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c#.netwindowsregistrywow64

Reading 64bit Registry from a 32bit application

I have a c# unit test project that is compiled for AnyCPU. Our build server is a 64bit machine, and has a 64bit SQL Express instance installed.

The test project uses code similar to the following to identify the path to the .MDF files:

private string GetExpressPath()
{
    RegistryKey sqlServerKey = Registry.LocalMachine.OpenSubKey( @"SOFTWARE\Microsoft\Microsoft SQL Server\Instance Names\SQL" );
    string sqlExpressKeyName = (string) sqlServerKey.GetValue( "SQLEXPRESS" );
    RegistryKey sqlInstanceSetupKey = sqlServerKey.OpenSubKey( sqlExpressKeyName + @"\Setup" );
    return sqlInstanceSetupKey.GetValue( "SQLDataRoot" ).ToString();
}

This code works fine on our 32bit workstations, and did work ok on the build server until I recently enabled code coverage analysis with NCover. Because NCover uses a 32bit COM component, the test runner (Gallio) runs as a 32bit process.

Checking the registry, there is no "Instance Names" key under

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Microsoft SQL Server

Is there a way for an application running in 32bit mode to access the registry outside Wow6432Node?

Solution

  • you have to use the KEY_WOW64_64KEY param when creating/opening the registry key. But AFAIK that's not possible with the Registry class but only when using the API directly.

    This might help to get you started.