SEBWIN-220: Re-integrated kiosk mode "Disable Explorer Shell".

SafeExamBrowser.Client.UnitTests/Behaviour/Operations/ProcessMonitorOperationTests.cs

@@ -9,6 +9,7 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Moq;
 using SafeExamBrowser.Client.Behaviour.Operations;
+using SafeExamBrowser.Contracts.Configuration.Settings;
 using SafeExamBrowser.Contracts.Logging;
 using SafeExamBrowser.Contracts.Monitoring;
 
@@ -17,46 +18,57 @@ namespace SafeExamBrowser.Client.UnitTests.Behaviour.Operations
 	[TestClass]
 	public class ProcessMonitorOperationTests
 	{
-		private Mock<ILogger> loggerMock;
+		private Mock<ILogger> logger;
-		private Mock<IProcessMonitor> processMonitorMock;
+		private Mock<IProcessMonitor> processMonitor;
-
+		private Settings settings;
 		private ProcessMonitorOperation sut;
 
 		[TestInitialize]
 		public void Initialize()
 		{
-			loggerMock = new Mock<ILogger>();
+			logger = new Mock<ILogger>();
-			processMonitorMock = new Mock<IProcessMonitor>();
+			processMonitor = new Mock<IProcessMonitor>();
+			settings = new Settings();
 
-			sut = new ProcessMonitorOperation(loggerMock.Object, processMonitorMock.Object);
+			sut = new ProcessMonitorOperation(logger.Object, processMonitor.Object,settings);
 		}
 
 		[TestMethod]
-		public void MustPerformCorrectly()
+		public void MustObserveExplorerWithDisableExplorerShell()
 		{
-			var order = 0;
+			var counter = 0;
+			var start = 0;
+			var stop = 0;
 
-			processMonitorMock.Setup(p => p.CloseExplorerShell()).Callback(() => Assert.AreEqual(++order, 1));
+			settings.KioskMode = KioskMode.DisableExplorerShell;
-			processMonitorMock.Setup(p => p.StartMonitoringExplorer()).Callback(() => Assert.AreEqual(++order, 2));
+			processMonitor.Setup(p => p.StartMonitoringExplorer()).Callback(() => start = ++counter);
+			processMonitor.Setup(p => p.StopMonitoringExplorer()).Callback(() => stop = ++counter);
 
 			sut.Perform();
+			sut.Revert();
 
-			processMonitorMock.Verify(p => p.CloseExplorerShell(), Times.Once);
+			processMonitor.Verify(p => p.StartMonitoringExplorer(), Times.Once);
-			processMonitorMock.Verify(p => p.StartMonitoringExplorer(), Times.Once);
+			processMonitor.Verify(p => p.StopMonitoringExplorer(), Times.Once);
+
+			Assert.AreEqual(1, start);
+			Assert.AreEqual(2, stop);
 		}
 
 		[TestMethod]
-		public void MustRevertCorrectly()
+		public void MustNotObserveExplorerWithOtherKioskModes()
 		{
-			var order = 0;
+			settings.KioskMode = KioskMode.CreateNewDesktop;
-
-			processMonitorMock.Setup(p => p.StopMonitoringExplorer()).Callback(() => Assert.AreEqual(++order, 1));
-			processMonitorMock.Setup(p => p.StartExplorerShell()).Callback(() => Assert.AreEqual(++order, 2));
 
+			sut.Perform();
 			sut.Revert();
 
-			processMonitorMock.Verify(p => p.StopMonitoringExplorer(), Times.Once);
+			settings.KioskMode = KioskMode.None;
-			processMonitorMock.Verify(p => p.StartExplorerShell(), Times.Once);
+
+			sut.Perform();
+			sut.Revert();
+
+			processMonitor.Verify(p => p.StartMonitoringExplorer(), Times.Never);
+			processMonitor.Verify(p => p.StopMonitoringExplorer(), Times.Never);
 		}
 	}
 }

