[cDAC] Implement simple DacDbi methods and IDebugger contract by max-charlamb · Pull Request #126032 · dotnet/runtime

max-charlamb · 2026-03-24T14:50:43Z

Summary

Implements 37 IDacDbiInterface methods in managed C# using cDAC contracts, replacing legacy native delegation stubs with actual implementations. Also introduces a new IDebugger contract for debugger state queries.

This builds on top of #125074 (COM conversion of IDacDbiInterface).

New IDebugger Contract

Adds the IDebugger contract with 5 APIs for reading debugger state:

Data descriptors in datadescriptor.inc and cdac_data<Debugger>
Debugger_1 implementation reading from Debugger data descriptor and CLRJitAttachState/MetadataUpdatesApplied globals
Contract documentation in docs/design/datacontracts/Debugger.md

Implemented DacDbi Methods by Contract Group

Debugger: IsLeftSideInitialized, GetDefinesBitField, GetMDStructuresVersion, GetAttachStateFlags, MetadataUpdatesApplied

Thread: EnumerateThreads, IsThreadMarkedDead, TryGetVolatileOSThreadID, GetUniqueThreadID, GetCurrentException, IsThreadSuspendedOrHijacked, HasUnhandledException

Loader: GetAssemblyFromDomainAssembly, GetAppDomainFullName, GetModuleSimpleName, GetAssemblyPath, GetModulePath, GetModuleForDomainAssembly, GetDomainAssemblyFromModule, EnumerateAssembliesInAppDomain, EnumerateModulesInAssembly, IsModuleMapped

Hardcoded: GetAppDomainId, GetAppDomainFromId, GetCurrentAppDomain, EnumerateAppDomains, IsAssemblyFullyTrusted, GetConnectionID, GetTaskID, IsWinRTModule, GetAppDomainIdFromVmObjectHandle, EnableNGENPolicy

Type: GetTypeDef, IsValueType, HasTypeParams

Object: GetObjectFromRefPtr, GetObject, GetVmObjectHandle, IsVmObjectHandleValid, GetHandleAddressFromVmHandle

Code/GC: GetMethodDescPtrFromIP, AreGCStructuresValid, GetGCHeapInformation, GetTypeID, GetTypeIDForType

All methods include #if DEBUG validation against the legacy DAC to verify consistency.

IStringHolder Vtable Calling

Since IStringHolder is not a COM interface (it's a plain C++ abstract class with a single virtual method), the managed implementation calls through its vtable directly using delegate* unmanaged function pointers.

Testing

48 unit tests for the IDebugger contract (DebuggerTests.cs)
29 dump tests across 6 test classes (DacDbi*DumpTests.cs) validating against real crash dumps
cDAC build: 0 errors, 0 warnings

Implement 37 IDacDbiInterface methods using cDAC contracts, replacing legacy delegation stubs with actual implementations: IDebugger contract (new): - Add IDebugger interface with 5 APIs for debugger state - Debugger_1 implementation reading from Debugger data descriptor and CLRJitAttachState/MetadataUpdatesApplied globals - Data descriptors in datadescriptor.inc and cdac_data<Debugger> - Contract documentation in docs/design/datacontracts/Debugger.md Implemented DacDbi methods by contract group: - Debugger: IsLeftSideInitialized, GetDefinesBitField, GetMDStructuresVersion, GetAttachStateFlags, MetadataUpdatesApplied - Thread: EnumerateThreads, IsThreadMarkedDead, TryGetVolatileOSThreadID, GetUniqueThreadID, GetCurrentException, IsThreadSuspendedOrHijacked, HasUnhandledException - Loader: GetAssemblyFromDomainAssembly, GetAppDomainFullName, GetModuleSimpleName, GetAssemblyPath, GetModulePath, GetModuleForDomainAssembly, GetDomainAssemblyFromModule, EnumerateAssembliesInAppDomain, EnumerateModulesInAssembly, IsModuleMapped - Hardcoded: GetAppDomainId, GetAppDomainFromId, GetCurrentAppDomain, EnumerateAppDomains, IsAssemblyFullyTrusted, GetConnectionID, GetTaskID, IsWinRTModule, GetAppDomainIdFromVmObjectHandle, EnableNGENPolicy - Type: GetTypeDef, IsValueType, HasTypeParams - Object: GetObjectFromRefPtr, GetObject, GetVmObjectHandle, IsVmObjectHandleValid, GetHandleAddressFromVmHandle - Code/GC: GetMethodDescPtrFromIP, AreGCStructuresValid, GetGCHeapInformation, GetTypeID, GetTypeIDForType All methods include #if DEBUG validation against legacy DAC. Tests: - 48 unit tests for IDebugger contract (DebuggerTests.cs) - 29 dump tests across 6 test classes (DacDbi*DumpTests.cs) Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

dotnet-policy-service · 2026-03-24T14:52:20Z

Tagging subscribers to this area: @steveisok, @tommcdon, @dotnet/dotnet-diag
See info in area-owners.md if you want to be subscribed.

rcj1 · 2026-03-24T14:53:58Z

@noahfalk

Copilot

Pull request overview

This PR adds a new Debugger cDAC contract and begins implementing IDacDbiInterface in managed C# using cDAC contracts, with accompanying unit tests and dump-based integration tests. It also wires up CoreCLR data descriptors/globals so the contract can read debugger state from targets.

