"C# Dev" wrote:

> Greetings all,
>
> Have a question regarding File.Move  / FileStreams
>
> My steps,
> 1. Create file1 demo.log  [FileMode.CreateNew]
> 2. Move file to demo1.log
> 3. Create file2 with same name as in #1: demo.log [FileMode.CreateNew]
>
> Now, problem is that the filehandle in #1 and #3 are the same.
> Are they expected to be?
>
> I suspect this is the reason why file2 inherits the CreateDate from file1
> which is my main problem :-/
>
> Can anyone please enlighten me what is going on?
>
> Cheers
>
> Sample code
> ==================================
> using System;
> using System.Collections.Generic;
> using System.Text;
> using System.IO;
>
> namespace FileMoveIssue
> {
>     class Program
>     {
>         static void Main(string[] args)
>         {
>             RecycleLogFile();
>         }
>
>         /// <summary> Illustreates how FileStream.Create after File.Move
> gets old file handle</summary>
>         public static void RecycleLogFile()
>         {
>
>             string path = Path.GetTempPath();
>             string fileName = "demo";
>             string extension = ".log";
>             FileStream fs0 = null;
>
>             if (File.Exists(path + fileName + extension))
>                 File.Delete(path + fileName + extension);
>
>             if (File.Exists(path + fileName + "1" + extension))
>                 File.Delete(path + fileName + "1" + extension);
>
>             fs0 = new FileStream(path + fileName + extension,
> FileMode.CreateNew, FileAccess.Write, FileShare.Read);
>             DateTime file1CreationDate = DateTime.Now.AddDays(-2);
>             int fileHandle1 = fs0.Handle.ToInt32();
>             fs0.Close();
>
>             File.SetCreationTime(fs0.Name, file1CreationDate); //creation
> time should be unique per file
>
>             //move file demo.log -> demo1.log
>             File.Move(fs0.Name, path + fileName + "1" + extension);
>
>             if (File.Exists(fs0.Name))
>             {
>                 Console.WriteLine("File should Not exist it has been moved");
>                 return;
>             }
>
>             FileStream fs1 = new FileStream(path + fileName + extension,
> FileMode.CreateNew, FileAccess.Write, FileShare.Read);
>             int fileHandle2 = fs1.Handle.ToInt32();
>
>             Console.WriteLine("filehandle1==filehandle2 {0} filehandle1 {1}
> filehandle2 {2}", fileHandle1 == fileHandle2, fileHandle1, fileHandle2);
>             DateTime file2CreationDate = File.GetCreationTime(fs1.Name);
>
>             Console.WriteLine("file1.CreationDate== file1.CreationDate {0}
> ", file1CreationDate == file2CreationDate);
>
>             if (fs0 != null)
>                 fs0.Close();
>
>             if (fs1 != null)
>                 fs1.Close();
>
>             Console.ReadLine();
>         }
>     }
> }
>
>
>

> "C# Dev" wrote:
>
> > Greetings all,
> >
> > Have a question regarding File.Move  / FileStreams
> >
> > My steps,
> > 1. Create file1 demo.log  [FileMode.CreateNew]
> > 2. Move file to demo1.log
> > 3. Create file2 with same name as in #1: demo.log [FileMode.CreateNew]
> >
> > Now, problem is that the filehandle in #1 and #3 are the same.
> > Are they expected to be?
> >
> > I suspect this is the reason why file2 inherits the CreateDate from file1
> > which is my main problem :-/
> >
> > Can anyone please enlighten me what is going on?
> >
> > Cheers
> >
> Anyone?
>
> If this can be replicated it seems like a bug to me..
>

> C# Dev wrote:
> > "C# Dev" wrote:
> >
> > > Greetings all,
> > >
> > > Have a question regarding File.Move  / FileStreams
> > >
> > > My steps,
> > > 1. Create file1 demo.log  [FileMode.CreateNew]
> > > 2. Move file to demo1.log
> > > 3. Create file2 with same name as in #1: demo.log [FileMode.CreateNew]
> > >
> > > Now, problem is that the filehandle in #1 and #3 are the same.
> > > Are they expected to be?
> > >
> > > I suspect this is the reason why file2 inherits the CreateDate from file1
> > > which is my main problem :-/
> > >
> > > Can anyone please enlighten me what is going on?
> > >
> > > Cheers
> > >
> > Anyone?
> >
> > If this can be replicated it seems like a bug to me..
> >
> I've managed to repeat this, using VB.Net. I believe it may be a
> windows filesystem "feature". I cannot find a reference for it, but I
> believe it's been done like this to support scenarios where an
> application is about to write out an updated copy of a file, but wants
> to support being able to retrieve the "old" version, if there's a
> problem during the write.
>
> Obviously, you cannot overwrite the existing file, so you have to
> rename it first, and then write out the new version using the old
> filename. And then windows (I believe. Might be .Net, but I suspect
> windows) steps in and says "Aha! This is obviously just an updated copy
> of the file that's just been moved, it should inherit some meta-data,
> such as the creation date (and permissions)". I think it's done on a
> per-process basis (so if one process renames a file, and another writes
> the new one, it will not inherit the meta data).
>

"Damien" wrote:

> Damien wrote:
> > C# Dev wrote:
> > > "C# Dev" wrote:
> > >
> > > > Greetings all,
> > > >
> > > > Have a question regarding File.Move  / FileStreams
> > > >
> > > > My steps,
> > > > 1. Create file1 demo.log  [FileMode.CreateNew]
> > > > 2. Move file to demo1.log
> > > > 3. Create file2 with same name as in #1: demo.log [FileMode.CreateNew]
> > > >
> > > > Now, problem is that the filehandle in #1 and #3 are the same.
> > > > Are they expected to be?
> > > >
> > > > I suspect this is the reason why file2 inherits the CreateDate from file1
> > > > which is my main problem :-/
> > > >
> > > > Can anyone please enlighten me what is going on?
> > > >
> > > > Cheers
> > > >
> > > Anyone?
> > >
> > > If this can be replicated it seems like a bug to me..
> > >
> > I've managed to repeat this, using VB.Net. I believe it may be a
> > windows filesystem "feature". I cannot find a reference for it, but I
> > believe it's been done like this to support scenarios where an
> > application is about to write out an updated copy of a file, but wants
> > to support being able to retrieve the "old" version, if there's a
> > problem during the write.
> >
> > Obviously, you cannot overwrite the existing file, so you have to
> > rename it first, and then write out the new version using the old
> > filename. And then windows (I believe. Might be .Net, but I suspect
> > windows) steps in and says "Aha! This is obviously just an updated copy
> > of the file that's just been moved, it should inherit some meta-data,
> > such as the creation date (and permissions)". I think it's done on a
> > per-process basis (so if one process renames a file, and another writes
> > the new one, it will not inherit the meta data).
> >
> Found it in MSDN, under CreateFile in Platform SDK, Storage. CreateFile
> is the Win32 call underneath the framework functionality.
>
> On the 2003 version, the link is
> ms-help://MS.MSDNQTR.2003FEB.1033/fileio/base/createfile.htm
>
> If you look down below the Remarks section, there is a section for each
> type of item that can be accessed using CreateFile. In the Files
> section, the fourth paragraph has:
>
> --Start quote
> If you rename or delete a file, then restore it shortly thereafter, the
> system searches the cache for file information to restore. Cached
> information includes its short/long name pair and creation time.
> --End Quote
>
> So, that's what you're getting.
>
> Damien
>
>