[cDAC] Add switch to load cDAC directly

src/Microsoft.Diagnostics.DebugServices.Implementation/Runtime.cs

@@ -98,7 +98,40 @@ public Version RuntimeVersion
 
         public string GetDacFilePath()
         {
-            _dacFilePath ??= GetLibraryPath(DebugLibraryKind.Dac);
+            if (_dacFilePath is not null)
+            {
+                return _dacFilePath;
+            }
+
+            // Optionally load the DAC through the cDAC
+            string str = Environment.GetEnvironmentVariable("DOTNET_SOS_LOAD_CDAC");
+            int.TryParse(str ?? string.Empty, out int val);
+
+            if (val == 0)
+            {
+                _dacFilePath ??= GetLibraryPath(DebugLibraryKind.Dac);
+            }
+            else
+            {
+                OSPlatform platform = Target.OperatingSystem;
+                if (platform == OSPlatform.Windows)
+                {
+                    _dacFilePath ??= GetLocalPath("cdacreader.dll");
+                }
+                else if (platform == OSPlatform.Linux)
+                {
+                    _dacFilePath ??= GetLocalPath("libcdacreader.so");
+                }
+                else if (platform == OSPlatform.OSX)
+                {
+                    _dacFilePath ??= GetLocalPath("libcdacreader.dylib");
+                }
+                else
+                {
+                    Trace.TraceError($"GetCdacFilePath: platform not supported - {platform}");
+                }
+            }
+
             return _dacFilePath;
         }
 

src/SOS/SOS.Hosting/DataTargetWrapper.cs

@@ -1,4 +1,4 @@
-// Licensed to the .NET Foundation under one or more agreements.
+// Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
@@ -17,10 +17,14 @@ internal sealed unsafe class DataTargetWrapper : COMCallableIUnknown
         private static readonly Guid IID_ICLRDataTarget4 = new("E799DC06-E099-4713-BDD9-906D3CC02CF2");
         private static readonly Guid IID_ICLRMetadataLocator = new("aa8fa804-bc05-4642-b2c5-c353ed22fc63");
         private static readonly Guid IID_ICLRRuntimeLocator = new("b760bf44-9377-4597-8be7-58083bdc5146");
+        private static readonly Guid IID_ICLRContractLocator = new("17d5b8c6-34a9-407f-af4f-a930201d4e02");
 
         // For ClrMD's magic hand shake
         private const ulong MagicCallbackConstant = 0x43;
 
+        // cDAC Contract Descriptor export symbol name
+        private const string ContractDescriptorExport = "DotNetRuntimeContractDescriptor";
+
         private readonly IRuntime _runtime;
         private readonly IContextService _contextService;
         private readonly ISymbolService _symbolService;
@@ -67,6 +71,10 @@ public DataTargetWrapper(IServiceProvider services, IRuntime runtime)
             builder.AddMethod(new GetRuntimeBaseDelegate(GetRuntimeBase));
             builder.Complete();
 
+            builder = AddInterface(IID_ICLRContractLocator, false);
+            builder.AddMethod(new GetContractDescriptorDelegate(GetContractDescriptor));
+            builder.Complete();
+
             AddRef();
         }
 
@@ -350,6 +358,26 @@ private int GetRuntimeBase(
 
         #endregion
 
+        #region ICLRContractLocator
+
+        private int GetContractDescriptor(
+            IntPtr self,
+            out ulong address)
+        {
+            address = 0;
+            IExportSymbols exportSymbols = _runtime.RuntimeModule.Services.GetService<IExportSymbols>();
+            if (exportSymbols is not null)
+            {
+                if (exportSymbols.TryGetSymbolAddress(ContractDescriptorExport, out address))
+                {
+                    return HResult.S_OK;
+                }
+            }
+            return HResult.E_FAIL;
+        }
+
+        #endregion
+
         #region ICLRDataTarget delegates
 
         [UnmanagedFunctionPointer(CallingConvention.Winapi)]
@@ -485,5 +513,13 @@ private delegate int GetRuntimeBaseDelegate(
             [Out] out ulong address);
 
