using System.IO;
using System.Runtime.InteropServices;
public static class FileLockHelper
{
// http://stackoverflow.com/questions/1304/how-to-check-for-file-lock-in-c
private const int NumberOfTries = 3;
private const int TimeIntervalBetweenTries = 1000;
public static bool IsFileLocked(string fileName)
{
if (File.Exists(fileName))
{
try
{
var tries = 0;
while (true)
{
try
{
using (File.Open(fileName, FileMode.Open, FileAccess.ReadWrite, FileShare.None))
{
return false;
}
}
catch (IOException e)
{
LogCentral.Current.Error(e,
$@"{nameof(FileLockHelper)}.{nameof(IsFileLocked)}: {nameof(IOException)} bei Datei „{fileName}“.");
if (!IsFileLocked(e))
throw;
if (++tries > NumberOfTries)
{
logLockingProcess(fileName);
return true;
}
Thread.Sleep(TimeIntervalBetweenTries);
}
catch (UnauthorizedAccessException e)
{
LogCentral.Current.Error(e,
$@"{nameof(FileLockHelper)}.{nameof(IsFileLocked)}: {
nameof(UnauthorizedAccessException)
} bei Datei „{fileName}“.");
if (!IsFileLocked(e))
throw;
if (++tries > NumberOfTries)
{
logLockingProcess(fileName);
return true;
}
Thread.Sleep(TimeIntervalBetweenTries);
}
}
}
catch (Exception e)
{
// 2017-04-27, Uwe Keim:
// Nie throwen.
LogCentral.Current.Error(e,
$@"{nameof(FileLockHelper)}.{nameof(IsFileLocked)}: {e.GetType()} bei Datei „{fileName}“.");
return false;
}
}
else
{
return false;
}
}
private static void logLockingProcess(string fileName)
{
LogCentral.Current.Info($@"File „{fileName}“ is locked by process „{WhoIsLocking(fileName, true).Message}“.");
}
private static bool IsFileLocked(Exception exception)
{
var errorCode = Marshal.GetHRForException(exception) & ((1 << 16) - 1);
return errorCode is 32 or 33;
}
/// <summary>
/// Find out what process(es) have a lock on the specified file.
/// </summary>
/// <param name="path">Path of the file.</param>
/// <param name="catchExceptions">Whether to return empty/partially filled list upon errors.</param>
/// <returns>Processes locking the file</returns>
/// <remarks>See also:
/// https://stackoverflow.com/a/20623311/107625
/// 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 WhoIsLockingResult WhoIsLocking(string path, bool catchExceptions)
{
var key = Guid.NewGuid().ToString();
var processes = new List<Process>();
var res = RmStartSession(out var 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 pnProcInfo = 0,
lpdwRebootReasons = RmRebootReasonNone;
var resources = new[] { 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 var pnProcInfoNeeded, ref pnProcInfo, null, ref lpdwRebootReasons);
if (res == ERROR_MORE_DATA)
{
// Create an array to store the process results
var 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 (var 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.");
}
catch (Exception x)
{
if (catchExceptions)
{
LogCentral.Current.Warn(x, $@"Ignoring exception while checking who is locking file „{path}“.");
}
else
{
throw;
}
}
finally
{
RmEndSession(handle);
}
return new WhoIsLockingResult(processes);
}
[StructLayout(LayoutKind.Sequential)]
private struct RM_UNIQUE_PROCESS
{
// ReSharper disable FieldCanBeMadeReadOnly.Local
// ReSharper disable MemberCanBePrivate.Local
public int dwProcessId;
public System.Runtime.InteropServices.ComTypes.FILETIME ProcessStartTime;
// ReSharper restore MemberCanBePrivate.Local
// ReSharper restore FieldCanBeMadeReadOnly.Local
}
private const int RmRebootReasonNone = 0;
private const int CCH_RM_MAX_APP_NAME = 255;
private const int CCH_RM_MAX_SVC_NAME = 63;
private enum RM_APP_TYPE
{
// ReSharper disable UnusedMember.Local
RmUnknownApp = 0,
RmMainWindow = 1,
RmOtherWindow = 2,
RmService = 3,
RmExplorer = 4,
RmConsole = 5,
RmCritical = 1000
// ReSharper restore UnusedMember.Local
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
private struct RM_PROCESS_INFO
{
// ReSharper disable FieldCanBeMadeReadOnly.Local
// ReSharper disable MemberCanBePrivate.Local
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;
// ReSharper restore MemberCanBePrivate.Local
// ReSharper restore FieldCanBeMadeReadOnly.Local
}
[DllImport(@"rstrtmgr.dll", CharSet = CharSet.Unicode)]
private 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)]
private static extern int RmStartSession(out uint pSessionHandle, int dwSessionFlags, string strSessionKey);
[DllImport(@"rstrtmgr.dll")]
private static extern int RmEndSession(uint pSessionHandle);
[DllImport(@"rstrtmgr.dll")]
private static extern int RmGetList(uint dwSessionHandle,
out uint pnProcInfoNeeded,
ref uint pnProcInfo,
[In, Out] RM_PROCESS_INFO[] rgAffectedApps,
ref uint lpdwRebootReasons);
}
public sealed class WhoIsLockingResult
{
public List<Process> Processes { get; }
internal WhoIsLockingResult(List<Process> processes)
{
Processes = processes;
}
public string Message
{
get
{
if (Processes is not {Count: > 0}) return string.Empty;
var result = new StringBuilder();
foreach (var process in Processes)
{
if (result.Length > 0) result.Append(@", ");
string name;
// Von https://stackoverflow.com/a/5497123/107625:
//
// "There is one catch with this API, if you are running this code in
// 32 bit application, you'll not be able to access 64-bit application paths."
//
// Deshalb hier abfangen.
try
{
name = process.MainModule?.FileName ?? string.Empty;
}
catch (Exception)
{
name = process.ProcessName;
}
result.Append(name);
}
return result.ToString();
}
}
}
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