CODEWITHSUNDEEP
c++windowsdebuggingwindbgpdb-files
Tony
Tony

Reputation: 3638

Read symbols in WinDBG without exe

I've been using WinDBG to view some structures for an attached C++ exe, e.g

dt blah::class::thingy
    +0x000 Flags: Uint4B
    +0x004 Whatever : Ptr64 something

But I've been given some older PDB files for an earlier version, and I'd like to view the same structures to compare changes, but I can't load the older PDBs as they don't match the current exe version.

So my question is there anyway to use the dt command in WinDBG without first loading/attaching to an exe? I've seen the DIA SDK, but it seems over my head in terms of complexity for what I need.

I'm not sure if there is anyway to even load a PDB without first loading an exe?

Upvotes: 0

Views: 676

Answers (1)

blabb
blabb

Reputation: 8987

use .symopt+ SYMOPT_LOAD_ANYTHING

to load an unmatched pdb to a current exe but be aware and use it with caution

Type information needed for structure recognition wont have much effect .

but source line numbers or Disassembly Address For a Function may not match and provide bogus information

you can check a module with a pdb using !chksym
if it is mismatched and you don't care about source lines and such stuff but only need typeinfo
you can load the mismatched pdb by using .symopt+ 0x40 and storing the mismatched pdb in pdbsearchpath (cache/curdir/sympath/etc)

0:000> !chksym loadany.exe loadany.pdb

loadany.exe
    Timestamp: 5F89E8D1
  SizeOfImage: 4E000
          pdb: C:\Users\XX\Desktop\loadany\loadany.pdb
      pdb sig: 2FDF9552-88E3-4452-9B5D-A03B24165869
          age: 1

loadany.pdb
      pdb sig: CB93F230-0E80-4485-AA6F-42202F1CF233
          age: 1

sig MISMATCH: loadany.pdb and loadany.exe

0:000> !sym noisy
noisy mode - symbol prompts off
0:000> .reload /f loadany.exe
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
DBGHELP: C:\Users\XX\Desktop\loadany\loadany.pdb - mismatched pdb
DBGHELP: Couldn't load mismatched pdb C:\Users\XX\Desktop\loadany\loadany.exe
DBGHELP: loadany - no symbols loaded

0:000> .symopt +0x40
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Symbol options are 0x800B0367:
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
0:000> .reload /f loadany.exe
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
DBGHELP: C:\Users\XX\Desktop\loadany\loadany.pdb - mismatched pdb
DBGHELP: Loaded mismatched pdb for C:\Users\XX\Desktop\loadany\loadany.exe
DBGHELP: loadany - private symbols & lines
        C:\Users\XX\Desktop\loadany\loadany.pdb - unmatched

Upvotes: 2

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