[Build] Move aapt2 download from xaprepare to MSBuild target

Configuration.props

@@ -108,17 +108,11 @@
     <AllSupported32BitTargetAndroidAbis>armeabi-v7a;x86</AllSupported32BitTargetAndroidAbis>
     <AllSupported64BitTargetAndroidAbis>arm64-v8a;x86_64</AllSupported64BitTargetAndroidAbis>
     <AllSupportedTargetAndroidAbis>$(AllSupported32BitTargetAndroidAbis);$(AllSupported64BitTargetAndroidAbis)</AllSupportedTargetAndroidAbis>
-    <!--
-      For some reason, the URL for platform-tools/build-tools 32.0.0 is prefixed with what appears to be a GIT commit hash or some other checksum...
-      Linux packages don't have any prefix, but this forces us to have *some* mechanism to handle this...
-    -->
-    <XABuildToolsPackagePrefixMacOS></XABuildToolsPackagePrefixMacOS>
-    <XABuildToolsPackagePrefixWindows></XABuildToolsPackagePrefixWindows>
-    <XABuildToolsPackagePrefixLinux></XABuildToolsPackagePrefixLinux>
-    <XABuildToolsPackagePrefix Condition=" '$(HostOS)' == 'Darwin' ">$(XABuildToolsPackagePrefixMacOS)</XABuildToolsPackagePrefix>
-    <XABuildToolsPackagePrefix Condition=" '$(HostOS)' == 'Windows' ">$(XABuildToolsPackagePrefixWindows)</XABuildToolsPackagePrefix>
     <XABuildToolsVersion>36</XABuildToolsVersion>
     <XABuildToolsFolder Condition="'$(XABuildToolsFolder)' == ''">36.0.0</XABuildToolsFolder>
+    <XABuildToolsHashMacOS>04E7F3A72044DE4926FA038FA0E251A37BBA1E1C3FB8BEAB6F8401BFD9EB4BF3</XABuildToolsHashMacOS>
+    <XABuildToolsHashLinux>5D9AC77FB6FF43D9DA518A337B4FCF8F9097113DF531D99CCEFE80EF7CE8250B</XABuildToolsHashLinux>
+    <XABuildToolsHashWindows>AA1095CB14D83E483818A748A2C06FAAEB8E601561B06A356A119A1B2CA280D3</XABuildToolsHashWindows>
     <XAPlatformToolsPackagePrefix Condition=" '$(HostOS)' == 'Darwin' "></XAPlatformToolsPackagePrefix>
     <XAPlatformToolsVersion>36.0.0</XAPlatformToolsVersion>
     <XABundleToolVersion Condition="'$(XABundleToolVersion)' == ''">1.18.3</XABundleToolVersion>

build-tools/xaprepare/xaprepare/Application/Context.cs

@@ -292,11 +292,6 @@ public string DebugFileExtension {
 		/// </summary>
 		public string? LocalDotNetSdkArchive { get; set; }
 
-		/// <summary>
-		///   Set by <see cref="Step_Get_Android_BuildTools"/> if the archive has been downloaded and validated.
-		/// </summary>
-		public bool BuildToolsArchiveDownloaded { get; set; }
-
 		/// <summary>
 		///   Determines whether or not we are running on a hosted azure pipelines agent.
 		///   These agents have certain limitations, the most pressing being the amount of available storage.

build-tools/xaprepare/xaprepare/Application/KnownProperties.cs

@@ -53,10 +53,6 @@ static class KnownProperties
 		public const string TestOutputDirectory                 = "TestOutputDirectory";
 		public const string XABuildToolsFolder                  = "XABuildToolsFolder";
 		public const string XABuildToolsVersion                 = "XABuildToolsVersion";
-		public const string XABuildToolsPackagePrefixMacOS      = "XABuildToolsPackagePrefixMacOS";
-		public const string XABuildToolsPackagePrefixWindows    = "XABuildToolsPackagePrefixWindows";
-		public const string XABuildToolsPackagePrefixLinux      = "XABuildToolsPackagePrefixLinux";
-		public const string XABuildToolsPackagePrefix           = "XABuildToolsPackagePrefix";
 		public const string XABinRelativeInstallPrefix          = "XABinRelativeInstallPrefix";
 		public const string XAInstallPrefix                     = "XAInstallPrefix";
 		public const string XAPackagesDir                       = "XAPackagesDir";