SafeExamBrowser.Client/Behaviour/ClientController.cs

@@ -25,12 +25,14 @@ using SafeExamBrowser.Contracts.UserInterface;
 using SafeExamBrowser.Contracts.UserInterface.MessageBox;
 using SafeExamBrowser.Contracts.UserInterface.Taskbar;
 using SafeExamBrowser.Contracts.UserInterface.Windows;
+using SafeExamBrowser.Contracts.WindowsApi;
 
 namespace SafeExamBrowser.Client.Behaviour
 {
 	internal class ClientController : IClientController
 	{
 		private IDisplayMonitor displayMonitor;
+		private IExplorerShell explorerShell;
 		private ILogger logger;
 		private IMessageBox messageBox;
 		private IOperationSequence operations;
@@ -64,6 +66,7 @@ namespace SafeExamBrowser.Client.Behaviour
 
 		public ClientController(
 			IDisplayMonitor displayMonitor,
+			IExplorerShell explorerShell,
 			ILogger logger,
 			IMessageBox messageBox,
 			IOperationSequence operations,
@@ -76,6 +79,7 @@ namespace SafeExamBrowser.Client.Behaviour
 			IWindowMonitor windowMonitor)
 		{
 			this.displayMonitor = displayMonitor;
+			this.explorerShell = explorerShell;
 			this.logger = logger;
 			this.messageBox = messageBox;
 			this.operations = operations;
@@ -188,8 +192,8 @@ namespace SafeExamBrowser.Client.Behaviour
 
 		private void ProcessMonitor_ExplorerStarted()
 		{
-			logger.Info("Trying to shut down explorer...");
+			logger.Info("Trying to terminate Windows explorer...");
-			processMonitor.CloseExplorerShell();
+			explorerShell.Terminate();
 			logger.Info("Reinitializing working area...");
 			displayMonitor.InitializePrimaryDisplay(taskbar.GetAbsoluteHeight());
 			logger.Info("Reinitializing taskbar bounds...");

SafeExamBrowser.Client/Behaviour/Operations/ProcessMonitorOperation.cs

@@ -7,6 +7,7 @@
  */
 
 using SafeExamBrowser.Contracts.Behaviour.OperationModel;
+using SafeExamBrowser.Contracts.Configuration.Settings;
 using SafeExamBrowser.Contracts.I18n;
 using SafeExamBrowser.Contracts.Logging;
 using SafeExamBrowser.Contracts.Monitoring;
@@ -18,26 +19,26 @@ namespace SafeExamBrowser.Client.Behaviour.Operations
 	{
 		private ILogger logger;
 		private IProcessMonitor processMonitor;
+		private Settings settings;
 
 		public IProgressIndicator ProgressIndicator { private get; set; }
 
-		public ProcessMonitorOperation(ILogger logger, IProcessMonitor processMonitor)
+		public ProcessMonitorOperation(ILogger logger, IProcessMonitor processMonitor, Settings settings)
 		{
 			this.logger = logger;
 			this.processMonitor = processMonitor;
+			this.settings = settings;
 		}
 
 		public OperationResult Perform()
 		{
 			logger.Info("Initializing process monitoring...");
-			ProgressIndicator?.UpdateText(TextKey.ProgressIndicator_WaitExplorerTermination, true);
-
-			processMonitor.CloseExplorerShell();
-			processMonitor.StartMonitoringExplorer();
-
 			ProgressIndicator?.UpdateText(TextKey.ProgressIndicator_InitializeProcessMonitoring);
 
-			// TODO: Implement process monitoring...
+			if (settings.KioskMode == KioskMode.DisableExplorerShell)
+			{
+				processMonitor.StartMonitoringExplorer();
+			}
 
 			return OperationResult.Success;
 		}
@@ -52,12 +53,10 @@ namespace SafeExamBrowser.Client.Behaviour.Operations
 			logger.Info("Stopping process monitoring...");
 			ProgressIndicator?.UpdateText(TextKey.ProgressIndicator_StopProcessMonitoring);
 
-			// TODO: Implement process monitoring...
+			if (settings.KioskMode == KioskMode.DisableExplorerShell)
-
+			{
-			ProgressIndicator?.UpdateText(TextKey.ProgressIndicator_WaitExplorerStartup, true);
+				processMonitor.StopMonitoringExplorer();
-
+			}
-			processMonitor.StopMonitoringExplorer();
-			processMonitor.StartExplorerShell();
 		}
 	}
 }

