Chessar.LongPaths 1.0.0-rc005

Chessar.LongPaths is a .NET library that allows you to enable long path support for the main System.IO classes:

FileStream, File, FileInfo, Directory, DirectoryInfo, ... (and others).

The library is based on replacing the internal NormalizePath and GetFullPathInternal functions from the static Path class. The replacement is done using JMP hooks (thanks to @wledfor2), in which the long path prefix \\?\ or \\?\UNC\ is added. Adding a prefix is done by calling the internal function Path.AddLongPathPrefix. Note also that the addition of such prefixes depends on the UseLegacyPathHandling and BlockLongPaths settings, which must necessarily be false (in the AppContextSwitchOverrides element).

In this case, your code does not need to directly add such prefixes to the paths.

Supported Platforms:

• .NET Framework 4.6.2+ (see .NET Blog)

How to use

1. Add the Chessar.LongPaths NuGet package to the project.
2. In the file app.config (or web.config), in the section runtime, add:

<configuration>
...
  <runtime>
    <AppContextSwitchOverrides value="Switch.System.IO.UseLegacyPathHandling=false;Switch.System.IO.BlockLongPaths=false" />
  </runtime>
...

3. In the code (when you start the application or at the beginning of Main) add code:

...
using static Chessar.Hooks;
...

    PatchLongPaths();

4. Usage

...
var fileInfo = new FileInfo(path);
var fullName = fileInfo.FullName; // with long path prefix
...

5. At the end of the application:

    RemoveLongPathsPatch();

See also Examples.

Notes

For the following list of ctors/methods, you must directly specify the prefix of long paths (because they are not supported by this library, see Unit Tests):

• new DirectorySecurity(String, AccessControlSections)
• new FileSecurity(String, AccessControlSections)
• Directory.GetAccessControl(String[, AccessControlSections])
• File.GetAccessControl(String[, AccessControlSections])
• Directory.Move(String, String)
• DirectoryInfo.MoveTo(String)

for example:

...
using static Chessar.Hooks;
...
    var ds = new DirectorySecurity(path.AddLongPathPrefix(), acs);

or use DirectoryInfo instead Directory (exclude MoveTo method) and FileInfo instead File.

Note that, next methods does not work for long paths, even if a prefix is added:

• Directory.SetCurrentDirectory
• Image.Save(String) (use Image.Save to Stream instead)

TODO

1. Speed up MethodInfo.Invoke in the class Hooks, using, for example, DynamicMethod.CreateDelegate.
2. Add long path support in ctors/methods from Notes.
3. Add more unit tests.
4. Make hooks more thread safe.

License

MIT - See LICENSE