Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web.Services/System/Web/Services/PartialTrustHelpers.cs

@@ -0,0 +1,40 @@
+//------------------------------------------------------------------------------
+// <copyright file="PartialTrustHelpers.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+namespace System.Web.Services
+{
+    using System.Security;
+    using System.Web.Hosting;
+    
+    internal static class PartialTrustHelpers
+    {
+        [SecurityCritical]
+        private static bool isInPartialTrustOutsideAspNet; // indicates if we are running in partial trust outside the ASP.NET context
+
+        [SecurityCritical]
+        private static bool isInPartialTrustOutsideAspNetInitialized = false;
+
+        /// <summary>
+        /// Used to guard usage of System.Web types in partial trust outside the ASP.NET context (because they are not secure), 
+        /// in which case we shutdown the process.
+        /// </summary>
+        [SecuritySafeCritical] // Critical because it uses security critical fields. Safe because it doesn't take user input and it doesn't leak security sensitive information.
+        internal static void FailIfInPartialTrustOutsideAspNet()
+        {
+            if (!isInPartialTrustOutsideAspNetInitialized)
+            {
+                // The HostingEnvironment.IsHosted property is safe to be called in partial trust outside the ASP.NET context.
+                isInPartialTrustOutsideAspNet = !(AppDomain.CurrentDomain.IsFullyTrusted || HostingEnvironment.IsHosted);
+                isInPartialTrustOutsideAspNetInitialized = true;
+            }
+
+            if (isInPartialTrustOutsideAspNet)
+            {
+                throw new SecurityException(Res.GetString(Res.CannotRunInPartialTrustOutsideAspNet));
+            }
+        }
+    }
+}