Develop Reference

Why does my file sometimes disappear in the process of reading from it or writing to it?

I have an app that reads from text files to determine which reports should be generated. It works as it should most of the time, but once in awhile, the program deletes one of the text files it reads from/writes to. Then an exception is thrown ("Could not find file") and progress ceases.
Here is some pertinent code.
First, reading from the file:
List<String> delPerfRecords = ReadFileContents(DelPerfFile);
. . .
private static List<String> ReadFileContents(string fileName)
{
List<String> fileContents = new List<string>();
try
{
fileContents = File.ReadAllLines(fileName).ToList();
}
catch (Exception ex)
{
RoboReporterConstsAndUtils.HandleException(ex);
}
return fileContents;
}
Then, writing to the file -- it marks the record/line in that file as having been processed, so that the same report is not re-generated the next time the file is examined:
MarkAsProcessed(DelPerfFile, qrRecord);
. . .
private static void MarkAsProcessed(string fileToUpdate, string
qrRecord)
{
try
{
var fileContents = File.ReadAllLines(fileToUpdate).ToList();
for (int i = 0; i < fileContents.Count; i++)
{
if (fileContents[i] == qrRecord)
{
fileContents[i] = string.Format("{0}{1} {2}"
qrRecord, RoboReporterConstsAndUtils.COMPLETED_FLAG, DateTime.Now);
}
}
// Will this automatically overwrite the existing?
File.Delete(fileToUpdate);
File.WriteAllLines(fileToUpdate, fileContents);
}
catch (Exception ex)
{
RoboReporterConstsAndUtils.HandleException(ex);
}
}
So I do delete the file, but immediately replace it:
File.Delete(fileToUpdate);
File.WriteAllLines(fileToUpdate, fileContents);
The files being read have contents such as this:
Opas,20170110,20161127,20161231-COMPLETED 1/10/2017 12:33:27 AM
Opas,20170209,20170101,20170128-COMPLETED 2/9/2017 11:26:04 AM
Opas,20170309,20170129,20170225-COMPLETED
Opas,20170409,20170226,20170401
If "-COMPLETED" appears at the end of the record/row/line, it is ignored - will not be processed.
Also, if the second element (at index 1) is a date in the future, it will not be processed (yet).
So, for these examples shown above, the first three have already been done, and will be subsequently ignored. The fourth one will not be acted on until on or after April 9th, 2017 (at which time the data within the data range of the last two dates will be retrieved).
Why is the file sometimes deleted? What can I do to prevent it from ever happening?
If helpful, in more context, the logic is like so:
internal static string GenerateAndSaveDelPerfReports()
{
string allUnitsProcessed = String.Empty;
bool success = false;
try
{
List<String> delPerfRecords = ReadFileContents(DelPerfFile);
List<QueuedReports> qrList = new List<QueuedReports>();
foreach (string qrRecord in delPerfRecords)
{
var qr = ConvertCRVRecordToQueuedReport(qrRecord);
// Rows that have already been processed return null
if (null == qr) continue;
// If the report has not yet been run, and it is due, add i
to the list
if (qr.DateToGenerate <= DateTime.Today)
{
var unit = qr.Unit;
qrList.Add(qr);
MarkAsProcessed(DelPerfFile, qrRecord);
if (String.IsNullOrWhiteSpace(allUnitsProcessed))
{
allUnitsProcessed = unit;
}
else if (!allUnitsProcessed.Contains(unit))
{
allUnitsProcessed = allUnitsProcessed + " and "
unit;
}
}
}
foreach (QueuedReports qrs in qrList)
{
GenerateAndSaveDelPerfReport(qrs);
success = true;
}
}
catch
{
success = false;
}
if (success)
{
return String.Format("Delivery Performance report[s] generate
for {0} by RoboReporter2017", allUnitsProcessed);
}
return String.Empty;
}
How can I ironclad this code to prevent the files from being periodically trashed?
UPDATE
I can't really test this, because the problem occurs so infrequently, but I wonder if adding a "pause" between the File.Delete() and the File.WriteAllLines() would solve the problem?
UPDATE 2
I'm not absolutely sure what the answer to my question is, so I won't add this as an answer, but my guess is that the File.Delete() and File.WriteAllLines() were occurring too close together and so the delete was sometimes occurring on both the old and the new copy of the file.
If so, a pause between the two calls may have solved the problem 99.42% of the time, but from what I found here, it seems the File.Delete() is redundant/superfluous anyway, and so I tested with the File.Delete() commented out, and it worked fine; so, I'm just doing without that occasionally problematic call now. I expect that to solve the issue.

