How can I obtain the case-sensitive path on Windows?

Question

I need to know which is the real path of a given path.

For example:

The real path is: d:\\src\\File.txt
And the user give me: D:\\src\\file.txt
I nee

Answer 1

Here's an alternate solution, works on files and directories. Uses GetFinalPathNameByHandle, which is only supported for desktop apps on Vista/Server2008 or above according to docs.

Note that it will resolve a symlink if you give it one, which is part of finding the "final" path.

// http://www.pinvoke.net/default.aspx/shell32/GetFinalPathNameByHandle.html
[DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
static extern uint GetFinalPathNameByHandle(SafeFileHandle hFile, [MarshalAs(UnmanagedType.LPTStr)] StringBuilder lpszFilePath, uint cchFilePath, uint dwFlags);
private const uint FILE_NAME_NORMALIZED = 0x0;

static string GetFinalPathNameByHandle(SafeFileHandle fileHandle)
{
    StringBuilder outPath = new StringBuilder(1024);

    var size = GetFinalPathNameByHandle(fileHandle, outPath, (uint)outPath.Capacity, FILE_NAME_NORMALIZED);
    if (size == 0 || size > outPath.Capacity)
        throw new Win32Exception(Marshal.GetLastWin32Error());

    // may be prefixed with \\?\, which we don't want
    if (outPath[0] == '\\' && outPath[1] == '\\' && outPath[2] == '?' && outPath[3] == '\\')
        return outPath.ToString(4, outPath.Length - 4);

    return outPath.ToString();
}

// http://www.pinvoke.net/default.aspx/kernel32.createfile
[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
static extern SafeFileHandle CreateFile(
     [MarshalAs(UnmanagedType.LPTStr)] string filename,
     [MarshalAs(UnmanagedType.U4)] FileAccess access,
     [MarshalAs(UnmanagedType.U4)] FileShare share,
     IntPtr securityAttributes, // optional SECURITY_ATTRIBUTES struct or IntPtr.Zero
     [MarshalAs(UnmanagedType.U4)] FileMode creationDisposition,
     [MarshalAs(UnmanagedType.U4)] FileAttributes flagsAndAttributes,
     IntPtr templateFile);
private const uint FILE_FLAG_BACKUP_SEMANTICS = 0x02000000;

public static string GetFinalPathName(string dirtyPath)
{
    // use 0 for access so we can avoid error on our metadata-only query (see dwDesiredAccess docs on CreateFile)
    // use FILE_FLAG_BACKUP_SEMANTICS for attributes so we can operate on directories (see Directories in remarks section for CreateFile docs)

    using (var directoryHandle = CreateFile(
        dirtyPath, 0, FileShare.ReadWrite | FileShare.Delete, IntPtr.Zero, FileMode.Open,
        (FileAttributes)FILE_FLAG_BACKUP_SEMANTICS, IntPtr.Zero))
    {
        if (directoryHandle.IsInvalid)
            throw new Win32Exception(Marshal.GetLastWin32Error());

        return GetFinalPathNameByHandle(directoryHandle);
    }
}