SafeExamBrowser.Client/CompositionRoot.cs

@@ -23,6 +23,7 @@ using SafeExamBrowser.Contracts.Communication.Proxies;
 using SafeExamBrowser.Contracts.Configuration;
 using SafeExamBrowser.Contracts.I18n;
 using SafeExamBrowser.Contracts.Logging;
+using SafeExamBrowser.Contracts.Monitoring;
 using SafeExamBrowser.Contracts.UserInterface;
 using SafeExamBrowser.Contracts.UserInterface.MessageBox;
 using SafeExamBrowser.Contracts.WindowsApi;
@@ -53,6 +54,7 @@ namespace SafeExamBrowser.Client
 		private IClientHost clientHost;
 		private ILogger logger;
 		private IMessageBox messageBox;
+		private IProcessMonitor processMonitor;
 		private INativeMethods nativeMethods;
 		private IRuntimeProxy runtimeProxy;
 		private ISystemInfo systemInfo;
@@ -75,11 +77,12 @@ namespace SafeExamBrowser.Client
 
 			text = new Text(logger);
 			messageBox = new MessageBox(text);
+			processMonitor = new ProcessMonitor(new ModuleLogger(logger, typeof(ProcessMonitor)), nativeMethods);
 			uiFactory = new UserInterfaceFactory(text);
 			runtimeProxy = new RuntimeProxy(runtimeHostUri, new ProxyObjectFactory(), new ModuleLogger(logger, typeof(RuntimeProxy)));
 
 			var displayMonitor = new DisplayMonitor(new ModuleLogger(logger, typeof(DisplayMonitor)), nativeMethods);
-			var processMonitor = new ProcessMonitor(new ModuleLogger(logger, typeof(ProcessMonitor)), nativeMethods);
+			var explorerShell = new ExplorerShell(new ModuleLogger(logger, typeof(ExplorerShell)), nativeMethods);
 			var windowMonitor = new WindowMonitor(new ModuleLogger(logger, typeof(WindowMonitor)), nativeMethods);
 
 			Taskbar = new Taskbar(new ModuleLogger(logger, typeof(Taskbar)));
@@ -94,7 +97,7 @@ namespace SafeExamBrowser.Client
 			// TODO
 			//operations.Enqueue(new DelayedInitializationOperation(BuildKeyboardInterceptorOperation));
 			//operations.Enqueue(new WindowMonitorOperation(logger, windowMonitor));
-			//operations.Enqueue(new ProcessMonitorOperation(logger, processMonitor));
+			operations.Enqueue(new DelayedInitializationOperation(BuildProcessMonitorOperation));
 			operations.Enqueue(new DisplayMonitorOperation(displayMonitor, logger, Taskbar));
 			operations.Enqueue(new DelayedInitializationOperation(BuildTaskbarOperation));
 			operations.Enqueue(new DelayedInitializationOperation(BuildBrowserOperation));
@@ -104,7 +107,7 @@ namespace SafeExamBrowser.Client
 
 			var sequence = new OperationSequence(logger, operations);
 
-			ClientController = new ClientController(displayMonitor, logger, messageBox, sequence, processMonitor, runtimeProxy, shutdown, Taskbar, text, uiFactory, windowMonitor);
+			ClientController = new ClientController(displayMonitor, explorerShell, logger, messageBox, sequence, processMonitor, runtimeProxy, shutdown, Taskbar, text, uiFactory, windowMonitor);
 		}
 
 		internal void LogStartupInformation()
@@ -191,6 +194,11 @@ namespace SafeExamBrowser.Client
 			return operation;
 		}
 
+		private IOperation BuildProcessMonitorOperation()
+		{
+			return new ProcessMonitorOperation(logger, processMonitor, configuration.Settings);
+		}
+
 		private IOperation BuildTaskbarOperation()
 		{
 			var keyboardLayout = new KeyboardLayout(new ModuleLogger(logger, typeof(KeyboardLayout)), text);

SafeExamBrowser.Configuration/ConfigurationRepository.cs

@@ -81,7 +81,7 @@ namespace SafeExamBrowser.Configuration
 
 			CurrentSettings = new Settings();
 
-			CurrentSettings.KioskMode = KioskMode.CreateNewDesktop;
+			CurrentSettings.KioskMode = KioskMode.DisableExplorerShell;
 			CurrentSettings.ServicePolicy = ServicePolicy.Optional;
 