Changes:

Introduce IDebugger contract (data descriptor + managed contract implementation) and register it in the contract registry.
Add a managed DacDbiImpl implementation (COM-visible) intended to replace legacy native delegation stubs for a set of IDacDbiInterface methods.
Add unit tests for the Debugger contract plus multiple dump-based DacDbi integration test classes.

Reviewed changes

Copilot reviewed 21 out of 21 changed files in this pull request and generated 16 comments.

Show a summary per file

File	Description
src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiThreadDumpTests.cs	Adds dump-based tests for DacDbi thread APIs (enumeration, thread state, OS thread id, exception).
src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiObjectDumpTests.cs	Adds dump-based tests for DacDbi object-handle identity and AppDomain-id-from-handle behavior.
src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiLoaderDumpTests.cs	Adds dump-based tests for loader/module/assembly DacDbi APIs, including string-returning methods and enumeration callbacks.
src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiGCDumpTests.cs	Adds dump-based tests for DacDbi GC APIs and cross-validation with GC contract.
src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiDebuggerDumpTests.cs	Adds dump-based tests for DacDbi Debugger-related APIs and cross-validation with Debugger contract.
src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiAppDomainDumpTests.cs	Adds dump-based tests for AppDomain/misc policy/flags-related DacDbi APIs.
src/native/managed/cdac/tests/DebuggerTests.cs	Adds unit tests for the new IDebugger contract using mock targets/memory.
src/native/managed/cdac/mscordaccore_universal/Entrypoints.cs	Adds unmanaged entrypoint for creating the managed COM DacDbi interface implementation.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader/CachingContractRegistry.cs	Registers the Debugger contract factory so it’s available via Target.Contracts.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs	Introduces the managed COM class implementing IDacDbiInterface methods via cDAC contracts (with DEBUG cross-validation against legacy DAC).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Debugger.cs	Adds processed-data reader for the Debugger data descriptor.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Debugger_1.cs	Implements IDebugger v1 using globals + processed data.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/DebuggerFactory.cs	Creates the correct Debugger contract implementation for a given version.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Constants.cs	Adds global names used by the Debugger contract implementation.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/DataType.cs	Adds DataType.Debugger for the new data descriptor.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/CorDbHResults.cs	Adds CORDBG_E_NOTREADY constant used by Debugger contract error behavior.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IDebugger.cs	Defines the IDebugger contract surface and default stub implementation.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/ContractRegistry.cs	Exposes Target.Contracts.Debugger accessor on the base registry.
src/coreclr/vm/datadescriptor/datadescriptor.inc	Adds Debugger data descriptor fields and global pointers (Debugger, CLRJitAttachState, MetadataUpdatesApplied) and registers the Debugger contract.
src/coreclr/debug/ee/debugger.h	Exposes Debugger field offsets to cDAC via cdac_data specialization.
docs/design/datacontracts/Debugger.md	Documents the Debugger contract’s APIs, globals, data descriptors, and algorithms.

src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiAppDomainDumpTests.cs

src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiLoaderDumpTests.cs

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs

src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiDebuggerDumpTests.cs

src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiLoaderDumpTests.cs

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs

src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiDebuggerDumpTests.cs

src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiAppDomainDumpTests.cs

docs/design/datacontracts/Debugger.md

src/coreclr/debug/ee/debugger.h

...tive/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Debugger_1.cs

…mplement 3 new methods - Redesign IDebugger: TryGetDebuggerData replaces separate APIs - Use Marshal.GetExceptionForHR, ReadGlobalPointer for CLRJitAttachState - Implement GetModuleSimpleName, GetCurrentException, EnumerateModulesInAssembly - Fix GetAppDomainIdFromVmObjectHandle null handle, allow null legacy in entrypoint - Fix test BOOL types, add checkedCount assertions, filter Dead/Unstarted threads - Replace TestStringHolder with NativeStringHolder (native vtable layout) - Update Debugger.md doc format, include cdacdata.h, remove unnecessary friend decl Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

noahfalk · 2026-03-24T22:39:49Z

src/native/managed/cdac/tests/DumpTests/DacDbi/NativeStringHolder.cs

+namespace Microsoft.Diagnostics.DataContractReader.DumpTests;
+
+/// <summary>
+/// Creates a native-memory object that mimics the C++ IStringHolder vtable layout.


Should we just make IStringHolder a COM interface so that our standard COM marshalling techniques work? Seems like it might be a little simpler.

Copilot AI review requested due to automatic review settings March 24, 2026 14:50

github-actions bot added the area-Diagnostics-coreclr label Mar 24, 2026

dotnet-policy-service bot assigned max-charlamb Mar 24, 2026

Copilot started reviewing on behalf of max-charlamb March 24, 2026 14:51 View session

Copilot AI reviewed Mar 24, 2026

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max-charlamb changed the title ~~Implement cDAC DacDbi methods and IDebugger contract~~ [cDAC] Implement simple DacDbi methods and IDebugger contract Mar 24, 2026

max-charlamb marked this pull request as draft March 24, 2026 16:36

max-charlamb commented Mar 24, 2026

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noahfalk approved these changes Mar 24, 2026

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The Operation will be canceled. The next steps may not contain expected logs. dotnet/dnceng#3008

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[cDAC] Implement simple DacDbi methods and IDebugger contract#126032

[cDAC] Implement simple DacDbi methods and IDebugger contract#126032
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max-charlamb commented Mar 24, 2026

Summary

New IDebugger Contract

Implemented DacDbi Methods by Contract Group

IStringHolder Vtable Calling

Testing

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Pull request overview

Reviewed changes

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