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c#pinvokekernel32

C# PInvoke I can't open the volume with CreateFile

I have to open the volume with CreateFile from PInvoke:

[DllImport("kernel32.dll", SetLastError = true)]
static extern SafeFileHandle CreateFile(string lpFileName, uint dwDesiredAccess, FileShare dwShareMode, IntPtr securityAttrs, FileMode dwCreationDisposition, FileOptions dwFlagsAndAttributes, IntPtr hTemplateFile);

But when I use it:

var fileName = @"C:\Users\myuser\Desktop\file.txt"
var root = Path.GetPathRoot(fileName);
var volumePath = @"\\.\" + root.Substring(0, root.Length - 1);

var volume = CreateFile(volumePath, GENERIC_READ, FileShare.Read, IntPtr.Zero, FileMode.Open, FileOptions.None, IntPtr.Zero);
if (volume.IsInvalid)
    throw new Win32Exception(Marshal.GetLastWin32Error());

It prints:

Access is denied

However, if I open it with elevated privileges, it prints:

The process cannot access the file because it is being used by another process

I've been trying everything, even picking up code from a lot of places but I can't make it work.

Solution

  • Using the PInvoke code taken from here:

    var volume = CreateFile(volumePath, EFileAccess.GenericRead, EFileShare.Read|EFileShare.Write, IntPtr.Zero, ECreationDisposition.OpenExisting, 0, IntPtr.Zero);

    I have managed to get it working.