1 files changed, 58 insertions, 0 deletions
diff --git a/src/ILCompiler.Compiler/src/Compiler/RuntimeConfigurationRootProvider.cs b/src/ILCompiler.Compiler/src/Compiler/RuntimeConfigurationRootProvider.cs
new file mode 100644
index 000000000..e4be79fc1
--- /dev/null
+++ b/src/ILCompiler.Compiler/src/Compiler/RuntimeConfigurationRootProvider.cs
@@ -0,0 +1,58 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Generic;
+
+namespace ILCompiler
+{
+    /// <summary>
+    /// A root provider that provides a runtime configuration blob that influences runtime behaviors.
+    /// See RhConfigValues.h for allowed values.
+    /// </summary>
+    public class RuntimeConfigurationRootProvider : ICompilationRootProvider
+    {
+        private readonly IEnumerable<string> _runtimeOptions;
+
+        public RuntimeConfigurationRootProvider(IEnumerable<string> runtimeOptions)
+        {
+            _runtimeOptions = runtimeOptions;
+        }
+
+        void ICompilationRootProvider.AddCompilationRoots(IRootingServiceProvider rootProvider)
+        {
+            rootProvider.RootReadOnlyDataBlob(GetRuntimeOptionsBlob(), 4, "Runtime configuration information", "g_compilerEmbeddedSettingsBlob");
+        }
+
+        protected byte[] GetRuntimeOptionsBlob()
+        {
+            const int HeaderSize = 4;
+
+            ArrayBuilder<byte> options = new ArrayBuilder<byte>();
+
+            // Reserve space for the header
+            options.ZeroExtend(HeaderSize);
+
+            foreach (string option in _runtimeOptions)
+            {
+                byte[] optionBytes = System.Text.Encoding.ASCII.GetBytes(option);
+                options.Append(optionBytes);
+
+                // Emit a null to separate the next option
+                options.Add(0);
+            }
+
+            byte[] result = options.ToArray();
+
+            int length = options.Count - HeaderSize;
+
+            // Encode the size of the blob into the header
+            result[0] = (byte)length;
+            result[1] = (byte)(length >> 8);
+            result[2] = (byte)(length >> 0x10);
+            result[3] = (byte)(length >> 0x18);
+
+            return result;
+        }
+    }
+}