How to create directory exceeding MAX_PATH

Question

For testing purpose, I would like to create on disk a directory which exceeds the Windows MAX_PATH limit. How can I do that?

(I tried Powershell, cmd, windows explorer => it's blocked.)

Edited: The use of ZlpIOHelper from ZetaLongPaths library allows to do that whereas the standard Directory class throws the dreaded exception:

        static void Main(string[] args)
    {
        var path = @"d:\temp\";
        var dirName = "LooooooooooooooooooooooooooooooooooooooooooooongSubDirectory";
        while (path.Length <= 280)
        {
            path = Path.Combine(path, dirName);
            ZlpIOHelper.CreateDirectory(path); //Directory.CreateDirectory(path);
        }
        Console.WriteLine(path);
        Console.ReadLine();
    }

In C# try this library: http://zetalongpaths.codeplex.com/....or if it's in WIN32 then you need to use the special prefix to allow for longer file names. see: http://msdn.microsoft.com/en-us/library/aa365247.aspx — Colin Smith, Jul 19 '13 at 13:43
There's a comment in some of the API methods that you can use "\\?\" with the Unicode calls as a prefix for long paths, but I don't know if that translates into command-line tools — Rup, Jul 19 '13 at 13:43

score 14 · Accepted Answer · answered Jul 19 '13 at 13:48

In WIN32 you need to use the special "\\?\" prefix to allow for longer file names.

See: http://msdn.microsoft.com/en-us/library/aa365247.aspx

For file I/O, the "\\?\" prefix to a path string tells the Windows APIs to disable all string parsing and to send the string that follows it straight to the file system. For example, if the file system supports large paths and file names, you can exceed the MAX_PATH limits that are otherwise enforced by the Windows APIs. For more information about the normal maximum path limitation, see the previous section Maximum Path Length Limitation.

As you are using C# then try this library which will save you having to do all the PInvokes to the WIN32 file API and adding the prefix to the paths.

http://zetalongpaths.codeplex.com/

score 2 · Answer 2 · answered Jul 19 '13 at 15:16

2

The easiest solution is to create a directory c:\A\averylongnamethatgoesonandonandon..., and then rename C:\A to something much longer. Windows does not check every child of A to see if the name of that child would exceed MAX_PATH.

answered Jul 19 '13 at 15:16

MSalters

173,980
10
155
350

1

You wouldn't rename an existing directory to a short name, then create a long sub-directory and then rename it back. No, not a good solution. Also, you can't do that if files of `A` are in use. – Thomas Weller Apr 22 '15 at 20:45

score 1 · Answer 3 · answered Jul 19 '13 at 13:44

1

How about something like this:

var path = "C:\\";
while (path.Length <= 260)
{
    path = Path.Combine(path, "Another Sub Directory");
}

answered Jul 19 '13 at 13:44

Mike Perrenoud

66,820
29
157
232

1

darn it, you beat me to it +1 – Sayse Jul 19 '13 at 13:46
1

I assumed he meant "create on disk"? – Rup Jul 19 '13 at 13:46
Just add the create dir from my comment and there you have it – Sayse Jul 19 '13 at 13:47
@Rup: yes. I edited the question@Sayse: you get the PathTooLongException – sthiers Jul 19 '13 at 14:07
@sthiers - But I'm pretty sure you will have created the directory up until that point – Sayse Jul 19 '13 at 14:11

How to create directory exceeding MAX_PATH

3 Answers3