Flush Crossgen2 R2R output stream before generating native PDB

src/coreclr/tools/PdbChecker/MSDiaSymbolReader.cs

@@ -6,6 +6,7 @@
 using System.IO;
 using System.Linq;
 using System.Reflection;
+using System.Reflection.PortableExecutable;
 using System.Runtime.InteropServices;
 using Dia2Lib;
 
@@ -32,7 +33,7 @@ void CreateInstance([MarshalAs(UnmanagedType.Interface)] object? aggregator,
 
     private readonly List<string> _pdbSymbols;
 
-    public MSDiaSymbolReader(string pdbFile)
+    public MSDiaSymbolReader(string pdbFile, string? imageFile = null)
     {
         try
         {
@@ -41,7 +42,24 @@ public MSDiaSymbolReader(string pdbFile)
             diaClassFactory.CreateInstance(null, typeof(IDiaDataSource).GetTypeInfo().GUID, out object comObject);
 
             _diaDataSource = (IDiaDataSource)comObject;
-            _diaDataSource.loadDataFromPdb(pdbFile);
+
+            if (imageFile is not null)
+            {
+                // Validate the PDB against the image's CodeView / RSDS identity. DIA throws if the
+                // PDB-info GUID / age don't match the image
+                (Guid imageGuid, uint imageAge) = ReadImageCodeViewIdentity(imageFile);
+                Console.WriteLine("Image file:     {0}", imageFile);
+                Console.WriteLine("Image GUID:     {0}", imageGuid);
+                Console.WriteLine("Image age:      {0}", imageAge);
+                // sig is 0: R2R images use the RSDS (PDB 7.0) CodeView record, whose identity is the
+                // GUID + age only; the legacy NB10 32-bit signature does not apply.
+                _diaDataSource.loadAndValidateDataFromPdb(pdbFile, ref imageGuid, 0, imageAge);
+            }
+            else
+            {
+                _diaDataSource.loadDataFromPdb(pdbFile);
+            }
+
             _diaDataSource.openSession(out _diaSession);
 
             _pdbSymbols = new List<string>();
@@ -57,7 +75,10 @@ public MSDiaSymbolReader(string pdbFile)
                 }
             }
 
+            IDiaSymbol globalScope = _diaSession.globalScope;
             Console.WriteLine("PDB file:       {0}", pdbFile);
+            Console.WriteLine("PDB GUID:       {0}", globalScope.guid);
+            Console.WriteLine("PDB age:        {0}", globalScope.age);
             Console.WriteLine("Total symbols:  {0}", symbolsTotal);
             Console.WriteLine("Public symbols: {0}", _pdbSymbols.Count);
         }
@@ -67,6 +88,25 @@ public MSDiaSymbolReader(string pdbFile)
         }
     }
 
+    /// <summary>
+    /// Read the CodeView / RSDS debug record identity (GUID and age) from a PE image.
+    /// </summary>
+    private static (Guid Guid, uint Age) ReadImageCodeViewIdentity(string imageFile)
+    {
+        using FileStream imageStream = File.OpenRead(imageFile);
+        using PEReader peReader = new PEReader(imageStream);
+        foreach (DebugDirectoryEntry entry in peReader.ReadDebugDirectory())
+        {
+            if (entry.Type == DebugDirectoryEntryType.CodeView)
+            {
+                CodeViewDebugDirectoryData codeViewData = peReader.ReadCodeViewDebugDirectoryData(entry);
+                return (codeViewData.Guid, (uint)codeViewData.Age);
+            }
+        }
+
+        throw new Exception($"Image file {imageFile} does not contain a CodeView (RSDS) debug directory entry");
+    }
+
     public void DumpSymbols()
     {
         Console.WriteLine("PDB public symbol list:");

