context: /*
    Copyright (C) 2009-2012 Jeroen Frijters
  
    This software is provided 'as-is', without any express or implied
    warranty.  In no event will the authors be held liable for any damages
    arising from the use of this software.
  
    Permission is granted to anyone to use this software for any purpose,
    including commercial applications, and to alter it and redistribute it
    freely, subject to the following restrictions:
  
    1. The origin of this software must not be misrepresented; you must not
       claim that you wrote the original software. If you use this software
       in a product, an acknowledgment in the product documentation would be
       appreciated but is not required.
    2. Altered source versions must be plainly marked as such, and must not be
       misrepresented as being the original software.
    3. This notice may not be removed or altered from any source distribution.
  
    Jeroen Frijters
    jeroen@frijters.net
    
  */
  using System;
  using System.IO;
  using System.Text;
  using System.Collections.Generic;
  using IKVM.Reflection.Metadata;
  
  namespace IKVM.Reflection.Reader
  {
  	sealed class StreamHeader
  	{
  		internal uint Offset;
  		internal uint Size;
  		internal string Name;
  
  		internal void Read(BinaryReader br)
  		{
  			Offset = br.ReadUInt32();
  			Size = br.ReadUInt32();
  			byte[] buf = new byte[32];
  			byte b;
  			int len = 0;
  			while ((b = br.ReadByte()) != 0)
  			{
  				buf[len++] = b;
  			}
  			Name = Encoding.UTF8.GetString(buf, 0, len); ;
  			int padding = -1 + ((len + 4) & ~3) - len;
  			br.BaseStream.Seek(padding, SeekOrigin.Current);
  		}
  	}
  
  	sealed class ModuleReader : Module
  	{
  		internal readonly Stream stream;
  		private readonly string location;
  		private Assembly assembly;
  		private readonly PEReader peFile = new PEReader();
  		private readonly CliHeader cliHeader = new CliHeader();
  		private string imageRuntimeVersion;
  		private int metadataStreamVersion;
  		private byte[] stringHeap;
  		private byte[] blobHeap;
  		private byte[] userStringHeap;
  		private byte[] guidHeap;
  		private TypeDefImpl[] typeDefs;
  		private TypeDefImpl moduleType;
  		private Assembly[] assemblyRefs;
  		private Type[] typeRefs;
  		private Type[] typeSpecs;
  		private FieldInfo[] fields;
  		private MethodBase[] methods;
  		private MemberInfo[] memberRefs;
  		private Dictionary<int, string> strings = new Dictionary<int, string>();
  		private Dictionary<TypeName, Type> types = new Dictionary<TypeName, Type>();
  		private Dictionary<TypeName, LazyForwardedType> forwardedTypes = new Dictionary<TypeName, LazyForwardedType>();
  
  		private sealed class LazyForwardedType
  		{
  			private readonly int assemblyRef;
  			private Type type;
  
  			internal LazyForwardedType(int assemblyRef)
  			{
  				this.assemblyRef = assemblyRef;
  			}
  
  			internal Type GetType(ModuleReader module, TypeName typeName)
  			{
  				if (type == null)
  				{
  					Assembly asm = module.ResolveAssemblyRef(assemblyRef);
  					type = asm.ResolveType(typeName);
  					if (type == null)
  					{
  						throw new TypeLoadException(typeName.ToString());
  					}
  				}
  				return type;
  			}
  		}
  
  		internal ModuleReader(AssemblyReader assembly, Universe universe, Stream stream, string location)
  			: base(universe)
  		{
  			this.stream = stream;
  			this.location = location;
  			Read();
  			if (assembly == null && AssemblyTable.records.Length != 0)
  			{
  				assembly = new AssemblyReader(location, this);
  			}
  			this.assembly = assembly;
  		}
  
