[WIP] runtime pack library dirs discovery

Author: grendello

src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.AssemblyResolution.targets

@@ -12,6 +12,7 @@ _ResolveAssemblies MSBuild target.
 
   <UsingTask TaskName="Xamarin.Android.Tasks.ProcessAssemblies"      AssemblyFile="$(_XamarinAndroidBuildTasksAssembly)" />
   <UsingTask TaskName="Xamarin.Android.Tasks.ProcessNativeLibraries" AssemblyFile="$(_XamarinAndroidBuildTasksAssembly)" />
+  <UsingTask TaskName="Xamarin.Android.Tasks.ProcessRuntimePackLibraryDirectories" AssemblyFile="$(_XamarinAndroidBuildTasksAssembly)" />
   <UsingTask TaskName="Xamarin.Android.Tasks.StripNativeLibraries" AssemblyFile="$(_XamarinAndroidBuildTasksAssembly)" />
 
   <!-- HACK: workaround for: https://github.com/dotnet/sdk/issues/25679 -->
@@ -114,8 +115,19 @@ _ResolveAssemblies MSBuild target.
       <Output TaskParameter="TargetOutputs" ItemName="ResolvedFileToPublish" />
     </MSBuild>
 
+    <!-- This must be done as early as possible, so the runtime libraries location is known to all
+         the tasks that need it and so that the shared library files that are never to be packaged
+         are never taken into consideration in any context.
+    -->
+    <ProcessRuntimePackLibraryDirectories
+        Condition=" '$(_AndroidRuntime)' != 'NativeAOT' "
+        ResolvedFilesToPublish="@(ResolvedFileToPublish)">
+      <Output TaskParameter="RuntimePackLibraryDirectories" ItemName="_RuntimePackLibraryDirectory" />
+      <Output TaskParameter="NativeLibrariesToRemove" ItemName="_NativeLibraryToRemove" />
+    </ProcessRuntimePackLibraryDirectories>
+
     <ItemGroup>
-      <ResolvedFileToPublish Include="@(_AddSharedLibrariesClrHack)" />
+      <ResolvedFileToPublish Remove="@(_NativeLibraryToRemove)" />
     </ItemGroup>
 
     <!-- Properties produced by the inner build in Microsoft.Android.Sdk.ILLink.targets -->
@@ -131,10 +143,6 @@ _ResolveAssemblies MSBuild target.
       <_ResolvedJavaLibraries Include="@(ResolvedFileToPublish)" Condition=" '%(ResolvedFileToPublish.Extension)' == '.jar' " />
     </ItemGroup>
 
-    <ItemGroup>
-      <ResolvedFileToPublish Remove="@(_ResolvedArchiveDSOStub)" />
-    </ItemGroup>
-
     <!-- All assemblies must be per-RID, thus no `->Distinct()` on `InputAssemblies` or `ResolvedSymbols` items -->
     <ProcessAssemblies
         RuntimeIdentifiers="@(_RIDs)"

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

@@ -0,0 +1,101 @@
+#nullable enable
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+
+using Microsoft.Build.Utilities;
+using Microsoft.Build.Framework;
+using Microsoft.Android.Build.Tasks;
+
+namespace Xamarin.Android.Tasks;
+
+public class ProcessRuntimePackLibraryDirectories : AndroidTask
+{
+	public override string TaskPrefix => "FRPLD";
+
+	static readonly HashSet<string> NativeLibraryNames = new (StringComparer.OrdinalIgnoreCase) {
+		"libarchive-dso-stub.so",
+		"libc.so",
+		"libdl.so",
+		"liblog.so",
+		"libm.so",
+		"libz.so",
+	};
+
+	[Required]
+	public ITaskItem[] ResolvedFilesToPublish { get; set; } = Array.Empty<ITaskItem> ();
+
+	[Output]
+	public ITaskItem[] RuntimePackLibraryDirectories { get; set; } = Array.Empty<ITaskItem> ();
+
+	[Output]
+	public ITaskItem[] NativeLibrariesToRemove { get; set; }  = Array.Empty<ITaskItem> ();
+
+	public override bool RunTask ()
+	{
+		var libDirs = new List<ITaskItem> ();
+		var librariesToRemove = new List<ITaskItem> ();
+		var seenRIDs = new HashSet<string> (StringComparer.OrdinalIgnoreCase);
+
+		foreach (ITaskItem item in ResolvedFilesToPublish) {
+			if (!IsInSupportedRuntimePack (item)) {
+				continue;
+			}
+
+			string? fileName = Path.GetFileName (item.ItemSpec);
+			if (String.IsNullOrEmpty (fileName) || !NativeLibraryNames.Contains (fileName)) {
+				continue;
+			}
+
+			string? rid = item.GetMetadata ("RuntimeIdentifier");
+			if (String.IsNullOrEmpty (rid)) {
+				Log.LogDebugMessage ($"Ignoring item '{item}' because it contains no runtime identifier metadata");
+				continue;
+			}
+
+			if (!seenRIDs.Contains (rid)) {
+				string? dirName = Path.GetDirectoryName (item.ItemSpec);
+				if (String.IsNullOrEmpty (dirName)) {
+					Log.LogDebugMessage ($"Item '{item}' path doesn't contain full file path");
+				} else {
+					libDirs.Add (MakeLibDirItem (item, dirName));
+				}
+				seenRIDs.Add (rid);
+				Log.LogDebugMessage ($"Discovered runtime pack library directory for '{rid}': {dirName}");
+			}
+
+			librariesToRemove.Add (item);
+			Log.LogDebugMessage ($"Item '{item}' will be removed from the set of native libraries to publish");
+		}
+
+		RuntimePackLibraryDirectories = libDirs.ToArray ();
+		NativeLibrariesToRemove = librariesToRemove.ToArray ();
+
+		return !Log.HasLoggedErrors;
+	}
+
+	ITaskItem MakeLibDirItem (ITaskItem sourceItem, string dir)
+	{
+		var ret = new TaskItem (dir);
+		sourceItem.CopyMetadataTo (ret);
+
+		// These make no sense for directories, remove just to be safe
+		ret.RemoveMetadata ("CopyLocal");
+		ret.RemoveMetadata ("CopyToPublishDirectory");
+		ret.RemoveMetadata ("DestinationSubPath");
+		ret.RemoveMetadata ("RelativePath");
+		return ret;
+	}
+
+	bool IsInSupportedRuntimePack (ITaskItem item)
+	{
+		string? NuGetPackageId = item.GetMetadata ("NuGetPackageId");
+		if (String.IsNullOrEmpty (NuGetPackageId)) {
+			return false;
+		}
+
+		return NuGetPackageId.StartsWith ("Microsoft.Android.Runtime.CoreCLR.", StringComparison.OrdinalIgnoreCase) ||
+		       NuGetPackageId.StartsWith ("Microsoft.Android.Runtime.Mono.", StringComparison.OrdinalIgnoreCase);
+	}
+}