Update the ResourceData API

src/coreclr/tools/Common/Compiler/Win32Resources/ResourceData.UpdateResourceDataModel.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections;
+using System.Diagnostics;
 
 #if HOST_MODEL
 namespace Microsoft.NET.HostModel.Win32Resources
@@ -26,6 +27,8 @@ private void AddResourceInternal(object name, object type, ushort language, byte
             }
             else
             {
+                Debug.Assert(type is string);
+                type = ToUpperForResource((string)type);
                 if (!_resTypeHeadName.TryGetValue((string)type, out resType))
                 {
                     resType = new ResType();
@@ -45,6 +48,8 @@ private void AddResourceInternal(object name, object type, ushort language, byte
             }
             else
             {
+                Debug.Assert(name is string);
+                name = ToUpperForResource((string)name);
                 if (!resType.NameHeadName.TryGetValue((string)name, out resName))
                 {
                     resName = new ResName();
@@ -57,28 +62,32 @@ private void AddResourceInternal(object name, object type, ushort language, byte
 
         private byte[] FindResourceInternal(object name, object type, ushort language)
         {
-            ResType resType = null;
+            ResType resType;
 
             if (type is ushort)
             {
                 _resTypeHeadID.TryGetValue((ushort)type, out resType);
             }
-            if (type is string)
+            else
             {
+                Debug.Assert(type is string);
+                type = ToUpperForResource((string)type);
                 _resTypeHeadName.TryGetValue((string)type, out resType);
             }
 
             if (resType == null)
                 return null;
 
-            ResName resName = null;
+            ResName resName;
 
             if (name is ushort)
             {
                 resType.NameHeadID.TryGetValue((ushort)name, out resName);
             }
-            if (name is string)
+            else
             {
+                Debug.Assert(name is string);
+                name = ToUpperForResource((string)name);
                 resType.NameHeadName.TryGetValue((string)name, out resName);
             }
 
@@ -90,5 +99,18 @@ private byte[] FindResourceInternal(object name, object type, ushort language)
 
             return (byte[])resLanguage.DataEntry.Clone();
         }
+
+        private static string ToUpperForResource(string str)
+        {
+            // Undocumented semantic for Win32 Resource APIs
+            // This ToUpper logic should only be applied to the
+            // latin range from 'a' to 'z'.
+            System.Text.StringBuilder builder = new(str.Length);
+            foreach (char c in str)
+            {
+                builder.Append('a' <= c && c <= 'z' ? (char)(c + ('A' - 'a')) : c);
+            }
+            return builder.ToString();
+        }
     }
 }

src/installer/managed/Microsoft.NET.HostModel/ComHost/ComHost.cs

@@ -57,7 +57,7 @@ public static void Create(
                             if (tlbFileBytes.Length == 0)
                                 throw new InvalidTypeLibraryException(typeLibrary.Value);
 
-                            updater.AddResource(tlbFileBytes, "typelib", (IntPtr)typeLibrary.Key);
+                            updater.AddResource(tlbFileBytes, "TYPELIB", (IntPtr)typeLibrary.Key);
                         }
                         catch (FileNotFoundException ex)
                         {

src/installer/tests/Microsoft.NET.HostModel.Tests/ResourceUpdaterTests.cs

@@ -78,6 +78,37 @@ void AddResource_AddToPEWithoutRsrc()
         }
     }
 
+    [Fact]
+    void AddResource_DifferentCasingInAPIs()
+    {
+        using var tempFile = CreateTestPEFileWithoutRsrc();
+
+        using (var updater = new ResourceUpdater(tempFile.Stream, true))
+        {
+            updater.AddResource("Test Resource1"u8.ToArray(), "testtype1", 0);
+            updater.AddResource("Test Resource2"u8.ToArray(), "TESTTYPE2", 0);
+            updater.AddResource("Test Resource3"u8.ToArray(), "\u0165ESTTYPE3", 0);
+            updater.Update();
+        }
+
+        tempFile.Stream.Seek(0, SeekOrigin.Begin);
+
+        using (var reader = new PEReader(tempFile.Stream, PEStreamOptions.LeaveOpen))
+        {
+            var resourceReader = new ResourceData(reader);
+            byte[]? testType1 = resourceReader.FindResource(0, "TESTTYPE1", 0);
+            Assert.Equal("Test Resource1"u8.ToArray(), testType1);
+            byte[]? testType2 = resourceReader.FindResource(0, "testtype2", 0);
+            Assert.Equal("Test Resource2"u8.ToArray(), testType2);
+            byte[]? testType3 = resourceReader.FindResource(0, "\u0165esttype3", 0);
+            Assert.Equal("Test Resource3"u8.ToArray(), testType3);
+
+            // Characters out of 'a' - 'z' are left unaltered
+            byte[]? missing = resourceReader.FindResource(0, "\u0164ESTTYPE3", 0);
+            Assert.Null(missing);
+        }
+    }
+
     [Fact]
     void AddResource_AddToExistingRsrc()
     {