  		private void Read()
  		{
  			BinaryReader br = new BinaryReader(stream);
  			peFile.Read(br);
  			stream.Seek(peFile.RvaToFileOffset(peFile.GetComDescriptorVirtualAddress()), SeekOrigin.Begin);
  			cliHeader.Read(br);
  			stream.Seek(peFile.RvaToFileOffset(cliHeader.MetaData.VirtualAddress), SeekOrigin.Begin);
  			foreach (StreamHeader sh in ReadStreamHeaders(br, out imageRuntimeVersion))
  			{
  				switch (sh.Name)
  				{
  					case "#Strings":
  						stringHeap = ReadHeap(stream, sh);
  						break;
  					case "#Blob":
  						blobHeap = ReadHeap(stream, sh);
  						break;
  					case "#US":
  						userStringHeap = ReadHeap(stream, sh);
  						break;
  					case "#GUID":
  						guidHeap = ReadHeap(stream, sh);
  						break;
  					case "#~":
  					case "#-":
  						stream.Seek(peFile.RvaToFileOffset(cliHeader.MetaData.VirtualAddress + sh.Offset), SeekOrigin.Begin);
  						ReadTables(br);
  						break;
  					default:
  						// we ignore unknown streams, because the CLR does so too
  						// (and some obfuscators add bogus streams)
  						break;
  				}
  			}
  		}
  
  		internal void SetAssembly(Assembly assembly)
  		{
  			this.assembly = assembly;
  		}
  
  		private static StreamHeader[] ReadStreamHeaders(BinaryReader br, out string Version)
  		{
  			uint Signature = br.ReadUInt32();
  			if (Signature != 0x424A5342)
  			{
  				throw new BadImageFormatException("Invalid metadata signature");
  			}
  			/*ushort MajorVersion =*/ br.ReadUInt16();
  			/*ushort MinorVersion =*/ br.ReadUInt16();
  			/*uint Reserved =*/ br.ReadUInt32();
  			uint Length = br.ReadUInt32();
  			byte[] buf = br.ReadBytes((int)Length);
  			Version = Encoding.UTF8.GetString(buf).TrimEnd('\u0000');
  			/*ushort Flags =*/ br.ReadUInt16();
  			ushort Streams = br.ReadUInt16();
  			StreamHeader[] streamHeaders = new StreamHeader[Streams];
  			for (int i = 0; i < streamHeaders.Length; i++)
  			{
  				streamHeaders[i] = new StreamHeader();
  				streamHeaders[i].Read(br);
  			}
  			return streamHeaders;
  		}
  
  		private void ReadTables(BinaryReader br)
  		{
  			Table[] tables = GetTables();
  			/*uint Reserved0 =*/ br.ReadUInt32();
  			byte MajorVersion = br.ReadByte();
  			byte MinorVersion = br.ReadByte();
  			metadataStreamVersion = MajorVersion << 16 | MinorVersion;
  			byte HeapSizes = br.ReadByte();
  			/*byte Reserved7 =*/ br.ReadByte();
  			ulong Valid = br.ReadUInt64();
  			ulong Sorted = br.ReadUInt64();
  			for (int i = 0; i < 64; i++)
  			{
  				if ((Valid & (1UL << i)) != 0)
  				{
  					tables[i].Sorted = (Sorted & (1UL << i)) != 0;
  					tables[i].RowCount = br.ReadInt32();
  				}
  				else if (tables[i] != null)
  				{
  					tables[i].RowCount = 0;
  				}
  			}
  			MetadataReader mr = new MetadataReader(this, br.BaseStream, HeapSizes);
  			for (int i = 0; i < 64; i++)
  			{
  				if ((Valid & (1UL << i)) != 0)
  				{
  					tables[i].Read(mr);
  				}
  			}
  			if (ParamPtr.RowCount != 0)
  			{
  				throw new NotImplementedException("ParamPtr table support has not yet been implemented.");
  			}
  		}
  
  		private byte[] ReadHeap(Stream stream, StreamHeader sh)
  		{
  			byte[] buf = new byte[sh.Size];
  			stream.Seek(peFile.RvaToFileOffset(cliHeader.MetaData.VirtualAddress + sh.Offset), SeekOrigin.Begin);
  			for (int pos = 0; pos < buf.Length; )
  			{
  				int read = stream.Read(buf, pos, buf.Length - pos);
  				if (read == 0)
  				{
  					throw new BadImageFormatException();
  				}
  				pos += read;
  			}
  			return buf;
  		}
  
  		internal void SeekRVA(int rva)
  		{
  			stream.Seek(peFile.RvaToFileOffset((uint)rva), SeekOrigin.Begin);
  		}
  
  		internal override void GetTypesImpl(List<Type> list)
  		{
  			PopulateTypeDef();
  			foreach (TypeDefImpl type in typeDefs)
  			{
  				if (type != moduleType)
  				{
  					list.Add(type);
  				}
  			}
  		}
  
