Gracefully stop vm on tart stop (#808)

* Give Virtualization.framework a chance to stop the VM on tart stop

We were letting the CancellationError bubble up all the way until
it terminated app, which meant we didn't hit the shutdown code
in run(), stopping the VM and the network.

We now catch CancellationError and proceed to gracefully shut down.

We only stop the VM if it's still running, as a VM that has been
stopped via the menu can't be stopped again.

* Gracefully shut down VM when Tart is quit via menu

Normally the quit action will result in AppKit calling exit(),
but we want to gracefully shut down the VM, so we use the same
path as for closing of the VM window, namely signal our own
process with SIGINT or SIGUSR1.

If that doesn't work we let AppKit terminate as before.

This fixes the "Warning: NSActivity <_NSActivityAssertion:
0x600001f785a0> was ended multiple times" warning seen on
the console when quitting Tart via the menu.

* Activate Tart after application finishes launching

This ensures that the VM window has been shown by the time we
activate, so that we consistently activate and bring the VM
window to the front.

Sources/tart/Commands/Run.swift

@@ -563,73 +563,69 @@ struct Run: AsyncParsableCommand {
   }
 
   private func runUI(_ suspendable: Bool, _ captureSystemKeys: Bool) {
-    let nsApp = NSApplication.shared
-    nsApp.setActivationPolicy(.regular)
-    nsApp.activate(ignoringOtherApps: true)
+    MainApp.suspendable = suspendable
+    MainApp.capturesSystemKeys = captureSystemKeys
+    MainApp.main()
+  }
+}
 
-    struct MainApp: App {
-      static var suspendable: Bool = false
-      static var capturesSystemKeys: Bool = false
+struct MainApp: App {
+  static var suspendable: Bool = false
+  static var capturesSystemKeys: Bool = false
 
-      @NSApplicationDelegateAdaptor private var appDelegate: MinimalMenuAppDelegate
+  @NSApplicationDelegateAdaptor private var appDelegate: MinimalMenuAppDelegate
 
-      var body: some Scene {
-        WindowGroup(vm!.name) {
-          Group {
-            VMView(vm: vm!, capturesSystemKeys: MainApp.capturesSystemKeys).onAppear {
-              NSWindow.allowsAutomaticWindowTabbing = false
-            }.onDisappear {
-              let ret = kill(getpid(), MainApp.suspendable ? SIGUSR1 : SIGINT)
-              if ret != 0 {
-                // Fallback to the old termination method that doesn't
-                // propagate the cancellation to Task's in case graceful
-                // termination via kill(2) is not successful
-                NSApplication.shared.terminate(self)
-              }
-            }
-          }.frame(
-            minWidth: CGFloat(vm!.config.display.width),
-            idealWidth: CGFloat(vm!.config.display.width),
-            maxWidth: .infinity,
-            minHeight: CGFloat(vm!.config.display.height),
-            idealHeight: CGFloat(vm!.config.display.height),
-            maxHeight: .infinity
-          )
-        }.commands {
-          // Remove some standard menu options
-          CommandGroup(replacing: .help, addition: {})
-          CommandGroup(replacing: .newItem, addition: {})
-          CommandGroup(replacing: .pasteboard, addition: {})
-          CommandGroup(replacing: .textEditing, addition: {})
-          CommandGroup(replacing: .undoRedo, addition: {})
-          CommandGroup(replacing: .windowSize, addition: {})
-          // Replace some standard menu options
-          CommandGroup(replacing: .appInfo) { AboutTart(config: vm!.config) }
-          CommandMenu("Control") {
-            Button("Start") {
-              Task { try await vm!.virtualMachine.start() }
-            }
-            Button("Stop") {
-              Task { try await vm!.virtualMachine.stop() }
-            }
-            Button("Request Stop") {
-              Task { try vm!.virtualMachine.requestStop() }
-            }
-            if #available(macOS 14, *) {
-              if (MainApp.suspendable) {
-                Button("Suspend") {
-                  kill(getpid(), SIGUSR1)
-                }
-              }
+  var body: some Scene {
+    WindowGroup(vm!.name) {
+      Group {
+        VMView(vm: vm!, capturesSystemKeys: MainApp.capturesSystemKeys).onAppear {
+          NSWindow.allowsAutomaticWindowTabbing = false
+        }.onDisappear {
+          let ret = kill(getpid(), MainApp.suspendable ? SIGUSR1 : SIGINT)
+          if ret != 0 {
+            // Fallback to the old termination method that doesn't
+            // propagate the cancellation to Task's in case graceful
+            // termination via kill(2) is not successful
+            NSApplication.shared.terminate(self)
+          }
+        }
+      }.frame(
+        minWidth: CGFloat(vm!.config.display.width),
+        idealWidth: CGFloat(vm!.config.display.width),
+        maxWidth: .infinity,
+        minHeight: CGFloat(vm!.config.display.height),
+        idealHeight: CGFloat(vm!.config.display.height),
+        maxHeight: .infinity
+      )
+    }.commands {
+      // Remove some standard menu options
+      CommandGroup(replacing: .help, addition: {})
+      CommandGroup(replacing: .newItem, addition: {})
+      CommandGroup(replacing: .pasteboard, addition: {})
+      CommandGroup(replacing: .textEditing, addition: {})
+      CommandGroup(replacing: .undoRedo, addition: {})
+      CommandGroup(replacing: .windowSize, addition: {})
+      // Replace some standard menu options
+      CommandGroup(replacing: .appInfo) { AboutTart(config: vm!.config) }
+      CommandMenu("Control") {
+        Button("Start") {
+          Task { try await vm!.virtualMachine.start() }
+        }
+        Button("Stop") {
+          Task { try await vm!.virtualMachine.stop() }
+        }
+        Button("Request Stop") {
+          Task { try vm!.virtualMachine.requestStop() }
+        }
+        if #available(macOS 14, *) {
+          if (MainApp.suspendable) {
+            Button("Suspend") {
+              kill(getpid(), SIGUSR1)
             }
           }
         }
       }
     }
-
-    MainApp.suspendable = suspendable
-    MainApp.capturesSystemKeys = captureSystemKeys
-    MainApp.main()
   }
 }
 
@@ -639,6 +635,18 @@ class MinimalMenuAppDelegate: NSObject, NSApplicationDelegate, ObservableObject
 
   func applicationDidFinishLaunching(_ : Notification) {
     NSApplication.shared.mainMenu?.removeItem(at: indexOfEditMenu)
+
+    let nsApp = NSApplication.shared
+    nsApp.setActivationPolicy(.regular)
+    nsApp.activate(ignoringOtherApps: true)
+  }
+
+  func applicationShouldTerminate(_ sender: NSApplication) -> NSApplication.TerminateReply {
+    if (kill(getpid(), MainApp.suspendable ? SIGUSR1 : SIGINT) == 0) {
+      return .terminateLater
+    } else {
+      return .terminateNow
+    }
   }
 }
 

Sources/tart/VM.swift

@@ -244,10 +244,18 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
   }
 
   func run() async throws {
-    try await sema.waitUnlessCancelled()
+    do {
+      try await sema.waitUnlessCancelled()
+    } catch is CancellationError {
+      // Triggered by "tart stop", Ctrl+C, or closing the
+      // VM window, so shut down the VM gracefully below.
+    }
 
     if Task.isCancelled {
-      try await stop()
+      if (self.virtualMachine.state == VZVirtualMachine.State.running) {
+        print("Stopping VM...")
+        try await stop()
+      }
     }
 
     try await network.stop()