         #endregion
+
+        #region ICLRContractLocator delegate
+
+        [UnmanagedFunctionPointer(CallingConvention.Winapi)]
+        private delegate int GetContractDescriptorDelegate(
+            [In] IntPtr self,
+            [Out] out ulong address);
+        #endregion
     }
 }

src/SOS/Strike/platform/datatarget.cpp

@@ -55,6 +55,12 @@ DataTarget::QueryInterface(
         AddRef();
         return S_OK;
     }
+    else if (InterfaceId == IID_ICLRContractLocator)
+    {
+        *Interface = (ICLRContractLocator*)this;
+        AddRef();
+        return S_OK;
+    }
     else
     {
         *Interface = NULL;
@@ -385,3 +391,13 @@ DataTarget::GetRuntimeBase(
     *baseAddress = m_baseAddress;
     return S_OK;
 }
+
+// ICLRContractLocator
+
+HRESULT STDMETHODCALLTYPE
+DataTarget::GetContractDescriptor(
+    /* out */ CLRDATA_ADDRESS* contractAddress)
+{
+    // TODO: IMPLEMENT
+    return E_FAIL;
+}

src/SOS/Strike/platform/datatarget.h

@@ -120,4 +120,9 @@ class DataTarget : public ICLRDataTarget2, ICorDebugDataTarget4, ICLRMetadataLoc
 
     virtual HRESULT STDMETHODCALLTYPE GetRuntimeBase(
         /* [out] */ CLRDATA_ADDRESS* baseAddress);
-};
+
+    // ICLRContractLocator
+
+    virtual HRESULT STDMETHODCALLTYPE  GetContractDescriptor(
+        /* [out] */ CLRDATA_ADDRESS* contractAddress);
+};

src/SOS/Strike/platform/runtimeimpl.cpp

@@ -14,6 +14,7 @@
 #include <psapi.h>
 #include <clrinternal.h>
 #include <metahost.h>
+#include <clrconfignocache.h>
 #include "runtimeimpl.h"
 #include "datatarget.h"
 #include "cordebugdatatarget.h"
@@ -299,6 +300,43 @@ LPCSTR Runtime::GetDacFilePath()
     return m_dacFilePath;
 }
 
+/**********************************************************************\
+ * Returns the cDAC module path to the rest of SOS.
+\**********************************************************************/
+LPCSTR Runtime::GetCdacFilePath()
+{
+    if (m_cdacFilePath == nullptr)
+    {
+        // No debugger service instance means that SOS is hosted by dotnet-dump,
+        // which does runtime enumeration in CLRMD. We should never get here.
+        IDebuggerServices* debuggerServices = GetDebuggerServices();
+        if (debuggerServices == nullptr)
+        {
+            ExtDbgOut("GetCdacFilePath: GetDebuggerServices returned nullptr\n");
+            return nullptr;
+        }
+
+        // TODO: Signature verification
+
+        LPCSTR directory = GetRuntimeDirectory();
+        if (directory != nullptr)
+        {
+            std::string dacModulePath(directory);
+            dacModulePath.append(DIRECTORY_SEPARATOR_STR_A);
+            dacModulePath.append(GetCdacDllName());
+    #ifdef FEATURE_PAL
+            // If DAC file exists in the runtime directory
+            if (access(dacModulePath.c_str(), F_OK) == 0)
+    #endif
+            {
+                m_cdacFilePath = _strdup(dacModulePath.c_str());
+            }
+        }
+    }
+    return m_cdacFilePath;
+}
+
+
 /**********************************************************************\
  * Returns the DBI module path to the rest of SOS
 \**********************************************************************/
@@ -427,7 +465,14 @@ HRESULT Runtime::GetClrDataProcess(IXCLRDataProcess** ppClrDataProcess)
     {
         *ppClrDataProcess = nullptr;
 
