Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Activities/System/Activities/Debugger/Symbol/SymbolHelper.cs

@@ -0,0 +1,114 @@
+//-----------------------------------------------------------------------
+// <copyright file="SymbolHelper.cs" company="Microsoft Corporation">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//-----------------------------------------------------------------------
+namespace System.Activities.Debugger.Symbol
+{
+    using System.Diagnostics.CodeAnalysis;
+    using System.IO;
+    using System.Linq;
+    using System.Runtime;
+    using System.Security;
+    using System.Security.Cryptography;
+
+    internal static class SymbolHelper
+    {
+        // This is the same Encode/Decode logic as the WCF FramingEncoder
+        public static int ReadEncodedInt32(BinaryReader reader)
+        {
+            int value = 0;
+            int bytesConsumed = 0;
+            while (true)
+            {
+                int next = reader.ReadByte();
+                value |= (next & 0x7F) << (bytesConsumed * 7);
+                bytesConsumed++;
+                if ((next & 0x80) == 0)
+                {
+                    break;
+                }
+            }
+
+            return value;
+        }
+
+        // This is the same Encode/Decode logic as the WCF FramingEncoder
+        public static void WriteEncodedInt32(BinaryWriter writer, int value)
+        {
+            Fx.Assert(value >= 0, "Must be non-negative");
+
+            while ((value & 0xFFFFFF80) != 0)
+            {
+                writer.Write((byte)((value & 0x7F) | 0x80));
+                value >>= 7;
+            }
+
+            writer.Write((byte)value);
+        }
+
+        public static int GetEncodedSize(int value)
+        {
+            Fx.Assert(value >= 0, "Must be non-negative");
+
+            int count = 1;
+            while ((value & 0xFFFFFF80) != 0)
+            {
+                count++;
+                value >>= 7;
+            }
+
+            return count;
+        }
+
+        [SuppressMessage("Microsoft.Cryptographic.Standard", "CA5350:MD5CannotBeUsed", 
+            Justification = "Design has been approved.  We are not using MD5 for any security or cryptography purposes but rather as a hash.")]
+        public static byte[] CalculateChecksum(string fileName)
+        {
+            Fx.Assert(!string.IsNullOrEmpty(fileName), "fileName should not be empty or null");
+            byte[] checksum;
+            try
+            {
+                using (StreamReader streamReader = new StreamReader(fileName))
+                {
+                    MD5 md5 = new MD5CryptoServiceProvider();
+                    checksum = md5.ComputeHash(streamReader.BaseStream);
+                }
+            }
+            catch (IOException)
+            {
+                // DirectoryNotFoundException and FileNotFoundException are expected
+                checksum = null;
+            }
+            catch (UnauthorizedAccessException)
+            {
+                // UnauthorizedAccessException is expected
+                checksum = null;
+            }
+            catch (SecurityException)
+            {
+                // Must not have had enough permissions to access the file.
+                checksum = null;
+            }
+
+            return checksum;
+        }
+
+        [Fx.Tag.SecurityNote(Critical = "Used to get a string from checksum that is provided by the user/from a file.",
+            Safe = "We not exposing any critical data. Just converting the byte array to a hex string.")]
+        [SecuritySafeCritical]
+        public static string GetHexStringFromChecksum(byte[] checksum)
+        {
+            return checksum == null ? string.Empty : string.Join(string.Empty, checksum.Select(x => x.ToString("X2")).ToArray());
+        }
+
+        [Fx.Tag.SecurityNote(Critical = "Used to validate checksum that is provided by the user/from a file.",
+            Safe = "We not exposing any critical data. Just validating that the provided checksum meets the format for the checksums we produce.")]
+        [SecuritySafeCritical]
+        internal static bool ValidateChecksum(byte[] checksumToValidate)
+        {
+            // We are using MD5.ComputeHash, which will return a 16 byte array.
+            return checksumToValidate.Length == 16;
+        }
+    }
+}