// Will this automatically overwrite the existing?
File.Delete(fileToUpdate);
File.WriteAllLines(fileToUpdate, fileContents);
I would simply add an extra parameter to WriteAllLines() (which could default to false) to tell the function to open the file in overwrite mode, and not call File.Delete() at all then.
Do you currently check the return value of the file open?
Update: ok, it looks like WriteAllLines() is a .Net Framework function and therefore cannot be changed, so I deleted this answer. However now this shows up in the comments, as a proposed solution on another forum:
"just use something like File.WriteAllText where if the file exists,
the data is just overwritten, if the file does not exist it will be
created."
And this was exactly what I meant (while thinking WriteAllLines() was a user defined function), because I've had similar problems in the past.
So, a solution like that could solve some tricky problems (instead of deleting/fast reopening, just overwriting the file) - also less work for the OS, and possibly less file/disk fragmentation.

Moving a folder, from one directory to another. in c#

Okay, so me and several others are trying to move a bunch of files from a game launcher. To said directory of your choice.
The problem is, the files wont move.
The way the launcher works, is you click install on the game, it installs a bunch of files to the location of your choice. But the files wont move.
Here' the code.
private void MoveFolders()
{
string sourceDir = Config.GetGamePath();
string destinationDir = textBoxFolder.Text;
try
{
if (Directory.Exists(sourceDir) == true)
{
if (bGameIsInstalled == true && textBoxFolder.TextLength > 0)
{
Directory.Move(sourceDir, destinationDir);
bMoveFolders = true;
}
else
{
MessageBox.Show("Select Arma 3 directory before starting game");
}
}
else
{
// Do somthing about source directory not existing -
}
}
catch (Exception ex)
{
//TODO: Handle the execption that has been thrown will do this on launcher update
}
}

You can use CopyFile. As you said this should be a installer, i wouldn't move them folders to another direction. Just copy it, because you can't use the installer one more time after all these files needed are moved away.
And if you debug it, please just don't use try and catch. Test your code simply.

How to empty contents of a log file being used by the same program

I have a C# application which uses log4net to write some log outputs in a file names "logfile.txt" residing in the application directory. I want to empty the contents of the file as soon as it reaches a size of 10GB.
For that I'm using a timer which keeps checking whether the size of the file crosses 10GB.
But I cannot perform any operation on "logfile.txt" since it is being used by other threads to write log outputs and it's throwing me,
System.IO.IOException "The process cannot access the file 'C:\Program Files\MyApps\TestApp1\logfile.txt' because it is being used by another process."
Here is the code of the timer which checks the size of the file "logfile.txt"
private void timer_file_size_check_Tick(object sender, EventArgs e)
{
try
{
string log_file_path = "C:\\Program Files\\MyApps\\TestApp1\\logfile.txt";
FileInfo f = new FileInfo(log_file_path);
bool ex;
long s1;
if (ex = f.Exists)
{
s1 = f.Length;
if (s1 > 10737418240)
{
System.GC.Collect();
System.GC.WaitForPendingFinalizers();
File.Delete(log_file_path);
//File.Create(log_file_path).Close();
//File.Delete(log_file_path);
//var fs = new FileStream(log_file_path, FileMode.Truncate);
}
}
else
{
MDIParent.log.Error("Log file doesn't exists..");
}
}
catch (Exception er)
{
MDIParent.log.Error("Exceptipon :: " + er.ToString());
}
}

You shouldn't delete a log file on your own because log4net can do it for you. If you use RollingFileAppender you can specify the maximum file size (maximumFileSize property). Additionally if you set maxSizeRollBackups property to 0, then the log file will be truncated when it reaches the limit. Please look at this question for an example.