src/coreclr/tools/PdbChecker/Program.cs

@@ -1,7 +1,8 @@
-// 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;
+using System.Collections.Generic;
 using Dia2Lib;
 class Program
 {
@@ -26,12 +27,36 @@ private static void TryMain(string[] args)
             DisplayUsage();
             return;
         }
-        MSDiaSymbolReader reader = new MSDiaSymbolReader(args[0]);
+
+        string pdbFile = args[0];
+        string? imageFile = null;
+        List<string> symbolNames = new List<string>();
+
+        for (int argIndex = 1; argIndex < args.Length; argIndex++)
+        {
+            string arg = args[argIndex];
+            if (arg.Equals("--image", StringComparison.OrdinalIgnoreCase))
+            {
+                if (++argIndex >= args.Length)
+                {
+                    throw new Exception("Missing image file path after --image");
+                }
+                imageFile = args[argIndex];
+            }
+            else
+            {
+                symbolNames.Add(arg);
+            }
+        }
+
+        // When an image is provided, MSDiaSymbolReader validates that the PDB-info identity
+        // matches the image's CodeView / RSDS record, guarding against the zero-GUID native PDB bug.
+        MSDiaSymbolReader reader = new MSDiaSymbolReader(pdbFile, imageFile);
+
         int matchedSymbols = 0;
         int missingSymbols = 0;
-        for (int symbolArgIndex = 1; symbolArgIndex < args.Length; symbolArgIndex++)
+        foreach (string symbolName in symbolNames)
         {
-            string symbolName = args[symbolArgIndex];
             if (reader.ContainsSymbol(symbolName))
             {
                 matchedSymbols++;
@@ -55,6 +80,6 @@ private static void TryMain(string[] args)
 
     private static void DisplayUsage()
     {
-        Console.WriteLine("Usage: PdbChecker <pdb file to check> { <symbol to check for existence in the PDB file> }");
+        Console.WriteLine("Usage: PdbChecker <pdb file to check> [--image <image file to match PDB identity>] { <symbol to check for existence in the PDB file> }");
     }
 }

src/coreclr/tools/aot/ILCompiler.ReadyToRun/CodeGen/ReadyToRunObjectWriter.cs

@@ -187,8 +187,15 @@ public void EmitReadyToRunObjects(ReadyToRunContainerFormat format, Logger logge
                     _ => throw new UnreachableException()
                 };
 
-                using FileStream stream = new FileStream(_objectFilePath, FileMode.Create);
-                objectWriter.EmitObject(stream, _nodes, dumper: null, logger);
+                long outputFileSize;
+                // Close and flush the output stream before generating symbol files (PDB / PerfMap),
+                // which read the finished image back from disk. Leaving the stream open here would
+                // let the PDB writer observe an incomplete file (e.g. a zeroed CodeView/RSDS GUID).
+                using (FileStream stream = new FileStream(_objectFilePath, FileMode.Create))
+                {
+                    objectWriter.EmitObject(stream, _nodes, dumper: null, logger);
+                    outputFileSize = stream.Length;
+                }
 
                 if (_outputInfoBuilder is not null)
                 {
@@ -198,7 +205,7 @@ public void EmitReadyToRunObjects(ReadyToRunContainerFormat format, Logger logge
 
                 if (_mapFileBuilder != null)
                 {
-                    _mapFileBuilder.SetFileSize(stream.Length);
+                    _mapFileBuilder.SetFileSize(outputFileSize);
                 }
 
                 if (_outputInfoBuilder is not null)

src/tests/Common/CLRTest.CrossGen.targets

@@ -402,7 +402,7 @@ if defined RunCrossGen2 (
         if defined CrossGen2TestCheckPdb (
             set __CheckPdbCommand=!__DotNet!
             set __CheckPdbCommand=!__CheckPdbCommand! "!CORE_ROOT!\PdbChecker\PdbChecker.dll"
-            set __CheckPdbCommand=!__CheckPdbCommand! !__PdbFile! @(CheckPdbSymbol->'%22%(Identity)%22', ' ')
+            set __CheckPdbCommand=!__CheckPdbCommand! !__PdbFile! --image !__OutputFile! @(CheckPdbSymbol->'%22%(Identity)%22', ' ')
             echo "!__CheckPdbCommand!"
             call !__CheckPdbCommand!
             if not !ERRORLEVEL!==0 (