-        LPCSTR dacFilePath = GetDacFilePath();
+        CLRConfigNoCache enable = CLRConfigNoCache::Get("SOS_LOAD_CDAC");
+        DWORD val = 0;
+        if (enable.IsSet())
+        {
+            enable.TryAsInteger(10, val);
+        }
+
+        LPCSTR dacFilePath = val != 0 ? GetCdacFilePath() : GetDacFilePath();
         if (dacFilePath == nullptr)
         {
             return CORDBG_E_NO_IMAGE_AVAILABLE;

src/SOS/Strike/platform/runtimeimpl.h

@@ -105,6 +105,12 @@ inline const char* GetDacDllName()
     return (g_pRuntime->GetRuntimeConfiguration() == IRuntime::WindowsDesktop) ? DESKTOP_DAC_DLL_NAME_A : NETCORE_DAC_DLL_NAME_A;
 }
 
+// Returns the cDAC module name
+inline const char* GetCdacDllName()
+{
+    return MAKEDLLNAME_A("cdacreader");
+}
+
 /**********************************************************************\
  * Local Runtime interface implementation
 \**********************************************************************/
@@ -121,6 +127,7 @@ class Runtime : public IRuntime
     RuntimeInfo* m_runtimeInfo;
     LPCSTR m_runtimeDirectory;
     LPCSTR m_dacFilePath;
+    LPCSTR m_cdacFilePath;
     LPCSTR m_dbiFilePath;
     IXCLRDataProcess* m_clrDataProcess;
     ICorDebugProcess* m_pCorDebugProcess;
@@ -150,6 +157,8 @@ class Runtime : public IRuntime
 
     LPCSTR GetDacFilePath();
 
+    LPCSTR GetCdacFilePath();
+
     LPCSTR GetDbiFilePath();
 
     void DisplayStatus();

src/shared/inc/clrdata.idl

@@ -211,6 +211,20 @@ interface ICLRRuntimeLocator : IUnknown
     HRESULT GetRuntimeBase([out] CLRDATA_ADDRESS* baseAddress);
 };
 
+[
+    object,
+    local,
+    uuid(17d5b8c6-34a9-407f-af4f-a930201d4e02),
+    pointer_default(unique)
+]
+interface ICLRContractLocator : IUnknown
+{
+    /*
+     Returns the address of the runtime's contract descriptor.
+     */
+    HRESULT GetContractDescriptor([out] CLRDATA_ADDRESS* contractAddress);
+}
+
 /*
  * Interface used by the data access services layer to locate metadata
  * of assemblies in a target.

src/shared/pal/prebuilt/idl/clrdata_i.cpp

@@ -8,10 +8,10 @@
 
  /* File created by MIDL compiler version 8.01.0626 */
 /* Compiler settings for clrdata.idl:
-    Oicf, W1, Zp8, env=Win64 (32b run), target_arch=AMD64 8.01.0626 
+    Oicf, W1, Zp8, env=Win64 (32b run), target_arch=AMD64 8.01.0626
     protocol : dce , ms_ext, c_ext, robust
-    error checks: allocation ref bounds_check enum stub_data 
-    VC __declspec() decoration level: 
+    error checks: allocation ref bounds_check enum stub_data
+    VC __declspec() decoration level:
          __declspec(uuid()), __declspec(selectany), __declspec(novtable)
          DECLSPEC_UUID(), MIDL_INTERFACE()
 */
@@ -22,7 +22,7 @@
 
 #ifdef __cplusplus
 extern "C"{
-#endif 
+#endif
 
 
 #include <rpc.h>
@@ -78,6 +78,9 @@ MIDL_DEFINE_GUID(IID, IID_ICLRDataTarget3,0xa5664f95,0x0af4,0x4a1b,0x96,0x0e,0x2
 MIDL_DEFINE_GUID(IID, IID_ICLRRuntimeLocator,0xb760bf44,0x9377,0x4597,0x8b,0xe7,0x58,0x08,0x3b,0xdc,0x51,0x46);
 
 
+MIDL_DEFINE_GUID(IID, IID_ICLRContractLocator,0x17d5b8c6,0x34a9,0x407f,0xaf,0x4f,0xa9,0x30,0x20,0x1d,0x4e,0x02);
+
+
 MIDL_DEFINE_GUID(IID, IID_ICLRMetadataLocator,0xaa8fa804,0xbc05,0x4642,0xb2,0xc5,0xc3,0x53,0xed,0x22,0xfc,0x63);