[Lldb-commits] [PATCH] D152189: [LLDB][PDB] Fix age field in UUID in PDB file.

[Zequan Wu via Phabricator via lldb-commits]

zequanwu created this revision.
zequanwu added reviewers: labath, rnk, aganea.
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There are two age fields in a PDB file. One from the PDB Stream and another one
from the DBI stream.

According to https://randomascii.wordpress.com/2011/11/11/source-indexing-is-underused-awesomeness/#comment-34328,
The age in DBI stream is used to against the binary's age. `Pdbstr.exe` is used
to only increment the age from PDB stream without changing the DBI age. I
also verified this by manually changing the DBI age of a PDB file and let
`windbg.exe` to load it. It shows the following logs before and after changing:

Before:

  SYMSRV:  BYINDEX: 0xA
           c:\symbols*https://msdl.microsoft.com/download/symbols
           nlaapi.pdb
           D72AA69CD5ABE5D28C74FADB17DE3F8C1
  SYMSRV:  PATH: c:\symbols\nlaapi.pdb\D72AA69CD5ABE5D28C74FADB17DE3F8C1\nlaapi.pdb
  SYMSRV:  RESULT: 0x00000000
  *** WARNING: Unable to verify checksum for NLAapi.dll
  DBGHELP: NLAapi - public symbols
          c:\symbols\nlaapi.pdb\D72AA69CD5ABE5D28C74FADB17DE3F8C1\nlaapi.pdb
  ...

After:

  SYMSRV:  BYINDEX: 0xA
           c:\symbols*https://msdl.microsoft.com/download/symbols
           nlaapi.pdb
           D72AA69CD5ABE5D28C74FADB17DE3F8C1
  SYMSRV:  PATH: c:\symbols\nlaapi.pdb\D72AA69CD5ABE5D28C74FADB17DE3F8C1\nlaapi.pdb
  SYMSRV:  RESULT: 0x00000000
  DBGHELP: c:\symbols\nlaapi.pdb\D72AA69CD5ABE5D28C74FADB17DE3F8C1\nlaapi.pdb - mismatched pdb
  SYMSRV:  BYINDEX: 0xB
           c:\symbols*https://chromium-browser-symsrv.commondatastorage.googleapis.com
           nlaapi.pdb
           D72AA69CD5ABE5D28C74FADB17DE3F8C1
  SYMSRV:  PATH: c:\symbols\nlaapi.pdb\D72AA69CD5ABE5D28C74FADB17DE3F8C1\nlaapi.pdb
  SYMSRV:  RESULT: 0x00000000
  DBGHELP: c:\symbols\nlaapi.pdb\D72AA69CD5ABE5D28C74FADB17DE3F8C1\nlaapi.pdb - mismatched pdb
  SYMSRV:  BYINDEX: 0xC
           c:\src\symbols*https://msdl.microsoft.com/download/symbols
           nlaapi.pdb
           D72AA69CD5ABE5D28C74FADB17DE3F8C1
  SYMSRV:  PATH: c:\src\symbols\nlaapi.pdb\D72AA69CD5ABE5D28C74FADB17DE3F8C1\nlaapi.pdb
  SYMSRV:  RESULT: 0x00000000
  *** WARNING: Unable to verify checksum for NLAapi.dll
  DBGHELP: NLAapi - public symbols
          c:\src\symbols\nlaapi.pdb\D72AA69CD5ABE5D28C74FADB17DE3F8C1\nlaapi.pdb

So, `windbg.exe` uses the DBI age to detect mismatched pdb, but it still loads
the pdb even if the age mismatched. Probably lldb should do the same and give
some warnings.

This fixes a bug that lldb can't load some windows system pdbs due to mismatched
uuid.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D152189

Files:
  lldb/source/Plugins/ObjectFile/PDB/ObjectFilePDB.cpp
  lldb/test/Shell/ObjectFile/PDB/object.test


Index: lldb/test/Shell/ObjectFile/PDB/object.test
===================================================================
--- lldb/test/Shell/ObjectFile/PDB/object.test
+++ lldb/test/Shell/ObjectFile/PDB/object.test
@@ -3,7 +3,7 @@
 
 # CHECK: Plugin name: pdb
 # CHECK: Architecture: x86_64-pc-windows-msvc
-# CHECK: UUID: 61AF583F-29A8-7A6C-4C4C-44205044422E-00000001
+# CHECK: UUID: 61AF583F-29A8-7A6C-4C4C-44205044422E-00000003
 # CHECK: Executable: false
 # CHECK: Stripped: false
 # CHECK: Type: debug info
@@ -52,7 +52,7 @@
   Version:         VC70
 DbiStream:
   VerHeader:       V70
-  Age:             1
+  Age:             3
   BuildNumber:     36363
   PdbDllVersion:   0
   PdbDllRbld:      0
Index: lldb/source/Plugins/ObjectFile/PDB/ObjectFilePDB.cpp
===================================================================
--- lldb/source/Plugins/ObjectFile/PDB/ObjectFilePDB.cpp
+++ lldb/source/Plugins/ObjectFile/PDB/ObjectFilePDB.cpp
@@ -27,10 +27,10 @@
 
 LLDB_PLUGIN_DEFINE(ObjectFilePDB)
 
-static UUID GetPDBUUID(InfoStream &IS) {
+static UUID GetPDBUUID(InfoStream &IS, DbiStream &DS) {
   UUID::CvRecordPdb70 debug_info;
   memcpy(&debug_info.Uuid, IS.getGuid().Guid, sizeof(debug_info.Uuid));
-  debug_info.Age = IS.getAge();
+  debug_info.Age = DS.getAge();
   return UUID(debug_info);
 }
 
@@ -82,7 +82,12 @@
     llvm::consumeError(info_stream.takeError());
     return false;
   }
-  m_uuid = GetPDBUUID(*info_stream);
+  auto dbi_stream = m_file_up->getPDBDbiStream();
+  if (!dbi_stream) {
+    llvm::consumeError(dbi_stream.takeError());
+    return false;
+  }
+  m_uuid = GetPDBUUID(*info_stream, *dbi_stream);
   return true;
 }
 
@@ -126,7 +131,7 @@
   }
 
   lldb_private::UUID &uuid = module_spec.GetUUID();
-  uuid = GetPDBUUID(*info_stream);
+  uuid = GetPDBUUID(*info_stream, *dbi_stream);
 
   ArchSpec &module_arch = module_spec.GetArchitecture();
   switch (dbi_stream->getMachineType()) {


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