  		private void PopulateTypeDef()
  		{
  			if (typeDefs == null)
  			{
  				typeDefs = new TypeDefImpl[TypeDef.records.Length];
  				for (int i = 0; i < typeDefs.Length; i++)
  				{
  					TypeDefImpl type = new TypeDefImpl(this, i);
  					typeDefs[i] = type;
  					if (type.IsModulePseudoType)
  					{
  						moduleType = type;
  					}
  					else if (!type.IsNestedByFlags)
  					{
  						types.Add(new TypeName(type.__Namespace, type.__Name), type);
  					}
  				}
  				// add forwarded types to forwardedTypes dictionary (because Module.GetType(string) should return them)
  				for (int i = 0; i < ExportedType.records.Length; i++)
  				{
  					int implementation = ExportedType.records[i].Implementation;
  					if (implementation >> 24 == AssemblyRefTable.Index)
  					{
  						TypeName typeName = GetTypeName(ExportedType.records[i].TypeNamespace, ExportedType.records[i].TypeName);
  						forwardedTypes.Add(typeName, new LazyForwardedType((implementation & 0xFFFFFF) - 1));
  					}
  				}
  			}
  		}
  
  		internal override string GetString(int index)
  		{
  			if (index == 0)
  			{
  				return null;
  			}
  			string str;
  			if (!strings.TryGetValue(index, out str))
  			{
  				int len = 0;
  				while (stringHeap[index + len] != 0)
  				{
  					len++;
  				}
  				str = Encoding.UTF8.GetString(stringHeap, index, len);
  				strings.Add(index, str);
  			}
  			return str;
  		}
  
  		private static int ReadCompressedUInt(byte[] buffer, ref int offset)
  		{
  			byte b1 = buffer[offset++];
  			if (b1 <= 0x7F)
  			{
  				return b1;
  			}
  			else if ((b1 & 0xC0) == 0x80)
  			{
  				byte b2 = buffer[offset++];
  				return ((b1 & 0x3F) << 8) | b2;
  			}
  			else
  			{
  				byte b2 = buffer[offset++];
  				byte b3 = buffer[offset++];
  				byte b4 = buffer[offset++];
  				return ((b1 & 0x3F) << 24) + (b2 << 16) + (b3 << 8) + b4;
  			}
  		}
  
  		internal byte[] GetBlobCopy(int blobIndex)
  		{
  			int len = ReadCompressedUInt(blobHeap, ref blobIndex);
  			byte[] buf = new byte[len];
  			Buffer.BlockCopy(blobHeap, blobIndex, buf, 0, len);
  			return buf;
  		}
  
  		internal override ByteReader GetBlob(int blobIndex)
  		{
  			return ByteReader.FromBlob(blobHeap, blobIndex);
  		}
  
  		public override string ResolveString(int metadataToken)
  		{
  			string str;
  			if (!strings.TryGetValue(metadataToken, out str))
  			{
  				if ((metadataToken >> 24) != 0x70)
  				{
  					throw TokenOutOfRangeException(metadataToken);
  				}
  				int index = metadataToken & 0xFFFFFF;
  				int len = ReadCompressedUInt(userStringHeap, ref index) & ~1;
  				StringBuilder sb = new StringBuilder(len / 2);
  				for (int i = 0; i < len; i += 2)
  				{
  					char ch = (char)(userStringHeap[index + i] | userStringHeap[index + i + 1] << 8);
  					sb.Append(ch);
  				}
  				str = sb.ToString();
  				strings.Add(metadataToken, str);
  			}
  			return str;
  		}
  
