Parse JSON and store the contracts

Until we get dotnet#101048 from
codeflow, work around dotnet#101205 by adding
a trimmer root for JsonDerivedTypeAttribute[].

Author: lambdageek

src/native/managed/cdacreader/src/CdacRoots.xml

@@ -0,0 +1,6 @@
+<linker>
+  <assembly fullname="libcdacreader">
+    <!-- https://github.com/dotnet/runtime/issues/101205 -->
+    <type fullname="Microsoft.Diagnostics.DataContractReader.Root" preserve="all" />
+  </assembly>
+</linker>

src/native/managed/cdacreader/src/ContractDescriptorParser.cs

@@ -29,7 +29,7 @@ public partial class ContractDescriptorParser
     }
 
     [JsonSerializable(typeof(ContractDescriptor))]
-    [JsonSerializable(typeof(int))]
+    [JsonSerializable(typeof(int?))]
     [JsonSerializable(typeof(string))]
     [JsonSerializable(typeof(Dictionary<string, int>))]
     [JsonSerializable(typeof(Dictionary<string, TypeDescriptor>))]
@@ -38,11 +38,17 @@ public partial class ContractDescriptorParser
     [JsonSerializable(typeof(TypeDescriptor))]
     [JsonSerializable(typeof(FieldDescriptor))]
     [JsonSerializable(typeof(GlobalDescriptor))]
+    [JsonSerializable(typeof(Dictionary<string, JsonElement>))]
     [JsonSourceGenerationOptions(AllowTrailingCommas = true,
                                 DictionaryKeyPolicy = JsonKnownNamingPolicy.Unspecified, // contracts, types and globals are case sensitive
                                 PropertyNamingPolicy = JsonKnownNamingPolicy.CamelCase,
                                 NumberHandling = JsonNumberHandling.AllowReadingFromString,
-                                ReadCommentHandling = JsonCommentHandling.Skip)]
+                                ReadCommentHandling = JsonCommentHandling.Skip,
+                                UnmappedMemberHandling = JsonUnmappedMemberHandling.Skip,
+                                UnknownTypeHandling = JsonUnknownTypeHandling.JsonElement,
+                                Converters = [typeof(TypeDescriptorConverter),
+                                            typeof(FieldDescriptorConverter),
+                                            typeof(GlobalDescriptorConverter)])]
     internal sealed partial class ContractDescriptorContext : JsonSerializerContext
     {
     }
@@ -58,7 +64,13 @@ public class ContractDescriptor
         public Dictionary<string, GlobalDescriptor>? Globals { get; set; }
 
         [JsonExtensionData]
-        public Dictionary<string, object?>? Extras { get; set; }
+        public Dictionary<string, JsonElement>? Extras { get; set; }
+
+        public override string ToString()
+        {
+            return $"Version: {Version}, Baseline: {Baseline}, Contracts: {Contracts?.Count}, Types: {Types?.Count}, Globals: {Globals?.Count}";
+        }
+
     }
 
     [JsonConverter(typeof(TypeDescriptorConverter))]

src/native/managed/cdacreader/src/Root.cs

@@ -0,0 +1,12 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Text.Json.Serialization;
+
+namespace Microsoft.Diagnostics.DataContractReader;
+
+internal static class Root
+{
+    // https://github.com/dotnet/runtime/issues/101205
+    public static JsonDerivedTypeAttribute[] R1 = new JsonDerivedTypeAttribute[] { null! };
+}

src/native/managed/cdacreader/src/Target.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Buffers.Binary;
+using System.Collections.Generic;
 
 namespace Microsoft.Diagnostics.DataContractReader;
 
@@ -25,6 +26,7 @@ internal sealed unsafe class Target
     private int _pointerSize;
 
     private TargetPointer[] _pointerData = [];
+    private IReadOnlyDictionary<string, int> _contracts = new Dictionary<string, int>();
 
     public Target(ulong contractDescriptor, delegate* unmanaged<ulong, byte*, uint, void*, int> readFromTarget, void* readContext)
     {
@@ -75,13 +77,23 @@ private void ReadContractDescriptor(ulong address)
         TargetPointer pointerData = ReadPointer(address);
 
         // Read descriptor
-        // TODO: [cdac] Pass to JSON parser
         Span<byte> descriptorBuffer = descriptorSize <= StackAllocByteThreshold
             ? stackalloc byte[(int)descriptorSize]
             : new byte[(int)descriptorSize];
         if (ReadFromTarget(descriptor.Value, descriptorBuffer) < 0)
             throw new InvalidOperationException("Failed to read descriptor.");
 
+        ContractDescriptorParser.ContractDescriptor? targetDescriptor = ContractDescriptorParser.ParseCompact(descriptorBuffer);
+
+        if (targetDescriptor is null)
+        {
+            throw new InvalidOperationException("Failed to parse descriptor.");
+        }
+
+        // TODO: [cdac] Read globals and types
+        // note: we will probably want to store the globals and types into a more usable form
+        _contracts = targetDescriptor.Contracts ?? new Dictionary<string, int>();
+
         // Read pointer data
         _pointerData = new TargetPointer[pointerDataCount];
         for (int i = 0; i < pointerDataCount; i++)

src/native/managed/cdacreader/src/cdacreader.csproj

@@ -9,8 +9,13 @@
     <!-- Do not produce a public package. This ships as part of the runtime -->
     <IsShippingPackage>false</IsShippingPackage>
     <InvariantGlobalization>true</InvariantGlobalization>
+    <JsonSerializerIsReflectionEnabledByDefault>false</JsonSerializerIsReflectionEnabledByDefault>
   </PropertyGroup>
 
+  <ItemGroup>
+    <TrimmerRootDescriptor Include="CdacRoots.xml" />
+  </ItemGroup>
+
   <ItemGroup>
     <Compile Include="$(LibrariesProjectRoot)Common\src\System\HResults.cs" Link="Common\System\HResults.cs" />
   </ItemGroup>

src/native/managed/cdacreader/tests/ContractDescriptorParserTests.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Text.Json;
 using System.Text.Unicode;
 using Xunit;
 
@@ -12,6 +13,7 @@ public class ContractDescriptorParserTests
     [Fact]
     public void ParsesEmptyContract()
     {
+        Assert.False(JsonSerializer.IsReflectionEnabledByDefault);
         ReadOnlySpan<byte> json = "{}"u8;
         ContractDescriptorParser.ContractDescriptor descriptor = ContractDescriptorParser.ParseCompact(json);
         Assert.Null(descriptor.Version);

src/native/managed/cdacreader/tests/Microsoft.Diagnostics.DataContractReader.Tests.csproj

@@ -2,6 +2,7 @@
   <PropertyGroup>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <TargetFramework>$(NetCoreAppToolCurrent)</TargetFramework>
+    <JsonSerializerIsReflectionEnabledByDefault>false</JsonSerializerIsReflectionEnabledByDefault>
   </PropertyGroup>