Cannot delete temporary file after File.Copy in C#

Question

After copying a file to a temporary directory, I am unable to delete the copy because of an UnauthorizedAccessException exception. The idea here is to get a copy of the file, zip it and then delete the copy, but after removing all the code between File.Copy and File.Delete I am still getting the exception. Exiting from the program frees the lock and allows me to delete the copy without issue.

Is there a way to copy without causing this persistent lock (and preserve file metadata like LastModified)? Or a way to release the lock? Should there even be a lock on the copied file after File.Copy finishes?

I am using Visual C# 2010 SP1 targeting .NET Framework 4.0.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.IO;
using System.Xml;

namespace Test
{
    class Program
    {
        static void Main(string[] args)
        {
            String FileName = "C:\\test.txt";
            // Generate temporary directory name
            String directory = Path.Combine(Path.GetTempPath(), Path.GetRandomFileName());
            // Temporary file path
            String tempfile = Path.Combine(directory, Path.GetFileName(FileName));
            // Create directory in file system
            Directory.CreateDirectory(directory);
            // Copy input file to the temporary directory
            File.Copy(FileName, tempfile);
            // Delete file in temporary directory
            File.Delete(tempfile);
        }
    }
}

Is it possible that you do not close tempFile in `Other operations performed` — I4V, May 06 '13 at 08:36
@I4V that's the thing. I removed all "other operations performed". There is no other code between File.Copy and File.Delete. — jveazey, May 06 '13 at 08:37
Have you read the Remarks on the page of `UnauthorizedAccessException`? `The reasons for the exception can be found in the details of the exception object` — Silvermind, May 06 '13 at 08:38
Sorry. There is no code between the copy and delete. The "other operations performed" comment line shouldn't have been there. I have removed it. — jveazey, May 06 '13 at 08:41
Are you sure you have enough access rights on a file in the root of your C:\ drive? — Yeronimo, May 06 '13 at 08:44
@Yeronimo The file copies fine. And I can delete the copy after I kill the debugger. — jveazey, May 06 '13 at 08:46
@AlexFilipovici There are no problems with the source file. The problem is deleting the copy. — jveazey, May 06 '13 at 08:50
[File.Copy Method (String, String)](http://msdn.microsoft.com/en-us/library/c6cfw35a.aspx): _The attributes of the original file are retained in the copied file._ So, if you can't delete the file in `C:\`, you will not be able to delete it anywhere using the same account. — Alex Filipovici, May 06 '13 at 08:51
@AlexFilipovici Thank you. That was it. The file was marked as readonly. — jveazey, May 06 '13 at 08:55

score 8 · Accepted Answer · answered May 06 '13 at 08:52

8

Check your "C:\\test.txt" file for read only or not.

based on your comments this may be the reason you can copy but you can't delete

try with below

File.SetAttributes(tempfile, FileAttributes.Normal);
File.Delete(tempfile);

answered May 06 '13 at 08:52

Damith

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How come that " Exiting from the program frees the lock and allows me to delete the copy without issue." ? – VdesmedT May 06 '13 at 11:51

score 0 · Answer 2 · answered May 06 '13 at 09:34

I see you've already found an answer, but I'll add this for reference anyway; A possible alternative approach for you, might be to create the copy in a memory stream instead of copying the file to your hard-drive.

Using the DotNetZip library, you could do something like this:

using (var ms = new MemoryStream())
{
    using (var zip = new ZipFile())
    {
        zip.AddEntry(fileName, data);
        zip.Save(ms);
    }
}

Cannot delete temporary file after File.Copy in C#

2 Answers2