Fix for IndexOutOfRangeException in ILReader.ReadOpCode() (#81)

* Allow testing internals

* Add ILReaderTests

* Skip inline operands in IL

src/Ben.Demystifier/Ben.Demystifier.csproj

@@ -27,4 +27,9 @@
     </PackageReference>
   </ItemGroup>
 
+  <ItemGroup Label="TestInternalsVisibleTo">
+    <AssemblyAttribute Include="System.Runtime.CompilerServices.InternalsVisibleToAttribute">
+        <_Parameter1>$(AssemblyName).Test, PublicKey=00240000048000009400000006020000002400005253413100040000010001005532489e147c0de0c5872048d20f7acf99d172a599d217950eba8fdbd1f98fa5ac47901b076d2bd7da8d436e6b5d6292694902e9748514bb0c3b17e6a0e0386f22447847c1c5cd9e034f79a8fe1c120a12785f7f79617414e63861cf13d6fd1cbb4211b87202c6a52c1e22962a6bd310413c37ca440fad14ab8422707517fbae</_Parameter1>
+    </AssemblyAttribute>
+  </ItemGroup>
 </Project>

src/Ben.Demystifier/Internal/ILReader.cs

@@ -41,6 +41,7 @@ namespace System.Diagnostics.Internal
         MemberInfo ReadOperand(OpCode code, MethodBase methodInfo)
         {
             MetadataToken = 0;
+            int inlineLength;
             switch (code.OperandType)
             {
                 case OperandType.InlineMethod:
@@ -64,7 +65,47 @@ namespace System.Diagnostics.Internal
                         // Can return System.ArgumentException : Token xxx is not a valid MemberInfo token in the scope of module xxx.dll
                         return null;
                     }
+
+                case OperandType.InlineNone:
+                    inlineLength = 0;
+                    break;
+
+                case OperandType.ShortInlineBrTarget:
+                case OperandType.ShortInlineVar:
+                    inlineLength = 1;
+                    break;
+
+                case OperandType.InlineVar:
+                    inlineLength = 2;
+                    break;
+
+                case OperandType.InlineBrTarget:
+                case OperandType.InlineField:
+                case OperandType.InlineI:
+                case OperandType.InlineString:
+                case OperandType.InlineSig:
+                case OperandType.InlineSwitch:
+                case OperandType.InlineTok:
+                case OperandType.InlineType:
+                case OperandType.ShortInlineR:
+                    inlineLength = 4;
+                    break;
+
+                case OperandType.InlineI8:
+                case OperandType.InlineR:
+                    inlineLength = 8;
+                    break;
+
+                default:
+                    // Can return System.ArgumentException : Unexpected operand type xxx
+                    return null;
             }
+
+            for (var i = 0; i < inlineLength; i++)
+            {
+                ReadByte();
+            }
+
             return null;
         }
 

test/Ben.Demystifier.Test/Ben.Demystifier.Test.csproj

@@ -2,7 +2,8 @@
   
   <PropertyGroup>
     <TargetFrameworks>netcoreapp2.0;net46</TargetFrameworks>
-
+    <SignAssembly>true</SignAssembly>
+    <AssemblyOriginatorKeyFile>..\..\src\Ben.Demystifier\key.snk</AssemblyOriginatorKeyFile>
     <IsPackable>false</IsPackable>
   </PropertyGroup>
 

test/Ben.Demystifier.Test/ILReaderTests.cs

@@ -0,0 +1,49 @@
+using System.Diagnostics.Internal;
+
+using Xunit;
+
+namespace Ben.Demystifier.Test
+{
+    public class ILReaderTests
+    {
+        public static TheoryData<byte[]> InlineCilSamples => 
+            new TheoryData<byte[]>
+            {
+                //  https://github.com/benaadams/Ben.Demystifier/issues/56#issuecomment-366490463
+                { new byte[] {
+                    2, 123, 209, 5, 0, 4, 20, 254, 1, 114, 193, 103, 1, 112, 40, 160, 22, 0, 6,
+                    2, 115, 183, 10, 0, 10, 125, 210, 5, 0, 4, 2, 123, 212, 5, 0, 4, 2, 123, 211,
+                    5, 0, 4, 40, 221, 15, 0, 6, 44, 68, 2, 123, 212, 5, 0, 4, 111, 103, 17, 0, 6, 2,
+                    111, 222, 9, 0, 6, 2, 40, 184, 10, 0, 10, 2, 254, 6, 249, 15, 0, 6, 115, 185, 10,
+                    0, 10, 2, 123, 210, 5, 0, 4, 111, 186, 10, 0, 10, 22, 40, 101, 6, 0, 10, 111, 221,
+                    0, 0, 43, 40, 188, 10, 0, 10, 125, 209, 5, 0, 4, 42, 2, 123, 212, 5, 0, 4, 111,
+                    103, 17, 0, 6, 111, 216, 9, 0, 6, 2, 123, 211, 5, 0, 4, 111, 166, 14, 0, 6, 111,
+                    125, 16, 0, 6, 254, 1, 22, 254, 1, 114, 235, 103, 1, 112, 40, 160, 22, 0, 6, 114,
+                    160, 104, 1, 112, 40, 210, 0, 0, 10, 114, 194, 5, 0, 112, 40, 221, 0, 0, 10, 44, 51,
+                    2, 40, 184, 10, 0, 10, 2, 254, 6, 250, 15, 0, 6, 115, 185, 10, 0, 10, 2, 123, 210,
+                    5, 0, 4, 111, 186, 10, 0, 10, 22, 40, 196, 21, 0, 6, 111, 221, 0, 0, 43, 40, 188,
+                    10, 0, 10, 125, 209, 5, 0, 4, 42, 2, 40, 184, 10, 0, 10, 2, 254, 6, 251, 15, 0, 6,
+                    115, 185, 10, 0, 10, 2, 123, 210, 5, 0, 4, 111, 186, 10, 0, 10, 24, 40, 101, 6, 0,
+                    10, 111, 221, 0, 0, 43, 40, 188, 10, 0, 10, 125, 209, 5, 0, 4, 42
+                } },
+
+                //  https://github.com/benaadams/Ben.Demystifier/issues/56#issuecomment-390654651
+                { new byte[] {
+                    115, 31, 5, 0, 6, 37, 2, 125, 94, 1, 0, 4, 37, 3, 125, 91, 1, 0, 4, 37, 4, 125, 92,
+                    1, 0, 4, 37, 5, 125, 93, 1, 0, 4, 37, 123, 91, 1, 0, 4, 40, 61, 0, 0, 10, 44, 16,
+                    40, 160, 4, 0, 6, 114, 253, 15, 0, 112, 115, 90, 0, 0, 10, 122, 254, 6, 32, 5, 0,
+                    6, 115, 137, 2, 0, 10, 115, 61, 2, 0, 6, 42
+                } },
+            };
+
+        //  https://github.com/benaadams/Ben.Demystifier/issues/56
+        [Theory, MemberData(nameof(InlineCilSamples))]
+        public void ReadsInlinedOpcodes(byte[] cil)
+        {
+            var sut = new ILReader(cil);
+            while (sut.Read(GetType().GetMethod(nameof(ReadsInlinedOpcodes))))
+            {
+            }
+        }
+    }
+}