  		internal override Type ResolveType(int metadataToken, IGenericContext context)
  		{
  			int index = (metadataToken & 0xFFFFFF) - 1;
  			if (index < 0)
  			{
  				throw TokenOutOfRangeException(metadataToken);
  			}
  			else if ((metadataToken >> 24) == TypeDefTable.Index && index < TypeDef.RowCount)
  			{
  				PopulateTypeDef();
  				return typeDefs[index];
  			}
  			else if ((metadataToken >> 24) == TypeRefTable.Index && index < TypeRef.RowCount)
  			{
  				if (typeRefs == null)
  				{
  					typeRefs = new Type[TypeRef.records.Length];
  				}
  				if (typeRefs[index] == null)
  				{
  					int scope = TypeRef.records[index].ResolutionScope;
  					switch (scope >> 24)
  					{
  						case AssemblyRefTable.Index:
  							{
  								Assembly assembly = ResolveAssemblyRef((scope & 0xFFFFFF) - 1);
  								TypeName typeName = GetTypeName(TypeRef.records[index].TypeNameSpace, TypeRef.records[index].TypeName);
  								typeRefs[index] = assembly.ResolveType(typeName);
  								break;
  							}
  						case TypeRefTable.Index:
  							{
  								Type outer = ResolveType(scope, null);
  								TypeName typeName = GetTypeName(TypeRef.records[index].TypeNameSpace, TypeRef.records[index].TypeName);
  								typeRefs[index] = outer.ResolveNestedType(typeName);
  								break;
  							}
  						case ModuleTable.Index:
  						case ModuleRefTable.Index:
  							{
  								Module module;
  								if (scope >> 24 == ModuleTable.Index)
  								{
  									if (scope == 0 || scope == 1)
  									{
  										module = this;
  									}
  									else
  									{
  										throw new NotImplementedException("self reference scope?");
  									}
  								}
  								else
  								{
  									module = ResolveModuleRef(ModuleRef.records[(scope & 0xFFFFFF) - 1]);
  								}
  								TypeName typeName = GetTypeName(TypeRef.records[index].TypeNameSpace, TypeRef.records[index].TypeName);
  								typeRefs[index] = module.FindType(typeName) ?? module.universe.GetMissingTypeOrThrow(module, null, typeName);
  								break;
  							}
  						default:
  							throw new NotImplementedException("ResolutionScope = " + scope.ToString("X"));
  					}
  				}
  				return typeRefs[index];
  			}
  			else if ((metadataToken >> 24) == TypeSpecTable.Index && index < TypeSpec.RowCount)
  			{
  				if (typeSpecs == null)
  				{
  					typeSpecs = new Type[TypeSpec.records.Length];
  				}
  				Type type = typeSpecs[index];
  				if (type == null)
  				{
  					TrackingGenericContext tc = context == null ? null : new TrackingGenericContext(context);
  					type = Signature.ReadTypeSpec(this, ByteReader.FromBlob(blobHeap, TypeSpec.records[index]), tc);
  					if (tc == null || !tc.IsUsed)
  					{
  						typeSpecs[index] = type;
  					}
  				}
  				return type;
  			}
  			else
  			{
  				throw TokenOutOfRangeException(metadataToken);
  			}
  		}
  
  		private Module ResolveModuleRef(int moduleNameIndex)
  		{
  			string moduleName = GetString(moduleNameIndex);
  			Module module = assembly.GetModule(moduleName);
  			if (module == null)
  			{
  				throw new FileNotFoundException(moduleName);
  			}
  			return module;
  		}
  
  		private sealed class TrackingGenericContext : IGenericContext
  		{
  			private readonly IGenericContext context;
  			private bool used;
  
  			internal TrackingGenericContext(IGenericContext context)
  			{
  				this.context = context;
  			}
  
  			internal bool IsUsed
  			{
  				get { return used; }
  			}
  
  			public Type GetGenericTypeArgument(int index)
  			{
  				used = true;
  				return context.GetGenericTypeArgument(index);
  			}
  
  			public Type GetGenericMethodArgument(int index)
  			{
  				used = true;
  				return context.GetGenericMethodArgument(index);
  			}
  		}
  
  		private TypeName GetTypeName(int typeNamespace, int typeName)
  		{
  			return new TypeName(GetString(typeNamespace), GetString(typeName));
  		}
  
  		internal Assembly ResolveAssemblyRef(int index)
  		{
  			if (assemblyRefs == null)
  			{
  				assemblyRefs = new Assembly[AssemblyRef.RowCount];
  			}
  			if (assemblyRefs[index] == null)
  			{
  				assemblyRefs[index] = ResolveAssemblyRefImpl(ref AssemblyRef.records[index]);
  			}
  			return assemblyRefs[index];
  		}
  
  		private Assembly ResolveAssemblyRefImpl(ref AssemblyRefTable.Record rec)
  		{
  			const int PublicKey = 0x0001;
  			string name = String.Format("{0}, Version={1}.{2}.{3}.{4}, Culture={5}, {6}={7}",
  				GetString(rec.Name),
  				rec.MajorVersion,
  				rec.MinorVersion,
  				rec.BuildNumber,
  				rec.RevisionNumber,
  				rec.Culture == 0 ? "neutral" : GetString(rec.Culture),
  				(rec.Flags & PublicKey) == 0 ? "PublicKeyToken" : "PublicKey",
  				PublicKeyOrTokenToString(rec.PublicKeyOrToken));
  			return universe.Load(name, this.Assembly, true);
  		}
  