 			CurrentSettings.Browser.StartUrl = "https://www.safeexambrowser.org/testing";

SafeExamBrowser.Contracts/Monitoring/IProcessMonitor.cs

@@ -26,16 +26,6 @@ namespace SafeExamBrowser.Contracts.Monitoring
 		/// </summary>
 		bool BelongsToAllowedProcess(IntPtr window);
 
-		/// <summary>
-		/// Terminates the Windows explorer shell, i.e. the taskbar.
-		/// </summary>
-		void CloseExplorerShell();
-
-		/// <summary>
-		/// Starts a new instance of the Windows explorer shell.
-		/// </summary>
-		void StartExplorerShell();
-
 		/// <summary>
 		/// Starts monitoring the Windows explorer, i.e. any newly created instances of <c>explorer.exe</c> will trigger the
 		/// <see cref="ExplorerStarted"/> event.

SafeExamBrowser.Contracts/SafeExamBrowser.Contracts.csproj

@@ -182,6 +182,7 @@
     <Compile Include="WindowsApi\IBounds.cs" />
     <Compile Include="WindowsApi\IDesktop.cs" />
     <Compile Include="WindowsApi\IDesktopFactory.cs" />
+    <Compile Include="WindowsApi\IExplorerShell.cs" />
     <Compile Include="WindowsApi\INativeMethods.cs" />
     <Compile Include="WindowsApi\IProcess.cs" />
     <Compile Include="WindowsApi\IProcessFactory.cs" />

SafeExamBrowser.Contracts/WindowsApi/IExplorerShell.cs

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2018 ETH Zürich, Educational Development and Technology (LET)
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+namespace SafeExamBrowser.Contracts.WindowsApi
+{
+	public interface IExplorerShell
+	{
+		/// <summary>
+		/// Starts the Windows explorer shell, if it isn't already running.
+		/// </summary>
+		void Start();
+
+		/// <summary>
+		/// Gracefully terminates the Windows explorer shell, if it is running.
+		/// </summary>
+		void Terminate();
+	}
+}

SafeExamBrowser.Monitoring/Processes/ProcessMonitor.cs

@@ -8,10 +8,7 @@
 
 using System;
 using System.Diagnostics;
-using System.IO;
-using System.Linq;
 using System.Management;
-using System.Threading;
 using SafeExamBrowser.Contracts.Logging;
 using SafeExamBrowser.Contracts.Monitoring;
 using SafeExamBrowser.Contracts.Monitoring.Events;
@@ -53,53 +50,6 @@ namespace SafeExamBrowser.Monitoring.Processes
 			return true;
 		}
 
-		public void CloseExplorerShell()
-		{
-			var processId = nativeMethods.GetShellProcessId();
-			var explorerProcesses = Process.GetProcessesByName("explorer");
-			var shellProcess = explorerProcesses.FirstOrDefault(p => p.Id == processId);
-
-			if (shellProcess != null)
-			{
-				logger.Info($"Found explorer shell processes with PID = {processId}. Sending close message...");
-
-				nativeMethods.PostCloseMessageToShell();
-
-				while (!shellProcess.HasExited)
-				{
-					shellProcess.Refresh();
-					Thread.Sleep(20);
-				}
-
-				logger.Info($"Successfully terminated explorer shell process with PID = {processId}.");
-			}
-			else
-			{
-				logger.Info("The explorer shell seems to already be terminated. Skipping this step...");
-			}
-		}
-
-		public void StartExplorerShell()
-		{
-			var process = new Process();
-			var explorerPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Windows), "explorer.exe");
-
-			logger.Info("Restarting explorer shell...");
-
-			process.StartInfo.CreateNoWindow = true;
-			process.StartInfo.FileName = explorerPath;
-			process.Start();
-
-			while (nativeMethods.GetShellWindowHandle() == IntPtr.Zero)
-			{
-				Thread.Sleep(20);
-			}
-
-			process.Refresh();
-			logger.Info($"Explorer shell successfully started with PID = {process.Id}.");
-			process.Close();
-		}
-
 		public void StartMonitoringExplorer()
 		{
 			explorerWatcher = new ManagementEventWatcher(@"\\.\root\CIMV2", GetQueryFor("explorer.exe"));

