[msbuild] Port Ditto to subclass XamarinTask.

This has a few advantages:

* We simplify and unify more of our code.
* We have more control over the error reporting / logging behavior.

Additionally:

* Allow for overriding the path to the command-line tool in question.
* Add support for cancellation.

Fixes https://github.com/xamarin/xamarin-macios/issues/21437.

docs/build-apps/build-properties.md

@@ -11,6 +11,12 @@ MSBuild properties control the behavior of the
 They're specified within the project file, for example **MyApp.csproj**, within
 an MSBuild PropertyGroup.
 
+## DittoPath
+
+The full path to the `ditto` executable.
+
+The default behavior is to use `/usr/bin/ditto`.
+
 ## MaciOSPrepareForBuildDependsOn
 
 A semi-colon delimited property that can be used to extend the build process.

dotnet/targets/Xamarin.Shared.Sdk.targets

@@ -869,8 +869,7 @@
 			Condition="'$(IsMacEnabled)' == 'true'"
 			AdditionalArguments="$(_DittoArchitectures)"
 			CopyFromWindows="true"
-			ToolExe="$(DittoExe)"
-			ToolPath="$(DittoPath)"
+			DittoPath="$(DittoPath)"
 			Source="%(_DirectoriesToPublish.SourceDirectory)"
 			Destination="%(_DirectoriesToPublish.TargetDirectory)"
 			TouchDestinationFiles="true"

msbuild/Xamarin.Localization.MSBuild/MSBStrings.resx

@@ -1576,6 +1576,19 @@
         <comment>SupportedOSPlatformVersion: don't translate (it's the name of an MSBuild property)</comment>
     </data>
 
+    <data name="E7131" xml:space="preserve">
+        <value>The source '{0}' does not exist.</value>
+        <comment>{0}: path to a file or a directory</comment>
+    </data>
+
+    <data name="E7132" xml:space="preserve">
+        <value>Unable to parse the 'AdditionalArguments' value: {0}</value>
+        <comment>
+            AdditionalArguments: don't translate (it's the name of an MSBuild property)
+            {0}: additional arguments passed to the task
+        </comment>
+    </data>
+
     <data name="XcodeBuild_CreateNativeRef" xml:space="preserve">
         <value>Adding reference to Xcode project output: '{0}'. The '%(CreateNativeReference)' metadata can be set to 'false' to opt out of this behavior.</value>
         <comment>

msbuild/Xamarin.MacDev.Tasks/Tasks/Ditto.cs

@@ -4,14 +4,19 @@ using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using System.Threading;
 
 using Microsoft.Build.Framework;
 using Microsoft.Build.Utilities;
 
+using Xamarin.Localization.MSBuild;
 using Xamarin.Messaging.Build.Client;
+using Xamarin.Utils;
 
 namespace Xamarin.MacDev.Tasks {
-	public class Ditto : XamarinToolTask, ITaskCallback {
+	public class Ditto : XamarinTask, ITaskCallback, ICancelableTask {
+		CancellationTokenSource? cancellationTokenSource;
+
 		#region Inputs
 
 		public string? AdditionalArguments { get; set; }
@@ -26,6 +31,8 @@ namespace Xamarin.MacDev.Tasks {
 		// the mode.
 		public bool CopyFromWindows { get; set; }
 
+		public string? DittoPath { get; set; }
+
 		[Required]
 		public ITaskItem? Source { get; set; }
 
@@ -40,32 +47,6 @@ namespace Xamarin.MacDev.Tasks {
 
 		#endregion
 
-		protected override string ToolName {
-			get { return "ditto"; }
-		}
-
-		protected override string GenerateFullPathToTool ()
-		{
-			if (!string.IsNullOrEmpty (ToolPath))
-				return Path.Combine (ToolPath, ToolExe);
-
-			var path = Path.Combine ("/usr/bin", ToolExe);
-
-			return File.Exists (path) ? path : ToolExe;
-		}
-
-		protected override string GenerateCommandLineCommands ()
-		{
-			var args = new CommandLineArgumentBuilder ();
-
-			args.AddQuoted (Path.GetFullPath (Source!.ItemSpec));
-			args.AddQuoted (Path.GetFullPath (Destination!.ItemSpec));
-			if (!string.IsNullOrEmpty (AdditionalArguments))
-				args.Add (AdditionalArguments);
-
-			return args.ToString ();
-		}
-
 		public override bool Execute ()
 		{
 			if (ShouldExecuteRemotely ()) {
@@ -76,8 +57,31 @@ namespace Xamarin.MacDev.Tasks {
 				return taskRunner.RunAsync (this).Result;
 			}
 
-			if (!base.Execute ())
+			var src = Source!.ItemSpec;
+			if (!File.Exists (src) && !Directory.Exists (src)) {
+				Log.LogError (MSBStrings.E7131 /* The source '{0}' does not exist. */, src);
 				return false;
+			}
+
+			var executable = string.IsNullOrEmpty (DittoPath) ? "/usr/bin/ditto" : DittoPath!;
+			var args = new List<string> ();
+			args.Add (Path.GetFullPath (Source!.ItemSpec));
+			args.Add (Path.GetFullPath (Destination!.ItemSpec));
+#if NET
+			if (!string.IsNullOrEmpty (AdditionalArguments)) {
+#else
+			if (AdditionalArguments is not null && !string.IsNullOrEmpty (AdditionalArguments)) {
+#endif
+				if (StringUtils.TryParseArguments (AdditionalArguments, out var additionalArgs, out var ex)) {
+					args.AddRange (additionalArgs);
+				} else {
+					Log.LogError (MSBStrings.E7132 /* Unable to parse the 'AdditionalArguments' value: {0} */, AdditionalArguments);
+					return false;
+				}
+			}
+
+			cancellationTokenSource = new CancellationTokenSource ();
+			ExecuteAsync (Log, executable, args, cancellationToken: cancellationTokenSource.Token).Wait ();
 
