[build] Remove unused System.IO.Hashing from runtime packs and build tasks

build-tools/create-packs/Microsoft.Android.Runtime.Managed.proj

@@ -47,11 +47,6 @@ projects that use the Microsoft.Android framework in .NET 6+.
       <_AndroidRuntimePackAssemblies Include="$(_MonoAndroidNETDefaultOutDir)Java.Interop.dll" />
       <_AndroidRuntimePackAssemblies Include="$(_MonoAndroidNETDefaultOutDir)Mono.Android.dll" />
       <_AndroidRuntimePackAssemblies Include="$(_MonoAndroidNETDefaultOutDir)Mono.Android.Runtime.dll" />
-      <!-- Always include a stable version of System.IO.Hashing. -->
-      <_AndroidRuntimePackAssemblies
-          Include="$(_MonoAndroidNETOutputRoot)$(AndroidLatestStableApiLevel)\System.IO.Hashing.dll"
-          NoSymbols="true"
-      />
     </ItemGroup>
 
     <ItemGroup>

src/Microsoft.Android.Runtime.NativeAOT/Microsoft.Android.Runtime.NativeAOT.csproj

@@ -21,10 +21,6 @@
     <ProjectReference Include="..\Mono.Android\Mono.Android.csproj" />
   </ItemGroup>
 
-  <ItemGroup>
-    <PackageReference Include="System.IO.Hashing" Version="$(SystemIOHashingPackageVersion)" />
-  </ItemGroup>
-
   <Import Project="Sdk.targets" Sdk="Microsoft.NET.Sdk" />
 
   <!-- Copy runtime assemblies to bin/$(Configuration)/dotnet/packs folder -->

src/Mono.Android/Mono.Android.csproj

@@ -390,7 +390,6 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="System.IO.Hashing" Version="$(SystemIOHashingPackageVersion)" />
     <PackageReference Include="Microsoft.CodeAnalysis.PublicApiAnalyzers" Version="5.6.0">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
@@ -432,7 +431,6 @@
       <_RefExtras Include="$(OutputPath)*.*" Exclude="$(OutputPath)*.dll" />
       <_SourceFiles Include="$(OutputPath)Mono.Android.*" />
       <_SourceFiles Include="$(OutputPath)Java.Interop.*" />
-      <_SourceFiles Include="$(OutputPath)System.IO.Hashing.dll" />
     </ItemGroup>
     <Copy
         SourceFiles="@(_RefExtras)"

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.ProjectTools/Xamarin.ProjectTools.csproj

@@ -26,7 +26,6 @@
     </Content>
   </ItemGroup>
   <ItemGroup>
-    <PackageReference Include="System.IO.Hashing" Version="$(SystemIOHashingPackageVersion)" />
     <ProjectReference Include="..\..\..\Xamarin.Android.Tools.AndroidSdk\Xamarin.Android.Tools.AndroidSdk.csproj">
       <Project>{E34BCFA0-CAA4-412C-AA1C-75DB8D67D157}</Project>
       <Name>Xamarin.Android.Tools.AndroidSdk</Name>

src/Xamarin.Android.Build.Tasks/Utilities/AssemblyStoreGenerator.cs

@@ -2,6 +2,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.IO.Hashing;
 
 using Microsoft.Android.Build.Tasks;
 using Microsoft.Build.Utilities;
@@ -140,8 +141,8 @@ string Generate (string baseOutputDirectory, AndroidTargetArch arch, List<Assemb
 				throw new InvalidOperationException ($"Internal error: corrupted store '{storePath}' stream");
 			}
 
-			uint name_with_ext_hash = TypeMapHelper.HashBytesForCLR (info.AssemblyNameBytes);
-			uint name_no_ext_hash = TypeMapHelper.HashBytesForCLR (info.AssemblyNameNoExtBytes);
+			uint name_with_ext_hash = HashAssemblyName (info.AssemblyNameBytes);
+			uint name_no_ext_hash = HashAssemblyName (info.AssemblyNameNoExtBytes);
 			index.Add (new AssemblyStoreIndexEntry (info.AssemblyName, name_with_ext_hash, entryIndex, info.Ignored));
 			index.Add (new AssemblyStoreIndexEntry (info.AssemblyNameNoExt, name_no_ext_hash, entryIndex, info.Ignored));
 
