Raise Error APT2265 If the Asset Path is Invalid

src/Xamarin.Android.Build.Tasks/Tasks/Aapt2.cs

@@ -22,7 +22,6 @@ namespace Xamarin.Android.Tasks {
 	public abstract class Aapt2 : AsyncTask {
 
 		private const int MAX_PATH = 260;
-		private const int ASCII_MAX_CHAR = 127;
 		private static readonly int DefaultMaxAapt2Daemons = 6;
 		protected Dictionary<string, string> _resource_name_case_map;
 
@@ -52,6 +51,17 @@ public abstract class Aapt2 : AsyncTask {
 		public static bool IsInvalidFilename (string path) =>
 			Path.GetFileName (path).StartsWith (".", StringComparison.Ordinal);
 
+		/// <summary>
+		/// Returns <see langword="true"/> if <paramref name="c"/> is an ASCII
+		/// character ([ U+0000..U+007F ]).
+		/// </summary>
+		/// <remarks>
+		/// Per http://www.unicode.org/glossary/#ASCII, ASCII is only U+0000..U+007F.
+		/// We cannot use Char.IsAscii cos we are .netstandard2.0
+		/// Source https://github.com/dotnet/runtime/blob/1d1bf92fcf43aa6981804dc53c5174445069c9e4/src/libraries/System.Private.CoreLib/src/System/Char.cs#L91
+		/// </remarks>
+		public static bool IsAscii(char c) => (uint)c <= '\x007f';
+
 		protected string ResourceDirectoryFullPath (string resourceDirectory)
 		{
 			return (Path.IsPathRooted (resourceDirectory) ? resourceDirectory : Path.Combine (WorkingDirectory, resourceDirectory)).TrimEnd ('\\');
@@ -226,13 +236,13 @@ static bool IsFilePathToLong (string filePath)
 			return false;
 		}
 
-		static bool IsPathOnlyASCII (string filePath)
+		static protected bool IsPathOnlyASCII (string filePath)
 		{
 			if (!OS.IsWindows)
 				return true;
 
 			foreach (var c in filePath)
-				if (c > ASCII_MAX_CHAR) // cannot use Char.IsAscii cos we are .netstandard2.0
+				if (!IsAscii (c))
 					return false;
 			return true;
 		}

src/Xamarin.Android.Build.Tasks/Tasks/Aapt2Link.cs

@@ -272,11 +272,16 @@ string [] GenerateCommandLineCommands (string ManifestFile, string currentAbi, s
 				}
 			}
 
+			var hasAssetsErrors = false;
 			// When adding Assets the first item found takes precedence.
-			// So we need to add the applicaiton Assets first.
+			// So we need to add the application Assets first.
 			if (!string.IsNullOrEmpty (AssetsDirectory)) {
 				var assetDir = GetFullPath (AssetsDirectory.TrimEnd ('\\'));
 				if (Directory.Exists (assetDir)) {
+					if (OS.IsWindows && !IsPathOnlyASCII (assetDir)) {
+						hasAssetsErrors = true;
+						LogCodedError ("APT2265", Properties.Resources.APT2265, assetDir);
+					}
 					cmd.Add ("-A");
 					cmd.Add (assetDir);
 				} else {
@@ -289,6 +294,11 @@ string [] GenerateCommandLineCommands (string ManifestFile, string currentAbi, s
 					var assetDir = GetFullPath (AdditionalAndroidAssetPaths [i].ItemSpec.TrimEnd ('\\'));
 					if (!string.IsNullOrWhiteSpace (assetDir)) {
 						if (Directory.Exists (assetDir)) {
+							if (OS.IsWindows && !IsPathOnlyASCII (assetDir)) {
+								hasAssetsErrors = true;
+								LogCodedError ("APT2265", Properties.Resources.APT2265, assetDir);
+								continue;
+							}
 							cmd.Add ("-A");
 							cmd.Add (GetFullPath (assetDir));
 						} else {
@@ -298,6 +308,10 @@ string [] GenerateCommandLineCommands (string ManifestFile, string currentAbi, s
 				}
 			}
 
+			if (hasAssetsErrors) {
+				return Array.Empty<string> ();
+			}
+
 			if (!string.IsNullOrEmpty (ProguardRuleOutput)) {
 				cmd.Add ("--proguard");
 				cmd.Add (GetFullPath (GetManifestRulesFile (manifestDir)));

src/Xamarin.Android.Build.Tasks/Tasks/Aapt2LinkAssetPack.cs

@@ -63,8 +63,13 @@ protected string[] GenerateCommandLineCommands (ITaskItem manifest, ITaskItem ou
 			cmd.Add ("--custom-package");
 			cmd.Add (PackageName);
 			foreach (var assetDirectory in AssetDirectories) {
+				var fullPath = GetFullPath (assetDirectory.ItemSpec);
+				if (OS.IsWindows && !IsPathOnlyASCII (fullPath)) {
+					LogCodedError ("APT2265", Properties.Resources.APT2265, fullPath);
+					continue;
+				}
 				cmd.Add ("-A");
-				cmd.Add (GetFullPath (assetDirectory.ItemSpec));
+				cmd.Add (fullPath);
 			}
 			cmd.Add ($"-o");
 			cmd.Add (GetFullPath (output.ItemSpec));

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/BuildAssetsTest.cs

@@ -133,6 +133,26 @@ public void CheckAssetsAreIncludedInAPK ()
 			}
 		}
 
+		[Test]
+		public void InvalidAssetDirectoryWithNonASCIIChars ()
+		{
+			var proj = new XamarinAndroidApplicationProject () {
+				ProjectName = "App1",
+				IsRelease = true,
+				OtherBuildItems = {
+					new AndroidItem.AndroidAsset ("Assets\\asset1.txt") {
+						TextContent = () => "Asset1",
+						Encoding = Encoding.ASCII,
+					},
+				},
+			};
+			using (var b = CreateApkBuilder (Path.Combine ("temp", "InvalidAssetDirectoryWithNonASCIIChars_Ümläüt", proj.ProjectName))) {
+				b.ThrowOnBuildFailure = false;
+				Assert.AreEqual (!IsWindows, b.Build (proj), $"{proj.ProjectName} should {(IsWindows ? "not " : "")}have built successfully.");
+				Assert.AreEqual (IsWindows, b.LastBuildOutput.ContainsText ("APT2265"), $"APT2265 should {(IsWindows ? "" : "not ")}have been raised.");
+			}
+		}
+
 		[Test]
 		public void FullPath ()
 		{

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/BuildTest.cs

@@ -659,7 +659,7 @@ public void BuildApplicationWithSpacesInPath ([Values (true, false)] bool enable
 				IsRelease = true,
 				AotAssemblies = true,
 				LinkTool = linkTool,
-				References = { new BuildItem ("ProjectReference", $"..\\{folderName}Library1\\Library1.csproj") }
+				References = { new BuildItem ("ProjectReference", $"..\\{folderName}Library1\\Library1.csproj") },
 			};
 			proj.OtherBuildItems.Add (new BuildItem ("AndroidJavaLibrary", "Hello (World).jar") { BinaryContent = () => Convert.FromBase64String (@"
 UEsDBBQACAgIAMl8lUsAAAAAAAAAAAAAAAAJAAQATUVUQS1JTkYv/soAAAMAUEsHCAAAAAACAAAAA