Posts Tagged ‘uninstaller’

The pains of making an installer + uninstaller

I’ve been working on an installer/uninstaller for firesync 2. The installer is fairly straightforward, although it is quite a bit of work to set registry keys and make shortcuts, but overall it’s all fairly standard stuff. The one unique aspect of the firesync installer is that it is multi-part and actually consists of 2 executables. The first executable, the setup.exe file that will be distributed, is a native code binary + a zip archive. This program checks that the .NET Framework 2.0 is installed and extracts the zip archive to a folder in the user’s temporary directory. The zip archive contains the firesync executable and data files, but also contains another setup executable setupx.exe (a .NET executable). This executable is the real setup, as it shows/prompts the user for setup information (installation directory, whether or not to make a desktop icon, etc.), copies over the necessary files, makes program shortcuts, and writes registry entries so that firesync appears in the Add/Remove Programs list.

The reason for the multi-part installation is that it is much easier to design an interface using the WinForms designer in Visual C# compared to MFC, wxWidgets, etc. However, a .NET executable alone won’t suffice because users without the framework will just be given a cryptic error message (I think you get dialog about mscoree.dll not being found) and they’re not actually told that they need to install the framework.

(fyi, the native code executable is being done with wxDevC++)

Now making an uninstaller should be simple, your just deleting files and removing a couple of registry entries (in general, I avoid the registry and for firesync I’m only using it for the entry in Add/Remove Programs). Also, I think it’s rare that a user will uninstall the .NET Framework then try to uninstall firesync, so it’s pretty safe to make the uninstaller a .NET executable. However, there’s one big issue (and it’s a major pain in the ass) that pops up when it comes to making an uninstaller, how do you delete the uninstaller executable itself? I was lucky enough to stumble across this old Q&A from Microsoft Systems Journal. It’s a very inter… well to be honest it’s a very boring read (how interesting can deleting a file be?), but it’s important stuff. Ultimately, I went with the simplest method, and just used a batch file (although I haven’t played around with setting thread priorities as mentioned in the article; I’m not crazy about doing it and I’m not sure if it’s even worth it).

Finally, some important issues I ran across that was not mentioned in the article:

  • The directory your attempting to remove may be in use by the OS or another application. Another loop in the batch file should take care of this.
  • You can’t have the batch file in the directory your trying to delete (you’ll never be able to delete it as it’ll be in use by cmd.exe, you’ll have to manually kill cmd.exe to delete the folder and free the CPU). This is simple to solve, I just put the batch file in the user’s temp directory.