PathTooLongException work around

Comments

# mabra said on August 6, 2008 8:47 AM:

Hi ! Your note about the methods of the framwork are wrong: System.IO.Directory.GetFiles() System.IO.Directory.GetDirectories() Both throw "path too log exception" in a test I made. I would like to see a sample using the Windows API from C# ;-) --mabra

# dwalker said on August 12, 2008 10:18 PM:

Okay Mabra. Just for you and because when called out I feel the urge to prove it. :)

Here's an example with all the code you need. Simply create a new Web Application and place a Literal called DirectoryLiteral. Then, in the code behind for Default.aspx put the following code:

protected void Page_Load(object sender, EventArgs e)
       {
           string path = Server.MapPath(".");
           if (Request.QueryString["path"] != null)
           {
               path = Request.QueryString["path"].ToString();
           }
           DirectoryLiteral.Text = LoadData(path);
       }

       private string LoadData(string path)
       {
           StringBuilder sb = new StringBuilder();
           sb.Append("<ol>");
           if (path.Length > 3)
           {
               string parent = System.IO.Directory.GetParent(path).ToString();
               sb.Append("<li><a href=\"?path=" + parent + "\">..</a></li>");
           }
           foreach (string directory in System.IO.Directory.GetDirectories(path))
           {
               sb.Append("<li><a href=\"?path=" + directory + "\">" + GetDisplayName(directory) + "</a></li>");
           }
           foreach (string directory in System.IO.Directory.GetFiles(path))
           {
               sb.Append("<li>" + GetDisplayName(directory) + "</li>");
           }
           sb.Append("</ol>");
           return sb.ToString();
       }

       private string GetDisplayName(string name)
       {
           int lastSlash = name.LastIndexOf('\\');
           if (lastSlash > 0)
           {
               ++lastSlash;
               name = name.Substring(lastSlash, name.Length - lastSlash);
           }
           return name;
       }

Now create a folder with a really long name, something like:

ReallyLongFolderNameThatWouldCausePathTooLongExceptionWindowsExplorerDoesntEvenSupportFoldersLongerThan260CharactersItStopsAndDoesntLetYouMakeAFolderNamedThatLongOnceYouReachThatManyCharactersInWindowsXPandVista

You will know when it's long enough (based on path where you created your WebApplication and what you named it), because Windows Explorer will not let you exceed 260 characters.

Remove a few back from 260, so that you can go into the folder and create a text file with a name PathTooLongException.txt. Don't worry, again Windows Explorer will not let the full path of the file and it's filename exceed 260 characters.

Once you've created the file, now go back and increase the name of the Folder (it doesn't / can't check the length of the files in the folder at this point). Once you've increased the length of the folder, the file inside the folder will have a full path that exceeds the 260 character limit.

This code will still work and retrieve it's full path and filename, where as, most other API's fail with the Path Too Long Exception.

I couldn't post the original code, since it was for a client I was a consultant with at the time. Since I no longer had the code and was called out, I went ahead and typed it up again real quick.

Let me know if you have any other questions or if someone has the time and a chance to test this issue with Windows Server 2008. My gut says it will exhibit the same behavior, since it's so similar to Windows Vista. I will be excited to learn when Windows OS and Windows Explorer fix this issue. Let us know if/when you find the issue resolved.

# dleo said on August 20, 2008 5:14 PM:

Do you know how to programmatically rename the file so that it is no longer greater than max_path? I have developed all the code that locates the files but can not figure out how to rename/fix the file name. Suggestions?

# dwalker said on September 4, 2008 6:40 PM:

HI dleo,

The easiest way to resolve this would be to move the file to a \\temp folder. Otherwise, there are several things to consider when trying to programmatically rename a file in this regard. Does the actual full path already exceed the max_path of (260 characters)? If so, you will not be able to rename the file at all and instead will have to rename the folder first, then the file. That's why I recommend moving it.

I would recommend simply reporting it and manually handle the situation. The solution could be as simple as just renaming a parent folder, etc.

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