Directory sharing support (#211)

Sources/tart/Commands/Create.swift

@@ -40,7 +40,7 @@ struct Create: AsyncParsableCommand {
           if #available(macOS 13, *) {
             _ = try await VM.linux(vmDir: tmpVMDir, diskSizeGB: diskSize)
           } else {
-            throw UnsupportedOSError()
+            throw UnsupportedOSError("Linux VMs", "are")
           }
         }
 

Sources/tart/Commands/Run.swift

@@ -37,13 +37,21 @@ struct Run: AsyncParsableCommand {
   @Flag var withSoftnet: Bool = false
 
   @Option(help: ArgumentHelp("""
-    Additional disk attachments with an optional read-only specifier\n(e.g. --disk=\"disk.bin\" --disk=\"disk.bin:ro\")
+    Additional disk attachments with an optional read-only specifier\n(e.g. --disk=\"disk.bin\" --disk=\"ubuntu.iso:ro\")
     """, discussion: """
     Learn how to create a disk image using Disk Utility here:
     https://support.apple.com/en-gb/guide/disk-utility/dskutl11888/mac
-    """))
+    """, valueName: "path[:ro]"))
   var disk: [String] = []
 
+  @Option(help: ArgumentHelp("""
+                             Additional directory shares with an optional read-only specifier\n(e.g. --dir=\"build:~/src/build\" --dir=\"sources:~/src/sources:ro\")
+                             """, discussion: """
+                                              All shared directories are automatically mounted to "/Volumes/My Shared Files" directory on macOS,
+                                              while on Linux you have to do it manually: "mount -t virtiofs com.apple.virtio-fs.automount /mount/point".
+                                              """, valueName: "name:path[:ro]"))
+  var dir: [String] = []
+
   func validate() throws {
     if vnc && vncExperimental {
       throw ValidationError("--vnc and --vnc-experimental are mutually exclusive")
@@ -56,7 +64,8 @@ struct Run: AsyncParsableCommand {
     vm = try VM(
       vmDir: vmDir,
       withSoftnet: withSoftnet,
-      additionalDiskAttachments: additionalDiskAttachments()
+      additionalDiskAttachments: additionalDiskAttachments(),
+      directoryShares: directoryShares()
     )
 
     let vncImpl: VNC? = try {
@@ -135,6 +144,34 @@ struct Run: AsyncParsableCommand {
     return result
   }
 
+  func directoryShares() throws -> [DirectoryShare] {
+    var result: [DirectoryShare] = []
+
+    for rawDir in dir {
+      let splits = rawDir.split(maxSplits: 2) { $0 == ":" }
+
+      if splits.count < 2 {
+        throw ValidationError("invalid --dir syntax: should at least include name and path, colon-separated")
+      }
+
+      var readOnly: Bool = false
+
+      if splits.count == 3 {
+        if splits[2] == "ro" {
+          readOnly = true
+        } else {
+          throw ValidationError("invalid --dir syntax: optional read-only specifier can only be \"ro\"")
+        }
+      }
+
+      let (name, path) = (String(splits[0]), String(splits[1]))
+
+      result.append(DirectoryShare(name: name, path: URL(fileURLWithPath: path), readOnly: readOnly))
+    }
+
+    return result
+  }
+
   private func runUI() {
     let nsApp = NSApplication.shared
     nsApp.setActivationPolicy(.regular)

Sources/tart/VM.swift

@@ -11,7 +11,11 @@ struct DownloadFailed: Error {
 }
 
 struct UnsupportedOSError: Error, CustomStringConvertible {
-  private(set) var description: String = "error: Linux VMs are only supported on macOS 13.0 (Ventura) or newer"
+  let description: String
+
+  init(_ what: String, _ plural: String) {
+    description = "error: \(what) \(plural) only supported on macOS 13.0 (Ventura) or newer"
+  }
 }
 
 struct UnsupportedArchitectureError: Error {
@@ -34,7 +38,8 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
 
   init(vmDir: VMDirectory,
        withSoftnet: Bool = false,
-       additionalDiskAttachments: [VZDiskImageStorageDeviceAttachment] = []
+       additionalDiskAttachments: [VZDiskImageStorageDeviceAttachment] = [],
+       directoryShares: [DirectoryShare] = []
   ) throws {
     name = vmDir.name
     config = try VMConfig.init(fromURL: vmDir.configURL)
@@ -50,7 +55,8 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
 
     let configuration = try Self.craftConfiguration(diskURL: vmDir.diskURL,
       nvramURL: vmDir.nvramURL, vmConfig: config,
-      softnet: softnet, additionalDiskAttachments: additionalDiskAttachments)
+      softnet: softnet, additionalDiskAttachments: additionalDiskAttachments,
+            directoryShares: directoryShares)
     virtualMachine = VZVirtualMachine(configuration: configuration)
 
     super.init()
@@ -149,7 +155,8 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
 
     let configuration = try Self.craftConfiguration(diskURL: vmDir.diskURL, nvramURL: vmDir.nvramURL,
       vmConfig: config, softnet: softnet,
-      additionalDiskAttachments: additionalDiskAttachments)
+      additionalDiskAttachments: additionalDiskAttachments,
+      directoryShares: [])
     virtualMachine = VZVirtualMachine(configuration: configuration)
 
     super.init()
@@ -228,7 +235,8 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
     nvramURL: URL,
     vmConfig: VMConfig,
     softnet: Softnet? = nil,
-    additionalDiskAttachments: [VZDiskImageStorageDeviceAttachment]
+    additionalDiskAttachments: [VZDiskImageStorageDeviceAttachment],
+    directoryShares: [DirectoryShare]
   ) throws -> VZVirtualMachineConfiguration {
     let configuration = VZVirtualMachineConfiguration()
 
@@ -278,6 +286,20 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
     // Entropy
     configuration.entropyDevices = [VZVirtioEntropyDeviceConfiguration()]
 
+    // Directory share
+    if #available(macOS 13, *) {
+      var directories: [String : VZSharedDirectory] = Dictionary()
+      directoryShares.forEach { directories[$0.name] = VZSharedDirectory(url: $0.path, readOnly: $0.readOnly) }
+
+      let automountTag = VZVirtioFileSystemDeviceConfiguration.macOSGuestAutomountTag
+      let sharingDevice = VZVirtioFileSystemDeviceConfiguration(tag: automountTag)
+      sharingDevice.share = VZMultipleDirectoryShare(directories: directories)
+
+      configuration.directorySharingDevices = [sharingDevice]
+    } else if !directoryShares.isEmpty {
+      throw UnsupportedOSError("directory sharing", "is")
+    }
+
     try configuration.validate()
 
     return configuration
@@ -298,3 +320,9 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
     sema.signal()
   }
 }
+
+struct DirectoryShare {
+  let name: String
+  let path: URL
+  let readOnly: Bool
+}

Sources/tart/VMConfig.swift

@@ -94,7 +94,7 @@ struct VMConfig: Codable {
       if #available(macOS 13, *) {
         platform = try Linux(from: decoder)
       } else {
-        throw UnsupportedOSError()
+        throw UnsupportedOSError("Linux VMs", "are")
       }
     }
     cpuCountMin = try container.decode(Int.self, forKey: .cpuCountMin)