}
[DllImport("rstrtmgr.dll", CharSet = CharSet.Unicode)]
static extern int RmRegisterResources(uint pSessionHandle, uint nFiles, string[] rgsFilenames,
uint nApplications, [In] RM_UNIQUE_PROCESS[] rgApplications, uint nServices,
string[] rgsServiceNames);
[DllImport("rstrtmgr.dll", CharSet = CharSet.Auto)]
static extern int RmStartSession(out uint pSessionHandle, int dwSessionFlags, string strSessionKey);
[DllImport("rstrtmgr.dll")]
static extern int RmEndSession(uint pSessionHandle);
[DllImport("rstrtmgr.dll")]
static extern int RmGetList(uint dwSessionHandle, out uint pnProcInfoNeeded,
ref uint pnProcInfo, [In, Out] RM_PROCESS_INFO[] rgAffectedApps,
ref uint lpdwRebootReasons);
private static List<Process> EnumerateProcesses(uint pnProcInfoNeeded, uint handle, uint lpdwRebootReasons)
{
var processes = new List<Process>(10);
// Create an array to store the process results
var processInfo = new RM_PROCESS_INFO[pnProcInfoNeeded];
var pnProcInfo = pnProcInfoNeeded;
// Get the list
var res = RmGetList(handle, out pnProcInfoNeeded, ref pnProcInfo, processInfo, ref lpdwRebootReasons);
if (res != 0) throw new Exception("Could not list processes locking resource.");
for (int i = 0; i < pnProcInfo; i++)
{
try
{
processes.Add(Process.GetProcessById(processInfo[i].Process.dwProcessId));
}
catch (ArgumentException) { } // catch the error -- in case the process is no longer running
}
return processes;
}
}
}

It is very complex to invoke Win32 from C#.
You should use the tool Handle.exe.
After that your C# code have to be the following:
string fileName = #"c:\aaa.doc";//Path to locked file
Process tool = new Process();
tool.StartInfo.FileName = "handle.exe";
tool.StartInfo.Arguments = fileName+" /accepteula";
tool.StartInfo.UseShellExecute = false;
tool.StartInfo.RedirectStandardOutput = true;
tool.Start();
tool.WaitForExit();
string outputTool = tool.StandardOutput.ReadToEnd();
string matchPattern = #"(?<=\s+pid:\s+)\b(\d+)\b(?=\s+)";
foreach(Match match in Regex.Matches(outputTool, matchPattern))
{
Process.GetProcessById(int.Parse(match.Value)).Kill();
}

One of the good things about handle.exe is that you can run it as a subprocess and parse the output.
We do this in our deployment script - works like a charm.

The code I found here,
https://vmccontroller.svn.codeplex.com/svn/VmcController/VmcServices/DetectOpenFiles.cs
Works for me much better than the code provided by Iain. Iain's code seemed to be acquiring a lock of its own. Here is my slightly modified version of the code above modified to return the string path of the files locked instead of the FileSystemInfo object,
using System;
using System.Collections.Generic;
//using System.EnterpriseServices;
using System.IO;
using System.Runtime.CompilerServices;
using System.Runtime.ConstrainedExecution;
using System.Runtime.InteropServices;
using System.Security.Permissions;
using System.Text;
using System.Threading;
using Microsoft.Win32.SafeHandles;
namespace Crmc.Core.BuildTasks
{
using System.Diagnostics;
using System.Linq;
#region ENUMs
internal enum NT_STATUS
{
STATUS_SUCCESS = 0x00000000,
STATUS_BUFFER_OVERFLOW = unchecked((int)0x80000005L),
STATUS_INFO_LENGTH_MISMATCH = unchecked((int)0xC0000004L)
}
internal enum SYSTEM_INFORMATION_CLASS
{
SystemBasicInformation = 0,
SystemPerformanceInformation = 2,
SystemTimeOfDayInformation = 3,
SystemProcessInformation = 5,
SystemProcessorPerformanceInformation = 8,
SystemHandleInformation = 16,
SystemInterruptInformation = 23,
SystemExceptionInformation = 33,
SystemRegistryQuotaInformation = 37,
SystemLookasideInformation = 45
}
internal enum OBJECT_INFORMATION_CLASS
{
ObjectBasicInformation = 0,
ObjectNameInformation = 1,
ObjectTypeInformation = 2,
ObjectAllTypesInformation = 3,
ObjectHandleInformation = 4
}
[Flags]
internal enum ProcessAccessRights
{
PROCESS_DUP_HANDLE = 0x00000040
}
[Flags]
internal enum DuplicateHandleOptions
{
DUPLICATE_CLOSE_SOURCE = 0x1,
DUPLICATE_SAME_ACCESS = 0x2
}
#endregion
[SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode = true)]
internal sealed class SafeObjectHandle : SafeHandleZeroOrMinusOneIsInvalid
{
private SafeObjectHandle()
: base(true)
{ }
internal SafeObjectHandle(IntPtr preexistingHandle, bool ownsHandle)
: base(ownsHandle)
{
base.SetHandle(preexistingHandle);
}
protected override bool ReleaseHandle()
{
return NativeMethods.CloseHandle(base.handle);
}
}
[SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode = true)]
internal sealed class SafeProcessHandle : SafeHandleZeroOrMinusOneIsInvalid
{
private SafeProcessHandle()
: base(true)
{ }
internal SafeProcessHandle(IntPtr preexistingHandle, bool ownsHandle)
: base(ownsHandle)
{
base.SetHandle(preexistingHandle);
}
protected override bool ReleaseHandle()
{
return NativeMethods.CloseHandle(base.handle);
}
}
#region Native Methods
internal static class NativeMethods
{
[DllImport("ntdll.dll")]
internal static extern NT_STATUS NtQuerySystemInformation(
[In] SYSTEM_INFORMATION_CLASS SystemInformationClass,
[In] IntPtr SystemInformation,
[In] int SystemInformationLength,
[Out] out int ReturnLength);
[DllImport("ntdll.dll")]
internal static extern NT_STATUS NtQueryObject(
[In] IntPtr Handle,
[In] OBJECT_INFORMATION_CLASS ObjectInformationClass,
[In] IntPtr ObjectInformation,
[In] int ObjectInformationLength,
[Out] out int ReturnLength);
[DllImport("kernel32.dll", SetLastError = true)]
internal static extern SafeProcessHandle OpenProcess(
[In] ProcessAccessRights dwDesiredAccess,
[In, MarshalAs(UnmanagedType.Bool)] bool bInheritHandle,
[In] int dwProcessId);
[DllImport("kernel32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
internal static extern bool DuplicateHandle(
[In] IntPtr hSourceProcessHandle,
[In] IntPtr hSourceHandle,
[In] IntPtr hTargetProcessHandle,
[Out] out SafeObjectHandle lpTargetHandle,
[In] int dwDesiredAccess,
[In, MarshalAs(UnmanagedType.Bool)] bool bInheritHandle,
[In] DuplicateHandleOptions dwOptions);
[DllImport("kernel32.dll")]
internal static extern IntPtr GetCurrentProcess();
[DllImport("kernel32.dll", SetLastError = true)]
internal static extern int GetProcessId(
[In] IntPtr Process);
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
[DllImport("kernel32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
internal static extern bool CloseHandle(
[In] IntPtr hObject);
[DllImport("kernel32.dll", SetLastError = true)]
internal static extern int QueryDosDevice(
[In] string lpDeviceName,
[Out] StringBuilder lpTargetPath,
[In] int ucchMax);
}
#endregion
//[ComVisible(true), EventTrackingEnabled(true)]
public class DetectOpenFiles// : ServicedComponent
{
private static Dictionary<string, string> deviceMap;
private const string networkDevicePrefix = "\\Device\\LanmanRedirector\\";
private const int MAX_PATH = 260;
private enum SystemHandleType
{
OB_TYPE_UNKNOWN = 0,
OB_TYPE_TYPE = 1,
OB_TYPE_DIRECTORY,
OB_TYPE_SYMBOLIC_LINK,
OB_TYPE_TOKEN,
OB_TYPE_PROCESS,
OB_TYPE_THREAD,
OB_TYPE_UNKNOWN_7,
OB_TYPE_EVENT,
OB_TYPE_EVENT_PAIR,
OB_TYPE_MUTANT,
OB_TYPE_UNKNOWN_11,
OB_TYPE_SEMAPHORE,
OB_TYPE_TIMER,
OB_TYPE_PROFILE,
OB_TYPE_WINDOW_STATION,
OB_TYPE_DESKTOP,
OB_TYPE_SECTION,
OB_TYPE_KEY,
OB_TYPE_PORT,
OB_TYPE_WAITABLE_PORT,
OB_TYPE_UNKNOWN_21,
OB_TYPE_UNKNOWN_22,
OB_TYPE_UNKNOWN_23,
OB_TYPE_UNKNOWN_24,
//OB_TYPE_CONTROLLER,
//OB_TYPE_DEVICE,
//OB_TYPE_DRIVER,
OB_TYPE_IO_COMPLETION,
OB_TYPE_FILE
};
private const int handleTypeTokenCount = 27;
private static readonly string[] handleTypeTokens = new string[] {
"", "", "Directory", "SymbolicLink", "Token",
"Process", "Thread", "Unknown7", "Event", "EventPair", "Mutant",
"Unknown11", "Semaphore", "Timer", "Profile", "WindowStation",
"Desktop", "Section", "Key", "Port", "WaitablePort",
"Unknown21", "Unknown22", "Unknown23", "Unknown24",
"IoCompletion", "File"
};
[StructLayout(LayoutKind.Sequential)]
private struct SYSTEM_HANDLE_ENTRY
{
public int OwnerPid;
public byte ObjectType;
public byte HandleFlags;
public short HandleValue;
public int ObjectPointer;
public int AccessMask;
}
/// <summary>
/// Gets the open files enumerator.
/// </summary>
/// <param name="processId">The process id.</param>
/// <returns></returns>
public static IEnumerable<String> GetOpenFilesEnumerator(int processId)
{
return new OpenFiles(processId);
}
public static List<Process> GetProcessesUsingFile(string fName)
{
List<Process> result = new List<Process>();
foreach (var p in Process.GetProcesses())
{
try
{
if (DetectOpenFiles.GetOpenFilesEnumerator(p.Id).Contains(fName))
{
result.Add(p);
}
}
catch { }//some processes will fail
}
return result;
}
private sealed class OpenFiles : IEnumerable<String>
{
private readonly int processId;
internal OpenFiles(int processId)
{
this.processId = processId;
}
#region IEnumerable<FileSystemInfo> Members
public IEnumerator<String> GetEnumerator()
{
NT_STATUS ret;
int length = 0x10000;
// Loop, probing for required memory.
do
{
IntPtr ptr = IntPtr.Zero;
RuntimeHelpers.PrepareConstrainedRegions();
try
{
RuntimeHelpers.PrepareConstrainedRegions();
try { }
finally
{
// CER guarantees that the address of the allocated
// memory is actually assigned to ptr if an
// asynchronous exception occurs.
ptr = Marshal.AllocHGlobal(length);
}
int returnLength;
ret = NativeMethods.NtQuerySystemInformation(SYSTEM_INFORMATION_CLASS.SystemHandleInformation, ptr, length, out returnLength);
if (ret == NT_STATUS.STATUS_INFO_LENGTH_MISMATCH)
{
// Round required memory up to the nearest 64KB boundary.
length = ((returnLength + 0xffff) & ~0xffff);
}
else if (ret == NT_STATUS.STATUS_SUCCESS)
{
int handleCount = Marshal.ReadInt32(ptr);
int offset = sizeof(int);
int size = Marshal.SizeOf(typeof(SYSTEM_HANDLE_ENTRY));
for (int i = 0; i < handleCount; i++)
{
SYSTEM_HANDLE_ENTRY handleEntry = (SYSTEM_HANDLE_ENTRY)Marshal.PtrToStructure((IntPtr)((int)ptr + offset), typeof(SYSTEM_HANDLE_ENTRY));
if (handleEntry.OwnerPid == processId)
{
IntPtr handle = (IntPtr)handleEntry.HandleValue;
SystemHandleType handleType;
if (GetHandleType(handle, handleEntry.OwnerPid, out handleType) && handleType == SystemHandleType.OB_TYPE_FILE)
{
string devicePath;
if (GetFileNameFromHandle(handle, handleEntry.OwnerPid, out devicePath))
{
string dosPath;
if (ConvertDevicePathToDosPath(devicePath, out dosPath))
{
if (File.Exists(dosPath))
{
yield return dosPath; // return new FileInfo(dosPath);
}
else if (Directory.Exists(dosPath))
{
yield return dosPath; // new DirectoryInfo(dosPath);
}
}
}
}
}
offset += size;
}
}
}
finally
{
// CER guarantees that the allocated memory is freed,
// if an asynchronous exception occurs.
Marshal.FreeHGlobal(ptr);
//sw.Flush();
//sw.Close();
}
}
while (ret == NT_STATUS.STATUS_INFO_LENGTH_MISMATCH);
}
#endregion
#region IEnumerable Members
System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
{
return GetEnumerator();
}
#endregion
}
#region Private Members
private static bool GetFileNameFromHandle(IntPtr handle, int processId, out string fileName)
{
IntPtr currentProcess = NativeMethods.GetCurrentProcess();
bool remote = (processId != NativeMethods.GetProcessId(currentProcess));
SafeProcessHandle processHandle = null;
SafeObjectHandle objectHandle = null;
try
{
if (remote)
{
processHandle = NativeMethods.OpenProcess(ProcessAccessRights.PROCESS_DUP_HANDLE, true, processId);
if (NativeMethods.DuplicateHandle(processHandle.DangerousGetHandle(), handle, currentProcess, out objectHandle, 0, false, DuplicateHandleOptions.DUPLICATE_SAME_ACCESS))
{
handle = objectHandle.DangerousGetHandle();
}
}
return GetFileNameFromHandle(handle, out fileName, 200);
}
finally
{
if (remote)
{
if (processHandle != null)
{
processHandle.Close();
}
if (objectHandle != null)
{
objectHandle.Close();
}
}
}
}
private static bool GetFileNameFromHandle(IntPtr handle, out string fileName, int wait)
{
using (FileNameFromHandleState f = new FileNameFromHandleState(handle))
{
ThreadPool.QueueUserWorkItem(new WaitCallback(GetFileNameFromHandle), f);
if (f.WaitOne(wait))
{
fileName = f.FileName;
return f.RetValue;
}
else
{
fileName = string.Empty;
return false;
}
}
}
private class FileNameFromHandleState : IDisposable
{
private ManualResetEvent _mr;
private IntPtr _handle;
private string _fileName;
private bool _retValue;
public IntPtr Handle
{
get
{
return _handle;
}
}
public string FileName
{
get
{
return _fileName;
}
set
{
_fileName = value;
}
}
public bool RetValue
{
get
{
return _retValue;
}
set
{
_retValue = value;
}
}
public FileNameFromHandleState(IntPtr handle)
{
_mr = new ManualResetEvent(false);
this._handle = handle;
}
public bool WaitOne(int wait)
{
return _mr.WaitOne(wait, false);
}
public void Set()
{
try
{
_mr.Set();
}
catch{}
}
#region IDisposable Members
public void Dispose()
{
if (_mr != null)
_mr.Close();
}
#endregion
}
private static void GetFileNameFromHandle(object state)
{
FileNameFromHandleState s = (FileNameFromHandleState)state;
string fileName;
s.RetValue = GetFileNameFromHandle(s.Handle, out fileName);
s.FileName = fileName;
s.Set();
}
private static bool GetFileNameFromHandle(IntPtr handle, out string fileName)
{
IntPtr ptr = IntPtr.Zero;
RuntimeHelpers.PrepareConstrainedRegions();
try
{
int length = 0x200; // 512 bytes
RuntimeHelpers.PrepareConstrainedRegions();
try { }
finally
{
// CER guarantees the assignment of the allocated
// memory address to ptr, if an ansynchronous exception
// occurs.
ptr = Marshal.AllocHGlobal(length);
}
NT_STATUS ret = NativeMethods.NtQueryObject(handle, OBJECT_INFORMATION_CLASS.ObjectNameInformation, ptr, length, out length);
if (ret == NT_STATUS.STATUS_BUFFER_OVERFLOW)
{
RuntimeHelpers.PrepareConstrainedRegions();
try { }
finally
{
// CER guarantees that the previous allocation is freed,
// and that the newly allocated memory address is
// assigned to ptr if an asynchronous exception occurs.
Marshal.FreeHGlobal(ptr);
ptr = Marshal.AllocHGlobal(length);
}
ret = NativeMethods.NtQueryObject(handle, OBJECT_INFORMATION_CLASS.ObjectNameInformation, ptr, length, out length);
}
if (ret == NT_STATUS.STATUS_SUCCESS)
{
fileName = Marshal.PtrToStringUni((IntPtr)((int)ptr + 8), (length - 9) / 2);
return fileName.Length != 0;
}
}
finally
{
// CER guarantees that the allocated memory is freed,
// if an asynchronous exception occurs.
Marshal.FreeHGlobal(ptr);
}
fileName = string.Empty;
return false;
}
private static bool GetHandleType(IntPtr handle, int processId, out SystemHandleType handleType)
{
string token = GetHandleTypeToken(handle, processId);
return GetHandleTypeFromToken(token, out handleType);
}
private static bool GetHandleType(IntPtr handle, out SystemHandleType handleType)
{
string token = GetHandleTypeToken(handle);
return GetHandleTypeFromToken(token, out handleType);
}
private static bool GetHandleTypeFromToken(string token, out SystemHandleType handleType)
{
for (int i = 1; i < handleTypeTokenCount; i++)
{
if (handleTypeTokens[i] == token)
{
handleType = (SystemHandleType)i;
return true;
}
}
handleType = SystemHandleType.OB_TYPE_UNKNOWN;
return false;
}
private static string GetHandleTypeToken(IntPtr handle, int processId)
{
IntPtr currentProcess = NativeMethods.GetCurrentProcess();
bool remote = (processId != NativeMethods.GetProcessId(currentProcess));
SafeProcessHandle processHandle = null;
SafeObjectHandle objectHandle = null;
try
{
if (remote)
{
processHandle = NativeMethods.OpenProcess(ProcessAccessRights.PROCESS_DUP_HANDLE, true, processId);
if (NativeMethods.DuplicateHandle(processHandle.DangerousGetHandle(), handle, currentProcess, out objectHandle, 0, false, DuplicateHandleOptions.DUPLICATE_SAME_ACCESS))
{
handle = objectHandle.DangerousGetHandle();
}
}
return GetHandleTypeToken(handle);
}
finally
{
if (remote)
{
if (processHandle != null)
{
processHandle.Close();
}
if (objectHandle != null)
{
objectHandle.Close();
}
}
}
}
private static string GetHandleTypeToken(IntPtr handle)
{
int length;
NativeMethods.NtQueryObject(handle, OBJECT_INFORMATION_CLASS.ObjectTypeInformation, IntPtr.Zero, 0, out length);
IntPtr ptr = IntPtr.Zero;
RuntimeHelpers.PrepareConstrainedRegions();
try
{
RuntimeHelpers.PrepareConstrainedRegions();
try { }
finally
{
ptr = Marshal.AllocHGlobal(length);
}
if (NativeMethods.NtQueryObject(handle, OBJECT_INFORMATION_CLASS.ObjectTypeInformation, ptr, length, out length) == NT_STATUS.STATUS_SUCCESS)
{
return Marshal.PtrToStringUni((IntPtr)((int)ptr + 0x60));
}
}
finally
{
Marshal.FreeHGlobal(ptr);
}
return string.Empty;
}
private static bool ConvertDevicePathToDosPath(string devicePath, out string dosPath)
{
EnsureDeviceMap();
int i = devicePath.Length;
while (i > 0 && (i = devicePath.LastIndexOf('\\', i - 1)) != -1)
{
string drive;
if (deviceMap.TryGetValue(devicePath.Substring(0, i), out drive))
{
dosPath = string.Concat(drive, devicePath.Substring(i));
return dosPath.Length != 0;
}
}
dosPath = string.Empty;
return false;
}
private static void EnsureDeviceMap()
{
if (deviceMap == null)
{
Dictionary<string, string> localDeviceMap = BuildDeviceMap();
Interlocked.CompareExchange<Dictionary<string, string>>(ref deviceMap, localDeviceMap, null);
}
}
private static Dictionary<string, string> BuildDeviceMap()
{
string[] logicalDrives = Environment.GetLogicalDrives();
Dictionary<string, string> localDeviceMap = new Dictionary<string, string>(logicalDrives.Length);
StringBuilder lpTargetPath = new StringBuilder(MAX_PATH);
foreach (string drive in logicalDrives)
{
string lpDeviceName = drive.Substring(0, 2);
NativeMethods.QueryDosDevice(lpDeviceName, lpTargetPath, MAX_PATH);
localDeviceMap.Add(NormalizeDeviceName(lpTargetPath.ToString()), lpDeviceName);
}
localDeviceMap.Add(networkDevicePrefix.Substring(0, networkDevicePrefix.Length - 1), "\\");
return localDeviceMap;
}
private static string NormalizeDeviceName(string deviceName)
{
if (string.Compare(deviceName, 0, networkDevicePrefix, 0, networkDevicePrefix.Length, StringComparison.InvariantCulture) == 0)
{
string shareName = deviceName.Substring(deviceName.IndexOf('\\', networkDevicePrefix.Length) + 1);
return string.Concat(networkDevicePrefix, shareName);
}
return deviceName;
}
#endregion
}
}

