Address PR feedback: use typed pointers, move validation inside try/catch, use heapData.GenerationTable.Count, and use local buffers for debug cross-validation

- Change void* to DacpGenerationData* in ISOSDacInterface8 methods
- Move null/validation checks inside try/catch blocks per PR #124814 pattern
- Replace ReadGlobal<uint>(TotalGenerationCount) with heapData.GenerationTable.Count
- Use local buffers for legacy DAC cross-validation to avoid overwriting cDAC data
- Use 'is null'/'is not null' instead of '== null'/'!= null'

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: noahfalk

eng/pipelines/runtime-diagnostics.yml

@@ -5,6 +5,13 @@ parameters:
   displayName: Diagnostics Branch
   type: string
   default: main
+- name: cdacDumpPlatforms
+  displayName: cDAC Dump Platforms
+  type: object
+  default:
+    - windows_x64
+    - linux_x64
+    # - osx_x64 # Temporarily due to CI capacity constraints. Will re-enable once osx queues are more available.
 
 resources:
   repositories:
@@ -103,8 +110,15 @@ extends:
             - task: PublishPipelineArtifact@1
               inputs:
                 targetPath: '$(Build.SourcesDirectory)/artifacts/tmp/$(_BuildConfig)/dumps'
-                artifactName: Dumps_$(_PhaseName)_Attempt$(System.JobAttempt)
-              displayName: 'Publish Dumps on Failure'
+                artifactName: 'Dumps_cDAC_$(osGroup)$(osSubgroup)_$(archType)_$(_BuildConfig)_Attempt$(System.JobAttempt)'
+              displayName: 'Publish Crash Dumps'
+              continueOnError: true
+              condition: failed()
+            - task: PublishPipelineArtifact@1
+              inputs:
+                targetPath: '$(Build.SourcesDirectory)/artifacts/TestResults'
+                artifactName: 'TestResults_cDAC_$(osGroup)$(osSubgroup)_$(archType)_$(_BuildConfig)_Attempt$(System.JobAttempt)'
+              displayName: 'Publish Test Results and SOS Logs'
               continueOnError: true
               condition: failed()
       - template: /eng/pipelines/common/platform-matrix.yml
@@ -144,7 +158,99 @@ extends:
             - task: PublishPipelineArtifact@1
               inputs:
                 targetPath: '$(Build.SourcesDirectory)/artifacts/tmp/$(_BuildConfig)/dumps'
-                artifactName: Dumps_$(_PhaseName)_Attempt$(System.JobAttempt)
-              displayName: 'Publish Dumps on Failure'
+                artifactName: 'Dumps_DAC_$(osGroup)$(osSubgroup)_$(archType)_$(_BuildConfig)_Attempt$(System.JobAttempt)'
+              displayName: 'Publish Crash Dumps'
+              continueOnError: true
+              condition: failed()
+            - task: PublishPipelineArtifact@1
+              inputs:
+                targetPath: '$(Build.SourcesDirectory)/artifacts/TestResults'
+                artifactName: 'TestResults_DAC_$(osGroup)$(osSubgroup)_$(archType)_$(_BuildConfig)_Attempt$(System.JobAttempt)'
+              displayName: 'Publish Test Results and SOS Logs'
               continueOnError: true
               condition: failed()
+
+    #
+    # cDAC Dump Creation — Build runtime, create crash dumps, publish dump artifacts
+    #
+    - stage: DumpCreation
+      dependsOn: []
+      jobs:
+      - template: /eng/pipelines/common/platform-matrix.yml
+        parameters:
+          jobTemplate: /eng/pipelines/common/global-build-job.yml
+          buildConfig: release
+          platforms: ${{ parameters.cdacDumpPlatforms }}
+          jobParameters:
+            buildArgs: -s clr+libs+tools.cdac -c $(_BuildConfig) -rc $(_BuildConfig) -lc $(_BuildConfig)
+            nameSuffix: CdacDumpGeneration
+            timeoutInMinutes: 120
+            postBuildSteps:
+            - script: $(Build.SourcesDirectory)$(dir).dotnet$(dir)dotnet$(exeExt) msbuild
+                $(Build.SourcesDirectory)/src/native/managed/cdac/tests/DumpTests/Microsoft.Diagnostics.DataContractReader.DumpTests.csproj
+                /t:GenerateAllDumps
+                /p:CIDumpVersionsOnly=true
+                /p:SetDisableAuxProviderSignatureCheck=true
+                /p:TargetArchitecture=$(archType)
+                -bl:$(Build.SourcesDirectory)/artifacts/log/DumpGeneration.binlog
+              displayName: 'Generate cDAC Dumps'
+            - template: /eng/pipelines/common/upload-artifact-step.yml
+              parameters:
+                rootFolder: $(Build.SourcesDirectory)/artifacts/dumps/cdac
+                includeRootFolder: false
+                archiveType: tar
+                archiveExtension: .tar.gz
+                tarCompression: gz
+                artifactName: CdacDumps_$(osGroup)_$(archType)
+                displayName: cDAC Dump Artifacts
+
+    #
+    # cDAC Dump Tests — Download dumps from all platforms, run tests cross-platform
+    #
+    - stage: DumpTest
+      dependsOn:
+      - DumpCreation
+      jobs:
+      - template: /eng/pipelines/common/platform-matrix.yml
+        parameters:
+          jobTemplate: /eng/pipelines/common/global-build-job.yml
+          buildConfig: release
+          platforms: ${{ parameters.cdacDumpPlatforms }}
+          jobParameters:
+            buildArgs: -s tools.cdacdumptests /p:SkipDumpVersions=net10.0
+            nameSuffix: CdacDumpTests
+            timeoutInMinutes: 60
+            postBuildSteps:
+            # Download and test against dumps from each platform
+            - ${{ each dumpPlatform in parameters.cdacDumpPlatforms }}:
+              - template: /eng/pipelines/common/download-artifact-step.yml
+                parameters:
+                  artifactName: CdacDumps_${{ dumpPlatform }}
+                  artifactFileName: CdacDumps_${{ dumpPlatform }}.tar.gz
+                  unpackFolder: $(Build.SourcesDirectory)/artifacts/dumps/${{ dumpPlatform }}
+                  displayName: '${{ dumpPlatform }} Dumps'
+              - script: $(Build.SourcesDirectory)$(dir).dotnet$(dir)dotnet$(exeExt) test
+                  $(Build.SourcesDirectory)/src/native/managed/cdac/tests/DumpTests/Microsoft.Diagnostics.DataContractReader.DumpTests.csproj
+                  --no-build
+                  --logger "trx;LogFileName=CdacDumpTests_${{ dumpPlatform }}.trx"
+                  --results-directory $(Build.SourcesDirectory)/artifacts/TestResults/$(_BuildConfig)/${{ dumpPlatform }}
+                displayName: 'Run cDAC Dump Tests (${{ dumpPlatform }} dumps)'
+                continueOnError: true
+                env:
+                  CDAC_DUMP_ROOT: $(Build.SourcesDirectory)/artifacts/dumps/${{ dumpPlatform }}
+              - task: PublishTestResults@2
+                displayName: 'Publish Results ($(osGroup)-$(archType) → ${{ dumpPlatform }})'
+                inputs:
+                  testResultsFormat: VSTest
+                  testResultsFiles: '**/*.trx'
+                  searchFolder: '$(Build.SourcesDirectory)/artifacts/TestResults/$(_BuildConfig)/${{ dumpPlatform }}'
+                  testRunTitle: 'cDAC Dump Tests $(osGroup)-$(archType) → ${{ dumpPlatform }}'
+                  failTaskOnFailedTests: true
+                  publishRunAttachments: true
+                  buildConfiguration: $(_BuildConfig)
+                continueOnError: true
+                condition: always()
+            # Fail the job if any test or publish step above reported issues.
+            - script: echo "One or more dump test steps failed." && exit 1
+              displayName: 'Fail if tests failed'
+              condition: eq(variables['Agent.JobStatus'], 'SucceededWithIssues')

