Windows/C++: Is it possible to find the line of code where exception was thrown having "Exception Offset"

Question

One of our users having an Exception on our product startup. She has sent us the following error message from Windows:

  Problem Event Name:                        APPCRASH
  Application Name:                          program.exe
  Application Version:                       1.0.0.1
  Application Timestamp:                     4ba62004
  Fault Module Name:                         agcutils.dll
  Fault Module Version:                      1.0.0.1
  Fault Module Timestamp:                    48dbd973
  Exception Code:                            c0000005
  Exception Offset:                          000038d7
  OS Version:                                6.0.6002.2.2.0.768.2
  Locale ID:                                 1033
  Additional Information 1:                  381d
  Additional Information 2:                  fdf78cd6110fd6ff90e9fff3d6ab377d
  Additional Information 3:                  b2df
  Additional Information 4:                  a3da65b92a4f9b2faa205d199b0aa9ef

Is it possible to locate the exact place in the source code where the exception has occured having this information?

What is the common technique for C++ programmers on Windows to locate the place of an error that has occured on user computer?

Our project is compiled with Release configuration, PDB file is generated.

I hope my question is not too naive.

Answer 1

Source code information isn't preserved in compiled C++ code, unlike in runtime-based metadata-aware languages (such as .NET or Java). The PDB file is a symbol index which can help a debugger map compiled code backwards to source, but it has to be done during program execution, not from a crash dump. Even with a PDB, Release-compiled code is subject to a number of optimizations that can prevent the debugger from identifying the source code.

Debugging problems which only manifest on end-user machines is usually a matter of careful state logging and a lot of detail-oriented time and effort combing over the source. Depending on your relationship with the user (for example, if you're internal corporate IT development), you may be able to make a virtual machine image of the user's machine and use it for debugging, which can help speed the process tremendously by precisely replicating the installed software and standard running processes on the user's workstation.

Answer 2

Yes, that's possible. Start debugging with the exact same binaries as ran by your user, make sure the DLL is loaded and you've got a matching PDB file for it. Look in Debug + Windows + Modules for the DLL base address. Add the offset. Debug + Windows + Disassembly and enter the calculated address in the Address field (prefix with 0x). That shows you the exact machine code instruction that caused the exception. Right-click + Go To Source code to see the matching source code line.

While that shows you the statement, this isn't typically good enough to diagnose the cause. The 0xc0000005 exception is an access violation, it has many possible causes. Often you don't even get any code, the program may have jumped into oblivion due to a corrupted stack. Or the real problem is located far away, some pointer manipulation that corrupted the heap. You also typically really need a stack trace that shows you how the program ended up at the statement that bombed.

What you need is a minidump. You can easily get one from your user if she runs Vista or Win7. Start TaskMgr.exe, Processes tab, select the bombed program while it is still displaying the crash dialog. Right-click it and Create Dump File.

To make this smooth, you really want to automate this procedure. You'll find hints in my answer in this thread.

Answer 3

If you have a minidump, open it in Visual Studio, set MODPATH to the appropriate folders with the original binaries and PDBs, and tell it to "run". You may also need to tell it to load symbols from the Microsoft symbol servers. It will display the call stack at the error location. If you try to look at the source code for a particular stack location, it may ask you where the source is; if so, select the appropriate source folder. MODPATH is set in the debug command-line properties for the "project" that has the name of the minidump file.