Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/Util/AssemblyUtil.cs

@@ -0,0 +1,31 @@
+//------------------------------------------------------------------------------
+// <copyright file="AssemblyUtil.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+using System;
+using System.Reflection;
+
+namespace System.Web.Util {
+    internal static class AssemblyUtil {
+        private const string _emptyFileVersion = "0.0.0.0";
+
+        public static string GetAssemblyFileVersion(Assembly assembly) {
+            AssemblyFileVersionAttribute[] attributes =
+                (AssemblyFileVersionAttribute[])assembly.GetCustomAttributes(typeof(AssemblyFileVersionAttribute), false);
+
+            string version;
+            if (attributes.Length > 0) {
+                version = attributes[0].Version;
+                if (String.IsNullOrEmpty(version)) {
+                    version = _emptyFileVersion;
+                }
+            }
+            else {
+                version = _emptyFileVersion;
+            }
+            return version;
+        }
+    }
+}