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/ISOSDacInterface.cs

@@ -830,13 +830,13 @@ public unsafe partial interface ISOSDacInterface8
 
     // WKS
     [PreserveSig]
-    int GetGenerationTable(uint cGenerations, /*struct DacpGenerationData*/ void* pGenerationData, uint* pNeeded);
+    int GetGenerationTable(uint cGenerations, DacpGenerationData* pGenerationData, uint* pNeeded);
     [PreserveSig]
     int GetFinalizationFillPointers(uint cFillPointers, ClrDataAddress* pFinalizationFillPointers, uint* pNeeded);
 
     // SVR
     [PreserveSig]
-    int GetGenerationTableSvr(ClrDataAddress heapAddr, uint cGenerations, /*struct DacpGenerationData*/ void* pGenerationData, uint* pNeeded);
+    int GetGenerationTableSvr(ClrDataAddress heapAddr, uint cGenerations, DacpGenerationData* pGenerationData, uint* pNeeded);
     [PreserveSig]
     int GetFinalizationFillPointersSvr(ClrDataAddress heapAddr, uint cFillPointers, ClrDataAddress* pFinalizationFillPointers, uint* pNeeded);
 

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/README.md

@@ -11,13 +11,13 @@ replace it with a cDAC implementation following this pattern:
 ```csharp
 int ISOSDacInterface8.ExampleMethod(uint* pResult)
 {
-    // 1. Validate pointer arguments before the try block
-    if (pResult == null)
-        return HResults.E_INVALIDARG;
-
     int hr = HResults.S_OK;
     try
     {
+        // 1. Validate pointer arguments inside the try block
+        if (pResult is null)
+            throw new ArgumentException();
+
         // 2. Get the relevant contract and call it
         IGC gc = _target.Contracts.GC;
         *pResult = gc.SomeMethod();
@@ -48,8 +48,8 @@ int ISOSDacInterface8.ExampleMethod(uint* pResult)
 
 - **HResult returns**: Methods return `int` HResult codes, not exceptions.
   Use `HResults.S_OK`, `HResults.S_FALSE`, `HResults.E_INVALIDARG`, etc.
-- **Null pointer checks**: Validate output pointer arguments *before* the try block
-  and return `E_INVALIDARG`. This matches the native DAC behavior.
+- **Null pointer checks**: Validate output pointer arguments *inside* the try block
+  and throw `ArgumentException`. The catch block converts this to an HResult code.
 - **Exception handling**: Wrap all contract calls in try/catch. The catch converts
   exceptions to HResult codes via `ex.HResult`. When the native DAC has an explicit
   readability check (e.g., `ptr.IsValid()` or `DACGetMethodTableFromObjectPointer`
@@ -88,7 +88,7 @@ int GetSomeTable(uint count, Data* buffer, uint* pNeeded)
 
 The protocol is:
 1. Always set `*pNeeded` to the required count (if `pNeeded` is not null).
-2. If `count > 0 && buffer == null`: return `E_INVALIDARG`.
+2. If `count > 0 && buffer is null`: throw `ArgumentException`.
 3. If `count < needed`: return `S_FALSE` (buffer too small, but `*pNeeded` is set).
 4. If `count >= needed`: populate `buffer` and return `S_OK`.