Quiet & Unattended Mode

private bool TestUninstallerForStalls(IEnumerable<string> childProcesses)
{
    // Create performance counters for CPU and I/O
    foreach (var childProcessName in childProcessNames)
    {
        var perfCounters = new[]
        {
            new PerformanceCounter("Process", "% Processor Time", childProcessName),
            new PerformanceCounter("Process", "IO Data Bytes/sec", childProcessName)
        };
        _perfCounterBuffer.Add(childProcessName, new PerfCounterEntry(perfCounters));
    }

    // Wait to gather data
    Thread.Sleep(1100);

    // Check if any process is active
    foreach (var perfCounterEntry in _perfCounterBuffer)
    {
        var cpuUsage = CalculateCpuUsage(perfCounterEntry);
        var ioUsage = CalculateIoUsage(perfCounterEntry);

        // Check if process seems to be doing anything
        // Use 1% for CPU and 10KB for I/O
        if (cpuUsage <= 1 && ioUsage <= 10240)
        {
            return true; // Process is stalled
        }
    }
    
    return false;
}

if (error != null)
{
    if (options.RetryFailedQuiet || 
        (UninstallerEntry.UninstallerKind == UninstallerType.Nsis && 
         !options.PreferQuiet))
    {
        retry = true;
        throw new IOException(
            Localisation.UninstallError_UninstallerReturnedCode + exitVar);
    }
}

if (retry && _canRetry)
{
    CurrentStatus = UninstallStatus.Waiting;
    _canRetry = false;  // Only retry once
}
else
{
    Finished = true;
}

var exitVar = uninstaller.ExitCode;
if (exitVar != 0)
{
    if (UninstallerEntry.UninstallerKind == UninstallerType.Msiexec &&
        exitVar == 1602)
    {
        // 1602 ERROR_INSTALL_USEREXIT - User cancelled
        _skipLevel = SkipCurrentLevel.Skip;
    }
    else if (UninstallerEntry.UninstallerKind == UninstallerType.Nsis &&
             (exitVar == 1 || exitVar == 2))
    {
        // 1 - Installation aborted by user
        // 2 - Installation aborted by script
        _skipLevel = SkipCurrentLevel.Skip;
    }
    else if (exitVar == -1073741510)
    {
        // 0xC000013A - Terminated by CTRL+C
        _skipLevel = SkipCurrentLevel.Terminate;
    }
    else
    {
        switch (exitVar)
        {
            case 2:
                throw new Exception("The system cannot find the file specified.");
            case 3:
                throw new Exception("The system cannot find the path specified.");
            case 5:
                throw new Exception("Access is denied.");
            case 9009:
                throw new Exception("Program is not recognized as an internal or external command.");
            default:
                if (options.RetryFailedQuiet)
                    retry = true;
                throw new IOException(
                    Localisation.UninstallError_UninstallerReturnedCode + exitVar);
        }
    }
}

var watchedProcesses = new List<Process> { uninstaller };
int[] previousWatchedProcessIds = { };

while (true)
{
    // Add all child processes
    foreach (var watchedProcess in watchedProcesses.ToList())
        watchedProcesses.AddRange(watchedProcess.GetChildProcesses());

    // For MSI, also track msiexec
    if (UninstallerEntry.UninstallerKind == UninstallerType.Msiexec)
    {
        foreach (var msiProcess in Process.GetProcessesByName("msiexec"))
            watchedProcesses.AddRange(msiProcess.GetChildProcesses());
    }

    watchedProcesses = CleanupDeadProcesses(watchedProcesses).ToList();

    // Check if we are done
    if (watchedProcesses.Count == 0)
        break;
        
    // Continue monitoring...
}