Not very straightforward, but on Windows Vista and above you can use the Restart Manager APIs to see who is using a file. Internet Explorer caches settings includes details on using this to detect which process has iexplore.exe open.
Omitting a lot of detail:
// Start an RM session
RmStartSession(&sessionHandle, 0, sessionKey);
// Register the file you are checking
RmRegisterResources(sessionHandle, 1, filePathArray, 0, NULL, 0, NULL);
// Get all processes that have that file open.
RmGetList(sessionHAndle, &nProcInfoNeeded, &nProcInfo, processes, &rebootReason);
RmEndSession(sessionHandle);

Handle, from Windows Sysinternals. This is a free command-line utility provided by Microsoft.
You could run it, and parse the result.

I had issues with stefan's solution. Below is a modified version which seems to work well.
using System;
using System.Collections;
using System.Diagnostics;
using System.Management;
using System.IO;
static class Module1
{
static internal ArrayList myProcessArray = new ArrayList();
private static Process myProcess;
public static void Main()
{
string strFile = "c:\\windows\\system32\\msi.dll";
ArrayList a = getFileProcesses(strFile);
foreach (Process p in a)
{
Debug.Print(p.ProcessName);
}
}
private static ArrayList getFileProcesses(string strFile)
{
myProcessArray.Clear();
Process[] processes = Process.GetProcesses();
int i = 0;
for (i = 0; i <= processes.GetUpperBound(0) - 1; i++)
{
myProcess = processes[i];
//if (!myProcess.HasExited) //This will cause an "Access is denied" error
if (myProcess.Threads.Count > 0)
{
try
{
ProcessModuleCollection modules = myProcess.Modules;
int j = 0;
for (j = 0; j <= modules.Count - 1; j++)
{
if ((modules[j].FileName.ToLower().CompareTo(strFile.ToLower()) == 0))
{
myProcessArray.Add(myProcess);
break;
// TODO: might not be correct. Was : Exit For
}
}
}
catch (Exception exception)
{
//MsgBox(("Error : " & exception.Message))
}
}
}
return myProcessArray;
}
}
UPDATE
If you just want to know which process(es) are locking a particular DLL, you can execute and parse the output of tasklist /m YourDllName.dll. Works on Windows XP and later. See
What does this do? tasklist /m "mscor*"

This works for DLLs locked by other processes. This routine will not find out for example that a text file is locked by a word process.
C#:
using System.Management;
using System.IO;
static class Module1
{
static internal ArrayList myProcessArray = new ArrayList();
private static Process myProcess;
public static void Main()
{
string strFile = "c:\\windows\\system32\\msi.dll";
ArrayList a = getFileProcesses(strFile);
foreach (Process p in a) {
Debug.Print(p.ProcessName);
}
}
private static ArrayList getFileProcesses(string strFile)
{
myProcessArray.Clear();
Process[] processes = Process.GetProcesses;
int i = 0;
for (i = 0; i <= processes.GetUpperBound(0) - 1; i++) {
myProcess = processes(i);
if (!myProcess.HasExited) {
try {
ProcessModuleCollection modules = myProcess.Modules;
int j = 0;
for (j = 0; j <= modules.Count - 1; j++) {
if ((modules.Item(j).FileName.ToLower.CompareTo(strFile.ToLower) == 0)) {
myProcessArray.Add(myProcess);
break; // TODO: might not be correct. Was : Exit For
}
}
}
catch (Exception exception) {
}
//MsgBox(("Error : " & exception.Message))
}
}
return myProcessArray;
}
}
VB.Net:
Imports System.Management
Imports System.IO
Module Module1
Friend myProcessArray As New ArrayList
Private myProcess As Process
Sub Main()
Dim strFile As String = "c:\windows\system32\msi.dll"
Dim a As ArrayList = getFileProcesses(strFile)
For Each p As Process In a
Debug.Print(p.ProcessName)
Next
End Sub
Private Function getFileProcesses(ByVal strFile As String) As ArrayList
myProcessArray.Clear()
Dim processes As Process() = Process.GetProcesses
Dim i As Integer
For i = 0 To processes.GetUpperBound(0) - 1
myProcess = processes(i)
If Not myProcess.HasExited Then
Try
Dim modules As ProcessModuleCollection = myProcess.Modules
Dim j As Integer
For j = 0 To modules.Count - 1
If (modules.Item(j).FileName.ToLower.CompareTo(strFile.ToLower) = 0) Then
myProcessArray.Add(myProcess)
Exit For
End If
Next j
Catch exception As Exception
'MsgBox(("Error : " & exception.Message))
End Try
End If
Next i
Return myProcessArray
End Function
End Module

