How to Detect the Currently Opened Files in VB.net for Media Centre

[robbietapping]

Hi Guys,

I am writing a Media Centre Addin in Vb.net and it was all going good until i got to the point where i want to find the "Currently Playing song FilePath or URl"

I have spend a number of hours racking my brain to figure out a way of seeing what the "Currently Opened Files" are on a machine at any point of time.

My idea is to get all the currently opened files, and then filter the Extensions from these and find the media item that is currently playing, and get the filepath..

Does anyone know how i can do this? and what methods or classes or Librarys i should be looking at or importing In.. This one has really got me thinking.

I was looking at the WMI Windows Management controls, but cant seem to find what i am looking for.. any help would be great..

Cheers

Robbie

[robbietapping]

Hi Guys,
Worked this one out, will post a reply in the next few days if anyone wants to know how to do it.

Cheers

Robbie

[Frinavale]

Sharing the solution is a great idea so that others facing the same problem will be able to find the answer....other wise you're just going to leave them hanging.

If you could share your solution it would be greatly appreciated.

Thanks

-Frinny

[robbietapping]

Hi Guys,

Thought i would send through the Vb.net code for how to get the currently playing song in a Media Centre Environment.

The way it works is it hooks on to the backgroup WMPlayer process, and sees what files it currently has opened, it then loops throught them until it finds a matching extention.

This code will also work in a standard application without media centre..

    Public Function GetCurrentlyPlayingMediaName() As String
        Try

            Dim pid As Integer = 0
            Dim filename As String = Nothing
            Dim mysession As Integer = 0
            ' Get the session ID for the current process 
            Using currentProcess As Process = Process.GetCurrentProcess()
                mysession = currentProcess.SessionId
            End Using

            ' Find the matching ehshell process in the same session 
            For Each proc As Process In Process.GetProcessesByName("wmplayer")
                If proc.SessionId = mysession Then
                    pid = proc.Id
                End If
                proc.Dispose()
            Next

            ' Check we found a process, if not, abort 
            If pid = 0 Then
                Trace.TraceWarning("No wmplaye process found")
                Return Nothing
            End If

            ' Get the list of open files by the ehshell process 
            Using openFiles As IEnumerator(Of FileSystemInfo) = DetectOpenFiles.GetOpenFilesEnumerator(pid)
                ' Iterate until we find a .dvr-ms file 
                While openFiles.MoveNext()
                    If openFiles.Current.Extension.ToLower(CultureInfo.InvariantCulture) = ".mp3" Then
                        filename = openFiles.Current.FullName
                        Exit While
                    End If
                    If openFiles.Current.Extension.ToLower(CultureInfo.InvariantCulture) = ".mp4" Then
                        filename = openFiles.Current.FullName
                        Exit While
                    End If
                    If openFiles.Current.Extension.ToLower(CultureInfo.InvariantCulture) = ".m4a" Then
                        filename = openFiles.Current.FullName
                        Exit While
                    End If
                    If openFiles.Current.Extension.ToLower(CultureInfo.InvariantCulture) = ".wma" Then
                        filename = openFiles.Current.FullName
                        Exit While
                    End If
                End While
            End Using

            Return filename

        Catch ex As Exception
            Log.Write("Unable to get Currently Playing Media: " & ex.Message)
            Return Nothing
        End Try

    End Function

Hope this helps someone out there

Cheers

Robbie

[Frinavale]

Thanks a lot Robbie :)
Your response is nicely detailed!

[waco78]

The DetectOpenFiles class seems to be missing? Where can I find this?


Thanks.

[robbietapping]

Hey Waco78, Apologies i forgot to add this code in here..

Johnathan Bradshaw (ABSOLUTE LEGEND) wrote this class to go and re-iterate through the process nodes and see what is being opened.

The way i did it was (Cause its in C#) instead of just converting the code.. i created a solution, and compiled the c# code as a library file, then was able to reference it in the C#. net, obviously there are easy ways, but the way my application has been set-up code wise, this was the easiest option.

if you have any problems let me know.... it should not be too fiddly or complicated at all.


Here is the C# Code:

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 VmcController.Services
{
    #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 IEnumerator<FileSystemInfo> GetOpenFilesEnumerator(int processId)
        {
            return new OpenFiles(processId).GetEnumerator();
        }

        private sealed class OpenFiles : IEnumerable<FileSystemInfo>
        {
            private readonly int processId;

            internal OpenFiles(int processId)
            {
                this.processId = processId;
            }

            #region IEnumerable<FileSystemInfo> Members

            public IEnumerator<FileSystemInfo> 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 new FileInfo(dosPath);
                                                }
                                                else if (Directory.Exists(dosPath))
                                                {
                                                    yield return 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()
            {
                _mr.Set();
            }
            #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
    }
}

[robbietapping]

btw, removed the namespace at the start, as you may have issues at runtime calling the class, and or at build time..

Cheers

Robbie

[aumsoft]

Hey Waco78, Apologies i forgot to add this code in here..

Johnathan Bradshaw (ABSOLUTE LEGEND) wrote this class to go and re-iterate through the process nodes and see what is being opened.

The way i did it was (Cause its in C#) instead of just converting the code.. i created a solution, and compiled the c# code as a library file, then was able to reference it in the C#. net, obviously there are easy ways, but the way my application has been set-up code wise, this was the easiest option.

if you have any problems let me know.... it should not be too fiddly or complicated at all.


Here is the C# Code:

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 VmcController.Services
{
    #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 IEnumerator<FileSystemInfo> GetOpenFilesEnumerator(int processId)
        {
            return new OpenFiles(processId).GetEnumerator();
        }

        private sealed class OpenFiles : IEnumerable<FileSystemInfo>
        {
            private readonly int processId;

            internal OpenFiles(int processId)
            {
                this.processId = processId;
            }

            #region IEnumerable<FileSystemInfo> Members

            public IEnumerator<FileSystemInfo> 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 new FileInfo(dosPath);
                                                }
                                                else if (Directory.Exists(dosPath))
                                                {
                                                    yield return 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()
            {
                _mr.Set();
            }
            #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
    }
}

I am using your C# library to check that file is open or not from my application. Everything works fine but it gives below error:
"ObjectDisposed Exception: Safe handle has been closed"
After getting this exception i am not able to end application process even in task manager by calling end Process. I have refered all the code in class but not able to identify where it uses disposed object again.
1) How to resolve this error?
2) This function works only on Xp machine. When i test this code on vista64bit, OpenFiles enumerator gives nothing value.

[Frinavale]

Have you considered using the File.Exists() method to check to see the file exists?

It's pretty easy to use and is included as part of the .NET Framework.


-Frinny

[aumsoft]

Hi frinavale....

Sorry to not explained well my question but i am looking for to check whether the file is open or not by other process included notepad, paint etc. I dont want check that file is exist or not. By the way we have resolve the issue of exception of "ObjectDisposed Exception: Safe handle has been closed". But after using this function we are not able to end/close the application even in from task manager by calling end process. Also awaiting for solution to run on vista64 OS.

Regards