VS Setup Project; How to restore a registry value on uninstall?

Question

I have a setup project in Visual Studio. As part of the regular installation, it creates/updates some keys and values in the Windows Registry. How can I make the updates reversible?

you may say "they are reversible", but I don't think so. Here's how I think it works: USe the VS designer to specify which Registry Keys and Values you want. Those keys and values are written during install, and deleted during uninstall. Simple. What's not reversible?

The problem comes in when there's an existing value in one of the keys that is written during install. Suppose it has a value of 1. Then with the new install it gets a value of 100. After uninstall, it has no value at all - the value is gone.

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I tried to work around this with "custom actions".

During install, if the user confirms, msiexec writes the values into the the registry. Whatever was in the registry key before, is gone. (Let's call this "Update A")

To preserve that value, on install, there's a custom action that reads and preserves the "before" setting. It runs before "Update A". So far, so good.

On uninstall, the normal course of action, is to remove the regular registry keys and values that were added during install. This works just fine. Call this "Update B".

To restore the original registry values, I have another "custom action". This one runs on uninstall. It successfully restores the original values into the Registry. The registry looks just as it was before the original install. I verified that this works using ProcMon (A tool that lets me monitor registry updates, among other things). Call this "Update C".

There's only one problem. On uninstall, Update B is happening after Update C. This means, after the custom action restores the original registry setting, msi wipes out the restored Value, as it does with all the other registry updates.

The result is the registry has empty Values instead of the restored ones.

Any help? How can I re-order the updates? Do I need Orca for this? I really don't want to install and learn another tool to make this happen. I also want it to be automatic. Definitely don't want to have to visually click through an MSI editor to make this happen.

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Can I do this with a Javascript post-build event that uses the WindowsInstaller.Installer class? Aaron Stebner published a script that adds a "Launch application after install?" dialog to an MSI produced by Visual Studio. Windows Installer supports a "launch app" capability but it is not exposed in the designers for VS2008/2005. A quick biolerplate script, run as a post-build step in VS, added in the Launch dialog.

Is something similar possible with the ordering of custom actions?

Answer 1

Some answers for me:

• Yes, it's possible to do this with a postbuild step implemented in Javascript.
• yes, I'd use the WindowsInstaller.Installer class.
• yes, orca was necessary to figure it all out

Orca clearly shows the custom action that is intended to restore registry values runs before the built-in action that removes registry values.

So I have to write a script to change the 1698 to 2620, and the registry values should get restored properly.

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Edit: not so fast. The idea is right, but it's not as simple as changing the sequence number. The problem is, the "preserved" registry value is in the registry tree that gets deleted by the uninstaller. Therefore, neither order works. If A is the restore, and B is the delete, A-B will restore the registry only to have the restored value later deleted. B-A will delete the value first, and then A will have no value to restore. The reason is that A (the restore part) stores the to-be-restored value in the tree that is to be deleted.

So the correct operation has to be something like A-B-A, where A takes the stored value-to-be-restored, and puts it in a place that won't get deleted by B. Then B deletes the app-specific keys and values in the registry. The A restores the setting that was socked away by A`.

To make all this happen I had to do some surgery on the MSI file, because the vanilla MSI designer in Visual Studio doesn't allow for setting specific sequence numbers. You need to use Orca, which is a GUI tool, or, in my case I used the COM interface to the WindowsInstaller to automate the changes via javascript.