  		private string PublicKeyOrTokenToString(int publicKeyOrToken)
  		{
  			if (publicKeyOrToken == 0)
  			{
  				return "null";
  			}
  			ByteReader br = GetBlob(publicKeyOrToken);
  			if (br.Length == 0)
  			{
  				return "null";
  			}
  			StringBuilder sb = new StringBuilder(br.Length * 2);
  			while (br.Length > 0)
  			{
  				sb.AppendFormat("{0:x2}", br.ReadByte());
  			}
  			return sb.ToString();
  		}
  
  		public override Guid ModuleVersionId
  		{
  			get
  			{
  				byte[] buf = new byte[16];
  				Buffer.BlockCopy(guidHeap, 16 * (ModuleTable.records[0].Mvid - 1), buf, 0, 16);
  				return new Guid(buf);
  			}
  		}
  
  		public override string FullyQualifiedName
  		{
  			get { return location ?? "<Unknown>"; }
  		}
  
  		public override string Name
  		{
  			get { return location == null ? "<Unknown>" : System.IO.Path.GetFileName(location); }
  		}
  
  		public override Assembly Assembly
  		{
  			get { return assembly; }
  		}
  
  		internal override Type FindType(TypeName typeName)
  		{
  			PopulateTypeDef();
  			Type type;
  			if (!types.TryGetValue(typeName, out type))
  			{
  				LazyForwardedType fw;
  				if (forwardedTypes.TryGetValue(typeName, out fw))
  				{
  					return fw.GetType(this, typeName);
  				}
  			}
  			return type;
  		}
  
  		internal override Type FindTypeIgnoreCase(TypeName lowerCaseName)
  		{
  			PopulateTypeDef();
  			foreach (Type type in types.Values)
  			{
  				if (new TypeName(type.__Namespace, type.__Name).ToLowerInvariant() == lowerCaseName)
  				{
  					return type;
  				}
  			}
  			foreach (TypeName name in forwardedTypes.Keys)
  			{
  				if (name.ToLowerInvariant() == lowerCaseName)
  				{
  					return forwardedTypes[name].GetType(this, name);
  				}
  			}
  			return null;
  		}
  
  		private Exception TokenOutOfRangeException(int metadataToken)
  		{
  			return new ArgumentOutOfRangeException("metadataToken", String.Format("Token 0x{0:x8} is not valid in the scope of module {1}.", metadataToken, this.Name));
  		}
  
  		public override MemberInfo ResolveMember(int metadataToken, Type[] genericTypeArguments, Type[] genericMethodArguments)
  		{
  			switch (metadataToken >> 24)
  			{
  				case FieldTable.Index:
  					return ResolveField(metadataToken, genericTypeArguments, genericMethodArguments);
  				case MemberRefTable.Index:
  					int index = (metadataToken & 0xFFFFFF) - 1;
  					if (index < 0 || index >= MemberRef.RowCount)
  					{
  						goto default;
  					}
  					return GetMemberRef(index, genericTypeArguments, genericMethodArguments);
  				case MethodDefTable.Index:
  				case MethodSpecTable.Index:
  					return ResolveMethod(metadataToken, genericTypeArguments, genericMethodArguments);
  				case TypeRefTable.Index:
  				case TypeDefTable.Index:
  				case TypeSpecTable.Index:
  					return ResolveType(metadataToken, genericTypeArguments, genericMethodArguments);
  				default:
  					throw TokenOutOfRangeException(metadataToken);
  			}
  		}
  
  		internal FieldInfo GetFieldAt(TypeDefImpl owner, int index)
  		{
  			if (fields == null)
  			{
  				fields = new FieldInfo[Field.records.Length];
  			}
  			if (fields[index] == null)
  			{
  				fields[index] = new FieldDefImpl(this, owner ?? FindFieldOwner(index), index);
  			}
  			return fields[index];
  		}
  
  		public override FieldInfo ResolveField(int metadataToken, Type[] genericTypeArguments, Type[] genericMethodArguments)
  		{
  			int index = (metadataToken & 0xFFFFFF) - 1;
  			if (index < 0)
  			{
  				throw TokenOutOfRangeException(metadataToken);
  			}
  			else if ((metadataToken >> 24) == FieldTable.Index && index < Field.RowCount)
  			{
  				return GetFieldAt(null, index);
  			}
  			else if ((metadataToken >> 24) == MemberRefTable.Index && index < MemberRef.RowCount)
  			{
  				FieldInfo field = GetMemberRef(index, genericTypeArguments, genericMethodArguments) as FieldInfo;
  				if (field != null)
  				{
  					return field;
  				}
  				throw new ArgumentException(String.Format("Token 0x{0:x8} is not a valid FieldInfo token in the scope of module {1}.", metadataToken, this.Name), "metadataToken");
  			}
  			else
  			{
  				throw TokenOutOfRangeException(metadataToken);
  			}
  		}
  