SafeExamBrowser.Runtime/Behaviour/Operations/KioskModeOperation.cs

@@ -20,6 +20,7 @@ namespace SafeExamBrowser.Runtime.Behaviour.Operations
 	{
 		private IConfigurationRepository configuration;
 		private IDesktopFactory desktopFactory;
+		private IExplorerShell explorerShell;
 		private KioskMode kioskMode;
 		private ILogger logger;
 		private IProcessFactory processFactory;
@@ -31,11 +32,13 @@ namespace SafeExamBrowser.Runtime.Behaviour.Operations
 		public KioskModeOperation(
 			IConfigurationRepository configuration,
 			IDesktopFactory desktopFactory,
+			IExplorerShell explorerShell,
 			ILogger logger,
 			IProcessFactory processFactory)
 		{
 			this.configuration = configuration;
 			this.desktopFactory = desktopFactory;
+			this.explorerShell = explorerShell;
 			this.logger = logger;
 			this.processFactory = processFactory;
 		}
@@ -53,7 +56,7 @@ namespace SafeExamBrowser.Runtime.Behaviour.Operations
 					CreateNewDesktop();
 					break;
 				case KioskMode.DisableExplorerShell:
-					DisableExplorerShell();
+					TerminateExplorerShell();
 					break;
 			}
 
@@ -62,7 +65,20 @@ namespace SafeExamBrowser.Runtime.Behaviour.Operations
 
 		public OperationResult Repeat()
 		{
-			// TODO: Depends on new kiosk mode!
+			var oldMode = kioskMode;
+			var newMode = configuration.CurrentSettings.KioskMode;
+
+			if (newMode == oldMode)
+			{
+				logger.Info($"New kiosk mode '{newMode}' is equal to the currently active '{oldMode}', skipping re-initialization...");
+			}
+			else
+			{
+				Revert();
+				Perform();
+			}
+
+			kioskMode = newMode;
 
 			return OperationResult.Success;
 		}
@@ -86,12 +102,14 @@ namespace SafeExamBrowser.Runtime.Behaviour.Operations
 		private void CreateNewDesktop()
 		{
 			originalDesktop = desktopFactory.GetCurrent();
-			logger.Info($"Current desktop is {ToString(originalDesktop)}.");
+			logger.Info($"Current desktop is {originalDesktop}.");
+
 			newDesktop = desktopFactory.CreateNew(nameof(SafeExamBrowser));
-			logger.Info($"Created new desktop {ToString(newDesktop)}.");
+			logger.Info($"Created new desktop {newDesktop}.");
+
 			newDesktop.Activate();
-			logger.Info("Successfully activated new desktop.");
 			processFactory.StartupDesktop = newDesktop;
+			logger.Info("Successfully activated new desktop.");
 		}
 
 		private void CloseNewDesktop()
@@ -100,37 +118,34 @@ namespace SafeExamBrowser.Runtime.Behaviour.Operations
 			{
 				originalDesktop.Activate();
 				processFactory.StartupDesktop = originalDesktop;
-				logger.Info($"Switched back to original desktop {ToString(originalDesktop)}.");
+				logger.Info($"Switched back to original desktop {originalDesktop}.");
 			}
 			else
 			{
-				logger.Warn($"No original desktop found when attempting to revert kiosk mode '{kioskMode}'!");
+				logger.Warn($"No original desktop found when attempting to close new desktop!");
 			}
 
 			if (newDesktop != null)
 			{
 				newDesktop.Close();
-				logger.Info($"Closed new desktop {ToString(newDesktop)}.");
+				logger.Info($"Closed new desktop {newDesktop}.");
 			}
 			else
 			{
-				logger.Warn($"No new desktop found when attempting to revert kiosk mode '{kioskMode}'!");
+				logger.Warn($"No new desktop found when attempting to close new desktop!");
 			}
 		}
 
-		private void DisableExplorerShell()
+		private void TerminateExplorerShell()
 		{
-			// TODO
+			ProgressIndicator?.UpdateText(TextKey.ProgressIndicator_WaitExplorerTermination, true);
+			explorerShell.Terminate();
 		}
 
 		private void RestartExplorerShell()
 		{
-			// TODO
+			ProgressIndicator?.UpdateText(TextKey.ProgressIndicator_WaitExplorerStartup, true);
-		}
+			explorerShell.Start();
-
-		private string ToString(IDesktop desktop)
-		{
-			return $"'{desktop.Name}' [{desktop.Handle}]";
 		}
 	}
 }

