From 67ef887900753483fad4d882ab92fb19b1bacff3 Mon Sep 17 00:00:00 2001
From: PowerShell Team <PowerShellTeam@hotmail.com>
Date: Fri, 17 Jun 2016 08:14:02 -0700
Subject: [PATCH] Add new file AssemblyMetadataHelper.cs from [SD:715912]

commit 77eda78
---
 .../CoreCLR/AssemblyMetadataHelper.cs         | 76 +++++++++++++++++++
 1 file changed, 76 insertions(+)
 create mode 100644 src/Microsoft.PowerShell.CoreCLR.AssemblyLoadContext/CoreCLR/AssemblyMetadataHelper.cs

diff --git a/src/Microsoft.PowerShell.CoreCLR.AssemblyLoadContext/CoreCLR/AssemblyMetadataHelper.cs b/src/Microsoft.PowerShell.CoreCLR.AssemblyLoadContext/CoreCLR/AssemblyMetadataHelper.cs
new file mode 100644
index 0000000000..062ff320e8
--- /dev/null
+++ b/src/Microsoft.PowerShell.CoreCLR.AssemblyLoadContext/CoreCLR/AssemblyMetadataHelper.cs
@@ -0,0 +1,76 @@
+/********************************************************************++
+Copyright (c) Microsoft Corporation.  All rights reserved.
+--********************************************************************/
+
+using System.Globalization;
+using System.Reflection;
+using System.Reflection.Metadata;
+using System.Security.Cryptography;
+
+namespace System.Management.Automation
+{
+    internal static class AssemblyMetadataHelper
+    {
+        /// <summary>
+        /// Construct the strong assembly name from metadata
+        /// </summary>
+        internal static string GetAssemblyStrongName(MetadataReader metadataReader)
+        {
+            AssemblyDefinition assemblyDefinition = metadataReader.GetAssemblyDefinition();
+            string asmName = metadataReader.GetString(assemblyDefinition.Name);
+            string asmVersion = assemblyDefinition.Version.ToString();
+            string asmCulture = metadataReader.GetString(assemblyDefinition.Culture);
+            asmCulture = (asmCulture == string.Empty) ? "neutral" : asmCulture;
+
+            AssemblyHashAlgorithm hashAlgorithm = assemblyDefinition.HashAlgorithm;
+            BlobHandle blobHandle = assemblyDefinition.PublicKey;
+            BlobReader blobReader = metadataReader.GetBlobReader(blobHandle);
+            
+            string publicKeyTokenString = "null";
+            // Extract public key token only if PublicKey exists in the metadata
+            if (blobReader.Length > 0)
+            {
+                byte[] publickey = blobReader.ReadBytes(blobReader.Length);
+
+                HashAlgorithm hashImpl = null;
+                switch (hashAlgorithm)
+                {
+                    case AssemblyHashAlgorithm.Sha1:
+                        hashImpl = SHA1.Create();
+                        break;
+                    case AssemblyHashAlgorithm.MD5:
+                        hashImpl = MD5.Create();
+                        break;
+                    case AssemblyHashAlgorithm.Sha256:
+                        hashImpl = SHA256.Create();
+                        break;
+                    case AssemblyHashAlgorithm.Sha384:
+                        hashImpl = SHA384.Create();
+                        break;
+                    case AssemblyHashAlgorithm.Sha512:
+                        hashImpl = SHA512.Create();
+                        break;
+                    default:
+                        throw new NotSupportedException();
+                }
+
+                byte[] publicKeyHash = hashImpl.ComputeHash(publickey);
+                byte[] publicKeyTokenBytes = new byte[8];
+                // Note that, the low 8 bytes of the hash of public key in reverse order is the public key tokens.
+                for (int i = 1; i <= 8; i++)
+                {
+                    publicKeyTokenBytes[i - 1] = publicKeyHash[publicKeyHash.Length - i];
+                }
+
+                // Convert bytes to hex format strings in lower case.
+                publicKeyTokenString = BitConverter.ToString(publicKeyTokenBytes).Replace("-", string.Empty).ToLowerInvariant();
+            }
+            
+            string strongAssemblyName = string.Format(CultureInfo.InvariantCulture,
+                                                      "{0}, Version={1}, Culture={2}, PublicKeyToken={3}",
+                                                      asmName, asmVersion, asmCulture, publicKeyTokenString);
+
+            return strongAssemblyName;
+        }
+    }
+}