mcs/class/referencesource/System.Data.Entity/System/Data/Metadata/ObjectLayer/MetadataAssemblyHelper.cs

   1 //---------------------------------------------------------------------
   2 // <copyright file="MetadataAssemblyHelper.cs" company="Microsoft">
   3 //      Copyright (c) Microsoft Corporation.  All rights reserved.
   4 // </copyright>
   5 //
   6 // @owner       Microsoft
   7 // @backupOwner Microsoft
   8 //---------------------------------------------------------------------
   9
  10 using System.Reflection;
  11 using System.Collections.Generic;
  12 using System.Diagnostics;
  13 using System.Data.Common.Utils;
  14
  15 namespace System.Data.Metadata.Edm
  16 {
  17     internal static class MetadataAssemblyHelper
  18     {
  19         static byte [] EcmaPublicKeyToken = System.Data.EntityModel.SchemaObjectModel.ScalarType.ConvertToByteArray(AssemblyRef.EcmaPublicKey);
  20         static byte [] MsPublicKeyToken = System.Data.EntityModel.SchemaObjectModel.ScalarType.ConvertToByteArray(AssemblyRef.MicrosoftPublicKey);
  21         private static Memoizer<Assembly, bool> _filterAssemblyCacheByAssembly = new Memoizer<Assembly, bool>(MetadataAssemblyHelper.ComputeShouldFilterAssembly, EqualityComparer<Assembly>.Default);
  22
  23         internal static Assembly SafeLoadReferencedAssembly(AssemblyName assemblyName)
  24         {
  25             Assembly assembly = null;
  26
  27             try
  28             {
  29                 assembly = Assembly.Load(assemblyName);
  30             }
  31             catch (System.IO.FileNotFoundException)
  32             {
  33                 // See 552932: ObjectItemCollection: fails on referenced assemblies that are not available
  34             }
  35
  36             return assembly;
  37         }
  38
  39         private static bool ComputeShouldFilterAssembly(Assembly assembly)
  40         {
  41             AssemblyName assemblyName = new AssemblyName(assembly.FullName);
  42             return ShouldFilterAssembly(assemblyName);
  43         }
  44
  45         internal static bool ShouldFilterAssembly(Assembly assembly)
  46         {
  47             return _filterAssemblyCacheByAssembly.Evaluate(assembly);
  48         }
  49
  50         /// <summary>Is the assembly and its referened assemblies not expected to have any metadata</summary>
  51         private static bool ShouldFilterAssembly(AssemblyName assemblyName)
  52         {
  53             return (ArePublicKeyTokensEqual(assemblyName.GetPublicKeyToken(), EcmaPublicKeyToken) ||
  54                     ArePublicKeyTokensEqual(assemblyName.GetPublicKeyToken(), MsPublicKeyToken));
  55         }
  56
  57         private static bool ArePublicKeyTokensEqual(byte [] left, byte [] right)
  58         {
  59             // some assemblies don't have public keys
  60             if (left.Length != right.Length)
  61             {
  62                 return false;
  63             }
  64
  65             for (int i = 0; i < left.Length; i++)
  66             {
  67                 if (left[i] != right[i])
  68                 {
  69                     return false;
  70                 }
  71             }
  72             return true;
  73         }
  74
  75         internal static IEnumerable<Assembly> GetNonSystemReferencedAssemblies(Assembly assembly)
  76         {
  77             foreach (AssemblyName name in assembly.GetReferencedAssemblies())
  78             {
  79                 if (!ShouldFilterAssembly(name))
  80                 {
  81                     Assembly referenceAssembly = SafeLoadReferencedAssembly(name);
  82                     if(referenceAssembly != null )
  83                     {
  84                         yield return referenceAssembly;
  85                     }
  86                 }
  87             }
  88         }
  89      }
  90 }