Add fallback support when update install fails

OpenTabletDriver.Desktop/Updater/Updater.cs

@@ -63,8 +63,8 @@ public Task Install(Update update)
             try
             {
                 UpdateInstalling?.Invoke(update);
-                PrepareForUpdate(update);
-                InstallUpdate(update);
+                PrepareForUpdate(update, out var binaryRollback);
+                InstallUpdate(update, binaryRollback);
                 installed = true;
             }
             finally
@@ -81,51 +81,72 @@ public Task Install(Update update)
             return Task.CompletedTask;
         }
 
-        private void InstallUpdate(Update update)
+        private void InstallUpdate(Update update, string binaryRollback)
         {
-            foreach (var source in update.Paths)
+            try
             {
-                var destination = Path.Join(BinaryDirectory, Path.GetFileName(source));
+                foreach (var source in update.Paths)
+                {
+                    var destination = Path.Join(BinaryDirectory, Path.GetFileName(source));
 
-                if (File.Exists(source))
-                    File.Move(source, destination);
-                else if (Directory.Exists(source))
-                    Directory.Move(source, destination);
+                    if (File.Exists(source))
+                        File.Move(source, destination);
+                    else if (Directory.Exists(source))
+                        Directory.Move(source, destination);
+                }
+            }
+            catch (Exception ex)
+            {
+                // redo the binary rollback and this time copy the files instead of moving them
+                Backup(binaryRollback, update.Paths, Copy, Copy);
+
+                // and then run fallback procedure
+                InstallUpdateFallback(update, ex);
             }
         }
 
         protected abstract Task<UpdateInfo?> CheckForUpdatesCore();
 
-        protected void PrepareForUpdate(Update update)
+        protected virtual void InstallUpdateFallback(Update update, Exception ex)
+        {
+            // throw by default
+            throw new UpdateInstallFailedException(ex);
+        }
+
+        protected void PrepareForUpdate(Update update, out string binaryRollback)
         {
             string timestamp = DateTime.UtcNow.ToString("-yyyy-MM-dd_hh-mm-ss");
             var rollback = Path.Join(RollbackDirectory, CurrentVersion + timestamp);
-            var binaryRollback = Path.Join(rollback, "bin");
+            binaryRollback = Path.Join(rollback, "bin");
             var appDataRollback = Path.Join(rollback, "appdata");
 
             Directory.CreateDirectory(rollback);
             Directory.CreateDirectory(binaryRollback);
             Directory.CreateDirectory(appDataRollback);
 
-            Backup(binaryRollback, update.Paths);
+            // Moves files/directories that would be updated to a rollback directory.
+            // Doing a move is necessary for Windows to allow the update to overwrite the files.
+            Backup(binaryRollback, update.Paths, File.Move, Directory.Move);
             BackupAppData(appDataRollback);
 
             RollbackCreated?.Invoke(rollback);
         }
 
-        // Moves files/directories that would be updated to a rollback directory.
-        // Doing a move is necessary for Windows to allow the update to overwrite the files.
-        protected void Backup(string binaryRollback, ImmutableArray<string> pathsToUpdate)
+        private void Backup(
+            string binaryRollback,
+            ImmutableArray<string> pathsToUpdate,
+            Action<string, string> fileAction,
+            Action<string, string> directoryAction)
         {
             foreach (var path in pathsToUpdate.Select(f => Path.GetFileName(f)))
             {
                 var source = Path.Join(BinaryDirectory, path);
                 var destination = Path.Join(binaryRollback, path);
 
                 if (File.Exists(source))
-                    File.Move(source, destination);
+                    fileAction(source, destination);
                 else if (Directory.Exists(source))
-                    Directory.Move(source, destination);
+                    directoryAction(source, destination);
             }
         }
 
@@ -184,4 +205,15 @@ public UpdateAlreadyInstalledException() : base("An update has already been inst
         {
         }
     }
+
+    public class UpdateInstallFailedException : Exception
+    {
+        public UpdateInstallFailedException() : base("Failed to install update.")
+        {
+        }
+
+        public UpdateInstallFailedException(Exception innerException) : base("Failed to install update.", innerException)
+        {
+        }
+    }
 }

OpenTabletDriver.Desktop/Updater/WindowsUpdater.cs

@@ -1,9 +1,12 @@
 using System;
+using System.Collections.Generic;
 using System.Collections.Immutable;
+using System.Diagnostics;
 using System.IO;
 using System.IO.Compression;
 using System.Linq;
 using System.Net.Http;
+using System.Threading;
 using System.Threading.Tasks;
 using Octokit;
 
@@ -18,6 +21,61 @@ public WindowsUpdater(AppInfo appInfo, IGitHubClient client)
         {
         }
 
+        protected override void InstallUpdateFallback(Update update, Exception ex)
+        {
+            var targetProcesses = new string[] {
+                "OpenTabletDriver.UX.Wpf.exe",
+                "OpenTabletDriver.Daemon.exe",
+                "OpenTabletDriver.Console.exe",
+            };
+
+            var batchCommands = new List<string>()
+            {
+                "@echo off"
+            };
+
+            // Kill all processes that are being updated
+            batchCommands.AddRange(targetProcesses
+                .Select(p => $"taskkill /F /IM \"{p}\" > nul"));
+
+            // Install the update
+            batchCommands.AddRange(update.Paths
+                .Select(p => $"move /Y \"{p}\" \"{BinaryDirectory}\""));
+
+            // Start the updated process
+            batchCommands.Add(
+                $$"""
+                set "executable="
+                for /R "{{BinaryDirectory}}" %%F in (OpenTabletDriver.UI*) do (
+                    if not defined executable (
+                        set "executable=%%F"
+                    )
+                )
+
+                if defined executable (
+                    start "" "%executable%"
+                ) else (
+                    start "" "{{Path.Join(BinaryDirectory, "OpenTabletDriver.UX.Wpf.exe")}}"
+                )
+                """
+            );
+
+            var batchCommand = string.Join("\n", batchCommands);
+            var updateScript = Path.Join(Path.GetTempPath(), Path.GetRandomFileName() + ".bat");
+            File.WriteAllText(updateScript, batchCommand);
+
+            var processInfo = new ProcessStartInfo()
+            {
+                FileName = updateScript,
+                CreateNoWindow = true,
+                UseShellExecute = false,
+                WorkingDirectory = BinaryDirectory,
+            };
+
+            Process.Start(processInfo);
+            Thread.Sleep(Timeout.Infinite);
+        }
+
         protected override async Task<Update> Download(Release release, Version version)
         {
             var downloadPath = GetDownloadPath();