[release/9.0-staging] Fix getting resource when ResourceResolve returns assembly with resource that is an assembly ref

src/coreclr/vm/peassembly.cpp

@@ -518,7 +518,6 @@ BOOL PEAssembly::GetResource(LPCSTR szName, DWORD *cbResource,
     }
     CONTRACTL_END;
 
-
     mdToken            mdLinkRef;
     DWORD              dwResourceFlags;
     DWORD              dwOffset;
@@ -567,30 +566,31 @@ BOOL PEAssembly::GetResource(LPCSTR szName, DWORD *cbResource,
     }
 
 
-    switch(TypeFromToken(mdLinkRef)) {
+    switch(TypeFromToken(mdLinkRef))
+    {
     case mdtAssemblyRef:
         {
             if (pAssembly == NULL)
                 return FALSE;
 
             AssemblySpec spec;
-            spec.InitializeSpec(mdLinkRef, GetMDImport(), pAssembly);
-            DomainAssembly* pDomainAssembly = spec.LoadDomainAssembly(FILE_LOADED);
+            spec.InitializeSpec(mdLinkRef, pAssembly->GetMDImport(), pAssembly);
+            Assembly* pLoadedAssembly = spec.LoadAssembly(FILE_LOADED);
 
             if (dwLocation) {
                 if (pAssemblyRef)
-                    *pAssemblyRef = pDomainAssembly->GetAssembly();
+                    *pAssemblyRef = pLoadedAssembly;
 
                 *dwLocation = *dwLocation | 2; // ResourceLocation.containedInAnotherAssembly
             }
 
-            return GetResource(szName,
-                                cbResource,
-                                pbInMemoryResource,
-                                pAssemblyRef,
-                                szFileName,
-                                dwLocation,
-                                pDomainAssembly->GetAssembly());
+            return pLoadedAssembly->GetResource(
+                        szName,
+                        cbResource,
+                        pbInMemoryResource,
+                        pAssemblyRef,
+                        szFileName,
+                        dwLocation);
         }
 
     case mdtFile:

src/tests/Loader/ResourceResolve/ManifestResourceAssemblyRef.il

@@ -0,0 +1,19 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+.assembly extern System.Runtime
+{
+  .publickeytoken = (B0 3F 5F 7F 11 D5 0A 3A )
+}
+
+.assembly extern ResourceAssembly
+{
+  .publickeytoken = (00 00 00 00 00 00 00 00)
+}
+
+.assembly ManifestResourceAssemblyRef { }
+
+.mresource public 'MyResource'
+{
+  .assembly extern 'ResourceAssembly'
+}

src/tests/Loader/ResourceResolve/ManifestResourceAssemblyRef.ilproj

@@ -0,0 +1,8 @@
+<Project Sdk="Microsoft.NET.Sdk.IL">
+  <PropertyGroup>
+    <OutputType>library</OutputType>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="ManifestResourceAssemblyRef.il" />
+  </ItemGroup>
+</Project>

src/tests/Loader/ResourceResolve/ResourceAssembly.csproj

@@ -0,0 +1,8 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Library</OutputType>
+  </PropertyGroup>
+  <ItemGroup>
+    <EmbeddedResource LogicalName="MyResource" Include="$(MSBuildProjectFile)" />
+  </ItemGroup>
+</Project>

src/tests/Loader/ResourceResolve/ResourceResolve.cs

@@ -0,0 +1,47 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.IO;
+using System.Reflection;
+using Xunit;
+
+[ConditionalClass(typeof(TestLibrary.Utilities), nameof(TestLibrary.Utilities.IsNotNativeAot))]
+public unsafe class ResourceResolve
+{
+    [Fact]
+    [SkipOnMono("AssemblyRef manifest resource is not supported")]
+    public static void AssemblyRef()
+    {
+        string resourceName = "MyResource";
+        Assembly assembly = typeof(ResourceResolve).Assembly;
+
+        // Manifest resource is not in the current assembly
+        Stream stream = assembly.GetManifestResourceStream(resourceName);
+        Assert.Null(stream);
+
+        // Handler returns assembly with a manifest resource assembly ref that
+        // points to another assembly with the resource
+        ResolveEventHandler handler = (sender, args) =>
+        {
+            if (args.Name == resourceName && args.RequestingAssembly == assembly)
+                return Assembly.Load("ManifestResourceAssemblyRef");
+
+            return null;
+        };
+        AppDomain.CurrentDomain.ResourceResolve += handler;
+        stream = assembly.GetManifestResourceStream(resourceName);
+        AppDomain.CurrentDomain.ResourceResolve -= handler;
+        Assert.NotNull(stream);
+
+        // Verify that the stream matches the expected one in the resource assembly
+        Assembly resourceAssembly = Assembly.Load("ResourceAssembly");
+        Stream expected = resourceAssembly.GetManifestResourceStream(resourceName);
+        Assert.Equal(expected.Length, stream.Length);
+        Span<byte> expectedBytes = new byte[expected.Length];
+        expected.Read(expectedBytes);
+        Span<byte> streamBytes = new byte[stream.Length];
+        stream.Read(streamBytes);
+        Assert.Equal(expectedBytes, streamBytes);
+    }
+}

src/tests/Loader/ResourceResolve/ResourceResolve.csproj

@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <ItemGroup>
+    <Compile Include="ResourceResolve.cs" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="$(TestLibraryProjectPath)" />
+    <ProjectReference Include="ManifestResourceAssemblyRef.ilproj" />
+    <ProjectReference Include="ResourceAssembly.csproj" />
+  </ItemGroup>
+</Project>