How to close a file in Autocad using C# keeping acad.exe running?

I am using visual studio 2010 and I am having a .DWG file which I want to open in autocad. Till now I have used this.
Process p = new Process();
ProcessStartInfo s = new ProcessStartInfo("D:/Test File/" + fileName);
p.StartInfo = s;
p.Start();
But what I want is to close the file inside the Autocad but not the autocad itself. (Means atocad.exe should be kept running).
Till now I hve used this but its closing the acad.exe not the file.
foreach (Process Proc in Process.GetProcesses())
{
if (Proc.ProcessName.Equals("acad"))
{
Proc.CloseMainWindow();
Proc.Kill();
}
}

Take the Autocad .NET libraries from Autodesk Sites (http://usa.autodesk.com/adsk/servlet/index?id=773204&siteID=123112)
Then you will be able to use Application and Document classes.
They will give you full control over opening and closing documents within the application.
You can find many articles on that, and can ask further questions.

AutoCAD does have an api. there are 4 assemblys. Two for in-process and two for COM.
inprocess :
acdbmgd.dll
acmgd.dll
COMInterop :
Autodesk.Autocad.Interop.dll
Autodesk.Autocad.Interop.Common.dll
this is a method that will open a new instance of AutoCAD or it will connect to an existing running instance of AutoCAD.
you will need to load these .dlls into your project references.
using Autodesk.AutoCAD.Interop;
using Autodesk.AutoCAD.Interop.Common;
namespace YourNameSpace {
public class YourClass {
AcadApplication AcApp;
private const string progID = "AutoCAD.Application.18.2";// this is AutoCAD 2012 program id
private string profileName = "<<Unnamed Profile>>";
private const string acadPath = #"C:\Program Files\Autodesk\AutoCAD 2012 - English\acad.exe";
public void GetAcApp()
{
try
{
AcApp = (AcadApplication)Marshal.GetActiveObject(progID);
} catch {
try {
var acadProcess = new Process();
acadProcess.StartInfo.Arguments = string.Format("/nologo /p \"{0}\"", profileName);
acadProcess.StartInfo.FileName = (#acadPath);
acadProcess.Start();
while(AcApp == null)
{
try { AcApp = (AcadApplication)Marshal.GetActiveObject(progID); }
catch { }
}
} catch(COMException) {
MessageBox.Show(String.Format("Cannot create object of type \"{0}\"",progID));
}
}
try {
int i = 0;
var appState = AcApp.GetAcadState();
while (!appState.IsQuiescent)
{
if(i == 120)
{
Application.Exit();
}
// Wait .25s
Thread.Sleep(250);
i++;
}
if(AcApp != null){
// set visibility
AcApp.Visible = true;
}
} catch (COMException err) {
if(err.ErrorCode.ToString() == "-2147417846"){
Thread.Sleep(5000);
}
}
}
}
}
closeing it is as simple as
Application.Exit();
and forgive the code. its atrocious, this was one of my first methods when i just started developing...

I doubt you will be able to do this unless AutoCAD has an API that you can hook into and ask it to close the file for you.
Your c# app can only do things to the process (acad.exe) , it doesn't have access to the internal operations of that process.

Also, you shouldn't use Kill unless the process has become unresponsive and certainly not immediately after CloseMainWindow.
CloseMainWindow is the polite way to ask an application to close itself. Kill is like pulling the power lead from the socket. You aren't giving it the chance to clean up after itself and exit cleanly.

