Service: pick up app updates by self-restarting onto the new binary

Local checkpoint - NOT for public release. Ed: an update should tear down the service, update it, and restart it. It didn't - the updater has no service awareness. Current (unchanged, verified correct): the auto-updater renames the install files aside and copies the new ones in, which a running service TOLERATES (no failed swap). The old version keeps streaming; the new files sit in place. New: the service now adopts the update itself. Because it runs as SYSTEM (which has the rights the non-elevated updater lacks), a 45s timer notices when a strictly-newer RemSound.exe has landed next to it and restarts itself onto the new binary (detached PowerShell Stop-Service+Start-Service). Loop-safe: only fires on a strictly-newer on-disk version; any uncertainty (file mid-swap, unparseable version) means don't restart, and after the restart on-disk == running so it never re-triggers. Test "Service registration args" now also covers the version-comparison logic (newer => restart; same/older/missing => no restart). Gate 27/27. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-07-13 09:38:52 +01:00
parent 941e0df99f
commit 56dbd0b80f
3 changed files with 88 additions and 1 deletions
@@ -0,0 +1,61 @@
+using System.Diagnostics;
+using System.Reflection;
+
+namespace RemSound.App;
+
+/// <summary>
+/// Lets the running Windows service pick up an app update on its own. The interactive auto-updater
+/// swaps the install files in place (rename-aside, which a running service tolerates) but has no admin
+/// rights to restart the service — so instead the SERVICE, which runs as SYSTEM and DOES have the rights,
+/// notices that a newer RemSound.exe has landed next to it and restarts itself onto the new binary.
+///
+/// <para>Loop-safe by construction: it only restarts when the on-disk version is STRICTLY newer than the
+/// running one, and any uncertainty (file missing mid-swap, unparseable version) means "don't restart".
+/// After the restart the new process's on-disk == running, so it never re-triggers.</para>
+/// </summary>
+internal static class ServiceUpdate
+{
+    /// <summary>Pure version comparison, unit-testable: is the on-disk version strictly newer than the
+    /// running one? False on any missing/unparseable input (so we never restart on uncertainty).</summary>
+    internal static bool IsNewer(Version? running, string? onDiskFileVersion)
+    {
+        if (running is null || string.IsNullOrWhiteSpace(onDiskFileVersion)) return false;
+        return Version.TryParse(onDiskFileVersion, out var onDisk) && onDisk > running;
+    }
+
+    /// <summary>True when a strictly-newer RemSound.exe sits next to the running service binary (i.e. an
+    /// update landed). Reads the on-disk exe's file version; never throws.</summary>
+    public static bool UpdateLanded()
+    {
+        try
+        {
+            var onDiskExe = Path.Combine(AppContext.BaseDirectory, "RemSound.exe");
+            if (!File.Exists(onDiskExe)) return false;
+            var running = Assembly.GetExecutingAssembly().GetName().Version;
+            var onDisk = FileVersionInfo.GetVersionInfo(onDiskExe).FileVersion;
+            return IsNewer(running, onDisk);
+        }
+        catch { return false; }
+    }
+
+    /// <summary>Restart the service onto the new binary. Spawns a DETACHED PowerShell (as SYSTEM, inherited
+    /// from the service) that stops this service — which exits this process — then starts it again, so the
+    /// SCM launches the freshly-installed exe. Never throws.</summary>
+    public static void RestartSelf()
+    {
+        try
+        {
+            var psi = new ProcessStartInfo
+            {
+                FileName = "powershell.exe",
+                Arguments = "-NonInteractive -WindowStyle Hidden -Command " +
+                            $"\"Stop-Service -Name {ServiceControl.ServiceName} -Force -ErrorAction SilentlyContinue; " +
+                            $"Start-Service -Name {ServiceControl.ServiceName} -ErrorAction SilentlyContinue\"",
+                UseShellExecute = false,
+                CreateNoWindow = true,
+            };
+            Process.Start(psi);
+        }
+        catch { /* best-effort; worst case the service picks up the update on next reboot */ }
+    }
+}