build-tools/xaprepare/xaprepare/Application/Properties.Defaults.cs.in

@@ -57,10 +57,6 @@ namespace Xamarin.Android.Prepare
 			properties.Add (KnownProperties.TestOutputDirectory,                 StripQuotes (@"@TestOutputDirectory@"));
 			properties.Add (KnownProperties.XABuildToolsFolder,                  StripQuotes (@"@XABuildToolsFolder@"));
 			properties.Add (KnownProperties.XABuildToolsVersion,                 StripQuotes ("@XABuildToolsVersion@"));
-			properties.Add (KnownProperties.XABuildToolsPackagePrefixMacOS,      StripQuotes ("@XABuildToolsPackagePrefixMacOS@"));
-			properties.Add (KnownProperties.XABuildToolsPackagePrefixWindows,    StripQuotes ("@XABuildToolsPackagePrefixWindows@"));
-			properties.Add (KnownProperties.XABuildToolsPackagePrefixLinux,      StripQuotes ("@XABuildToolsPackagePrefixLinux@"));
-			properties.Add (KnownProperties.XABuildToolsPackagePrefix,           StripQuotes ("@XABuildToolsPackagePrefix@"));
 			properties.Add (KnownProperties.XABinRelativeInstallPrefix,          StripQuotes (@"@XABinRelativeInstallPrefix@"));
 			properties.Add (KnownProperties.XAInstallPrefix,                     StripQuotes (@"@XAInstallPrefix@"));
 			properties.Add (KnownProperties.XAPackagesDir,                       StripQuotes (@"@XAPackagesDir@"));

build-tools/xaprepare/xaprepare/ConfigAndData/Dependencies/AndroidToolchain.cs

@@ -25,7 +25,6 @@ public AndroidToolchain ()
 			string EmulatorPkgRevision     = GetRequiredProperty (KnownProperties.EmulatorPkgRevision);
 			string XABuildToolsFolder      = GetRequiredProperty (KnownProperties.XABuildToolsFolder);
 			string XABuildToolsVersion         = GetRequiredProperty (KnownProperties.XABuildToolsVersion);
-			string XABuildToolsPackagePrefix   = Context.Instance.Properties [KnownProperties.XABuildToolsPackagePrefix] ?? String.Empty;
 			string XAPlatformToolsVersion  = GetRequiredProperty (KnownProperties.XAPlatformToolsVersion);
 			string XAPlatformToolsPackagePrefix = Context.Instance.Properties [KnownProperties.XAPlatformToolsPackagePrefix] ?? String.Empty;
 			bool isArm64Apple = Context.Instance.OS.Flavor == "macOS" && RuntimeInformation.OSArchitecture == Architecture.Arm64;
@@ -107,7 +106,7 @@ public AndroidToolchain ()
 					buildToolName: $"android-ndk-r{AndroidNdkVersion}",
 					buildToolVersion: AndroidPkgRevision
 				),
-				new AndroidToolchainComponent ($"{XABuildToolsPackagePrefix}build-tools_r{XABuildToolsVersion}_{altOsTag}",
+				new AndroidToolchainComponent ($"build-tools_r{XABuildToolsVersion}_{altOsTag}",
 					destDir: Path.Combine ("build-tools", XABuildToolsFolder),
 					isMultiVersion: true,
 					buildToolName: "android-sdk-build-tools",

build-tools/xaprepare/xaprepare/Scenarios/Scenario_Standard.cs

@@ -24,7 +24,6 @@ protected override void AddSteps (Context context)
 			Steps.Add (new Step_GenerateFiles (atBuildStart: true));
 			Steps.Add (new Step_PrepareProps ());
 			Steps.Add (new Step_GenerateCGManifest ());
-			Steps.Add (new Step_Get_Android_BuildTools ());
 		}
 
 		protected override void AddEndSteps (Context context)

