Tony Camilli

Senior Product Management and Technology Professional

Product Management

Innovation

Design Thinking

Business Model Development

UX & Design

Go-to-Market

Disabling WOW64 File System Redirection from C#

[Posted on my MSN Space on June 28, 2005]

A long time ago on a blog now gone (looks like erablog.net disappeared!) I wrote a post about interacting with WOW64 (Windows on Windows 64) from a 32-bit application. The example I posted was unmanaged C++. Yesterday, a coworker wanted to implement the same functionality in C#. I don't know of any managed interfaces to WOW64 (if you know of one let me know) so I used Interop and DllImport to call Wow64EnableWow64FsRedirection from Kernel32.dll. A nice feature of interop is that you can simply throw the function in a try-catch block so that if the application is run on an OS that doesn't support the API (32-bit Windows XP, for example), you can simply catch the exception and continue. In the unmanaged C++ world you have to use runtime dynamic linking.
Here's what it looks like from unmanaged C++:


typedef WINBASEAPI BOOLEAN WINAPI LPFN_ENABLEFSREDIRECTION(BOOLEAN);
...
LPFN_ENABLEFSREDIRECTION *fnEnableFSRedirection;
fnEnableFSRedirection = (LPFN_ENABLEFSREDIRECTION*) GetProcAddress(GetModuleHandle("kernel32"),"Wow64EnableWow64FsRedirection");

if(NULL != fnEnableFSRedirection)
{

if(fnEnableFSRedirection(bEnable))
{

cprintf(TEXT("Success disabling FS Redirection"));
}
}

else
{
cprintf(TEXT("Error disabling FS Redirection"));
}

Here's what it looks like in C#:


class Wow64Mgr
{
[STAThread]

static void Main(string[] args)
{

try
{
if(Wow64Interop.EnableWow64FSRedirection(false))
Console.WriteLine("WOW64 File System Redirection Disabled");

else
Console.WriteLine("Failure Disabling WOW64 File System Redirection");
}

catch (Exception exc)
{
Console.WriteLine("Failure Setting WOW64 File System Redirection.");
Console.WriteLine(exc.Message);
}

}
}
public class Wow64Interop
{
[DllImport("Kernel32.Dll", EntryPoint="Wow64EnableWow64FsRedirection")]

public static extern bool EnableWow64FSRedirection(bool enable);
}