The following was produced based on Iain Ballard's code dump. It is broken: it will occasionally lock up when you retrieve the handle name. This code doesn't contain any work-arounds for that issue, and .NET leaves few options: Thread.Abort can no longer abort a thread that's currently in a native method.
So, with that disclaimer, here is the code to retrieve handles which has been adapted to work (apart from the occasional lock-up) both in 32 and 64 bit modes:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.ConstrainedExecution;
using System.Runtime.InteropServices;
namespace BrokenHandleRetrieval
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Enumerates open handles.");
Console.WriteLine("This *will* lock up on calling HandleInfo.Name from time to time. Thread.Abort() won't help.");
foreach (var hi in HandleUtil.GetHandles().Where(hi => hi.Type == HandleType.File))
Console.WriteLine("pid: " + hi.ProcessId + ", name: " + hi.Name);
}
}
public enum HandleType
{
Unknown,
Other,
File, Directory, SymbolicLink, Key,
Process, Thread, Job, Session, WindowStation,
Timer, Desktop, Semaphore, Token,
Mutant, Section, Event, KeyedEvent, IoCompletion, IoCompletionReserve,
TpWorkerFactory, AlpcPort, WmiGuid, UserApcReserve,
}
public class HandleInfo
{
public int ProcessId { get; private set; }
public ushort Handle { get; private set; }
public int GrantedAccess { get; private set; }
public byte RawType { get; private set; }
public HandleInfo(int processId, ushort handle, int grantedAccess, byte rawType)
{
ProcessId = processId;
Handle = handle;
GrantedAccess = grantedAccess;
RawType = rawType;
}
private static Dictionary<byte, string> _rawTypeMap = new Dictionary<byte, string>();
private string _name, _typeStr;
private HandleType _type;
public string Name { get { if (_name == null) initTypeAndName(); return _name; } }
public string TypeString { get { if (_typeStr == null) initType(); return _typeStr; } }
public HandleType Type { get { if (_typeStr == null) initType(); return _type; } }
private void initType()
{
if (_rawTypeMap.ContainsKey(RawType))
{
_typeStr = _rawTypeMap[RawType];
_type = HandleTypeFromString(_typeStr);
}
else
initTypeAndName();
}
bool _typeAndNameAttempted = false;
private void initTypeAndName()
{
if (_typeAndNameAttempted)
return;
_typeAndNameAttempted = true;
IntPtr sourceProcessHandle = IntPtr.Zero;
IntPtr handleDuplicate = IntPtr.Zero;
try
{
sourceProcessHandle = NativeMethods.OpenProcess(0x40 /* dup_handle */, true, ProcessId);
// To read info about a handle owned by another process we must duplicate it into ours
// For simplicity, current process handles will also get duplicated; remember that process handles cannot be compared for equality
if (!NativeMethods.DuplicateHandle(sourceProcessHandle, (IntPtr) Handle, NativeMethods.GetCurrentProcess(), out handleDuplicate, 0, false, 2 /* same_access */))
return;
// Query the object type
if (_rawTypeMap.ContainsKey(RawType))
_typeStr = _rawTypeMap[RawType];
else
{
int length;
NativeMethods.NtQueryObject(handleDuplicate, OBJECT_INFORMATION_CLASS.ObjectTypeInformation, IntPtr.Zero, 0, out length);
IntPtr ptr = IntPtr.Zero;
try
{
ptr = Marshal.AllocHGlobal(length);
if (NativeMethods.NtQueryObject(handleDuplicate, OBJECT_INFORMATION_CLASS.ObjectTypeInformation, ptr, length, out length) != NT_STATUS.STATUS_SUCCESS)
return;
_typeStr = Marshal.PtrToStringUni((IntPtr) ((int) ptr + 0x58 + 2 * IntPtr.Size));
_rawTypeMap[RawType] = _typeStr;
}
finally
{
Marshal.FreeHGlobal(ptr);
}
}
_type = HandleTypeFromString(_typeStr);
// Query the object name
if (_typeStr != null && GrantedAccess != 0x0012019f && GrantedAccess != 0x00120189 && GrantedAccess != 0x120089) // don't query some objects that could get stuck
{
int length;
NativeMethods.NtQueryObject(handleDuplicate, OBJECT_INFORMATION_CLASS.ObjectNameInformation, IntPtr.Zero, 0, out length);
IntPtr ptr = IntPtr.Zero;
try
{
ptr = Marshal.AllocHGlobal(length);
if (NativeMethods.NtQueryObject(handleDuplicate, OBJECT_INFORMATION_CLASS.ObjectNameInformation, ptr, length, out length) != NT_STATUS.STATUS_SUCCESS)
return;
_name = Marshal.PtrToStringUni((IntPtr) ((int) ptr + 2 * IntPtr.Size));
}
finally
{
Marshal.FreeHGlobal(ptr);
}
}
}
finally
{
NativeMethods.CloseHandle(sourceProcessHandle);
if (handleDuplicate != IntPtr.Zero)
NativeMethods.CloseHandle(handleDuplicate);
}
}
public static HandleType HandleTypeFromString(string typeStr)
{
switch (typeStr)
{
case null: return HandleType.Unknown;
case "File": return HandleType.File;
case "IoCompletion": return HandleType.IoCompletion;
case "TpWorkerFactory": return HandleType.TpWorkerFactory;
case "ALPC Port": return HandleType.AlpcPort;
case "Event": return HandleType.Event;
case "Section": return HandleType.Section;
case "Directory": return HandleType.Directory;
case "KeyedEvent": return HandleType.KeyedEvent;
case "Process": return HandleType.Process;
case "Key": return HandleType.Key;
case "SymbolicLink": return HandleType.SymbolicLink;
case "Thread": return HandleType.Thread;
case "Mutant": return HandleType.Mutant;
case "WindowStation": return HandleType.WindowStation;
case "Timer": return HandleType.Timer;
case "Semaphore": return HandleType.Semaphore;
case "Desktop": return HandleType.Desktop;
case "Token": return HandleType.Token;
case "Job": return HandleType.Job;
case "Session": return HandleType.Session;
case "IoCompletionReserve": return HandleType.IoCompletionReserve;
case "WmiGuid": return HandleType.WmiGuid;
case "UserApcReserve": return HandleType.UserApcReserve;
default: return HandleType.Other;
}
}
}
public static class HandleUtil
{
public static IEnumerable<HandleInfo> GetHandles()
{
// Attempt to retrieve the handle information
int length = 0x10000;
IntPtr ptr = IntPtr.Zero;
try
{
while (true)
{
ptr = Marshal.AllocHGlobal(length);
int wantedLength;
var result = NativeMethods.NtQuerySystemInformation(SYSTEM_INFORMATION_CLASS.SystemHandleInformation, ptr, length, out wantedLength);
if (result == NT_STATUS.STATUS_INFO_LENGTH_MISMATCH)
{
length = Math.Max(length, wantedLength);
Marshal.FreeHGlobal(ptr);
ptr = IntPtr.Zero;
}
else if (result == NT_STATUS.STATUS_SUCCESS)
break;
else
throw new Exception("Failed to retrieve system handle information.");
}
int handleCount = IntPtr.Size == 4 ? Marshal.ReadInt32(ptr) : (int) Marshal.ReadInt64(ptr);
int offset = IntPtr.Size;
int size = Marshal.SizeOf(typeof(SystemHandleEntry));
for (int i = 0; i < handleCount; i++)
{
var struc = (SystemHandleEntry) Marshal.PtrToStructure((IntPtr) ((int) ptr + offset), typeof(SystemHandleEntry));
yield return new HandleInfo(struc.OwnerProcessId, struc.Handle, struc.GrantedAccess, struc.ObjectTypeNumber);
offset += size;
}
}
finally
{
if (ptr != IntPtr.Zero)
Marshal.FreeHGlobal(ptr);
}
}
[StructLayout(LayoutKind.Sequential)]
private struct SystemHandleEntry
{
public int OwnerProcessId;
public byte ObjectTypeNumber;
public byte Flags;
public ushort Handle;
public IntPtr Object;
public int GrantedAccess;
}
}
enum NT_STATUS
{
STATUS_SUCCESS = 0x00000000,
STATUS_BUFFER_OVERFLOW = unchecked((int) 0x80000005L),
STATUS_INFO_LENGTH_MISMATCH = unchecked((int) 0xC0000004L)
}
enum SYSTEM_INFORMATION_CLASS
{
SystemBasicInformation = 0,
SystemPerformanceInformation = 2,
SystemTimeOfDayInformation = 3,
SystemProcessInformation = 5,
SystemProcessorPerformanceInformation = 8,
SystemHandleInformation = 16,
SystemInterruptInformation = 23,
SystemExceptionInformation = 33,
SystemRegistryQuotaInformation = 37,
SystemLookasideInformation = 45
}
enum OBJECT_INFORMATION_CLASS
{
ObjectBasicInformation = 0,
ObjectNameInformation = 1,
ObjectTypeInformation = 2,
ObjectAllTypesInformation = 3,
ObjectHandleInformation = 4
}
static class NativeMethods
{
[DllImport("ntdll.dll")]
internal static extern NT_STATUS NtQuerySystemInformation(
[In] SYSTEM_INFORMATION_CLASS SystemInformationClass,
[In] IntPtr SystemInformation,
[In] int SystemInformationLength,
[Out] out int ReturnLength);
[DllImport("ntdll.dll")]
internal static extern NT_STATUS NtQueryObject(
[In] IntPtr Handle,
[In] OBJECT_INFORMATION_CLASS ObjectInformationClass,
[In] IntPtr ObjectInformation,
[In] int ObjectInformationLength,
[Out] out int ReturnLength);
[DllImport("kernel32.dll")]
internal static extern IntPtr GetCurrentProcess();
[DllImport("kernel32.dll", SetLastError = true)]
public static extern IntPtr OpenProcess(
[In] int dwDesiredAccess,
[In, MarshalAs(UnmanagedType.Bool)] bool bInheritHandle,
[In] int dwProcessId);
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
[DllImport("kernel32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
internal static extern bool CloseHandle(
[In] IntPtr hObject);
[DllImport("kernel32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool DuplicateHandle(
[In] IntPtr hSourceProcessHandle,
[In] IntPtr hSourceHandle,
[In] IntPtr hTargetProcessHandle,
[Out] out IntPtr lpTargetHandle,
[In] int dwDesiredAccess,
[In, MarshalAs(UnmanagedType.Bool)] bool bInheritHandle,
[In] int dwOptions);
}
}

This is probably irrelevant and if it is please someone comment but there was a work-around I've used in explorer before to get around file locks.
If a file was locked by a process that had died Windows often wouldn't let you delete it but if you created a new file of the same name somewhere else, moved it to the folder it would succeed. You could then delete the new file and all was well.
To use this for your app you'd have to be able to read the file and hold it in memory before you did this then you write it back out after you'd got rid of the old one.
Maybe it will help, maybe not but it's worth trying.

Try Unlocker. If you try and delete the file that is locked by another process, it will list the process(es) that have the file locked. You can then unlock the file by shutting down those processes.

foreach (var process in Process.GetProcessesByName("excel")) //whatever you need to close
{
if (process.MainWindowTitle.Contains("test.xlsx"))
{
process.Kill();
break;
}
}
or
foreach (var process in Process.GetProcesses())
{
if (process.MainWindowTitle.Contains("test.dat"))
{
process.Kill();
break;
}
}

I believe that you need code running in kernel mode to completely answer the question (but I haven't looked at the restart manager API).
You can enumerate all processes and their modules - so if the file you're looking for is a module (DLL, EXE, OCX...), you're good to go. But if it's a text file for example, you have to look at the kernel handle table which you cannot see from user mode. Handle.exe has a kernel driver in order to do that.

