1 files changed, 85 insertions, 0 deletions

diff --git a/src/WixToolset.Mba.Host/BootstrapperApplicationFactory.cs b/src/WixToolset.Mba.Host/BootstrapperApplicationFactory.cs
new file mode 100644
index 00000000..9385d1d1
--- /dev/null
+++ b/src/WixToolset.Mba.Host/BootstrapperApplicationFactory.cs
@@ -0,0 +1,85 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+namespace WixToolset.Mba.Host
+{
+    using System;
+    using System.Configuration;
+    using System.Reflection;
+    using System.Runtime.InteropServices;
+    using WixToolset.Mba.Core;
+
+    /// <summary>
+    /// Entry point for the MBA host to create and return the BA to the engine.
+    /// </summary>
+    [ClassInterface(ClassInterfaceType.None)]
+    public sealed class BootstrapperApplicationFactory : MarshalByRefObject, IBootstrapperApplicationFactory
+    {
+        /// <summary>
+        /// Creates a new instance of the <see cref="BootstrapperApplicationFactory"/> class.
+        /// </summary>
+        public BootstrapperApplicationFactory()
+        {
+        }
+
+        /// <summary>
+        /// Loads the bootstrapper application assembly and calls its IBootstrapperApplicationFactory.Create method.
+        /// </summary>
+        /// <param name="pArgs">Pointer to BOOTSTRAPPER_CREATE_ARGS struct.</param>
+        /// <param name="pResults">Pointer to BOOTSTRAPPER_CREATE_RESULTS struct.</param>
+        /// <exception cref="MissingAttributeException">The bootstrapper application assembly
+        /// does not define the <see cref="BootstrapperApplicationFactoryAttribute"/>.</exception>
+        public void Create(IntPtr pArgs, IntPtr pResults)
+        {
+            // Get the wix.boostrapper section group to get the name of the bootstrapper application assembly to host.
+            var section = ConfigurationManager.GetSection("wix.bootstrapper/host") as HostSection;
+            if (null == section)
+            {
+                throw new MissingAttributeException(); // TODO: throw a more specific exception than this.
+            }
+
+            // Load the BA's IBootstrapperApplicationFactory.
+            var baFactoryType = BootstrapperApplicationFactory.GetBAFactoryTypeFromAssembly(section.AssemblyName);
+            var baFactory = (IBootstrapperApplicationFactory)Activator.CreateInstance(baFactoryType);
+            if (null == baFactory)
+            {
+                throw new InvalidBootstrapperApplicationFactoryException();
+            }
+
+            baFactory.Create(pArgs, pResults);
+        }
+
+        /// <summary>
+        /// Locates the <see cref="BootstrapperApplicationFactoryAttribute"/> and returns the specified type.
+        /// </summary>
+        /// <param name="assemblyName">The assembly that defines the IBootstrapperApplicationFactory implementation.</param>
+        /// <returns>The bootstrapper application factory <see cref="Type"/>.</returns>
+        private static Type GetBAFactoryTypeFromAssembly(string assemblyName)
+        {
+            Type baFactoryType = null;
+
+            // Load the requested assembly.
+            Assembly asm = AppDomain.CurrentDomain.Load(assemblyName);
+
+            // If an assembly was loaded and is not the current assembly, check for the required attribute.
+            // This is done to avoid using the BootstrapperApplicationFactoryAttribute which we use at build time
+            // to specify the BootstrapperApplicationFactory assembly in the manifest.
+            if (!Assembly.GetExecutingAssembly().Equals(asm))
+            {
+                // There must be one and only one BootstrapperApplicationFactoryAttribute.
+                // The attribute prevents multiple declarations already.
+                var attrs = (BootstrapperApplicationFactoryAttribute[])asm.GetCustomAttributes(typeof(BootstrapperApplicationFactoryAttribute), false);
+                if (null != attrs)
+                {
+                    baFactoryType = attrs[0].BootstrapperApplicationFactoryType;
+                }
+            }
+
+            if (null == baFactoryType)
+            {
+                throw new MissingAttributeException();
+            }
+
+            return baFactoryType;
+        }
+    }
+}