Environment: C#, Framework 1.1, WinXP SP2

Okay, first off I admit I don't really know what I'm doing here.

I find that I must dip into the Windows API because MS, in its infinite wisdom, "bound" the File and
FileInfo objects in the Framework to the "short path" version of the file API functions (i.e., if
you use a path over MAX_PATH in a call to File object methods or in creating a FileInfo object
you'll get a PathTooLong exception).

Unfortunately, I must deal with some file names that are longer than MAX_PATH in my application. The
file names are specified via UNC.

I tried reading up on how to invoke GetFileAttributesEx, but I must be doing something wrong. Here's
some pseudocode that fails:

[StructLayout(LayoutKind.Sequential)]
public struct WIN32_FILE_ATTRIBUTE_DATA
{
    public uint fileAttributes;
    public FILETIME creationTime;
    public FILETIME lastAccessTime;
    public FILETIME lastWriteTime;
    public uint fileSizeHigh;
    public uint fileSizeLow;
}

[DllImport("kernel32.dll", CharSet=CharSet.Auto)]
public static extern bool GetFileAttributesEx(string path, int level, out WIN32_FILE_ATTRIBUTE_DATA
dat );

private void Junk( string fileName )
{
    WIN32_FILE_ATTRIBUTE_DATA atx;

    // the following call always fails...but it generally succeeds if the "override"
    // preamble (the \\?\UNC\) is left off
    bool ok = GetFileAttributesExW( @"\\?\UNC\" + fileName, 0, out atx );
}

I tried changing CharSet to Unicode, marshaling the path variable as:

[MarshalAs(UnmanagedType.LPWStr)]

and changing the extern function reference to GetFileAttributesExW

None of this worked.

So... what do I do to make this work?

- Mark