  		private TypeDefImpl FindFieldOwner(int fieldIndex)
  		{
  			// TODO use binary search?
  			for (int i = 0; i < TypeDef.records.Length; i++)
  			{
  				int field = TypeDef.records[i].FieldList - 1;
  				int end = TypeDef.records.Length > i + 1 ? TypeDef.records[i + 1].FieldList - 1 : Field.records.Length;
  				if (field <= fieldIndex && fieldIndex < end)
  				{
  					PopulateTypeDef();
  					return typeDefs[i];
  				}
  			}
  			throw new InvalidOperationException();
  		}
  
  		internal MethodBase GetMethodAt(TypeDefImpl owner, int index)
  		{
  			if (methods == null)
  			{
  				methods = new MethodBase[MethodDef.records.Length];
  			}
  			if (methods[index] == null)
  			{
  				MethodDefImpl method = new MethodDefImpl(this, owner ?? FindMethodOwner(index), index);
  				methods[index] = method.IsConstructor ? new ConstructorInfoImpl(method) : (MethodBase)method;
  			}
  			return methods[index];
  		}
  
  		public override MethodBase ResolveMethod(int metadataToken, Type[] genericTypeArguments, Type[] genericMethodArguments)
  		{
  			int index = (metadataToken & 0xFFFFFF) - 1;
  			if (index < 0)
  			{
  				throw TokenOutOfRangeException(metadataToken);
  			}
  			else if ((metadataToken >> 24) == MethodDefTable.Index && index < MethodDef.RowCount)
  			{
  				return GetMethodAt(null, index);
  			}
  			else if ((metadataToken >> 24) == MemberRefTable.Index && index < MemberRef.RowCount)
  			{
  				MethodBase method = GetMemberRef(index, genericTypeArguments, genericMethodArguments) as MethodBase;
  				if (method != null)
  				{
  					return method;
  				}
  				throw new ArgumentException(String.Format("Token 0x{0:x8} is not a valid MethodBase token in the scope of module {1}.", metadataToken, this.Name), "metadataToken");
  			}
  			else if ((metadataToken >> 24) == MethodSpecTable.Index && index < MethodSpec.RowCount)
  			{
  				MethodInfo method = (MethodInfo)ResolveMethod(MethodSpec.records[index].Method, genericTypeArguments, genericMethodArguments);
  				ByteReader instantiation = ByteReader.FromBlob(blobHeap, MethodSpec.records[index].Instantiation);
  				return method.MakeGenericMethod(Signature.ReadMethodSpec(this, instantiation, new GenericContext(genericTypeArguments, genericMethodArguments)));
  			}
  			else
  			{
  				throw TokenOutOfRangeException(metadataToken);
  			}
  		}
  
  		public override Type[] __ResolveOptionalParameterTypes(int metadataToken, Type[] genericTypeArguments, Type[] genericMethodArguments, out CustomModifiers[] customModifiers)
  		{
  			int index = (metadataToken & 0xFFFFFF) - 1;
  			if (index < 0)
  			{
  				throw TokenOutOfRangeException(metadataToken);
  			}
  			else if ((metadataToken >> 24) == MemberRefTable.Index && index < MemberRef.RowCount)
  			{
  				int sig = MemberRef.records[index].Signature;
  				return Signature.ReadOptionalParameterTypes(this, GetBlob(sig), new GenericContext(genericTypeArguments, genericMethodArguments), out customModifiers);
  			}
  			else if ((metadataToken >> 24) == MethodDefTable.Index && index < MethodDef.RowCount)
  			{
  				// for convenience, we support passing a MethodDef token as well, because in some places
  				// it makes sense to have a vararg method that is referred to by its methoddef (e.g. ldftn).
  				// Note that MethodSpec doesn't make sense, because generic methods cannot be vararg.
  				customModifiers = Empty<CustomModifiers>.Array;
  				return Type.EmptyTypes;
  			}
  			else
  			{
  				throw TokenOutOfRangeException(metadataToken);
  			}
  		}
  
