文件太长异常

Question

I am trying to delete file from remote computer like this:

fileinfo undelteablefile = new fileinfo(
 @"\\CompName\c$\documents and settings\UserName\local settings\temporary internet files\content.ie5\k9ef0hmj\%d7%a9%d7%a2%a8%20%d7%9c%20%d7%a2%93%d7%9b%d7%95%d7%9f%20%d7%98%d7%9d%a0%d795%d7%9c%d7%d7%95%d7%92%d7%99%20%d7%97%95%d7%93%d7%a9%d7%99 [1] .jpg");

undeleteablefile.delete();

It gave me an exception that the file name or path are too long.

I tried adding \\\\?\\ but it didnt work... Why is this happening and what to do to solve this?

Answer 1

Map a network share to one of the directories closer to the file. Try deleting it with a wildcard.

Answer 2

There are three approaches that I have used, but be warned that they require unmanaged P/Invoke code. Not much, so you can probably copy/paste if you don't understand how it works.

1. Use the 8.3 filenames (ala DOS compatible filenames)

2. Use the \\?\\ syntax that you mention. However, I don't believe that you can use it directly from C# - you will need to invoke the native methods. Note - this has security implications, as the string is not parsed, but passed directly to the filesystem.

3. Use the unmanaged File APIs.

This is a great series of blog posts that address exactly this issue .

Erick

Answer 3

The long path prefix \\\\?\\ can only be used with non UNC paths. Use the \\\\?\\UNC\\ pefix for UNC paths instead and call the Win32 API function DeleteFile . See the following MSDN article for more information about naming files and paths.

Here is a small example:

[DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool DeleteFile(string lpFileName);

static void Main(string[] args)
{
  string yourLongUncPath = @"\\?\UNC\server\path";

  if(DeleteFile(yourLongUncPath))
  {
    Console.Out.WriteLine("Successfully deleted file...");
  }
}

Please note, that you have to use the Unicode version of DeleteFile to use the long path prefix \\\\?\\UNC\\ .

Answer 4

Looking at the end of the file-name it seems that Windows is not able to handle it due to obscure characters in the name.

I used the online facility to decode the file name part, which could theoretically explain why its not able to delete it.

%d7%a9%d7%a2%a8%20%d7%9c%20%d7%a2%93%d7%9b%d7%95%d7%9f%20%d7%98%d7%9d%a0%d795%d7%9c%d7%d7%95%d7%92%d7%99%20%d7%97%95%d7%93%d7%a9%d7%99 1 .jpg

When converted it looks like this, with US-ASCII

95 1 .jpg

Likewise for UTF-8

שע ל ע כון טם 95ל וגי ח דשי 1 .jpg

Have you not considered that you may have to url-decode it to make it more safer and thereby reducing the length of the filename itself.