There is one other possibility - this will only work if your C# code is running on the same machine as the AutoCAD process and it is not really recommended, but, if you are really stuck and are prepared to put up with the hassle of window switching you can send key strokes to an application using the SendKeys command.
MSDN articles here:
http://msdn.microsoft.com/EN-US/library/ms171548(v=VS.110,d=hv.2).aspx
http://msdn.microsoft.com/en-us/library/system.windows.forms.sendkeys.send.aspx
Using this you could send the key strokes to simulate the user using the menu commands to close the file.

To perform the closing of file, best way out is to follow the steps at this ObjectARX SDK for c# and change the following code with the below code.
[CommandMethod("CD", CommandFlags.Session)]
static public void CloseDocuments()
{
DocumentCollection docs = Application.DocumentManager;
foreach (Document doc in docs)
{
// First cancel any running command
if (doc.CommandInProgress != "" &&
doc.CommandInProgress != "CD")
{
AcadDocument oDoc =
(AcadDocument)doc.AcadDocument;
oDoc.SendCommand("\x03\x03");
}
if (doc.IsReadOnly)
{
doc.CloseAndDiscard();
}
else
{
// Activate the document, so we can check DBMOD
if (docs.MdiActiveDocument != doc)
{
docs.MdiActiveDocument = doc;
}
int isModified =
System.Convert.ToInt32(
Application.GetSystemVariable("DBMOD")
);
// No need to save if not modified
if (isModified == 0)
{
doc.CloseAndDiscard();
}
else
{
// This may create documents in strange places
doc.CloseAndSave(doc.Name);
}
}
}

Detecting a File Delete on an Open File

I am opening a file with read access and allowing subsequent read|write|delete file share access to the file (tailing the file). If the file is deleted during processing is there a way to detect that the file is pending delete (see Files section http://msdn.microsoft.com/en-us/library/aa363858(v=VS.85).aspx)? If some outside process (the owning process) has issued a delete, I want to close my handle as soon as possible to allow the file deletion so as not to interfere with any logic in the owning process.
I'm in C# and see no method of detecting the pending delete. The file was opened using a FileStream object. Is there some method for detecting the delete in C# or in some other windows function?

You can use the Windows API function GetFileInformationByHandleEx to detect a pending delete on a file you have open. The second argument is an enumeration value which lets you specify what kind of information the function should return. The FileStandardInfo (1) value will cause it to return the FILE_STANDARD_INFO structure, which includes a DeletePending boolean.
Here is a demonstration utility:
using System;
using System.Text;
using System.IO;
using System.Runtime.InteropServices;
using System.Threading;
internal static class Native
{
[DllImport("kernel32.dll", SetLastError = true)]
public extern static bool GetFileInformationByHandleEx(IntPtr hFile,
int FileInformationClass,
IntPtr lpFileInformation,
uint dwBufferSize);
public struct FILE_STANDARD_INFO
{
public long AllocationSize;
public long EndOfFile;
public uint NumberOfLinks;
public byte DeletePending;
public byte Directory;
}
public const int FileStandardInfo = 1;
}
internal static class Program
{
public static bool IsDeletePending(FileStream fs)
{
IntPtr buf = Marshal.AllocHGlobal(4096);
try
{
IntPtr handle = fs.SafeFileHandle.DangerousGetHandle();
if (!Native.GetFileInformationByHandleEx(handle,
Native.FileStandardInfo,
buf,
4096))
{
Exception ex = new Exception("GetFileInformationByHandleEx() failed");
ex.Data["error"] = Marshal.GetLastWin32Error();
throw ex;
}
else
{
Native.FILE_STANDARD_INFO info = Marshal.PtrToStructure<Native.FILE_STANDARD_INFO>(buf);
return info.DeletePending != 0;
}
}
finally
{
Marshal.FreeHGlobal(buf);
}
}
public static int Main(string[] args)
{
TimeSpan MAX_WAIT_TIME = TimeSpan.FromSeconds(10);
if (args.Length == 0)
{
args = new string[] { "deleteme.txt" };
}
for (int i = 0; i < args.Length; ++i)
{
string filename = args[i];
FileStream fs = null;
try
{
fs = File.Open(filename,
FileMode.CreateNew,
FileAccess.Write,
FileShare.ReadWrite | FileShare.Delete);
byte[] buf = new byte[4096];
UTF8Encoding utf8 = new UTF8Encoding(false);
string text = "hello world!\r\n";
int written = utf8.GetBytes(text, 0, text.Length, buf, 0);
fs.Write(buf, 0, written);
fs.Flush();
Console.WriteLine("{0}: created and wrote line", filename);
DateTime t0 = DateTime.UtcNow;
for (;;)
{
Thread.Sleep(16);
if (IsDeletePending(fs))
{
Console.WriteLine("{0}: detected pending delete", filename);
break;
}
if (DateTime.UtcNow - t0 > MAX_WAIT_TIME)
{
Console.WriteLine("{0}: timeout reached with no delete", filename);
break;
}
}
}
catch (Exception ex)
{
Console.WriteLine("{0}: {1}", filename, ex.Message);
}
finally
{
if (fs != null)
{
Console.WriteLine("{0}: closing", filename);
fs.Dispose();
}
}
}
return 0;
}
}