@@ -285,4 +286,13 @@ void WriteNames (BinaryWriter writer, List<AssemblyStoreAssemblyInfo> infos)
 			writer.Write (info.AssemblyNameBytes);
 		}
 	}
+
+	static uint HashAssemblyName (ReadOnlySpan<byte> bytes)
+	{
+		if (bytes.Length == 0) {
+			return UInt32.MaxValue;
+		}
+
+		return Crc32.HashToUInt32 (bytes);
+	}
 }

src/Xamarin.Android.Build.Tasks/Utilities/CoreClrBootstrapBuilder.cs

@@ -2,6 +2,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.IO.Hashing;
 
 using Java.Interop.Tools.TypeNameMappings;
 using Microsoft.Android.Build.Tasks;
@@ -66,7 +67,7 @@ public byte [] Create ()
 	{
 		var state = CreateDsoCache ();
 		foreach (var entry in state.Entries) {
-			entry.Hash = TypeMapHelper.HashNameForCLR (entry.HashedName);
+			entry.Hash = HashLibraryName (entry.HashedName);
 		}
 		state.Entries.Sort ((a, b) => a.Hash.CompareTo (b.Hash));
 
@@ -206,4 +207,13 @@ static ICollection<string> MakeJniPreloadIgnoreCollection (TaskLoggingHelper log
 		}
 		return name;
 	}
+
+	static uint HashLibraryName (string name)
+	{
+		if (name.Length == 0) {
+			return UInt32.MaxValue;
+		}
+
+		return Crc32.HashToUInt32 (MonoAndroidHelper.Utf8StringToBytes (name));
+	}
 }

src/Xamarin.Android.Build.Tasks/Utilities/MibcProfileWriter.cs

@@ -4,11 +4,11 @@
 using System.Collections.Generic;
 using System.IO;
 using System.IO.Compression;
-using System.IO.Hashing;
 using System.Reflection;
 using System.Reflection.Metadata;
 using System.Reflection.Metadata.Ecma335;
 using System.Reflection.PortableExecutable;
+using System.Security.Cryptography;
 using System.Text;
 
 namespace Xamarin.Android.Tasks;
@@ -557,22 +557,8 @@ void WritePE (string outputPath, BlobContentId contentId)
 	/// </param>
 	static BlobContentId ContentId (string fingerprint)
 	{
-		// This is only a content fingerprint, so a non cryptographic hash is fine, and unlike
-		// System.Security.Cryptography the System.IO.Hashing APIs are span based on netstandard2.0.
-		int byteCount = Encoding.UTF8.GetByteCount (fingerprint);
-		Span<byte> bytes = byteCount <= TypeMapHelper.StackallocThresholdBytes
-			? stackalloc byte [byteCount]
-			: new byte [byteCount];
-		TypeMapHelper.GetBytes (fingerprint, Encoding.UTF8, bytes);
-
-		// BlobContentId.FromHash turns hash bytes into an MVID and timestamp for us, including the
-		// RFC 4122 version and variant bits and the byte order of the Guid fields.  It reads 20
-		// bytes: 0..16 become the MVID and 16..20 become the timestamp.  XxHash128 only produces
-		// 16, so the timestamp slot repeats the first four rather than hashing the input again.
-		// This cannot be a stackalloc: FromHash only overloads on byte[] and ImmutableArray<byte>.
-		var hash = new byte [20];
-		XxHash128.Hash (bytes, hash.AsSpan (0, 16));
-		hash.AsSpan (0, 4).CopyTo (hash.AsSpan (16));
+		using var sha256 = SHA256.Create ();
+		byte[] hash = sha256.ComputeHash (Encoding.UTF8.GetBytes (fingerprint));
 		return BlobContentId.FromHash (hash);
 	}
 }

src/Xamarin.Android.Build.Tasks/Utilities/MonoAndroidHelper.Basic.cs

@@ -2,7 +2,6 @@
 using System;
 using System.Collections.Generic;
 using System.Globalization;
-using System.IO.Hashing;
 using System.Text;
 