  		public override string ScopeName
  		{
  			get { return GetString(ModuleTable.records[0].Name); }
  		}
  
  		private TypeDefImpl FindMethodOwner(int methodIndex)
  		{
  			// TODO use binary search?
  			for (int i = 0; i < TypeDef.records.Length; i++)
  			{
  				int method = TypeDef.records[i].MethodList - 1;
  				int end = TypeDef.records.Length > i + 1 ? TypeDef.records[i + 1].MethodList - 1 : MethodDef.records.Length;
  				if (method <= methodIndex && methodIndex < end)
  				{
  					PopulateTypeDef();
  					return typeDefs[i];
  				}
  			}
  			throw new InvalidOperationException();
  		}
  
  		private MemberInfo GetMemberRef(int index, Type[] genericTypeArguments, Type[] genericMethodArguments)
  		{
  			if (memberRefs == null)
  			{
  				memberRefs = new MemberInfo[MemberRef.records.Length];
  			}
  			if (memberRefs[index] == null)
  			{
  				int owner = MemberRef.records[index].Class;
  				int sig = MemberRef.records[index].Signature;
  				string name = GetString(MemberRef.records[index].Name);
  				switch (owner >> 24)
  				{
  					case MethodDefTable.Index:
  						return GetMethodAt(null, (owner & 0xFFFFFF) - 1);
  					case ModuleRefTable.Index:
  						memberRefs[index] = ResolveTypeMemberRef(ResolveModuleType(owner), name, ByteReader.FromBlob(blobHeap, sig));
  						break;
  					case TypeDefTable.Index:
  					case TypeRefTable.Index:
  						memberRefs[index] = ResolveTypeMemberRef(ResolveType(owner), name, ByteReader.FromBlob(blobHeap, sig));
  						break;
  					case TypeSpecTable.Index:
  					{
  						Type type = ResolveType(owner, genericTypeArguments, genericMethodArguments);
  						if (type.IsArray)
  						{
  							MethodSignature methodSig = MethodSignature.ReadSig(this, ByteReader.FromBlob(blobHeap, sig), new GenericContext(genericTypeArguments, genericMethodArguments));
  							return type.FindMethod(name, methodSig)
  								?? universe.GetMissingMethodOrThrow(type, name, methodSig);
  						}
  						else if (type.IsConstructedGenericType)
  						{
  							MemberInfo member = ResolveTypeMemberRef(type.GetGenericTypeDefinition(), name, ByteReader.FromBlob(blobHeap, sig));
  							MethodBase mb = member as MethodBase;
  							if (mb != null)
  							{
  								member = mb.BindTypeParameters(type);
  							}
  							FieldInfo fi = member as FieldInfo;
  							if (fi != null)
  							{
  								member = fi.BindTypeParameters(type);
  							}
  							return member;
  						}
  						else
  						{
  							return ResolveTypeMemberRef(type, name, ByteReader.FromBlob(blobHeap, sig));
  						}
  					}
  					default:
  						throw new BadImageFormatException();
  				}
  			}
  			return memberRefs[index];
  		}
  
  		private Type ResolveModuleType(int token)
  		{
  			int index = (token & 0xFFFFFF) - 1;
  			string name = GetString(ModuleRef.records[index]);
  			Module module = assembly.GetModule(name);
  			if (module == null || module.IsResource())
  			{
  				throw new BadImageFormatException();
  			}
  			return module.GetModuleType();
  		}
  
  		private MemberInfo ResolveTypeMemberRef(Type type, string name, ByteReader sig)
  		{
  			if (sig.PeekByte() == Signature.FIELD)
  			{
  				Type org = type;
  				FieldSignature fieldSig = FieldSignature.ReadSig(this, sig, type);
  				FieldInfo field = type.FindField(name, fieldSig);
  				if (field == null && universe.MissingMemberResolution)
  				{
  					return universe.GetMissingFieldOrThrow(type, name, fieldSig);
  				}
  				while (field == null && (type = type.BaseType) != null)
  				{
  					field = type.FindField(name, fieldSig);
  				}
  				if (field != null)
  				{
  					return field;
  				}
  				throw new MissingFieldException(org.ToString(), name);
  			}
  			else
  			{
  				Type org = type;
  				MethodSignature methodSig = MethodSignature.ReadSig(this, sig, type);
  				MethodBase method = type.FindMethod(name, methodSig);
  				if (method == null && universe.MissingMemberResolution)
  				{
  					return universe.GetMissingMethodOrThrow(type, name, methodSig);
  				}
  				while (method == null && (type = type.BaseType) != null)
  				{
  					method = type.FindMethod(name, methodSig);
  				}
  				if (method != null)
  				{
  					return method;
  				}
  				throw new MissingMethodException(org.ToString(), name);
  			}
  		}
  