SafeExamBrowser.Runtime/CompositionRoot.cs

@@ -51,6 +51,7 @@ namespace SafeExamBrowser.Runtime
 			var text = new Text(logger);
 			var messageBox = new MessageBox(text);
 			var desktopFactory = new DesktopFactory(new ModuleLogger(logger, typeof(DesktopFactory)));
+			var explorerShell = new ExplorerShell(new ModuleLogger(logger, typeof(ExplorerShell)), nativeMethods);
 			var processFactory = new ProcessFactory(new ModuleLogger(logger, typeof(ProcessFactory)));
 			var proxyFactory = new ProxyFactory(new ProxyObjectFactory(), logger);
 			var resourceLoader = new ResourceLoader();
@@ -68,7 +69,7 @@ namespace SafeExamBrowser.Runtime
 			sessionOperations.Enqueue(new SessionInitializationOperation(configuration, logger, runtimeHost));
 			sessionOperations.Enqueue(new ServiceOperation(configuration, logger, serviceProxy, text));
 			sessionOperations.Enqueue(new ClientTerminationOperation(configuration, logger, processFactory, proxyFactory, runtimeHost, TEN_SECONDS));
-			sessionOperations.Enqueue(new KioskModeOperation(configuration, desktopFactory, logger, processFactory));
+			sessionOperations.Enqueue(new KioskModeOperation(configuration, desktopFactory, explorerShell, logger, processFactory));
 			sessionOperations.Enqueue(new ClientOperation(configuration, logger, processFactory, proxyFactory, runtimeHost, TEN_SECONDS));
 
 			var bootstrapSequence = new OperationSequence(logger, bootstrapOperations);

SafeExamBrowser.WindowsApi/Desktop.cs

@@ -43,5 +43,10 @@ namespace SafeExamBrowser.WindowsApi
 				throw new Win32Exception(Marshal.GetLastWin32Error());
 			}
 		}
+
+		public override string ToString()
+		{
+			return $"'{Name}' [{Handle}]";
+		}
 	}
 }

SafeExamBrowser.WindowsApi/DesktopFactory.cs

@@ -37,9 +37,11 @@ namespace SafeExamBrowser.WindowsApi
 				throw new Win32Exception(Marshal.GetLastWin32Error());
 			}
 
-			logger.Debug($"Successfully created desktop '{name}' [{handle}].");
+			var desktop = new Desktop(handle, name);
 
-			return new Desktop(handle, name);
+			logger.Debug($"Successfully created desktop {desktop}.");
+
+			return desktop;
 		}
 
 		public IDesktop GetCurrent()
@@ -49,17 +51,15 @@ namespace SafeExamBrowser.WindowsApi
 			var name = String.Empty;
 			var nameLength = 0;
 
-			if (handle != IntPtr.Zero)
+			if (handle == IntPtr.Zero)
 			{
-				logger.Debug($"Found desktop handle {handle} for thread {threadId}. Attempting to get desktop name...");
+				logger.Error($"Failed to get desktop handle for thread with ID = {threadId}!");
-			}
-			else
-			{
-				logger.Error($"Failed to get desktop handle for thread {threadId}!");
 
 				throw new Win32Exception(Marshal.GetLastWin32Error());
 			}
 
+			logger.Debug($"Found desktop handle for thread with ID = {threadId}. Attempting to get desktop name...");
+
 			User32.GetUserObjectInformation(handle, Constant.UOI_NAME, IntPtr.Zero, 0, ref nameLength);
 
 			var namePointer = Marshal.AllocHGlobal(nameLength);
@@ -67,7 +67,7 @@ namespace SafeExamBrowser.WindowsApi
 
 			if (!success)
 			{
-				logger.Error($"Failed to retrieve name for desktop with handle {handle}!");
+				logger.Error($"Failed to retrieve name for desktop with handle = {handle}!");
 
 				throw new Win32Exception(Marshal.GetLastWin32Error());
 			}
@@ -75,9 +75,11 @@ namespace SafeExamBrowser.WindowsApi
 			name = Marshal.PtrToStringAnsi(namePointer);
 			Marshal.FreeHGlobal(namePointer);
 
