Fix wrong calculation of native methods checksum (#81)

***UPDATE_DEPENDENTS***

Author: josesimoes

source/MetadataProcessor.Core/Utility/NativeMethodsCrc.cs

@@ -25,6 +25,9 @@ public sealed class NativeMethodsCrc
 
         private readonly List<string> _classNamesToExclude;
 
+        private int _methodsWithNativeImplementation = 0;
+        private uint _currentCrc = 0;
+
         public NativeMethodsCrc(
             AssemblyDefinition assembly,
             List<string> classNamesToExclude)
@@ -33,7 +36,24 @@ public NativeMethodsCrc(
             _classNamesToExclude = classNamesToExclude;
         }
 
-        public uint Current { get; private set; }
+        /// <summary>
+        /// Current CRC32 of the native methods.
+        /// Will return 0 if there are no methods with native implementation.
+        /// </summary>
+        public uint CurrentCrc
+        {
+            get
+            {
+                if(_methodsWithNativeImplementation > 0)
+                {
+                    return _currentCrc;
+                }
+                else
+                {
+                    return 0;
+                }
+            }
+        }
 
         public void UpdateCrc(MethodDefinition method)
         {
@@ -42,13 +62,15 @@ public void UpdateCrc(MethodDefinition method)
             if (type.IncludeInStub() &&
                 (method.RVA == 0 && !method.IsAbstract) )
             {
-                Current = Crc32.Compute(_name, Current);
-                Current = Crc32.Compute(Encoding.ASCII.GetBytes(GetClassName(type)), Current);
-                Current = Crc32.Compute(Encoding.ASCII.GetBytes(GetMethodName(method)), Current);
+                _currentCrc = Crc32.Compute(_name, CurrentCrc);
+                _currentCrc = Crc32.Compute(Encoding.ASCII.GetBytes(GetClassName(type)), CurrentCrc);
+                _currentCrc = Crc32.Compute(Encoding.ASCII.GetBytes(GetMethodName(method)), CurrentCrc);
+
+                _methodsWithNativeImplementation++;
             }
             else
             {
-                Current = Crc32.Compute(_null, Current);
+                _currentCrc = Crc32.Compute(_null, CurrentCrc);
             }
         }
 

source/MetadataProcessor.Core/nanoAssemblyBuilder.cs

@@ -267,16 +267,7 @@ public string GetNativeChecksum()
         {
             if(_tablesContext.MinimizeComplete)
             {
-                // check if there are any native methods
-                if (_tablesContext.MethodDefinitionTable.Items.Any(method => method.RVA == 0 && !method.IsAbstract))
-                {
-                    return $"0x{_tablesContext.NativeMethodsCrc.Current.ToString("X")}";
-                }
-                else
-                {
-                    // this assembly doesn't have native implementation
-                    return "0x00000000";
-                }
+                return $"0x{_tablesContext.NativeMethodsCrc.CurrentCrc.ToString("X8")}";
             }
             else
             {

source/MetadataProcessor.Core/nanoAssemblyDefinition.cs

@@ -89,21 +89,8 @@ public void Write(
             // current builds are for little endian targets only
             // keeping this here for now, just for compatibility
             writer.WriteUInt32(0);
-
-            var nativeMethdodsCount = _context.MethodDefinitionTable.Items.Count(method => method.RVA == 0 && !method.IsAbstract);
-
-            // native methods CRC32
-            // this is used by other tools to check if the assembly has native implementation 
-            // (like the deployment provider in the VS extension)
-            if (nativeMethdodsCount > 0)
-            {
-                writer.WriteUInt32(_context.NativeMethodsCrc.Current);
-            }
-            else
-            {
-                // this assembly doesn't have any native methods implemented
-                writer.WriteUInt32(0);
-            }
+            
+            writer.WriteUInt32(_context.NativeMethodsCrc.CurrentCrc);
 
             // Native methods offset
             writer.WriteUInt32(0xFFFFFFFF);

source/MetadataProcessor.Core/nanoSkeletonGenerator.cs

@@ -50,7 +50,7 @@ public nanoSkeletonGenerator(
         public void GenerateSkeleton()
         {
             // check if there are any native methods
-            if(_tablesContext.MethodDefinitionTable.Items.Any(method => method.RVA == 0 && !method.IsAbstract))
+            if(_tablesContext.NativeMethodsCrc.CurrentCrc > 0)
             {
                 // create <assembly>.h with the structs declarations
                 GenerateAssemblyHeader();
@@ -63,7 +63,7 @@ public void GenerateSkeleton()
 
                 // output native checksum so it shows in build log
                 Console.WriteLine("++++++++++++++++++++++++++++++++++++++++++++");
-                Console.WriteLine($"+ Native declaration checksum: 0x{_tablesContext.NativeMethodsCrc.Current.ToString("X")} +");
+                Console.WriteLine($"+ Native declaration checksum: 0x{_tablesContext.NativeMethodsCrc.CurrentCrc.ToString("X8")} +");
                 Console.WriteLine("++++++++++++++++++++++++++++++++++++++++++++");
             }
             else
@@ -327,7 +327,7 @@ private void GenerateAssemblyLookup()
                 AssemblyName = _tablesContext.AssemblyDefinition.Name.Name,
                 HeaderFileName = _safeProjectName,
                 NativeVersion = nativeVersion,
-                NativeCRC32 = "0x" + _tablesContext.NativeMethodsCrc.Current.ToString("X")
+                NativeCRC32 = "0x" + _tablesContext.NativeMethodsCrc.CurrentCrc.ToString("X8")
             };