I rewrote the GetProcessesLockingFile() method in the solution. The code was not working.
For example, you have a folder "C:\folder1\folder2" and a process in folder2 (process1). If the process was running, GetProcessesLockingFile() was returning "C:\folder1\folder2". So the condition if (files.Contains(filePath)) => if ("C:\folder1\folder2".contains("C:\folder1\folder2\process1")) was never true.
So this is my solution:
public static List<Process> GetProcessesLockingFile(FileInfo file)
{
var procs = new List<Process>();
var processListSnapshot = Process.GetProcesses();
foreach (var process in processListSnapshot)
{
if (process.Id <= 4) { continue; } // system processes
List<string> paths = GetFilesLockedBy(process);
foreach (string path in paths)
{
string pathDirectory = path;
if (!pathDirectory.EndsWith(Constants.DOUBLE_BACKSLASH))
{
pathDirectory = pathDirectory + Constants.DOUBLE_BACKSLASH;
}
string lastFolderName = Path.GetFileName(Path.GetDirectoryName(pathDirectory));
if (file.FullName.Contains(lastFolderName))
{
procs.Add(process);
}
}
}
return procs;
}
Or with a string parameter:
public static List<Process> GetProcessesLockingFile(string filePath)
{
var procs = new List<Process>();
var processListSnapshot = Process.GetProcesses();
foreach (var process in processListSnapshot)
{
if (process.Id <= 4) { continue; } // system processes
List<string> paths = GetFilesLockedBy(process);
foreach (string path in paths)
{
string pathDirectory = path;
if (!pathDirectory.EndsWith(Constants.DOUBLE_BACKSLASH))
{
pathDirectory = pathDirectory + Constants.DOUBLE_BACKSLASH;
}
string lastFolderName = Path.GetFileName(Path.GetDirectoryName(pathDirectory));
if (filePath.Contains(lastFolderName))
{
procs.Add(process);
}
}
}
return procs;
}

You absolutely don't need to run in Kernel mode (!!!)
It's a Win32 FAQ since Windows 95 (!) (in C, Google groups, Win32) : read the handle table, from User mode of course, and get the PID from the File handle ...

Using dotnet core (net6) I solved this problem by using the win32 restart manager (as others have also mentioned). However some of the linked articles have elaborate code importing DLLs and calling those.
After finding an app to kill processes that lock a file written by meziantou. I found out that he publishes .Net wrappers for win32 dlls (including the restart manager).
Leveraging his work, I was able to fix this problem with the following code:
using Meziantou.Framework.Win32;
public static IEnumerable<Process> GetProcessesLockingFile(string filePath)
{
using var session = RestartManager.CreateSession();
session.RegisterFile(filePath);
return session.GetProcessesLockingResources();
}

simpler with linq:
public void KillProcessesAssociatedToFile(string file)
{
GetProcessesAssociatedToFile(file).ForEach(x =>
{
x.Kill();
x.WaitForExit(10000);
});
}
public List<Process> GetProcessesAssociatedToFile(string file)
{
return Process.GetProcesses()
.Where(x => !x.HasExited
&& x.Modules.Cast<ProcessModule>().ToList()
.Exists(y => y.FileName.ToLowerInvariant() == file.ToLowerInvariant())
).ToList();
}

Replicate functionality of DebugView in .NET - Global Win32 debug hooks?

I'm interested in how plausible it would be to capture Win32 debug traces system-wide in the way DebugView does. I'm not interested in kernel messages thankfully, so I don't need any help there. This needs to be in C#, but I'm happy with unmanaged/unsafe if necessary.
Is there any global hook I can get or am I setting off down a difficult road?
I'm really not sure where the best place is to start on this.

I finally got there. It took some serious googling, but I found an article which helped...
All kudos go to Chritian Birkl for his rather excellent Code Project DbMon.NET - A simple .NET OutputDebugString capturer.
The code is pretty heavy-going, but here it is:
using System;
using System.Threading;
using System.Runtime.InteropServices;
public delegate void OnOutputDebugStringHandler(int pid, string text);
public sealed class DebugMonitor
{
private DebugMonitor()
{
;
}
#region Win32 API Imports
[StructLayout(LayoutKind.Sequential)]
private struct SECURITY_DESCRIPTOR
{
public byte revision;
public byte size;
public short control;
public IntPtr owner;
public IntPtr group;
public IntPtr sacl;
public IntPtr dacl;
}
[StructLayout(LayoutKind.Sequential)]
private struct SECURITY_ATTRIBUTES
{
public int nLength;
public IntPtr lpSecurityDescriptor;
public int bInheritHandle;
}
[Flags]
private enum PageProtection : uint
{
NoAccess = 0x01,
Readonly = 0x02,
ReadWrite = 0x04,
WriteCopy = 0x08,
Execute = 0x10,
ExecuteRead = 0x20,
ExecuteReadWrite = 0x40,
ExecuteWriteCopy = 0x80,
Guard = 0x100,
NoCache = 0x200,
WriteCombine = 0x400,
}
private const int WAIT_OBJECT_0 = 0;
private const uint INFINITE = 0xFFFFFFFF;
private const int ERROR_ALREADY_EXISTS = 183;
private const uint SECURITY_DESCRIPTOR_REVISION = 1;
private const uint SECTION_MAP_READ = 0x0004;
[DllImport("kernel32.dll", SetLastError = true)]
private static extern IntPtr MapViewOfFile(IntPtr hFileMappingObject, uint
dwDesiredAccess, uint dwFileOffsetHigh, uint dwFileOffsetLow,
uint dwNumberOfBytesToMap);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool UnmapViewOfFile(IntPtr lpBaseAddress);
[DllImport("advapi32.dll", SetLastError = true)]
private static extern bool InitializeSecurityDescriptor(ref SECURITY_DESCRIPTOR sd, uint dwRevision);
[DllImport("advapi32.dll", SetLastError = true)]
private static extern bool SetSecurityDescriptorDacl(ref SECURITY_DESCRIPTOR sd, bool daclPresent, IntPtr dacl, bool daclDefaulted);
[DllImport("kernel32.dll")]
private static extern IntPtr CreateEvent(ref SECURITY_ATTRIBUTES sa, bool bManualReset, bool bInitialState, string lpName);
[DllImport("kernel32.dll")]
private static extern bool PulseEvent(IntPtr hEvent);
[DllImport("kernel32.dll")]
private static extern bool SetEvent(IntPtr hEvent);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern IntPtr CreateFileMapping(IntPtr hFile,
ref SECURITY_ATTRIBUTES lpFileMappingAttributes, PageProtection flProtect, uint dwMaximumSizeHigh,
uint dwMaximumSizeLow, string lpName);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool CloseHandle(IntPtr hHandle);
[DllImport("kernel32", SetLastError = true, ExactSpelling = true)]
private static extern Int32 WaitForSingleObject(IntPtr handle, uint milliseconds);
#endregion
public static event OnOutputDebugStringHandler OnOutputDebugString;
private static IntPtr m_AckEvent = IntPtr.Zero;
private static IntPtr m_ReadyEvent = IntPtr.Zero;
private static IntPtr m_SharedFile = IntPtr.Zero;
private static IntPtr m_SharedMem = IntPtr.Zero;
private static Thread m_Capturer = null;
private static object m_SyncRoot = new object();
private static Mutex m_Mutex = null;
public static void Start()
{
lock (m_SyncRoot)
{
if (m_Capturer != null)
throw new ApplicationException("This DebugMonitor is already started.");
if (Environment.OSVersion.ToString().IndexOf("Microsoft") == -1)
throw new NotSupportedException("This DebugMonitor is only supported on Microsoft operating systems.");
bool createdNew = false;
m_Mutex = new Mutex(false, typeof(DebugMonitor).Namespace, out createdNew);
if (!createdNew)
throw new ApplicationException("There is already an instance of 'DbMon.NET' running.");
SECURITY_DESCRIPTOR sd = new SECURITY_DESCRIPTOR();
if (!InitializeSecurityDescriptor(ref sd, SECURITY_DESCRIPTOR_REVISION))
{
throw CreateApplicationException("Failed to initializes the security descriptor.");
}
if (!SetSecurityDescriptorDacl(ref sd, true, IntPtr.Zero, false))
{
throw CreateApplicationException("Failed to initializes the security descriptor");
}
SECURITY_ATTRIBUTES sa = new SECURITY_ATTRIBUTES();
m_AckEvent = CreateEvent(ref sa, false, false, "DBWIN_BUFFER_READY");
if (m_AckEvent == IntPtr.Zero)
{
throw CreateApplicationException("Failed to create event 'DBWIN_BUFFER_READY'");
}
m_ReadyEvent = CreateEvent(ref sa, false, false, "DBWIN_DATA_READY");
if (m_ReadyEvent == IntPtr.Zero)
{
throw CreateApplicationException("Failed to create event 'DBWIN_DATA_READY'");
}
m_SharedFile = CreateFileMapping(new IntPtr(-1), ref sa, PageProtection.ReadWrite, 0, 4096, "DBWIN_BUFFER");
if (m_SharedFile == IntPtr.Zero)
{
throw CreateApplicationException("Failed to create a file mapping to slot 'DBWIN_BUFFER'");
}
m_SharedMem = MapViewOfFile(m_SharedFile, SECTION_MAP_READ, 0, 0, 512);
if (m_SharedMem == IntPtr.Zero)
{
throw CreateApplicationException("Failed to create a mapping view for slot 'DBWIN_BUFFER'");
}
m_Capturer = new Thread(new ThreadStart(Capture));
m_Capturer.Start();
}
}
private static void Capture()
{
try
{
IntPtr pString = new IntPtr(
m_SharedMem.ToInt32() + Marshal.SizeOf(typeof(int))
);
while (true)
{
SetEvent(m_AckEvent);
int ret = WaitForSingleObject(m_ReadyEvent, INFINITE);
if (m_Capturer == null)
break;
if (ret == WAIT_OBJECT_0)
{
FireOnOutputDebugString(
Marshal.ReadInt32(m_SharedMem),
Marshal.PtrToStringAnsi(pString));
}
}
}
catch
{
throw;
}
finally
{
Dispose();
}
}
private static void FireOnOutputDebugString(int pid, string text)
{
if (OnOutputDebugString == null)
return;
#if !DEBUG
try
{
#endif
OnOutputDebugString(pid, text);
#if !DEBUG
}
catch (Exception ex)
{
Console.WriteLine("An 'OnOutputDebugString' handler failed to execute: " + ex.ToString());
}
#endif
}
private static void Dispose()
{
if (m_AckEvent != IntPtr.Zero)
{
if (!CloseHandle(m_AckEvent))
{
throw CreateApplicationException("Failed to close handle for 'AckEvent'");
}
m_AckEvent = IntPtr.Zero;
}
if (m_ReadyEvent != IntPtr.Zero)
{
if (!CloseHandle(m_ReadyEvent))
{
throw CreateApplicationException("Failed to close handle for 'ReadyEvent'");
}
m_ReadyEvent = IntPtr.Zero;
}
if (m_SharedFile != IntPtr.Zero)
{
if (!CloseHandle(m_SharedFile))
{
throw CreateApplicationException("Failed to close handle for 'SharedFile'");
}
m_SharedFile = IntPtr.Zero;
}
if (m_SharedMem != IntPtr.Zero)
{
if (!UnmapViewOfFile(m_SharedMem))
{
throw CreateApplicationException("Failed to unmap view for slot 'DBWIN_BUFFER'");
}
m_SharedMem = IntPtr.Zero;
}
if (m_Mutex != null)
{
m_Mutex.Close();
m_Mutex = null;
}
}
public static void Stop()
{
lock (m_SyncRoot)
{
if (m_Capturer == null)
throw new ObjectDisposedException("DebugMonitor", "This DebugMonitor is not running.");
m_Capturer = null;
PulseEvent(m_ReadyEvent);
while (m_AckEvent != IntPtr.Zero)
;
}
}
private static ApplicationException CreateApplicationException(string text)
{
if (text == null || text.Length < 1)
throw new ArgumentNullException("text", "'text' may not be empty or null.");
return new ApplicationException(string.Format("{0}. Last Win32 Error was {1}",
text, Marshal.GetLastWin32Error()));
}
}

I wrote a tool that does it. It's not 100% equivalent to DebugView, but it has some other nice features (like the ability to colorize traces) :-).
It's available here: TraceSpy
Since it's 100% open source, it contains C# code that demonstrates how to do it.

I would start with the TraceListener class, although I'm not sure if this can be used to capture Win32 debug tracing.