-			logger.Debug($"Successfully determined current desktop as '{name}' [{handle}].");
+			var desktop = new Desktop(handle, name);
 
-			return new Desktop(handle, name);
+			logger.Debug($"Successfully determined current desktop {desktop}.");
+
+			return desktop;
 		}
 	}
 }

SafeExamBrowser.WindowsApi/ExplorerShell.cs

@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2018 ETH Zürich, Educational Development and Technology (LET)
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+using System;
+using System.IO;
+using System.Linq;
+using System.Threading;
+using SafeExamBrowser.Contracts.Logging;
+using SafeExamBrowser.Contracts.WindowsApi;
+
+namespace SafeExamBrowser.WindowsApi
+{
+	public class ExplorerShell : IExplorerShell
+	{
+		private ILogger logger;
+		private INativeMethods nativeMethods;
+
+		public ExplorerShell(ILogger logger, INativeMethods nativeMethods)
+		{
+			this.logger = logger;
+			this.nativeMethods = nativeMethods;
+		}
+
+		public void Start()
+		{
+			var process = new System.Diagnostics.Process();
+			var explorerPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Windows), "explorer.exe");
+
+			logger.Info("Restarting explorer shell...");
+
+			process.StartInfo.CreateNoWindow = true;
+			process.StartInfo.FileName = explorerPath;
+			process.Start();
+
+			while (nativeMethods.GetShellWindowHandle() == IntPtr.Zero)
+			{
+				Thread.Sleep(20);
+			}
+
+			process.Refresh();
+			logger.Info($"Explorer shell successfully started with PID = {process.Id}.");
+			process.Close();
+		}
+
+		public void Terminate()
+		{
+			var processId = nativeMethods.GetShellProcessId();
+			var explorerProcesses = System.Diagnostics.Process.GetProcessesByName("explorer");
+			var shellProcess = explorerProcesses.FirstOrDefault(p => p.Id == processId);
+
+			if (shellProcess != null)
+			{
+				logger.Debug($"Found explorer shell processes with PID = {processId}. Sending close message...");
+
+				nativeMethods.PostCloseMessageToShell();
+
+				while (!shellProcess.HasExited)
+				{
+					shellProcess.Refresh();
+					Thread.Sleep(20);
+				}
+
+				logger.Info($"Successfully terminated explorer shell process with PID = {processId}.");
+			}
+			else
+			{
+				logger.Info("The explorer shell seems to already be terminated. Skipping this step...");
+			}
+		}
+	}
+}

SafeExamBrowser.WindowsApi/ProcessFactory.cs

@@ -41,18 +41,18 @@ namespace SafeExamBrowser.WindowsApi
 
 			var success = Kernel32.CreateProcess(null, commandLine, IntPtr.Zero, IntPtr.Zero, true, Constant.NORMAL_PRIORITY_CLASS, IntPtr.Zero, null, ref startupInfo, ref processInfo);
 
-			if (success)
+			if (!success)
-			{
-				logger.Info($"Successfully started process '{Path.GetFileName(path)}' with ID {processInfo.dwProcessId}.");
-			}
-			else
 			{
 				logger.Error($"Failed to start process '{Path.GetFileName(path)}'!");
 
 				throw new Win32Exception(Marshal.GetLastWin32Error());
 			}
 
-			return new Process(processInfo.dwProcessId);
+			var process = new Process(processInfo.dwProcessId);
+
+			logger.Info($"Successfully started process '{Path.GetFileName(path)}' with ID = {process.Id}.");
+
+			return process;
 		}
 	}
 }

SafeExamBrowser.WindowsApi/SafeExamBrowser.WindowsApi.csproj

@@ -59,6 +59,7 @@
     <Compile Include="Delegates\HookDelegate.cs" />
     <Compile Include="Desktop.cs" />
     <Compile Include="DesktopFactory.cs" />
+    <Compile Include="ExplorerShell.cs" />
     <Compile Include="Monitoring\MouseHook.cs" />
     <Compile Include="Process.cs" />
     <Compile Include="ProcessFactory.cs" />