How to reference the registry in MSBuild4.0 (Visual Studio 2010) and later on a 64 bit OS

In the past I’ve written about using the Windows Registry to reference  assembly paths in Visual Studio. In it I made reference to the seminal article New Registry syntax in MSBuild v3.5, which is the dialect Visual Studio 2008 speaks. That syntax has served me well until recently.

See fate lead me to writing a small C++/CLI program. In it I had to refer to some .NET assemblies that were not installed in the GAC. They were however installed as part of a software package that wrote its install path to the registry. So I figured out which value it wrote the install directory to and referenced it in the .vcxproj file using the $(Registry:HKEY_LOCAL_MACHINE\Software\Company\Product@TargetDir). Unfortunately, it didn’t work!

I did some troubleshooting and discovered it worked when I build the vcxproj from the command line with msbuild.exe. It seemed logical to blame it one the fact that I was using C++. Devenv.exe (the Visual Studio executable) must have been treating .vcxproj files differently than csproj and vbproj files. Then suddenly it dawned it me, the problem was I was running on a 64 bit version of Windows! This was a relief, because it meant that .vcxproj were not special or subject to unique bugs.

To make a long story short, Visual Studio is a 32 bit application, and by default when a 32 bit process interacts with the registry on a 64 bit version of Windows, HKEY_LOCAL_MACHINE\Software gets redirected to HKEY_LOCAL_MACHINE\Software\Wow6432Node. This MSDN article explains the gory details.

At first it seemed the only workaround was a custom MSBuild task line the MSBuild Extension Pack. I complained on twitter to Scott Hanselman (blog|twitter).  He replied with this article talking about how the page faults, addressable memory space, etc was not an issue. That article made some good points. However, it didn’t address my (at the time) very real and legitimate concern. Scott said he’d ask around internally if I filed a connect bug and got David Kean (blog|twitter) involved in the conversation.  I filed a connect bug. Then David pointed out a link to the MSBuild 4.0 key GetRegistryValueFromView.

Here is a comparison of the old and new syntax using msbuild <Message/> msbuild tasks, the printf() of msbuild.

<Target Name="BeforeBuild">
	<!-- Read the registry using the native MSBUILD 3.5 method: http://blogs.msdn.com/b/msbuild/archive/2007/05/04/new-registry-syntax-in-msbuild-v3-5.aspx -->
	<PropertyGroup>
		<MsBuildNativeProductId>$(Registry:HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion@ProductId)</MsBuildNativeProductId>
		<MsBuildNativeProductName>$(Registry:HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion@ProductName)</MsBuildNativeProductName>
		<MsBuild4NativeProductId>$([MSBuild]::GetRegistryValueFromView('HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion', 'ProductId', null, RegistryView.Registry64))</MsBuild4NativeProductId>
		<MsBuild4NativeProductName>$([MSBuild]::GetRegistryValueFromView('HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion', 'ProductName', null, RegistryView.Registry64))</MsBuild4NativeProductName>
	</PropertyGroup>
	<!-- Lets use the MSBuild Extension Pack (still no joy) http://www.msbuildextensionpack.com/help/4.0.5.0/html/9c8ecf24-3d8d-2b2d-e986-3e026dda95fe.htm -->
	<MSBuild.ExtensionPack.Computer.Registry TaskAction="Get" RegistryHive="LocalMachine" Key="SOFTWARE\Microsoft\Windows NT\CurrentVersion" Value="ProductId">
		<Output PropertyName="MsBuildExtProductId" TaskParameter="Data" />
	</MSBuild.ExtensionPack.Computer.Registry>
	<MSBuild.ExtensionPack.Computer.Registry TaskAction="Get" RegistryHive="LocalMachine" Key="SOFTWARE\Microsoft\Windows NT\CurrentVersion" Value="ProductName">
		<Output PropertyName="MsBuildExtProductName" TaskParameter="Data" />
	</MSBuild.ExtensionPack.Computer.Registry>
	<!-- And now RegistryView: http://msdn.microsoft.com/en-us/library/microsoft.win32.registryview.aspx -->
	<MSBuild.ExtensionPack.Computer.Registry TaskAction="Get" RegistryHive="LocalMachine" Key="SOFTWARE\Microsoft\Windows NT\CurrentVersion" Value="ProductId" RegistryView="Registry64">
		<Output PropertyName="MsBuildExt64ProductId" TaskParameter="Data" />
	</MSBuild.ExtensionPack.Computer.Registry>
	<MSBuild.ExtensionPack.Computer.Registry TaskAction="Get" RegistryHive="LocalMachine" Key="SOFTWARE\Microsoft\Windows NT\CurrentVersion" Value="ProductName" RegistryView="Registry64">
		<Output PropertyName="MsBuildExt64ProductName" TaskParameter="Data" />
	</MSBuild.ExtensionPack.Computer.Registry>
	<!-- All messages are of high importance so Visual Studio will display them by default. See: http://stackoverflow.com/questions/7557562/how-do-i-get-the-message-msbuild-task-that-shows-up-in-the-visual-studio-proje -->
	<Message Importance="High" Text="Using Msbuild Native: ProductId: $(MsBuildNativeProductId) ProductName: $(MsBuildNativeProductName)" />
	<Message Importance="High" Text="Using Msbuild v4  Native: ProductId: $(MsBuild4NativeProductId) ProductName: $(MsBuild4NativeProductName)" />
	<Message Importance="High" Text="Using Msbuild Extension Pack: ProductId: $(MsBuildExtProductId) ProductName: $(MsBuildExtProductName)" />
	<Message Importance="High" Text="Using Msbuild Extension Pack: ProductId: $(MsBuildExt64ProductId) ProductName: $(MsBuildExt64ProductName)" />
</Target>

That MSBuild code has been tested via this github project on two machines running Visual Studio 2010 SP1. One has Windows XP3 32 bit and the other runs Windows 8 64 bit. I’ve verified that $([MSBuild]::GetRegistryValueFromView('HKEY_LOCAL_MACHINE\SOFTWARE\whatever', 'value', null, RegistryView.Registry64)) will give you the same value as you see in regedit.exe

Yes MSBuild 4.0, and therefore Visual Studio 2010 solved this problem and I simply didn’t google hard enough for the answer. However, I googled pretty hard, and I’m pretty good at googling. I didn’t think I was particularly rash in “pulling the Hanselman card.” The best I can do is write this blog post, comment on other blogs and answer questions on StackOverflow to fill the internet with references to the MSBuild syntax.