Don't crash when trying to decode invalid attribute/secdecl blobs.

src/Libraries/NewNRefactory/ICSharpCode.NRefactory/TypeSystem/CecilLoader.cs

@@ -806,7 +806,8 @@ namespace ICSharpCode.NRefactory.TypeSystem
 		sealed class CecilResolvedAttribute : IAttribute
 		{
 			readonly ITypeResolveContext context;
-			readonly CecilUnresolvedAttribute unresolved;
+			readonly byte[] blob;
+			readonly IList<ITypeReference> ctorParameterTypes;
 			readonly IType attributeType;
 			
 			IMethod constructor;
@@ -818,10 +819,18 @@ namespace ICSharpCode.NRefactory.TypeSystem
 			public CecilResolvedAttribute(ITypeResolveContext context, CecilUnresolvedAttribute unresolved)
 			{
 				this.context = context;
-				this.unresolved = unresolved;
+				this.blob = unresolved.blob;
+				this.ctorParameterTypes = unresolved.ctorParameterTypes;
 				this.attributeType = unresolved.attributeType.Resolve(context);
 			}
 			
+			public CecilResolvedAttribute(ITypeResolveContext context, IType attributeType)
+			{
+				this.context = context;
+				this.attributeType = attributeType;
+				this.ctorParameterTypes = EmptyList<ITypeReference>.Instance;
+			}
+			
 			public DomRegion Region {
 				get { return DomRegion.Empty; }
 			}
@@ -842,7 +851,7 @@ namespace ICSharpCode.NRefactory.TypeSystem
 			
 			IMethod ResolveConstructor()
 			{
-				var parameterTypes = unresolved.ctorParameterTypes.Resolve(context);
+				var parameterTypes = ctorParameterTypes.Resolve(context);
 				foreach (var ctor in attributeType.GetConstructors(m => m.Parameters.Count == parameterTypes.Count)) {
 					bool ok = true;
 					for (int i = 0; i < parameterTypes.Count; i++) {
@@ -901,12 +910,14 @@ namespace ICSharpCode.NRefactory.TypeSystem
 			
 			void DecodeBlob(List<ResolveResult> positionalArguments, List<KeyValuePair<IMember, ResolveResult>> namedArguments)
 			{
-				BlobReader reader = new BlobReader(unresolved.blob, context.CurrentAssembly);
+				if (blob == null)
+					return;
+				BlobReader reader = new BlobReader(blob, context.CurrentAssembly);
 				if (reader.ReadUInt16() != 0x0001) {
 					Debug.WriteLine("Unknown blob prolog");
 					return;
 				}
-				foreach (var ctorParameter in unresolved.ctorParameterTypes.Resolve(context)) {
+				foreach (var ctorParameter in ctorParameterTypes.Resolve(context)) {
 					positionalArguments.Add(reader.ReadFixedArg(ctorParameter));
 				}
 				ushort numNamed = reader.ReadUInt16();
@@ -1151,7 +1162,7 @@ namespace ICSharpCode.NRefactory.TypeSystem
 					case KnownTypeCode.String:
 						return ReadSerString();
 					default:
-						return ErrorResolveResult.UnknownError;
+						throw new NotSupportedException();
 				}
 			}
 			
@@ -1318,14 +1329,30 @@ namespace ICSharpCode.NRefactory.TypeSystem
 				
 				ITypeResolveContext context = new SimpleTypeResolveContext(currentAssembly);
 				BlobReader reader = new BlobReader(blob, currentAssembly);
-				IList<IAttribute> result = new List<IAttribute>();
 				if (reader.ReadByte() != '.') {
 					// should not use UnresolvedSecurityDeclaration for XML secdecls
 					throw new InvalidOperationException();
 				}
 				ResolveResult securityActionRR = securityAction.Resolve(context);
 				uint attributeCount = reader.ReadCompressedUInt32();
-				for (uint i = 0; i < attributeCount; i++) {
+				IAttribute[] attributes = new IAttribute[attributeCount];
+				try {
+					ReadSecurityBlob(reader, attributes, context, securityActionRR);
+				} catch (NotSupportedException ex) {
+					// ignore invalid blobs
+					Debug.WriteLine(ex.ToString());
+				}
+				for (int i = 0; i < attributes.Length; i++) {
+					if (attributes[i] == null)
+						attributes[i] = new CecilResolvedAttribute(context, SpecialType.UnknownType);
+				}
+				return attributes;
+//				return (IList<IAttribute>)cache.GetOrAddShared(this, attributes);
+			}
+			
+			void ReadSecurityBlob(BlobReader reader, IAttribute[] attributes, ITypeResolveContext context, ResolveResult securityActionRR)
+			{
+				for (int i = 0; i < attributes.Length; i++) {
 					string attributeTypeName = reader.ReadSerString();
 					ITypeReference attributeTypeRef = ReflectionHelper.ParseReflectionName(attributeTypeName);
 					IType attributeType = attributeTypeRef.Resolve(context);
@@ -1341,15 +1368,12 @@ namespace ICSharpCode.NRefactory.TypeSystem
 							namedArgs.Add(namedArg);
 						
 					}
-					result.Add(new ResolvedSecurityAttribute {
-					           	AttributeType = attributeType,
-					           	NamedArguments = namedArgs,
-					           	PositionalArguments = new ResolveResult[] { securityActionRR }
-					           });
+					attributes[i] = new ResolvedSecurityAttribute {
+						AttributeType = attributeType,
+						NamedArguments = namedArgs,
+						PositionalArguments = new ResolveResult[] { securityActionRR }
+					};
 				}
-				
-				return result;
-//				return (IList<IAttribute>)cache.GetOrAddShared(this, result);
 			}
 			
 			void ISupportsInterning.PrepareForInterning(IInterningProvider provider)