How do I find out which process is locking a file using .NET?

I've seen several of answers about using Handle or Process Monitor, but I would like to be able to find out in my own code (C#)
which process is locking a file.
I have a nasty feeling that I'm going to have to spelunk around in the win32 API, but if anyone has already done this and can put me on the right track, I'd really appreciate the help.
Update
Links to similar questions
How does one figure out what process locked a file using c#?
Command line tool
Across a Network
Locking a USB device
Unit test fails with locked file
deleting locked file

Long ago it was impossible to reliably get the list of processes locking a file because Windows simply did not track that information. To support the Restart Manager API, that information is now tracked.
I put together code that takes the path of a file and returns a List<Process> of all processes that are locking that file.
using System.Runtime.InteropServices;
using System.Diagnostics;
using System;
using System.Collections.Generic;
static public class FileUtil
{
[StructLayout(LayoutKind.Sequential)]
struct RM_UNIQUE_PROCESS
{
public int dwProcessId;
public System.Runtime.InteropServices.ComTypes.FILETIME ProcessStartTime;
}
const int RmRebootReasonNone = 0;
const int CCH_RM_MAX_APP_NAME = 255;
const int CCH_RM_MAX_SVC_NAME = 63;
enum RM_APP_TYPE
{
RmUnknownApp = 0,
RmMainWindow = 1,
RmOtherWindow = 2,
RmService = 3,
RmExplorer = 4,
RmConsole = 5,
RmCritical = 1000
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
struct RM_PROCESS_INFO
{
public RM_UNIQUE_PROCESS Process;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = CCH_RM_MAX_APP_NAME + 1)]
public string strAppName;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = CCH_RM_MAX_SVC_NAME + 1)]
public string strServiceShortName;
public RM_APP_TYPE ApplicationType;
public uint AppStatus;
public uint TSSessionId;
[MarshalAs(UnmanagedType.Bool)]
public bool bRestartable;
}
[DllImport("rstrtmgr.dll", CharSet = CharSet.Unicode)]
static extern int RmRegisterResources(uint pSessionHandle,
UInt32 nFiles,
string[] rgsFilenames,
UInt32 nApplications,
[In] RM_UNIQUE_PROCESS[] rgApplications,
UInt32 nServices,
string[] rgsServiceNames);
[DllImport("rstrtmgr.dll", CharSet = CharSet.Auto)]
static extern int RmStartSession(out uint pSessionHandle, int dwSessionFlags, string strSessionKey);
[DllImport("rstrtmgr.dll")]
static extern int RmEndSession(uint pSessionHandle);
[DllImport("rstrtmgr.dll")]
static extern int RmGetList(uint dwSessionHandle,
out uint pnProcInfoNeeded,
ref uint pnProcInfo,
[In, Out] RM_PROCESS_INFO[] rgAffectedApps,
ref uint lpdwRebootReasons);
/// <summary>
/// Find out what process(es) have a lock on the specified file.
/// </summary>
/// <param name="path">Path of the file.</param>
/// <returns>Processes locking the file</returns>
/// <remarks>See also:
/// http://msdn.microsoft.com/en-us/library/windows/desktop/aa373661(v=vs.85).aspx
/// http://wyupdate.googlecode.com/svn-history/r401/trunk/frmFilesInUse.cs (no copyright in code at time of viewing)
///
/// </remarks>
static public List<Process> WhoIsLocking(string path)
{
uint handle;
string key = Guid.NewGuid().ToString();
List<Process> processes = new List<Process>();
int res = RmStartSession(out handle, 0, key);
if (res != 0) throw new Exception("Could not begin restart session. Unable to determine file locker.");
try
{
const int ERROR_MORE_DATA = 234;
uint pnProcInfoNeeded = 0,
pnProcInfo = 0,
lpdwRebootReasons = RmRebootReasonNone;
string[] resources = new string[] { path }; // Just checking on one resource.
res = RmRegisterResources(handle, (uint)resources.Length, resources, 0, null, 0, null);
if (res != 0) throw new Exception("Could not register resource.");
//Note: there's a race condition here -- the first call to RmGetList() returns
// the total number of process. However, when we call RmGetList() again to get
// the actual processes this number may have increased.
res = RmGetList(handle, out pnProcInfoNeeded, ref pnProcInfo, null, ref lpdwRebootReasons);
if (res == ERROR_MORE_DATA)
{
// Create an array to store the process results
RM_PROCESS_INFO[] processInfo = new RM_PROCESS_INFO[pnProcInfoNeeded];
pnProcInfo = pnProcInfoNeeded;
// Get the list
res = RmGetList(handle, out pnProcInfoNeeded, ref pnProcInfo, processInfo, ref lpdwRebootReasons);
if (res == 0)
{
processes = new List<Process>((int)pnProcInfo);
// Enumerate all of the results and add them to the
// list to be returned
for (int i = 0; i < pnProcInfo; i++)
{
try
{
processes.Add(Process.GetProcessById(processInfo[i].Process.dwProcessId));
}
// catch the error -- in case the process is no longer running
catch (ArgumentException) { }
}
}
else throw new Exception("Could not list processes locking resource.");
}
else if (res != 0) throw new Exception("Could not list processes locking resource. Failed to get size of result.");
}
finally
{
RmEndSession(handle);
}
return processes;
}
}
Using from Limited Permission (e.g. IIS)
This call accesses the registry. If the process does not have permission to do so, you will get ERROR_WRITE_FAULT, meaning An operation was unable to read or write to the registry. You could selectively grant permission to your restricted account to the necessary part of the registry. It is more secure though to have your limited access process set a flag (e.g. in the database or the file system, or by using an interprocess communication mechanism such as queue or named pipe) and have a second process call the Restart Manager API.
Granting other-than-minimal permissions to the IIS user is a security risk.

This question had an original answer that is now over 7 years old. That code is preserved at https://gist.github.com/i-e-b/2290426
This old version might work for you if you need to use Windows XP for some reason.
A much better answer is at How to check for file lock?
I've replicated Eric J's answer below (with using statements added, and class & method names to match the old code that was here) Please note that the comments to this answer may be out-of-date.
Research by user 'Walkman' is ongoing to improve the older code, as there are some conditions where the Restart Manager does not list all locks. See Github repo: https://github.com/Walkman100/FileLocks
Use like:
List<Process> locks = Win32Processes.GetProcessesLockingFile(#"C:\Hello.docx");
Code:
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Runtime.InteropServices;
namespace FileLockInfo
{
public static class Win32Processes
{
/// <summary>
/// Find out what process(es) have a lock on the specified file.
/// </summary>
/// <param name="path">Path of the file.</param>
/// <returns>Processes locking the file</returns>
/// <remarks>See also:
/// http://msdn.microsoft.com/en-us/library/windows/desktop/aa373661(v=vs.85).aspx
/// http://wyupdate.googlecode.com/svn-history/r401/trunk/frmFilesInUse.cs (no copyright in code at time of viewing)
/// </remarks>
public static List<Process> GetProcessesLockingFile(string path)
{
uint handle;
string key = Guid.NewGuid().ToString();
int res = RmStartSession(out handle, 0, key);
if (res != 0) throw new Exception("Could not begin restart session. Unable to determine file locker.");
try
{
const int MORE_DATA = 234;
uint pnProcInfoNeeded, pnProcInfo = 0, lpdwRebootReasons = RmRebootReasonNone;
string[] resources = {path}; // Just checking on one resource.
res = RmRegisterResources(handle, (uint) resources.Length, resources, 0, null, 0, null);
if (res != 0) throw new Exception("Could not register resource.");
//Note: there's a race condition here -- the first call to RmGetList() returns
// the total number of process. However, when we call RmGetList() again to get
// the actual processes this number may have increased.
res = RmGetList(handle, out pnProcInfoNeeded, ref pnProcInfo, null, ref lpdwRebootReasons);
if (res == MORE_DATA)
{
return EnumerateProcesses(pnProcInfoNeeded, handle, lpdwRebootReasons);
}
else if (res != 0) throw new Exception("Could not list processes locking resource. Failed to get size of result.");
}
finally
{
RmEndSession(handle);
}
return new List<Process>();
}
[StructLayout(LayoutKind.Sequential)]
public struct RM_UNIQUE_PROCESS
{
public int dwProcessId;
public System.Runtime.InteropServices.ComTypes.FILETIME ProcessStartTime;
}
const int RmRebootReasonNone = 0;
const int CCH_RM_MAX_APP_NAME = 255;
const int CCH_RM_MAX_SVC_NAME = 63;
public enum RM_APP_TYPE
{
RmUnknownApp = 0,
RmMainWindow = 1,
RmOtherWindow = 2,
RmService = 3,
RmExplorer = 4,
RmConsole = 5,
RmCritical = 1000
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct RM_PROCESS_INFO
{
public RM_UNIQUE_PROCESS Process;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = CCH_RM_MAX_APP_NAME + 1)] public string strAppName;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = CCH_RM_MAX_SVC_NAME + 1)] public string strServiceShortName;
public RM_APP_TYPE ApplicationType;
public uint AppStatus;
public uint TSSessionId;
[MarshalAs(UnmanagedType.Bool)] public bool bRestartable;
}
[DllImport("rstrtmgr.dll", CharSet = CharSet.Unicode)]
static extern int RmRegisterResources(uint pSessionHandle, uint nFiles, string[] rgsFilenames,
uint nApplications, [In] RM_UNIQUE_PROCESS[] rgApplications, uint nServices,
string[] rgsServiceNames);
[DllImport("rstrtmgr.dll", CharSet = CharSet.Auto)]
static extern int RmStartSession(out uint pSessionHandle, int dwSessionFlags, string strSessionKey);
[DllImport("rstrtmgr.dll")]
static extern int RmEndSession(uint pSessionHandle);
[DllImport("rstrtmgr.dll")]
static extern int RmGetList(uint dwSessionHandle, out uint pnProcInfoNeeded,
ref uint pnProcInfo, [In, Out] RM_PROCESS_INFO[] rgAffectedApps,
ref uint lpdwRebootReasons);
private static List<Process> EnumerateProcesses(uint pnProcInfoNeeded, uint handle, uint lpdwRebootReasons)
{
var processes = new List<Process>(10);
// Create an array to store the process results
var processInfo = new RM_PROCESS_INFO[pnProcInfoNeeded];
var pnProcInfo = pnProcInfoNeeded;
// Get the list
var res = RmGetList(handle, out pnProcInfoNeeded, ref pnProcInfo, processInfo, ref lpdwRebootReasons);
if (res != 0) throw new Exception("Could not list processes locking resource.");
for (int i = 0; i < pnProcInfo; i++)
{
try
{
processes.Add(Process.GetProcessById(processInfo[i].Process.dwProcessId));
}
catch (ArgumentException) { } // catch the error -- in case the process is no longer running
}
return processes;
}
}
}

It is very complex to invoke Win32 from C#.
You should use the tool Handle.exe.
After that your C# code have to be the following:
string fileName = #"c:\aaa.doc";//Path to locked file
Process tool = new Process();
tool.StartInfo.FileName = "handle.exe";
tool.StartInfo.Arguments = fileName+" /accepteula";
tool.StartInfo.UseShellExecute = false;
tool.StartInfo.RedirectStandardOutput = true;
tool.Start();
tool.WaitForExit();
string outputTool = tool.StandardOutput.ReadToEnd();
string matchPattern = #"(?<=\s+pid:\s+)\b(\d+)\b(?=\s+)";
foreach(Match match in Regex.Matches(outputTool, matchPattern))
{
Process.GetProcessById(int.Parse(match.Value)).Kill();
}

One of the good things about handle.exe is that you can run it as a subprocess and parse the output.
We do this in our deployment script - works like a charm.

