[Xamarin.Android.Build.Utilities] Xamarin can't use NDK 12b as ndk-stack.exe is now ndk-stack.cmd (#188)

Fixes https://bugzilla.xamarin.com/show_bug.cgi?id=42566

The problem was that we did not UPDATE the ndk-stack.exe property
to be ndk-stack.cmd once we had verified that the ndk was valid.
Seeing as this is not the first time google has changed an extension
on a executable we need to do some re-work on these classes.

Firstly we'll default all the values to the 'unix' ones. We will
then use the new Executables method to search for the other exe's
on initalization and update the properties accordinly.

However because some of the files (the java related ones) are in
other paths (like build-tools/x.x.x.x) we will override those
on windows to give them the exepcted .exe extension.

Author: dellis1972

src/Xamarin.Android.Build.Utilities/Sdks/AndroidSdkBase.cs

@@ -34,18 +34,18 @@ public string[] AllAndroidNdks {
 		public string AndroidToolsPathShort { get; private set; }
 		public string AndroidPlatformToolsPathShort { get; private set; }
 
-		public abstract string Adb { get; }
-		public abstract string Android { get; }
-		public abstract string Emulator { get; }
-		public abstract string Monitor { get; }
-		public abstract string ZipAlign { get; }
-		public abstract string JarSigner { get; }
-		public abstract string KeyTool { get; }
-
-		public abstract string NdkStack { get; }
+		public virtual string Adb { get; protected set; } = "adb";
+		public virtual string Android { get; protected set; } = "android";
+		public virtual string Emulator { get; protected set; } = "emulator";
+		public virtual string Monitor { get; protected set; } = "monitor";
+		public virtual string ZipAlign { get; protected set; } = "zipalign";
+		public virtual string JarSigner { get; protected set; } = "jarsigner";
+		public virtual string KeyTool { get; protected set; } = "keytool";
+
+		public virtual string NdkStack { get; protected set; } = "ndk-stack";
 		public abstract string NdkHostPlatform32Bit { get; }
 		public abstract string NdkHostPlatform64Bit { get; }
-		public abstract string Javac { get; }
+		public virtual string Javac { get; protected set; } = "javac";
 
 		public abstract string PreferedAndroidSdkPath { get; }
 		public abstract string PreferedAndroidNdkPath { get; }
@@ -81,6 +81,13 @@ public virtual void Initialize (string androidSdkPath = null, string androidNdkP
 				IsNdk64Bit = Directory.EnumerateDirectories (toolchainsDir, "arm-linux-androideabi-*")
 					.Any (dir => Directory.Exists (Path.Combine (dir, "prebuilt", NdkHostPlatform64Bit)));
 			}
+			// we need to look for extensions other than the default .exe|.bat
+			// google have a habbit of changing them.
+			Adb = GetExecutablePath (AndroidPlatformToolsPath, Adb);
+			Android = GetExecutablePath (AndroidToolsPath, Android);
+			Emulator = GetExecutablePath (AndroidToolsPath, Emulator);
+			Monitor = GetExecutablePath (AndroidToolsPath, Monitor);
+			NdkStack = GetExecutablePath (AndroidNdkPath, NdkStack);
 		}
 
 		protected abstract IEnumerable<string> GetAllAvailableAndroidSdks ();
@@ -119,26 +126,40 @@ public virtual bool ValidateJavaSdkLocation (string loc)
 		/// </summary>
 		public bool ValidateAndroidNdkLocation (string loc)
 		{
-			return !string.IsNullOrEmpty (loc) && File.Exists (Path.Combine (loc, NdkStack));
+			return !string.IsNullOrEmpty (loc) && FindExecutableInDirectory(NdkStack, loc).Any();
 		}
 
 		protected IEnumerable<string> FindExecutableInPath (string executable)
 		{
 			var path = Environment.GetEnvironmentVariable ("PATH");
 			var pathDirs = path.Split (new char[] { Path.PathSeparator }, StringSplitOptions.RemoveEmptyEntries);
-			var pathExt = Environment.GetEnvironmentVariable ("PATHEXT");
-			var pathExts = pathExt?.Split (new char [] { Path.PathSeparator }, StringSplitOptions.RemoveEmptyEntries);
 