 using Xamarin.Android.Tools;
@@ -218,18 +217,6 @@ public static string MakeDiscreteAssembliesEntryName (string name, string? cultu
 	}
 
 	public static byte[] Utf8StringToBytes (string str) => Encoding.UTF8.GetBytes (str);
-	public static byte[] Utf16StringToBytes (string str) => Encoding.Unicode.GetBytes (str);
-
-	public static ulong GetXxHash (string str, bool is64Bit) => GetXxHash (Utf8StringToBytes (str), is64Bit);
-
-	public static ulong GetXxHash (byte[] stringBytes, bool is64Bit)
-	{
-		if (is64Bit) {
-			return XxHash3.HashToUInt64 (stringBytes);
-		}
-
-		return (ulong)XxHash32.HashToUInt32 (stringBytes);
-	}
 
 	/// <summary>
 	/// Helper method to compare two strings with specified comparison mode.

src/native/clr/include/runtime-base/crc32.hh

@@ -14,7 +14,7 @@ namespace xamarin::android {
 	{
 		// An empty input deliberately maps to UINT32_MAX rather than to the standard CRC32 of the
 		// empty string (0). This is a sentinel that must stay in lockstep with the managed generators
-		// (TypeMapHelper.HashNameForCLR / HashBytesForCLR, which likewise special-case a zero-length
+		// (AssemblyStoreGenerator and CoreClrBootstrapBuilder, which likewise special-case a zero-length
 		// input to UInt32.MaxValue); the build-time and runtime hashes must agree, so do not "fix"
 		// this to 0.
 		if (len == 0) [[unlikely]] {

tools/tmt/XamarinAppReleaseDSO_V2.cs

@@ -5,7 +5,6 @@
 using System.Text;
 
 using ELFSharp.ELF.Sections;
-using Xamarin.Android.Tasks;
 
 namespace tmt;
 
@@ -353,7 +352,7 @@ List<string> LoadJavaTypeNames (string filePath)
 
 			ret.Add (name ?? String.Empty);
 
-			ulong hash = TypeMapHelper.HashJavaName (name ?? String.Empty, Is64Bit);
+			ulong hash = HashJavaName (name ?? String.Empty, Is64Bit);
 			int javaTypeIndex = javaTypeNameHashes!.IndexOf (hash);
 
 			if (javaTypeIndex < 0) {
@@ -537,4 +536,24 @@ string GetJavaTypeName (TypeMapJava tmj)
 	}
 
 	string HashToHexString (ulong hash) => Is64Bit ? $"{hash:X16}" : $"{hash:X8}";
+
+	static ulong HashJavaName (string name, bool is64Bit)
+	{
+		if (name.Length == 0) {
+			return UInt64.MaxValue;
+		}
+
+		const int StackallocThresholdBytes = 256;
+		int byteCount = Encoding.Unicode.GetByteCount (name);
+		Span<byte> buffer = byteCount <= StackallocThresholdBytes
+			? stackalloc byte [byteCount]
+			: new byte [byteCount];
+		Encoding.Unicode.GetBytes (name.AsSpan (), buffer);
+
+		if (is64Bit) {
+			return XxHash3.HashToUInt64 (buffer);
+		}
+
+		return (ulong)XxHash32.HashToUInt32 (buffer);
+	}
 }

tools/tmt/tmt.csproj

@@ -8,13 +8,11 @@
     <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
     <OutputPath>../../bin/$(Configuration)/bin/typemap-tool</OutputPath>
     <OutputType>Exe</OutputType>
-    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <Nullable>enable</Nullable>
     <RollForward>Major</RollForward>
   </PropertyGroup>
 
   <ItemGroup>
-    <Compile Include="../../src/Xamarin.Android.Build.Tasks/Utilities/TypeMapHelper.cs" />
     <Compile Include="..\..\.github\skills\read-assembly-store\src\AssemblyStore\V1\*.cs" />
     <Compile Include="..\..\.github\skills\read-assembly-store\src\AssemblyStore\AssemblyCompression.cs" />
   </ItemGroup>