I would use a different signaling mechanism. (I am making the assumption all file access is within your control and not from a closed external program, mainly due to the flags being employed.)
The only "solution" within those bounds I can think of is a poll on file-access and check the exception (if any) you get back. Perhaps there is something much more tricky (at a lower-level than the win32 file API?!?), but this is already going down the "uhg path" :-)

FileSystemWatcher would probably be the closest thing, but it can't detect a "pending" delete; when the file IS deleted, an event will be raised on FileSystemWatcher, and you can attach a handler that will gracefully interrupt your file processing. If the lock (or lack of one) you acquire in opening the file makes it possible for the file to be deleted at all, simply closing your read-only FileStream when that happens should not affect the file system.
The basic steps of a file watcher are to create one, passing an instance of a FileInfo object to the constructor. FileInfos can be created inexpensively by just instantiating one, passing it the path and filename of the file as a string. Then, set its NotifyFilter to the type(s) of file system modifications you want to watch for on this file. Finally, attach your process's event handler to the OnDeleted event. This event handler can probably be as simple as setting a bit flag somewhere that your main process can read, and closing the FileStream. You'll then get an exception on your next attempt to work with the stream; catch it, read the flag, and if it's set just gracefully stop doing file stuff. You can also put the file processing in a seperate worker thread, and the event handler can just tell the thread to die in some graceful method.

If the file is small enough, your application could process a copy of the file, rather than the file itself. Also, if your application needs to know whether the owning process deleted the original file, set up a FileSystemWatcher (FSW) on the file. When the file disappears, the FSW could set a flag to interrupt processing:
private bool _fileExists = true;
public void Process(string pathToOriginalFile, string pathToCopy)
{
File.Copy(pathToOriginalFile, pathToCopy);
FileSystemWatcher watcher = new FileSystemWatcher();
watcher.Path = pathToOriginalFile;
watcher.Deleted += new FileSystemEventHandler(OnFileDeleted);
bool doneProcessing = false;
watcher.EnableRaisingEvents = true;
while(_fileExists && !doneProcessing)
{
// process the copy here
}
...
}
private void OnFileDeleted(object source, FileSystemEventArgs e)
{
_fileExists = false;
}

No, there's no clean way to do this. If you were concerned about other processes opening and/or modifying the file, then oplocks could help you. But if you're just looking for notification of when the delete disposition gets set to deleted, there isn't a straightforward way to do this (sans building a file system filter, hooking the APIs, etc. all of which spooky for an application do be doing w/o very good reason).