Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/Configuration/IISVersionHelper.cs

@@ -0,0 +1,76 @@
+//------------------------------------------------------------------------------
+// <copyright file="IISVersionHelper.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+using System.Runtime.InteropServices;
+namespace System.Web.Configuration {
+    internal class IISVersionHelper : IDisposable {
+        const int IIS_PRODUCT_EXPRESS = 2;
+
+        [ComImport, Guid("1B036F99-B240-4116-A6A0-B54EC5B2438E"), InterfaceType((short)1)]
+        interface IIISVersion {
+            [return: MarshalAs(UnmanagedType.Struct)]
+            object GetPropertyValue([In, MarshalAs(UnmanagedType.BStr)] string bstrName);
+            [return: MarshalAs(UnmanagedType.Struct)]
+            object CreateObjectFromProgId([In, MarshalAs(UnmanagedType.BStr)] string bstrObjectName);
+            [return: MarshalAs(UnmanagedType.Struct)]
+            object CreateObjectFromClsId([In] Guid clsidObject);
+            void ApplyIISEnvironmentVariables();
+            void ClearIISEnvironmentVariables();
+            void ApplyManifestContext();
+            void ClearManifestContext();
+        }
+
+        [ComImport, InterfaceType((short)1), Guid("9CDA0717-2EB5-42b3-B5B0-16F4941B2029")]
+        interface IIISVersionManager {
+            [return: MarshalAs(UnmanagedType.Interface)]
+            IIISVersion GetVersionObject([In, MarshalAs(UnmanagedType.BStr)] string bstrVersion, [In, MarshalAs(UnmanagedType.I4)] int productType);
+            [return: MarshalAs(UnmanagedType.SafeArray, SafeArraySubType = VarEnum.VT_VARIANT)]
+            IIISVersion[] GetAllVersionObjects();
+        }
+
+        IIISVersionManager _versionManager;
+        IIISVersion _version;
+
+        internal IISVersionHelper(string version) {
+            // version is null if we're supposed to use the OS's IIS installation
+            if (version == null)
+                return;
+
+            try {
+                _versionManager = CreateVersionManager();
+                _version = _versionManager.GetVersionObject(version, IIS_PRODUCT_EXPRESS);
+                _version.ApplyManifestContext();
+            }
+            catch {
+                Release();
+                throw;
+            }
+        }
+
+        private static IIISVersionManager CreateVersionManager() {
+            Type type = Type.GetTypeFromProgID("Microsoft.IIS.VersionManager", throwOnError: true);
+            return (IIISVersionManager)Activator.CreateInstance(type);
+        }
+
+        public void Dispose() {
+            if (_version != null) {
+                _version.ClearManifestContext();
+                Release();
+            }
+        }
+
+        private void Release() {
+            if (_version != null) {
+                Marshal.ReleaseComObject(_version);
+                _version = null;
+            }
+            if (_versionManager != null) {
+                Marshal.ReleaseComObject(_versionManager);
+                _versionManager = null;
+            }
+        }
+    }
+}