Question

I created a app that downloads all document libraries in a SP Site , but at one point it giving me this error (I tried looking at google but couldn;t find anything, now if anyone knows any trick to solve this problem please respond otherwise thanks for looking at it)

System.IO.PathTooLongException: The specified path, file name, or both are too long. The fully qualified file name must be less than 260 characters, and the directory name must be less than 248 characters.
at System.IO.Path.NormalizePathFast(String path, Boolean fullCheck)
at System.IO.Path.GetFullPathInternal(String path)
at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy)
at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options)
at System.IO.File.Create(String path)

it reaches the limit for string, Code is given below,

#region Downloading Schemes

    private void btnDownload_Click(object sender, EventArgs e)
    {
        TreeNode currentNode = tvWebs.SelectedNode;
        SPObjectData objectData = (SPObjectData)currentNode.Tag;
        try
        {
            CreateLoggingFile();
            using (SPWeb TopLevelWeb = objectData.Web)
            {
                if(TopLevelWeb != null)
                    dwnEachWeb(TopLevelWeb, TopLevelWeb.Title, tbDirectory.Text);
            }
        }
        catch (Exception ex)
        {
            Trace.WriteLine(string.Format("Exception caught when tried to pass TopLevelWeb:{1}, Title = {2}, object data to (dwnEachWeb_method), Exception: {0}", ex.ToString(), objectData.Web, objectData.Title));
        }
        finally
        {
            CloseLoggingFile();
        }
    }

    private void dwnEachWeb(SPWeb TopLevelWeb, string FolderName, string CurrentDirectory)
    {
        if (TopLevelWeb != null)
        {
            if (TopLevelWeb.Webs != null)
            {
                CurrentDirectory = CurrentDirectory + "\\" + TopLevelWeb.Title;
                CreateFolder(CurrentDirectory);
                foreach (SPWeb ChildWeb in TopLevelWeb.Webs)
                {

                    dwnEachWeb(ChildWeb, ChildWeb.Title, CurrentDirectory);
                    ChildWeb.Dispose();
                }
                dwnEachList(TopLevelWeb, CurrentDirectory);
                //dwnEachList(TopLevelWeb, FolderName, CurrentDirectory);
            }
        }
    }

    private void dwnEachList(SPWeb oWeb, string CurrentDirectory)
    {
        foreach (SPList oList in oWeb.Lists)
        {
            if (oList is SPDocumentLibrary && !oList.Hidden)
            {
                dwnEachFile(oList.RootFolder, CurrentDirectory);
            }
        }
    }

    private void dwnEachFile(SPFolder oFolder, string CurrentDirectory)
    {
        if (oFolder.Files.Count != 0)
        {
            CurrentDirectory = CurrentDirectory + "\\" + oFolder.Name;
            CreateFolder(CurrentDirectory);
            foreach (SPFile ofile in oFolder.Files)
            {
                if (CreateDirectoryStructure(CurrentDirectory, ofile.Url))
                {
                    var filepath = System.IO.Path.Combine(CurrentDirectory, ofile.Url);
                    byte[] binFile = ofile.OpenBinary();
                    System.IO.FileStream fstream = System.IO.File.Create(filepath);
                    fstream.Write(binFile, 0, binFile.Length);
                    fstream.Close();
                }
            }
        }
    }

    //creating directory where files will be download        
    private bool CreateDirectoryStructure(string baseFolder, string filepath)
    {
        if (!Directory.Exists(baseFolder)) return false;

        var paths = filepath.Split('/');

        for (var i = 0; i < paths.Length - 1; i++)
        {
            baseFolder = System.IO.Path.Combine(baseFolder, paths[i]);
            Directory.CreateDirectory(baseFolder);
        }
        return true;
    }

    //creating folders
    private bool CreateFolder(string CurrentDirectory)
    {
        if (!Directory.Exists(CurrentDirectory))
        {
            Directory.CreateDirectory(CurrentDirectory);
        }
        return true;
    }

    //shorting string

    #endregion

Answer 1

As the cause of the error is obvious, here’s some information that should help you solve the problem:

See this MS article about Naming Files, Paths, and Namespaces

Here’s a quote from the link:

Maximum Path Length Limitation In the Windows API (with some exceptions discussed in the following paragraphs), the maximum length
for a path is MAX_PATH, which is defined as 260 characters. A local
path is structured in the following order: drive letter, colon,
backslash, name components separated by backslashes, and a terminating
null character. For example, the maximum path on drive D is “D:\some
256-character path string<NUL>” where “<NUL>” represents the invisible
terminating null character for the current system codepage. (The
characters < > are used here for visual clarity and cannot be part of
a valid path string.)

And a few workarounds (taken from the comments):

There are ways to solve the various problems. The basic idea of the solutions listed below is always the same: Reduce the path-length in order to have path-length + name-length < MAX_PATH. You may:

• Share a subfolder
• Use the commandline to assign a drive letter by means of SUBST
• Use AddConnection under VB to assign a drive letter to a path