 			foreach (var dir in pathDirs) {
-				if (File.Exists (Path.Combine (dir, (executable))))
-					yield return dir;
-				if (pathExts == null)
-					continue;
-				foreach (var ext in pathExts)
-					if (File.Exists (Path.Combine (dir, Path.ChangeExtension (executable, ext))))
-						yield return dir;
+				foreach (var directory in FindExecutableInDirectory(executable, dir)) {
+					yield return directory;
+				}
 			}
 		}
+		
+		protected IEnumerable<string> FindExecutableInDirectory(string executable, string dir)
+		{			
+			foreach (var exe in Executables (executable))
+				if (File.Exists (Path.Combine (dir, exe)))
+					yield return dir;
+		}
+
+		IEnumerable<string> Executables (string executable)
+		{
+			yield return executable;
+			var pathExt = Environment.GetEnvironmentVariable ("PATHEXT");
+			var pathExts = pathExt?.Split (new char [] { Path.PathSeparator }, StringSplitOptions.RemoveEmptyEntries);
+
+			if (pathExts == null)
+				yield break;
+
+			foreach (var ext in pathExts)
+				yield return Path.ChangeExtension (executable, ext);
+		}
 
 		protected string NullIfEmpty (string s)
 		{
@@ -147,6 +168,14 @@ protected string NullIfEmpty (string s)
 
 			return null;
 		}
+
+		string GetExecutablePath (string dir, string exe)
+		{
+			foreach (var e in Executables (exe))
+				if (File.Exists (Path.Combine (dir, e)))
+					return e;
+			return exe;
+		}
 	}
 }
 

src/Xamarin.Android.Build.Utilities/Sdks/AndroidSdkUnix.cs

@@ -8,24 +8,13 @@ namespace Xamarin.Android.Build.Utilities
 {
 	class AndroidSdkUnix : AndroidSdkBase
 	{
-		public override string Adb { get { return "adb"; } }
-		public override string Android { get { return "android"; } }
-		public override string Emulator { get { return "emulator"; } }
-		public override string Monitor { get { return "monitor"; } }
-		public override string ZipAlign { get { return "zipalign"; } }
-		public override string JarSigner { get { return "jarsigner"; } }
-		public override string KeyTool { get { return "keytool"; } }
-		public override string NdkStack { get { return "ndk-stack"; } }
-
 		public override string NdkHostPlatform32Bit {
 			get { return OS.IsMac ? "darwin-x86" : "linux-x86"; }
 		}
 		public override string NdkHostPlatform64Bit {
 			get { return OS.IsMac ? "darwin-x86_64" : "linux-x86_64"; }
 		}
 
-		public override string Javac { get { return "javac"; } }
-
 		public override string PreferedAndroidSdkPath { 
 			get {
 				var config_file = GetUnixConfigFile ();

src/Xamarin.Android.Build.Utilities/Sdks/AndroidSdkWindows.cs

@@ -15,17 +15,13 @@ class AndroidSdkWindows : AndroidSdkBase
 		const string XAMARIN_ANDROID_INSTALLER_PATH = @"SOFTWARE\Xamarin\MonoAndroid";
 		const string XAMARIN_ANDROID_INSTALLER_KEY = "PrivateAndroidSdkPath";
 
-		public override string Adb { get { return "adb.exe"; } }
-		public override string Android { get { return "android.bat"; } }
-		public override string Emulator { get { return "emulator.exe"; } }
-		public override string Monitor { get { return "monitor.bat"; } }
-		public override string ZipAlign { get { return "zipalign.exe"; } }
-		public override string JarSigner { get { return "jarsigner.exe"; } }
-		public override string KeyTool { get { return "keytool.exe"; } }
-		public override string NdkStack { get { return "ndk-stack.exe"; } }
+		public override string ZipAlign { get; protected set; } = "zipalign.exe";
+		public override string JarSigner { get; protected set; } = "jarsigner.exe";
+		public override string KeyTool { get; protected set; } = "keytool.exe";
+
 		public override string NdkHostPlatform32Bit { get { return "windows"; } }
 		public override string NdkHostPlatform64Bit { get { return "windows-x86_64"; } }
-		public override string Javac { get { return "javac.exe"; } }
+		public override string Javac { get; protected set; } = "javac.exe";
 
 		public override string PreferedAndroidSdkPath {
 			get {