Option to run in recovery mode (#91)

* Option to run in recovery mode

* Fixed typo

* Use Dynamic package to call private APIs

* Improved comment

* Move options closer to invocation

Package.resolved

@@ -1,5 +1,14 @@
 {
   "pins" : [
+    {
+      "identity" : "dynamic",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/mhdhejazi/Dynamic",
+      "state" : {
+        "branch" : "master",
+        "revision" : "772883073d044bc754d401cabb6574624eb3778f"
+      }
+    },
     {
       "identity" : "swift-argument-parser",
       "kind" : "remoteSourceControl",

Package.swift

@@ -13,10 +13,12 @@ let package = Package(
   dependencies: [
     .package(url: "https://github.com/apple/swift-argument-parser", from: "1.1.2"),
     .package(url: "https://github.com/pointfreeco/swift-parsing", from: "0.9.2"),
+    .package(url: "https://github.com/mhdhejazi/Dynamic", branch: "master"),
   ],
   targets: [
     .executableTarget(name: "tart", dependencies: [
       .product(name: "ArgumentParser", package: "swift-argument-parser"),
+      .product(name: "Dynamic", package: "Dynamic"),
       .product(name: "Parsing", package: "swift-parsing"),
     ]),
     .testTarget(name: "TartTests", dependencies: ["tart"])

Sources/tart/Commands/Run.swift

@@ -13,6 +13,8 @@ struct Run: AsyncParsableCommand {
 
   @Flag var noGraphics: Bool = false
 
+  @Flag var recovery: Bool = false
+
   @MainActor
   func run() async throws {
     let vmDir = try VMStorageLocal().open(name)
@@ -21,7 +23,7 @@ struct Run: AsyncParsableCommand {
     await withThrowingTaskGroup(of: Void.self) { group in
       group.addTask {
         do {
-          try await vm!.run()
+          try await vm!.run(recovery)
 
           Foundation.exit(0)
         } catch {

Sources/tart/VM+Recovery.swift

@@ -0,0 +1,37 @@
+import Foundation
+import Virtualization
+import Dynamic
+
+// Kudos to @saagarjha's VirtualApple for finding about _VZVirtualMachineStartOptions
+
+extension VZVirtualMachine {
+  func start(_ recovery: Bool) async throws {
+    if !recovery {
+      // just use the regular API
+      return try await withCheckedThrowingContinuation { continuation in
+        DispatchQueue.main.async {
+          self.start(completionHandler: { result in
+            continuation.resume(with: result)
+          })
+        }
+      }
+    }
+
+    // use some private stuff only for recovery
+    return try await withCheckedThrowingContinuation { (continuation: CheckedContinuation<Void, Error>) in
+      DispatchQueue.main.async {
+        let handler: @convention(block) (_ result: Any?) -> Void = { result in
+          if let error = result as? Error {
+            continuation.resume(throwing: error)
+          } else {
+            continuation.resume(returning: ())
+          }
+        }
+        // dynamic magic
+        let options = Dynamic._VZVirtualMachineStartOptions()
+        options.bootMacOSRecovery = recovery
+        Dynamic(self)._start(withOptions: options, completionHandler: handler)
+      }
+    }
+  }
+}

Sources/tart/VM.swift

@@ -133,14 +133,8 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
     }
   }
 
-  func run() async throws {
-    try await withCheckedThrowingContinuation { continuation in
-      DispatchQueue.main.async {
-        self.virtualMachine.start(completionHandler: { result in
-          continuation.resume(with: result)
-        })
-      }
-    }
+  func run(_ recovery: Bool) async throws {
+    try await virtualMachine.start(recovery)
 
     await withTaskCancellationHandler(operation: {
       sema.wait()