tart ip: keep waiting for the /var/db/dhcpd_leases file to appear (#254)

I initially wanted a one-second wait but made a human mistake.

Fixes #249

Resources/tart.entitlements

@@ -4,7 +4,5 @@
 <dict>
 	<key>com.apple.security.virtualization</key>
 	<true/>
-	<key>com.apple.vm.networking</key>
-	<true/>
 </dict>
 </plist>

Sources/tart/Commands/IP.swift

@@ -44,11 +44,12 @@ struct IP: AsyncParsableCommand {
     let waitUntil = Calendar.current.date(byAdding: .second, value: Int(secondsToWait), to: Date.now)!
 
     repeat {
-      if let ip = try Leases().resolveMACAddress(macAddress: vmMACAddress) {
+      if let leases = try Leases(), let ip = try leases.resolveMACAddress(macAddress: vmMACAddress) {
         return ip
       }
 
-      try await Task.sleep(nanoseconds: 1_000_000)
+      // wait a second
+      try await Task.sleep(nanoseconds: 1_000_000_000)
     } while Date.now < waitUntil
 
     return nil

Sources/tart/Commands/Run.swift

@@ -19,6 +19,9 @@ struct Run: AsyncParsableCommand {
           discussion: "Useful for integrating Tart VMs into other tools.\nUse `tart ip` in order to get an IP for SSHing or VNCing into the VM.")) 
   var noGraphics: Bool = false
 
+  @Flag(help: "Force open a UI window, even when VNC is enabled.")
+  var graphics: Bool = false
+
   @Flag(help: "Boot into recovery mode") 
   var recovery: Bool = false
   
@@ -69,6 +72,10 @@ struct Run: AsyncParsableCommand {
     if withSoftnet && netBridged != nil {
       throw ValidationError("--with-softnet and --net-bridged are mutually exclusive")
     }
+
+    if graphics && noGraphics {
+      throw ValidationError("--graphics and --no-graphics are mutually exclusive")
+    }
   }
 
   @MainActor
@@ -129,7 +136,8 @@ struct Run: AsyncParsableCommand {
     }
     sigintSrc.activate()
 
-    if noGraphics || vnc || vncExperimental {
+    let useVNCWithoutGraphics = (vnc || vncExperimental) && !graphics
+    if noGraphics || useVNCWithoutGraphics {
       dispatchMain()
     } else {
       runUI()

Sources/tart/MACAddressResolver/Leases.swift

@@ -19,14 +19,21 @@ enum LeasesError: Error {
 class Leases {
   private let leases: [MACAddress : Lease]
 
-  convenience init() throws {
+  convenience init?() throws {
     try self.init(URL(fileURLWithPath: "/var/db/dhcpd_leases"))
   }
 
-  convenience init(_ fromURL: URL) throws {
-    let fileContents = try String(contentsOf: fromURL, encoding: .utf8)
+  convenience init?(_ fromURL: URL) throws {
+    do {
+      let urlContents = try String(contentsOf: fromURL, encoding: .utf8)
+      try self.init(urlContents)
+    } catch {
+      if error.isFileNotFound() {
+        return nil
+      }
 
-    try self.init(fileContents)
+      throw error
+    }
   }
 
   init(_ fromString: String) throws {

Sources/tart/Root.swift

@@ -33,6 +33,9 @@ struct Root: AsyncParsableCommand {
     }
     sigintSrc.activate()
 
+    // Set line-buffered output for stdout
+    setlinebuf(stdout)
+
     // Parse and run command
     do {
       var command = try parseAsRoot()