The code I found here,
https://vmccontroller.svn.codeplex.com/svn/VmcController/VmcServices/DetectOpenFiles.cs
Works for me much better than the code provided by Iain. Iain's code seemed to be acquiring a lock of its own. Here is my slightly modified version of the code above modified to return the string path of the files locked instead of the FileSystemInfo object,
using System;
using System.Collections.Generic;
//using System.EnterpriseServices;
using System.IO;
using System.Runtime.CompilerServices;
using System.Runtime.ConstrainedExecution;
using System.Runtime.InteropServices;
using System.Security.Permissions;
using System.Text;
using System.Threading;
using Microsoft.Win32.SafeHandles;
namespace Crmc.Core.BuildTasks
{
using System.Diagnostics;
using System.Linq;
#region ENUMs
internal enum NT_STATUS
{
STATUS_SUCCESS = 0x00000000,
STATUS_BUFFER_OVERFLOW = unchecked((int)0x80000005L),
STATUS_INFO_LENGTH_MISMATCH = unchecked((int)0xC0000004L)
}
internal enum SYSTEM_INFORMATION_CLASS
{
SystemBasicInformation = 0,
SystemPerformanceInformation = 2,
SystemTimeOfDayInformation = 3,
SystemProcessInformation = 5,
SystemProcessorPerformanceInformation = 8,
SystemHandleInformation = 16,
SystemInterruptInformation = 23,
SystemExceptionInformation = 33,
SystemRegistryQuotaInformation = 37,
SystemLookasideInformation = 45
}
internal enum OBJECT_INFORMATION_CLASS
{
ObjectBasicInformation = 0,
ObjectNameInformation = 1,
ObjectTypeInformation = 2,
ObjectAllTypesInformation = 3,
ObjectHandleInformation = 4
}
[Flags]
internal enum ProcessAccessRights
{
PROCESS_DUP_HANDLE = 0x00000040
}
[Flags]
internal enum DuplicateHandleOptions
{
DUPLICATE_CLOSE_SOURCE = 0x1,
DUPLICATE_SAME_ACCESS = 0x2
}
#endregion
[SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode = true)]
internal sealed class SafeObjectHandle : SafeHandleZeroOrMinusOneIsInvalid
{
private SafeObjectHandle()
: base(true)
{ }
internal SafeObjectHandle(IntPtr preexistingHandle, bool ownsHandle)
: base(ownsHandle)
{
base.SetHandle(preexistingHandle);
}
protected override bool ReleaseHandle()
{
return NativeMethods.CloseHandle(base.handle);
}
}
[SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode = true)]
internal sealed class SafeProcessHandle : SafeHandleZeroOrMinusOneIsInvalid
{
private SafeProcessHandle()
: base(true)
{ }
internal SafeProcessHandle(IntPtr preexistingHandle, bool ownsHandle)
: base(ownsHandle)
{
base.SetHandle(preexistingHandle);
}
protected override bool ReleaseHandle()
{
return NativeMethods.CloseHandle(base.handle);
}
}
#region Native Methods
internal static class NativeMethods
{
[DllImport("ntdll.dll")]
internal static extern NT_STATUS NtQuerySystemInformation(
[In] SYSTEM_INFORMATION_CLASS SystemInformationClass,
[In] IntPtr SystemInformation,
[In] int SystemInformationLength,
[Out] out int ReturnLength);
[DllImport("ntdll.dll")]
internal static extern NT_STATUS NtQueryObject(
[In] IntPtr Handle,
[In] OBJECT_INFORMATION_CLASS ObjectInformationClass,
[In] IntPtr ObjectInformation,
[In] int ObjectInformationLength,
[Out] out int ReturnLength);
[DllImport("kernel32.dll", SetLastError = true)]
internal static extern SafeProcessHandle OpenProcess(
[In] ProcessAccessRights dwDesiredAccess,
[In, MarshalAs(UnmanagedType.Bool)] bool bInheritHandle,
[In] int dwProcessId);
[DllImport("kernel32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
internal static extern bool DuplicateHandle(
[In] IntPtr hSourceProcessHandle,
[In] IntPtr hSourceHandle,
[In] IntPtr hTargetProcessHandle,
[Out] out SafeObjectHandle lpTargetHandle,
[In] int dwDesiredAccess,
[In, MarshalAs(UnmanagedType.Bool)] bool bInheritHandle,
[In] DuplicateHandleOptions dwOptions);
[DllImport("kernel32.dll")]
internal static extern IntPtr GetCurrentProcess();
[DllImport("kernel32.dll", SetLastError = true)]
internal static extern int GetProcessId(
[In] IntPtr Process);
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
[DllImport("kernel32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
internal static extern bool CloseHandle(
[In] IntPtr hObject);
[DllImport("kernel32.dll", SetLastError = true)]
internal static extern int QueryDosDevice(
[In] string lpDeviceName,
[Out] StringBuilder lpTargetPath,
[In] int ucchMax);
}
#endregion
//[ComVisible(true), EventTrackingEnabled(true)]
public class DetectOpenFiles// : ServicedComponent
{
private static Dictionary<string, string> deviceMap;
private const string networkDevicePrefix = "\\Device\\LanmanRedirector\\";
private const int MAX_PATH = 260;
private enum SystemHandleType
{
OB_TYPE_UNKNOWN = 0,
OB_TYPE_TYPE = 1,
OB_TYPE_DIRECTORY,
OB_TYPE_SYMBOLIC_LINK,
OB_TYPE_TOKEN,
OB_TYPE_PROCESS,
OB_TYPE_THREAD,
OB_TYPE_UNKNOWN_7,
OB_TYPE_EVENT,
OB_TYPE_EVENT_PAIR,
OB_TYPE_MUTANT,
OB_TYPE_UNKNOWN_11,
OB_TYPE_SEMAPHORE,
OB_TYPE_TIMER,
OB_TYPE_PROFILE,
OB_TYPE_WINDOW_STATION,
OB_TYPE_DESKTOP,
OB_TYPE_SECTION,
OB_TYPE_KEY,
OB_TYPE_PORT,
OB_TYPE_WAITABLE_PORT,
OB_TYPE_UNKNOWN_21,
OB_TYPE_UNKNOWN_22,
OB_TYPE_UNKNOWN_23,
OB_TYPE_UNKNOWN_24,
//OB_TYPE_CONTROLLER,
//OB_TYPE_DEVICE,
//OB_TYPE_DRIVER,
OB_TYPE_IO_COMPLETION,
OB_TYPE_FILE
};
private const int handleTypeTokenCount = 27;
private static readonly string[] handleTypeTokens = new string[] {
"", "", "Directory", "SymbolicLink", "Token",
"Process", "Thread", "Unknown7", "Event", "EventPair", "Mutant",
"Unknown11", "Semaphore", "Timer", "Profile", "WindowStation",
"Desktop", "Section", "Key", "Port", "WaitablePort",
"Unknown21", "Unknown22", "Unknown23", "Unknown24",
"IoCompletion", "File"
};
[StructLayout(LayoutKind.Sequential)]
private struct SYSTEM_HANDLE_ENTRY
{
public int OwnerPid;
public byte ObjectType;
public byte HandleFlags;
public short HandleValue;
public int ObjectPointer;
public int AccessMask;
}
/// <summary>
/// Gets the open files enumerator.
/// </summary>
/// <param name="processId">The process id.</param>
/// <returns></returns>
public static IEnumerable<String> GetOpenFilesEnumerator(int processId)
{
return new OpenFiles(processId);
}
public static List<Process> GetProcessesUsingFile(string fName)
{
List<Process> result = new List<Process>();
foreach (var p in Process.GetProcesses())
{
try
{
if (DetectOpenFiles.GetOpenFilesEnumerator(p.Id).Contains(fName))
{
result.Add(p);
}
}
catch { }//some processes will fail
}
return result;
}
private sealed class OpenFiles : IEnumerable<String>
{
private readonly int processId;
internal OpenFiles(int processId)
{
this.processId = processId;
}
#region IEnumerable<FileSystemInfo> Members
public IEnumerator<String> GetEnumerator()
{
NT_STATUS ret;
int length = 0x10000;
// Loop, probing for required memory.
do
{
IntPtr ptr = IntPtr.Zero;
RuntimeHelpers.PrepareConstrainedRegions();
try
{
RuntimeHelpers.PrepareConstrainedRegions();
try { }
finally
{
// CER guarantees that the address of the allocated
// memory is actually assigned to ptr if an
// asynchronous exception occurs.
ptr = Marshal.AllocHGlobal(length);
}
int returnLength;
ret = NativeMethods.NtQuerySystemInformation(SYSTEM_INFORMATION_CLASS.SystemHandleInformation, ptr, length, out returnLength);
if (ret == NT_STATUS.STATUS_INFO_LENGTH_MISMATCH)
{
// Round required memory up to the nearest 64KB boundary.
length = ((returnLength + 0xffff) & ~0xffff);
}
else if (ret == NT_STATUS.STATUS_SUCCESS)
{
int handleCount = Marshal.ReadInt32(ptr);
int offset = sizeof(int);
int size = Marshal.SizeOf(typeof(SYSTEM_HANDLE_ENTRY));
for (int i = 0; i < handleCount; i++)
{
SYSTEM_HANDLE_ENTRY handleEntry = (SYSTEM_HANDLE_ENTRY)Marshal.PtrToStructure((IntPtr)((int)ptr + offset), typeof(SYSTEM_HANDLE_ENTRY));
if (handleEntry.OwnerPid == processId)
{
IntPtr handle = (IntPtr)handleEntry.HandleValue;
SystemHandleType handleType;
if (GetHandleType(handle, handleEntry.OwnerPid, out handleType) && handleType == SystemHandleType.OB_TYPE_FILE)
{
string devicePath;
if (GetFileNameFromHandle(handle, handleEntry.OwnerPid, out devicePath))
{
string dosPath;
if (ConvertDevicePathToDosPath(devicePath, out dosPath))
{
if (File.Exists(dosPath))
{
yield return dosPath; // return new FileInfo(dosPath);
}
else if (Directory.Exists(dosPath))
{
yield return dosPath; // new DirectoryInfo(dosPath);
}
}
}
}
}
offset += size;
}
}
}
finally
{
// CER guarantees that the allocated memory is freed,
// if an asynchronous exception occurs.
Marshal.FreeHGlobal(ptr);
//sw.Flush();
//sw.Close();
}
}
while (ret == NT_STATUS.STATUS_INFO_LENGTH_MISMATCH);
}
#endregion
#region IEnumerable Members
System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
{
return GetEnumerator();
}
#endregion
}
#region Private Members
private static bool GetFileNameFromHandle(IntPtr handle, int processId, out string fileName)
{
IntPtr currentProcess = NativeMethods.GetCurrentProcess();
bool remote = (processId != NativeMethods.GetProcessId(currentProcess));
SafeProcessHandle processHandle = null;
SafeObjectHandle objectHandle = null;
try
{
if (remote)
{
processHandle = NativeMethods.OpenProcess(ProcessAccessRights.PROCESS_DUP_HANDLE, true, processId);
if (NativeMethods.DuplicateHandle(processHandle.DangerousGetHandle(), handle, currentProcess, out objectHandle, 0, false, DuplicateHandleOptions.DUPLICATE_SAME_ACCESS))
{
handle = objectHandle.DangerousGetHandle();
}
}
return GetFileNameFromHandle(handle, out fileName, 200);
}
finally
{
if (remote)
{
if (processHandle != null)
{
processHandle.Close();
}
if (objectHandle != null)
{
objectHandle.Close();
}
}
}
}
private static bool GetFileNameFromHandle(IntPtr handle, out string fileName, int wait)
{
using (FileNameFromHandleState f = new FileNameFromHandleState(handle))
{
ThreadPool.QueueUserWorkItem(new WaitCallback(GetFileNameFromHandle), f);
if (f.WaitOne(wait))
{
fileName = f.FileName;
return f.RetValue;
}
else
{
fileName = string.Empty;
return false;
}
}
}
private class FileNameFromHandleState : IDisposable
{
private ManualResetEvent _mr;
private IntPtr _handle;
private string _fileName;
private bool _retValue;
public IntPtr Handle
{
get
{
return _handle;
}
}
public string FileName
{
get
{
return _fileName;
}
set
{
_fileName = value;
}
}
public bool RetValue
{
get
{
return _retValue;
}
set
{
_retValue = value;
}
}
public FileNameFromHandleState(IntPtr handle)
{
_mr = new ManualResetEvent(false);
this._handle = handle;
}
public bool WaitOne(int wait)
{
return _mr.WaitOne(wait, false);
}
public void Set()
{
try
{
_mr.Set();
}
catch{}
}
#region IDisposable Members
public void Dispose()
{
if (_mr != null)
_mr.Close();
}
#endregion
}
private static void GetFileNameFromHandle(object state)
{
FileNameFromHandleState s = (FileNameFromHandleState)state;
string fileName;
s.RetValue = GetFileNameFromHandle(s.Handle, out fileName);
s.FileName = fileName;
s.Set();
}
private static bool GetFileNameFromHandle(IntPtr handle, out string fileName)
{
IntPtr ptr = IntPtr.Zero;
RuntimeHelpers.PrepareConstrainedRegions();
try
{
int length = 0x200; // 512 bytes
RuntimeHelpers.PrepareConstrainedRegions();
try { }
finally
{
// CER guarantees the assignment of the allocated
// memory address to ptr, if an ansynchronous exception
// occurs.
ptr = Marshal.AllocHGlobal(length);
}
NT_STATUS ret = NativeMethods.NtQueryObject(handle, OBJECT_INFORMATION_CLASS.ObjectNameInformation, ptr, length, out length);
if (ret == NT_STATUS.STATUS_BUFFER_OVERFLOW)
{
RuntimeHelpers.PrepareConstrainedRegions();
try { }
finally
{
// CER guarantees that the previous allocation is freed,
// and that the newly allocated memory address is
// assigned to ptr if an asynchronous exception occurs.
Marshal.FreeHGlobal(ptr);
ptr = Marshal.AllocHGlobal(length);
}
ret = NativeMethods.NtQueryObject(handle, OBJECT_INFORMATION_CLASS.ObjectNameInformation, ptr, length, out length);
}
if (ret == NT_STATUS.STATUS_SUCCESS)
{
fileName = Marshal.PtrToStringUni((IntPtr)((int)ptr + 8), (length - 9) / 2);
return fileName.Length != 0;
}
}
finally
{
// CER guarantees that the allocated memory is freed,
// if an asynchronous exception occurs.
Marshal.FreeHGlobal(ptr);
}
fileName = string.Empty;
return false;
}
private static bool GetHandleType(IntPtr handle, int processId, out SystemHandleType handleType)
{
string token = GetHandleTypeToken(handle, processId);
return GetHandleTypeFromToken(token, out handleType);
}
private static bool GetHandleType(IntPtr handle, out SystemHandleType handleType)
{
string token = GetHandleTypeToken(handle);
return GetHandleTypeFromToken(token, out handleType);
}
private static bool GetHandleTypeFromToken(string token, out SystemHandleType handleType)
{
for (int i = 1; i < handleTypeTokenCount; i++)
{
if (handleTypeTokens[i] == token)
{
handleType = (SystemHandleType)i;
return true;
}
}
handleType = SystemHandleType.OB_TYPE_UNKNOWN;
return false;
}
private static string GetHandleTypeToken(IntPtr handle, int processId)
{
IntPtr currentProcess = NativeMethods.GetCurrentProcess();
bool remote = (processId != NativeMethods.GetProcessId(currentProcess));
SafeProcessHandle processHandle = null;
SafeObjectHandle objectHandle = null;
try
{
if (remote)
{
processHandle = NativeMethods.OpenProcess(ProcessAccessRights.PROCESS_DUP_HANDLE, true, processId);
if (NativeMethods.DuplicateHandle(processHandle.DangerousGetHandle(), handle, currentProcess, out objectHandle, 0, false, DuplicateHandleOptions.DUPLICATE_SAME_ACCESS))
{
handle = objectHandle.DangerousGetHandle();
}
}
return GetHandleTypeToken(handle);
}
finally
{
if (remote)
{
if (processHandle != null)
{
processHandle.Close();
}
if (objectHandle != null)
{
objectHandle.Close();
}
}
}
}
private static string GetHandleTypeToken(IntPtr handle)
{
int length;
NativeMethods.NtQueryObject(handle, OBJECT_INFORMATION_CLASS.ObjectTypeInformation, IntPtr.Zero, 0, out length);
IntPtr ptr = IntPtr.Zero;
RuntimeHelpers.PrepareConstrainedRegions();
try
{
RuntimeHelpers.PrepareConstrainedRegions();
try { }
finally
{
ptr = Marshal.AllocHGlobal(length);
}
if (NativeMethods.NtQueryObject(handle, OBJECT_INFORMATION_CLASS.ObjectTypeInformation, ptr, length, out length) == NT_STATUS.STATUS_SUCCESS)
{
return Marshal.PtrToStringUni((IntPtr)((int)ptr + 0x60));
}
}
finally
{
Marshal.FreeHGlobal(ptr);
}
return string.Empty;
}
private static bool ConvertDevicePathToDosPath(string devicePath, out string dosPath)
{
EnsureDeviceMap();
int i = devicePath.Length;
while (i > 0 && (i = devicePath.LastIndexOf('\\', i - 1)) != -1)
{
string drive;
if (deviceMap.TryGetValue(devicePath.Substring(0, i), out drive))
{
dosPath = string.Concat(drive, devicePath.Substring(i));
return dosPath.Length != 0;
}
}
dosPath = string.Empty;
return false;
}
private static void EnsureDeviceMap()
{
if (deviceMap == null)
{
Dictionary<string, string> localDeviceMap = BuildDeviceMap();
Interlocked.CompareExchange<Dictionary<string, string>>(ref deviceMap, localDeviceMap, null);
}
}
private static Dictionary<string, string> BuildDeviceMap()
{
string[] logicalDrives = Environment.GetLogicalDrives();
Dictionary<string, string> localDeviceMap = new Dictionary<string, string>(logicalDrives.Length);
StringBuilder lpTargetPath = new StringBuilder(MAX_PATH);
foreach (string drive in logicalDrives)
{
string lpDeviceName = drive.Substring(0, 2);
NativeMethods.QueryDosDevice(lpDeviceName, lpTargetPath, MAX_PATH);
localDeviceMap.Add(NormalizeDeviceName(lpTargetPath.ToString()), lpDeviceName);
}
localDeviceMap.Add(networkDevicePrefix.Substring(0, networkDevicePrefix.Length - 1), "\\");
return localDeviceMap;
}
private static string NormalizeDeviceName(string deviceName)
{
if (string.Compare(deviceName, 0, networkDevicePrefix, 0, networkDevicePrefix.Length, StringComparison.InvariantCulture) == 0)
{
string shareName = deviceName.Substring(deviceName.IndexOf('\\', networkDevicePrefix.Length) + 1);
return string.Concat(networkDevicePrefix, shareName);
}
return deviceName;
}
#endregion
}
}

