How can I find the upgrade code for an installed application in C#?

c#, registry, windows-installer, wix

Solution

I have discovered the upgrade codes are stored in the following registry location.

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UpgradeCodes

The registry key name is the upgrade code and the registry key value name is the product code. I can easily extract these values however the codes are stored in a different format. The red circle shows the formatted upgrade code, the blue circle shows the formatted product code when viewing it in `regedit.exe`.

The hyphens are stripped out of the `Guid` and then a series of string reversals are done. The first 8 characters are reversed, then the next 4, then the following 4 and then the rest of the string is reversed in sets of 2 characters. Normally when reversing a string we need to take care in making sure control and special characters are handled correctly (see Jon Skeet's aricle here) but as we are, in this case, dealing with a `Guid` string we can be confident the string will be reversed correctly.

Below is the complete code I used to extract the upgrade code for a known product code from the registry.

internal static class RegistryHelper
{
    private const string UpgradeCodeRegistryKey = @"SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UpgradeCodes";

    private static readonly int[] GuidRegistryFormatPattern = new[] { 8, 4, 4, 2, 2, 2, 2, 2, 2, 2, 2 };

    public static Guid? GetUpgradeCode(Guid productCode)
    {
        // Convert the product code to the format found in the registry
        var productCodeSearchString = ConvertToRegistryFormat(productCode);

        // Open the upgrade code registry key
        var localMachine = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry64);
        var upgradeCodeRegistryRoot = localMachine.OpenSubKey(UpgradeCodeRegistryKey);

        if (upgradeCodeRegistryRoot == null)
            return null;

        // Iterate over each sub-key
        foreach (var subKeyName in upgradeCodeRegistryRoot.GetSubKeyNames())
        {
            var subkey = upgradeCodeRegistryRoot.OpenSubKey(subKeyName);

            if (subkey == null)
                continue;

            // Check for a value containing the product code
            if (subkey.GetValueNames().Any(s => s.IndexOf(productCodeSearchString, StringComparison.OrdinalIgnoreCase) >= 0))
            {
                // Extract the name of the subkey from the qualified name
                var formattedUpgradeCode = subkey.Name.Split('\\').LastOrDefault();

                // Convert it back to a Guid
                return ConvertFromRegistryFormat(formattedUpgradeCode);
            }
        }

        return null;
    }

    private static string ConvertToRegistryFormat(Guid productCode)
    {
        return Reverse(productCode, GuidRegistryFormatPattern);
    }

    private static Guid ConvertFromRegistryFormat(string upgradeCode)
    {
        if (upgradeCode == null || upgradeCode.Length != 32)
            throw new FormatException("Product code was in an invalid format");

        upgradeCode = Reverse(upgradeCode, GuidRegistryFormatPattern);

        return Guid.Parse(upgradeCode);
    }

    private static string Reverse(object value, params int[] pattern)
    {
        // Strip the hyphens
        var inputString = value.ToString().Replace("-", "");

        var returnString = new StringBuilder();

        var index = 0;

        // Iterate over the reversal pattern
        foreach (var length in pattern)
        {
            // Reverse the sub-string and append it
            returnString.Append(inputString.Substring(index, length).Reverse().ToArray());

            // Increment our posistion in the string
            index += length;
        }

        return returnString.ToString();
    }
}

Problem

Original source

Related problems

• How can I find the Upgrade Code for an installed MSI file?
• How to find the UpgradeCode and ProductCode of an installed application in Windows 7