  		internal ByteReader GetStandAloneSig(int index)
  		{
  			return ByteReader.FromBlob(blobHeap, StandAloneSig.records[index]);
  		}
  
  		public override byte[] ResolveSignature(int metadataToken)
  		{
  			int index = (metadataToken & 0xFFFFFF) - 1;
  			if ((metadataToken >> 24) == StandAloneSigTable.Index && index >= 0 && index < StandAloneSig.RowCount)
  			{
  				ByteReader br = GetStandAloneSig(index);
  				return br.ReadBytes(br.Length);
  			}
  			else
  			{
  				throw TokenOutOfRangeException(metadataToken);
  			}
  		}
  
  		public override __StandAloneMethodSig __ResolveStandAloneMethodSig(int metadataToken, Type[] genericTypeArguments, Type[] genericMethodArguments)
  		{
  			int index = (metadataToken & 0xFFFFFF) - 1;
  			if ((metadataToken >> 24) == StandAloneSigTable.Index && index >= 0 && index < StandAloneSig.RowCount)
  			{
  				return MethodSignature.ReadStandAloneMethodSig(this, GetStandAloneSig(index), new GenericContext(genericTypeArguments, genericMethodArguments));
  			}
  			else
  			{
  				throw TokenOutOfRangeException(metadataToken);
  			}
  		}
  
  		internal MethodInfo GetEntryPoint()
  		{
  			if (cliHeader.EntryPointToken != 0 && (cliHeader.Flags & CliHeader.COMIMAGE_FLAGS_NATIVE_ENTRYPOINT) == 0)
  			{
  				return (MethodInfo)ResolveMethod((int)cliHeader.EntryPointToken);
  			}
  			return null;
  		}
  
  		internal string[] GetManifestResourceNames()
  		{
  			string[] names = new string[ManifestResource.records.Length];
  			for (int i = 0; i < ManifestResource.records.Length; i++)
  			{
  				names[i] = GetString(ManifestResource.records[i].Name);
  			}
  			return names;
  		}
  
  		internal ManifestResourceInfo GetManifestResourceInfo(string resourceName)
  		{
  			for (int i = 0; i < ManifestResource.records.Length; i++)
  			{
  				if (resourceName == GetString(ManifestResource.records[i].Name))
  				{
  					ManifestResourceInfo info = new ManifestResourceInfo(this, i);
  					Assembly asm = info.ReferencedAssembly;
  					if (asm != null && !asm.__IsMissing && asm.GetManifestResourceInfo(resourceName) == null)
  					{
  						return null;
  					}
  					return info;
  				}
  			}
  			return null;
  		}
  
  		internal Stream GetManifestResourceStream(string resourceName)
  		{
  			for (int i = 0; i < ManifestResource.records.Length; i++)
  			{
  				if (resourceName == GetString(ManifestResource.records[i].Name))
  				{
  					if (ManifestResource.records[i].Implementation != 0x26000000)
  					{
  						ManifestResourceInfo info = new ManifestResourceInfo(this, i);
  						switch (ManifestResource.records[i].Implementation >> 24)
  						{
  							case FileTable.Index:
  								string fileName = Path.Combine(Path.GetDirectoryName(location), info.FileName);
  								if (System.IO.File.Exists(fileName))
  								{
  									// note that, like System.Reflection, we return null for zero length files and
  									// ManifestResource.Offset is ignored
  									FileStream fs = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read | FileShare.Delete);
  									if (fs.Length == 0)
  									{
  										fs.Close();
  										return null;
  									}
  									return fs;
  								}
  								return null;
  							case AssemblyRefTable.Index:
  								Assembly asm = info.ReferencedAssembly;
  								if (asm.__IsMissing)
  								{
  									return null;
  								}
  								return asm.GetManifestResourceStream(resourceName);
  							default:
  								throw new BadImageFormatException();
  						}
  					}
  					SeekRVA((int)cliHeader.Resources.VirtualAddress + ManifestResource.records[i].Offset);
  
gt: 					BinaryReader br = new BinaryReader(stream);