C# | Check if app is installed for “All users” or "Just me"

Today I bring a very HARD-to-find topic about getting an installed application "Installation context".
An installation context may be Per-Machine Installation Context (ALLUSERS=1) and Per-User Installation Context (ALLUSERS="").

When installing an application, the user may select one of two options:
a. Install [APP] for yourself
b. or for anyone who uses this computer
[a] installs only for the current user(just me) while [b] installs for the Local System user which is for all-users(everyone).

In this post I will give a code for checking is an installed application was installed for "Everyone" or "Just me".

The validation process is check if the APPLICATION-NAME exists in the registry keys under UserData.
(*) Everyone - check under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\S-1-5-18\Products\ (S-1-5-18 represents the Local System user)

(*) Just me (Current user) - check under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\S-?!?!?!?!\Products\ (S-?!?!?!?! represents the Current user. this value found by the code: WindowsIdentity.GetCurrent().User.Value.


[Code] Method's return type:

private enum InstallationContexts { NotInstalled, Everyone, JustMe };

[Code] Method declaration:

private InstallationContexts GetInstalledContext(string p_appDisplayName)
{
    //The S-1-5-18  =
Local System user (Everyone) | HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\S-1-5-18\Products\

    //The S-XXXXXX  =
Current user (Just me)       |
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\S-?!?!?!?!\Products\

    string key;
    string keyFormat = @"SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\{0}\Products\";
 
    // Check if installed for -> Everyone
    key = string.Format(keyFormat, "S-1-5-18");
    bool res = GetInstalledContext_IsRegKeyExists(key, p_appDisplayName, StringComparison.OrdinalIgnoreCase);
    if (res == true)
    {
        return InstallationContexts.Everyone;
    }
 
    // Check if installed for -> Just me
    key = string.Format(keyFormat, WindowsIdentity.GetCurrent().User.Value);
    res = GetInstalledContext_IsRegKeyExists(key, p_appDisplayName, StringComparison.OrdinalIgnoreCase);
    if (res == true)
    {
        return InstallationContexts.JustMe;
    }
 
    return InstallationContexts.NotInstalled;
}
private bool GetInstalledContext_IsRegKeyExists(string p_regKey, string p_appDisplayName, StringComparison p_scompare)
{
    using (RegistryKey regkey = Registry.LocalMachine.OpenSubKey(p_regKey))
    {
        if (regkey != null)
        {
            RegistryKey rk;
            string[] arrProducs = regkey.GetSubKeyNames();
            for (int i = 0; i < arrProducs.Length; i++)
            {
               using (rk = regkey.OpenSubKey(arrProducs[i] + @"\InstallProperties"))
               {
if (rk != null &&
                        p_appDisplayName.Equals(rk.GetValue("DisplayName").ToString(), p_scompare) == true)
                   {
                        return true;
                   }
               }
            }
        }
    }
 
    return false;
}

[Code] Method's usage example:

InstallationContexts appContext = GetInstalledContext("APP-DISPLAY-NAME");

This code gives the ability to detect previously installed application or previously installed software is installed to ALLUSERS (everyone) or only to CURRENT USER (just me).



Addition on 19.12.2010:
(*) This checking operation is valid ONLY for an application and software which were installed using Microsoft's Windows Installer.
For general checking for installed application, check my post about check if program/application is installed.


Enjoy...
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