 			// Create a list of all the files we've copied
 			var copiedFiles = new List<ITaskItem> ();
@@ -96,18 +100,13 @@ namespace Xamarin.MacDev.Tasks {
 			return !Log.HasLoggedErrors;
 		}
 
-		protected override void LogEventsFromTextOutput (string singleLine, MessageImportance messageImportance)
+		public void Cancel ()
 		{
-			// TODO: do proper parsing of error messages and such
-			Log.LogMessage (messageImportance, "{0}", singleLine);
-		}
-
-		public override void Cancel ()
-		{
-			base.Cancel ();
-
-			if (ShouldExecuteRemotely ())
+			if (ShouldExecuteRemotely ()) {
 				BuildConnection.CancelAsync (BuildEngine4).Wait ();
+			} else {
+				cancellationTokenSource?.Cancel ();
+			}
 		}
 
 		public IEnumerable<ITaskItem> GetAdditionalItemsToBeCopied ()

msbuild/Xamarin.Shared/Xamarin.Shared.targets

@@ -2505,8 +2505,7 @@ Copyright (C) 2018 Microsoft. All rights reserved.
 		<Ditto
 			SessionId="$(BuildSessionId)"
 			Condition="'$(IsMacEnabled)' == 'true'"
-			ToolExe="$(DittoExe)"
-			ToolPath="$(DittoPath)"
+			DittoPath="$(DittoPath)"
 			Source="@(_ResolvedAppExtensionReferences)"
 			Destination="$(_AppExtensionRoot)%(_ResolvedAppExtensionReferences.ContainerName)\%(_ResolvedAppExtensionReferences.FileName)%(_ResolvedAppExtensionReferences.Extension)"
 			TouchDestinationFiles="true"

msbuild/Xamarin.Shared/Xamarin.WatchOS.App.Common.targets

@@ -81,8 +81,7 @@ Copyright (C) 2015-2016 Xamarin. All rights reserved.
 			SessionId="$(BuildSessionId)"
 			Condition="'$(IsMacEnabled)'"
 			AdditionalArguments="$(WKDittoArchitectures)"
-			ToolExe="$(DittoExe)"
-			ToolPath="$(DittoPath)"
+			DittoPath="$(DittoPath)"
 			Source="$(_NativeWatchApp)"
 			Destination="$(_AppBundlePath)$(AssemblyName)"
 		/>
@@ -93,8 +92,7 @@ Copyright (C) 2015-2016 Xamarin. All rights reserved.
 			SessionId="$(BuildSessionId)"
 			Condition="'$(IsMacEnabled)'"
 			AdditionalArguments="$(WKDittoArchitectures)"
-			ToolExe="$(DittoExe)"
-			ToolPath="$(DittoPath)"
+			DittoPath="$(DittoPath)"
 			Source="$(_NativeWatchApp)"
 			Destination="$(_AppBundlePath)_WatchKitStub\WK"
 		/>

msbuild/Xamarin.Shared/Xamarin.iOS.Common.targets

@@ -371,8 +371,7 @@ Copyright (C) 2013-2016 Xamarin. All rights reserved.
 		<Ditto
 			SessionId="$(BuildSessionId)"
 			Condition="'$(IsMacEnabled)' == 'true' And '@(_ResolvedWatchAppReferences)' != '' And '%(_ResolvedWatchAppReferences.Identity)' != ''"
-			ToolExe="$(DittoExe)"
-			ToolPath="$(DittoPath)"
+			DittoPath="$(DittoPath)"
 			Source="@(_ResolvedWatchAppReferences)"
 			Destination="$(_AppBundlePath)Watch\%(_ResolvedWatchAppReferences.FileName)%(_ResolvedWatchAppReferences.Extension)"
 		/>
@@ -391,8 +390,7 @@ Copyright (C) 2013-2016 Xamarin. All rights reserved.
 		<Ditto
 			SessionId="$(BuildSessionId)"
 			Condition="'$(IsMacEnabled)' == 'true'"
-			ToolExe="$(DittoExe)"
-			ToolPath="$(DittoPath)"
+			DittoPath="$(DittoPath)"
 			Source="$(AppBundleDir)"
 			Destination="$(_IpaAppBundleDir)"
 		/>
@@ -481,8 +479,7 @@ Copyright (C) 2013-2016 Xamarin. All rights reserved.
 		<Ditto
 			SessionId="$(BuildSessionId)"
 			Condition="'$(IsMacEnabled)' == 'true' And Exists('$(DeviceSpecificOutputPath)OnDemandResources\')"
-			ToolExe="$(DittoExe)"
-			ToolPath="$(DittoPath)"
+			DittoPath="$(DittoPath)"
 			Source="$(DeviceSpecificOutputPath)OnDemandResources\"
 			Destination="$(_IntermediateODRDir)"
 			/>