build-tools/xaprepare/xaprepare/xaprepare.targets

@@ -91,10 +91,6 @@
       <Replacement Include="@TestOutputDirectory@=$(TestOutputDirectory)" />
       <Replacement Include="@XABuildToolsFolder@=$(XABuildToolsFolder)" />
       <Replacement Include="@XABuildToolsVersion@=$(XABuildToolsVersion)" />
-      <Replacement Include="@XABuildToolsPackagePrefixMacOS@=$(XABuildToolsPackagePrefixMacOS)" />
-      <Replacement Include="@XABuildToolsPackagePrefixWindows@=$(XABuildToolsPackagePrefixWindows)" />
-      <Replacement Include="@XABuildToolsPackagePrefixLinux@=$(XABuildToolsPackagePrefixLinux)" />
-      <Replacement Include="@XABuildToolsPackagePrefix@=$(XABuildToolsPackagePrefix)" />
       <Replacement Include="@XAPlatformToolsVersion@=$(XAPlatformToolsVersion)" />
       <Replacement Include="@XAInstallPrefix@=$(XAInstallPrefix)" />
       <Replacement Include="@XABinRelativeInstallPrefix@=$(_XABinRelativeInstallPrefix)" />

src/aapt2/aapt2.targets

@@ -3,29 +3,60 @@
     <Aapt2Version>4.0.0-6051327</Aapt2Version>
     <_Destination>$(MicrosoftAndroidSdkOutDir)</_Destination>
     <IntermediateOutputPath>obj\$(Configuration)\</IntermediateOutputPath>
+    <_AndroidRepositoryUrl>https://dl.google.com/android/repository/</_AndroidRepositoryUrl>
   </PropertyGroup>
 
+  <!--
+    Google's SDK manifest (repository2-3.xml) only provides SHA-1 checksums,
+    but MSBuild's GetFileHash task only supports SHA-256 and above.
+    So we hardcode SHA-256 hashes in Configuration.props instead.
+  -->
   <ItemGroup>
     <_BuildTools Include="build-tools_r$(XABuildToolsVersion)_macosx.zip">
       <Platform>osx</Platform>
       <HostOS>Darwin</HostOS>
+      <Hash>$(XABuildToolsHashMacOS)</Hash>
       <FilesToExtract>aapt2</FilesToExtract>
     </_BuildTools>
     <_BuildTools Include="build-tools_r$(XABuildToolsVersion)_linux.zip">
       <Platform>linux</Platform>
       <HostOS>Linux</HostOS>
+      <Hash>$(XABuildToolsHashLinux)</Hash>
       <FilesToExtract>aapt2</FilesToExtract>
     </_BuildTools>
     <_BuildTools Include="build-tools_r$(XABuildToolsVersion)_windows.zip">
       <Platform>windows</Platform>
       <HostOS></HostOS>
+      <Hash>$(XABuildToolsHashWindows)</Hash>
       <FilesToExtract>aapt2.exe</FilesToExtract>
     </_BuildTools>
   </ItemGroup>
 
   <UsingTask AssemblyFile="$(BootstrapTasksAssembly)" TaskName="Xamarin.Android.Tools.BootstrapTasks.UnzipDirectoryChildren" TaskFactory="TaskHostFactory" Runtime="NET" />
 
-  <Target Name="_ExtractAapt2" BeforeTargets="Build">
+  <Target Name="_DownloadBuildTools"
+      Inputs="$(MSBuildThisFileFullPath);$(MSBuildProjectFullPath);..\..\Configuration.props"
+      Outputs="$(AndroidToolchainCacheDirectory)\%(_BuildTools.Identity)">
+    <DownloadFile
+        SourceUrl="$(_AndroidRepositoryUrl)%(_BuildTools.Identity)"
+        DestinationFolder="$(AndroidToolchainCacheDirectory)"
+        DestinationFileName="%(_BuildTools.Identity)"
+        Retries="3"
+    />
+    <GetFileHash Files="$(AndroidToolchainCacheDirectory)\%(_BuildTools.Identity)" Algorithm="SHA256">
+      <Output TaskParameter="Hash" PropertyName="_ActualHash" />
+    </GetFileHash>
+    <Delete
+        Condition=" '$(_ActualHash)' != '%(_BuildTools.Hash)' "
+        Files="$(AndroidToolchainCacheDirectory)\%(_BuildTools.Identity)"
+    />
+    <Error
+        Condition=" '$(_ActualHash)' != '%(_BuildTools.Hash)' "
+        Text="SHA256 mismatch for %(_BuildTools.Identity). Expected: %(_BuildTools.Hash) Actual: $(_ActualHash)"
+    />
+  </Target>
+
+  <Target Name="_ExtractAapt2" BeforeTargets="Build" DependsOnTargets="_DownloadBuildTools">
     <UnzipDirectoryChildren
         NoSubdirectory="False"
         SourceFiles="$(AndroidToolchainCacheDirectory)\%(_BuildTools.Identity)"