Not very straightforward, but on Windows Vista and above you can use the Restart Manager APIs to see who is using a file. Internet Explorer caches settings includes details on using this to detect which process has iexplore.exe open.
Omitting a lot of detail:
// Start an RM session
RmStartSession(&sessionHandle, 0, sessionKey);
// Register the file you are checking
RmRegisterResources(sessionHandle, 1, filePathArray, 0, NULL, 0, NULL);
// Get all processes that have that file open.
RmGetList(sessionHAndle, &nProcInfoNeeded, &nProcInfo, processes, &rebootReason);
RmEndSession(sessionHandle);

Handle, from Windows Sysinternals. This is a free command-line utility provided by Microsoft.
You could run it, and parse the result.

I had issues with stefan's solution. Below is a modified version which seems to work well.
using System;
using System.Collections;
using System.Diagnostics;
using System.Management;
using System.IO;
static class Module1
{
static internal ArrayList myProcessArray = new ArrayList();
private static Process myProcess;
public static void Main()
{
string strFile = "c:\\windows\\system32\\msi.dll";
ArrayList a = getFileProcesses(strFile);
foreach (Process p in a)
{
Debug.Print(p.ProcessName);
}
}
private static ArrayList getFileProcesses(string strFile)
{
myProcessArray.Clear();
Process[] processes = Process.GetProcesses();
int i = 0;
for (i = 0; i <= processes.GetUpperBound(0) - 1; i++)
{
myProcess = processes[i];
//if (!myProcess.HasExited) //This will cause an "Access is denied" error
if (myProcess.Threads.Count > 0)
{
try
{
ProcessModuleCollection modules = myProcess.Modules;
int j = 0;
for (j = 0; j <= modules.Count - 1; j++)
{
if ((modules[j].FileName.ToLower().CompareTo(strFile.ToLower()) == 0))
{
myProcessArray.Add(myProcess);
break;
// TODO: might not be correct. Was : Exit For
}
}
}
catch (Exception exception)
{
//MsgBox(("Error : " & exception.Message))
}
}
}
return myProcessArray;
}
}
UPDATE
If you just want to know which process(es) are locking a particular DLL, you can execute and parse the output of tasklist /m YourDllName.dll. Works on Windows XP and later. See
What does this do? tasklist /m "mscor*"

This works for DLLs locked by other processes. This routine will not find out for example that a text file is locked by a word process.
C#:
using System.Management;
using System.IO;
static class Module1
{
static internal ArrayList myProcessArray = new ArrayList();
private static Process myProcess;
public static void Main()
{
string strFile = "c:\\windows\\system32\\msi.dll";
ArrayList a = getFileProcesses(strFile);
foreach (Process p in a) {
Debug.Print(p.ProcessName);
}
}
private static ArrayList getFileProcesses(string strFile)
{
myProcessArray.Clear();
Process[] processes = Process.GetProcesses;
int i = 0;
for (i = 0; i <= processes.GetUpperBound(0) - 1; i++) {
myProcess = processes(i);
if (!myProcess.HasExited) {
try {
ProcessModuleCollection modules = myProcess.Modules;
int j = 0;
for (j = 0; j <= modules.Count - 1; j++) {
if ((modules.Item(j).FileName.ToLower.CompareTo(strFile.ToLower) == 0)) {
myProcessArray.Add(myProcess);
break; // TODO: might not be correct. Was : Exit For
}
}
}
catch (Exception exception) {
}
//MsgBox(("Error : " & exception.Message))
}
}
return myProcessArray;
}
}
VB.Net:
Imports System.Management
Imports System.IO
Module Module1
Friend myProcessArray As New ArrayList
Private myProcess As Process
Sub Main()
Dim strFile As String = "c:\windows\system32\msi.dll"
Dim a As ArrayList = getFileProcesses(strFile)
For Each p As Process In a
Debug.Print(p.ProcessName)
Next
End Sub
Private Function getFileProcesses(ByVal strFile As String) As ArrayList
myProcessArray.Clear()
Dim processes As Process() = Process.GetProcesses
Dim i As Integer
For i = 0 To processes.GetUpperBound(0) - 1
myProcess = processes(i)
If Not myProcess.HasExited Then
Try
Dim modules As ProcessModuleCollection = myProcess.Modules
Dim j As Integer
For j = 0 To modules.Count - 1
If (modules.Item(j).FileName.ToLower.CompareTo(strFile.ToLower) = 0) Then
myProcessArray.Add(myProcess)
Exit For
End If
Next j
Catch exception As Exception
'MsgBox(("Error : " & exception.Message))
End Try
End If
Next i
Return myProcessArray
End Function
End Module

The following was produced based on Iain Ballard's code dump. It is broken: it will occasionally lock up when you retrieve the handle name. This code doesn't contain any work-arounds for that issue, and .NET leaves few options: Thread.Abort can no longer abort a thread that's currently in a native method.
So, with that disclaimer, here is the code to retrieve handles which has been adapted to work (apart from the occasional lock-up) both in 32 and 64 bit modes:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.ConstrainedExecution;
using System.Runtime.InteropServices;
namespace BrokenHandleRetrieval
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Enumerates open handles.");
Console.WriteLine("This *will* lock up on calling HandleInfo.Name from time to time. Thread.Abort() won't help.");
foreach (var hi in HandleUtil.GetHandles().Where(hi => hi.Type == HandleType.File))
Console.WriteLine("pid: " + hi.ProcessId + ", name: " + hi.Name);
}
}
public enum HandleType
{
Unknown,
Other,
File, Directory, SymbolicLink, Key,
Process, Thread, Job, Session, WindowStation,
Timer, Desktop, Semaphore, Token,
Mutant, Section, Event, KeyedEvent, IoCompletion, IoCompletionReserve,
TpWorkerFactory, AlpcPort, WmiGuid, UserApcReserve,
}
public class HandleInfo
{
public int ProcessId { get; private set; }
public ushort Handle { get; private set; }
public int GrantedAccess { get; private set; }
public byte RawType { get; private set; }
public HandleInfo(int processId, ushort handle, int grantedAccess, byte rawType)
{
ProcessId = processId;
Handle = handle;
GrantedAccess = grantedAccess;
RawType = rawType;
}
private static Dictionary<byte, string> _rawTypeMap = new Dictionary<byte, string>();
private string _name, _typeStr;
private HandleType _type;
public string Name { get { if (_name == null) initTypeAndName(); return _name; } }
public string TypeString { get { if (_typeStr == null) initType(); return _typeStr; } }
public HandleType Type { get { if (_typeStr == null) initType(); return _type; } }
private void initType()
{
if (_rawTypeMap.ContainsKey(RawType))
{
_typeStr = _rawTypeMap[RawType];
_type = HandleTypeFromString(_typeStr);
}
else
initTypeAndName();
}
bool _typeAndNameAttempted = false;
private void initTypeAndName()
{
if (_typeAndNameAttempted)
return;
_typeAndNameAttempted = true;
IntPtr sourceProcessHandle = IntPtr.Zero;
IntPtr handleDuplicate = IntPtr.Zero;
try
{
sourceProcessHandle = NativeMethods.OpenProcess(0x40 /* dup_handle */, true, ProcessId);
// To read info about a handle owned by another process we must duplicate it into ours
// For simplicity, current process handles will also get duplicated; remember that process handles cannot be compared for equality
if (!NativeMethods.DuplicateHandle(sourceProcessHandle, (IntPtr) Handle, NativeMethods.GetCurrentProcess(), out handleDuplicate, 0, false, 2 /* same_access */))
return;
// Query the object type
if (_rawTypeMap.ContainsKey(RawType))
_typeStr = _rawTypeMap[RawType];
else
{
int length;
NativeMethods.NtQueryObject(handleDuplicate, OBJECT_INFORMATION_CLASS.ObjectTypeInformation, IntPtr.Zero, 0, out length);
IntPtr ptr = IntPtr.Zero;
try
{
ptr = Marshal.AllocHGlobal(length);
if (NativeMethods.NtQueryObject(handleDuplicate, OBJECT_INFORMATION_CLASS.ObjectTypeInformation, ptr, length, out length) != NT_STATUS.STATUS_SUCCESS)
return;
_typeStr = Marshal.PtrToStringUni((IntPtr) ((int) ptr + 0x58 + 2 * IntPtr.Size));
_rawTypeMap[RawType] = _typeStr;
}
finally
{
Marshal.FreeHGlobal(ptr);
}
}
_type = HandleTypeFromString(_typeStr);
// Query the object name
if (_typeStr != null && GrantedAccess != 0x0012019f && GrantedAccess != 0x00120189 && GrantedAccess != 0x120089) // don't query some objects that could get stuck
{
int length;
NativeMethods.NtQueryObject(handleDuplicate, OBJECT_INFORMATION_CLASS.ObjectNameInformation, IntPtr.Zero, 0, out length);
IntPtr ptr = IntPtr.Zero;
try
{
ptr = Marshal.AllocHGlobal(length);
if (NativeMethods.NtQueryObject(handleDuplicate, OBJECT_INFORMATION_CLASS.ObjectNameInformation, ptr, length, out length) != NT_STATUS.STATUS_SUCCESS)
return;
_name = Marshal.PtrToStringUni((IntPtr) ((int) ptr + 2 * IntPtr.Size));
}
finally
{
Marshal.FreeHGlobal(ptr);
}
}
}
finally
{
NativeMethods.CloseHandle(sourceProcessHandle);
if (handleDuplicate != IntPtr.Zero)
NativeMethods.CloseHandle(handleDuplicate);
}
}
public static HandleType HandleTypeFromString(string typeStr)
{
switch (typeStr)
{
case null: return HandleType.Unknown;
case "File": return HandleType.File;
case "IoCompletion": return HandleType.IoCompletion;
case "TpWorkerFactory": return HandleType.TpWorkerFactory;
case "ALPC Port": return HandleType.AlpcPort;
case "Event": return HandleType.Event;
case "Section": return HandleType.Section;
case "Directory": return HandleType.Directory;
case "KeyedEvent": return HandleType.KeyedEvent;
case "Process": return HandleType.Process;
case "Key": return HandleType.Key;
case "SymbolicLink": return HandleType.SymbolicLink;
case "Thread": return HandleType.Thread;
case "Mutant": return HandleType.Mutant;
case "WindowStation": return HandleType.WindowStation;
case "Timer": return HandleType.Timer;
case "Semaphore": return HandleType.Semaphore;
case "Desktop": return HandleType.Desktop;
case "Token": return HandleType.Token;
case "Job": return HandleType.Job;
case "Session": return HandleType.Session;
case "IoCompletionReserve": return HandleType.IoCompletionReserve;
case "WmiGuid": return HandleType.WmiGuid;
case "UserApcReserve": return HandleType.UserApcReserve;
default: return HandleType.Other;
}
}
}
public static class HandleUtil
{
public static IEnumerable<HandleInfo> GetHandles()
{
// Attempt to retrieve the handle information
int length = 0x10000;
IntPtr ptr = IntPtr.Zero;
try
{
while (true)
{
ptr = Marshal.AllocHGlobal(length);
int wantedLength;
var result = NativeMethods.NtQuerySystemInformation(SYSTEM_INFORMATION_CLASS.SystemHandleInformation, ptr, length, out wantedLength);
if (result == NT_STATUS.STATUS_INFO_LENGTH_MISMATCH)
{
length = Math.Max(length, wantedLength);
Marshal.FreeHGlobal(ptr);
ptr = IntPtr.Zero;
}
else if (result == NT_STATUS.STATUS_SUCCESS)
break;
else
throw new Exception("Failed to retrieve system handle information.");
}
int handleCount = IntPtr.Size == 4 ? Marshal.ReadInt32(ptr) : (int) Marshal.ReadInt64(ptr);
int offset = IntPtr.Size;
int size = Marshal.SizeOf(typeof(SystemHandleEntry));
for (int i = 0; i < handleCount; i++)
{
var struc = (SystemHandleEntry) Marshal.PtrToStructure((IntPtr) ((int) ptr + offset), typeof(SystemHandleEntry));
yield return new HandleInfo(struc.OwnerProcessId, struc.Handle, struc.GrantedAccess, struc.ObjectTypeNumber);
offset += size;
}
}
finally
{
if (ptr != IntPtr.Zero)
Marshal.FreeHGlobal(ptr);
}
}
[StructLayout(LayoutKind.Sequential)]
private struct SystemHandleEntry
{
public int OwnerProcessId;
public byte ObjectTypeNumber;
public byte Flags;
public ushort Handle;
public IntPtr Object;
public int GrantedAccess;
}
}
enum NT_STATUS
{
STATUS_SUCCESS = 0x00000000,
STATUS_BUFFER_OVERFLOW = unchecked((int) 0x80000005L),
STATUS_INFO_LENGTH_MISMATCH = unchecked((int) 0xC0000004L)
}
enum SYSTEM_INFORMATION_CLASS
{
SystemBasicInformation = 0,
SystemPerformanceInformation = 2,
SystemTimeOfDayInformation = 3,
SystemProcessInformation = 5,
SystemProcessorPerformanceInformation = 8,
SystemHandleInformation = 16,
SystemInterruptInformation = 23,
SystemExceptionInformation = 33,
SystemRegistryQuotaInformation = 37,
SystemLookasideInformation = 45
}
enum OBJECT_INFORMATION_CLASS
{
ObjectBasicInformation = 0,
ObjectNameInformation = 1,
ObjectTypeInformation = 2,
ObjectAllTypesInformation = 3,
ObjectHandleInformation = 4
}
static class NativeMethods
{
[DllImport("ntdll.dll")]
internal static extern NT_STATUS NtQuerySystemInformation(
[In] SYSTEM_INFORMATION_CLASS SystemInformationClass,
[In] IntPtr SystemInformation,
[In] int SystemInformationLength,
[Out] out int ReturnLength);
[DllImport("ntdll.dll")]
internal static extern NT_STATUS NtQueryObject(
[In] IntPtr Handle,
[In] OBJECT_INFORMATION_CLASS ObjectInformationClass,
[In] IntPtr ObjectInformation,
[In] int ObjectInformationLength,
[Out] out int ReturnLength);
[DllImport("kernel32.dll")]
internal static extern IntPtr GetCurrentProcess();
[DllImport("kernel32.dll", SetLastError = true)]
public static extern IntPtr OpenProcess(
[In] int dwDesiredAccess,
[In, MarshalAs(UnmanagedType.Bool)] bool bInheritHandle,
[In] int dwProcessId);
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
[DllImport("kernel32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
internal static extern bool CloseHandle(
[In] IntPtr hObject);
[DllImport("kernel32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool DuplicateHandle(
[In] IntPtr hSourceProcessHandle,
[In] IntPtr hSourceHandle,
[In] IntPtr hTargetProcessHandle,
[Out] out IntPtr lpTargetHandle,
[In] int dwDesiredAccess,
[In, MarshalAs(UnmanagedType.Bool)] bool bInheritHandle,
[In] int dwOptions);
}
}

This is probably irrelevant and if it is please someone comment but there was a work-around I've used in explorer before to get around file locks.
If a file was locked by a process that had died Windows often wouldn't let you delete it but if you created a new file of the same name somewhere else, moved it to the folder it would succeed. You could then delete the new file and all was well.
To use this for your app you'd have to be able to read the file and hold it in memory before you did this then you write it back out after you'd got rid of the old one.
Maybe it will help, maybe not but it's worth trying.

Try Unlocker. If you try and delete the file that is locked by another process, it will list the process(es) that have the file locked. You can then unlock the file by shutting down those processes.

foreach (var process in Process.GetProcessesByName("excel")) //whatever you need to close
{
if (process.MainWindowTitle.Contains("test.xlsx"))
{
process.Kill();
break;
}
}
or
foreach (var process in Process.GetProcesses())
{
if (process.MainWindowTitle.Contains("test.dat"))
{
process.Kill();
break;
}
}

I believe that you need code running in kernel mode to completely answer the question (but I haven't looked at the restart manager API).
You can enumerate all processes and their modules - so if the file you're looking for is a module (DLL, EXE, OCX...), you're good to go. But if it's a text file for example, you have to look at the kernel handle table which you cannot see from user mode. Handle.exe has a kernel driver in order to do that.

I rewrote the GetProcessesLockingFile() method in the solution. The code was not working.
For example, you have a folder "C:\folder1\folder2" and a process in folder2 (process1). If the process was running, GetProcessesLockingFile() was returning "C:\folder1\folder2". So the condition if (files.Contains(filePath)) => if ("C:\folder1\folder2".contains("C:\folder1\folder2\process1")) was never true.
So this is my solution:
public static List<Process> GetProcessesLockingFile(FileInfo file)
{
var procs = new List<Process>();
var processListSnapshot = Process.GetProcesses();
foreach (var process in processListSnapshot)
{
if (process.Id <= 4) { continue; } // system processes
List<string> paths = GetFilesLockedBy(process);
foreach (string path in paths)
{
string pathDirectory = path;
if (!pathDirectory.EndsWith(Constants.DOUBLE_BACKSLASH))
{
pathDirectory = pathDirectory + Constants.DOUBLE_BACKSLASH;
}
string lastFolderName = Path.GetFileName(Path.GetDirectoryName(pathDirectory));
if (file.FullName.Contains(lastFolderName))
{
procs.Add(process);
}
}
}
return procs;
}
Or with a string parameter:
public static List<Process> GetProcessesLockingFile(string filePath)
{
var procs = new List<Process>();
var processListSnapshot = Process.GetProcesses();
foreach (var process in processListSnapshot)
{
if (process.Id <= 4) { continue; } // system processes
List<string> paths = GetFilesLockedBy(process);
foreach (string path in paths)
{
string pathDirectory = path;
if (!pathDirectory.EndsWith(Constants.DOUBLE_BACKSLASH))
{
pathDirectory = pathDirectory + Constants.DOUBLE_BACKSLASH;
}
string lastFolderName = Path.GetFileName(Path.GetDirectoryName(pathDirectory));
if (filePath.Contains(lastFolderName))
{
procs.Add(process);
}
}
}
return procs;
}

You absolutely don't need to run in Kernel mode (!!!)
It's a Win32 FAQ since Windows 95 (!) (in C, Google groups, Win32) : read the handle table, from User mode of course, and get the PID from the File handle ...

Using dotnet core (net6) I solved this problem by using the win32 restart manager (as others have also mentioned). However some of the linked articles have elaborate code importing DLLs and calling those.
After finding an app to kill processes that lock a file written by meziantou. I found out that he publishes .Net wrappers for win32 dlls (including the restart manager).
Leveraging his work, I was able to fix this problem with the following code:
using Meziantou.Framework.Win32;
public static IEnumerable<Process> GetProcessesLockingFile(string filePath)
{
using var session = RestartManager.CreateSession();
session.RegisterFile(filePath);
return session.GetProcessesLockingResources();
}

simpler with linq:
public void KillProcessesAssociatedToFile(string file)
{
GetProcessesAssociatedToFile(file).ForEach(x =>
{
x.Kill();
x.WaitForExit(10000);
});
}
public List<Process> GetProcessesAssociatedToFile(string file)
{
return Process.GetProcesses()
.Where(x => !x.HasExited
&& x.Modules.Cast<ProcessModule>().ToList()
.Exists(y => y.FileName.ToLowerInvariant() == file.ToLowerInvariant())
).ToList();
}

Develop Reference

C# (C-Sharp) is a programming language developed by Microsoft that runs on the .NET Framework.

SEHException when calling WTSVirtualChannelClose - c#

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