Creating minidump for access violation exception using SetUnhandledExceptionFilter()

Question

I am using the following code to create a minidump file whenever there is a structured exception generated from my code:

void CreateMiniDump( EXCEPTION_POINTERS* pep ) 
{
  // Open the file 
typedef BOOL (*PDUMPFN)( 
  HANDLE hProcess, 
  DWORD ProcessId, 
  HANDLE hFile, 
  MINIDUMP_TYPE DumpType, 
  PMINIDUMP_EXCEPTION_INFORMATION ExceptionParam, 
  PMINIDUMP_USER_STREAM_INFORMATION UserStreamParam, 
  PMINIDUMP_CALLBACK_INFORMATION CallbackParam
);


    HANDLE hFile = CreateFile( _T("C:/temp/MiniDump.dmp"), GENERIC_READ | GENERIC_WRITE, 
    0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL ); 

    HMODULE h = ::LoadLibrary(L"DbgHelp.dll");
    PDUMPFN pFn = (PDUMPFN)GetProcAddress(h, "MiniDumpWriteDump");

  if( ( hFile != NULL ) && ( hFile != INVALID_HANDLE_VALUE ) ) 
  {
    // Create the minidump 

    MINIDUMP_EXCEPTION_INFORMATION mdei; 

    mdei.ThreadId           = GetCurrentThreadId(); 
    mdei.ExceptionPointers  = pep; 
    mdei.ClientPointers     = TRUE; 

    MINIDUMP_TYPE mdt       = MiniDumpNormal; 

    BOOL rv = (*pFn)( GetCurrentProcess(), GetCurrentProcessId(), 
      hFile, mdt, (pep != 0) ? &mdei : 0, 0, 0 ); 



    // Close the file 

    CloseHandle( hFile ); 

  }

}

LONG WINAPI MyUnhandledExceptionFilter(
 struct _EXCEPTION_POINTERS *ExceptionInfo
)
 {
     CreateMiniDump(ExceptionInfo);
     return EXCEPTION_EXECUTE_HANDLER;
 }

And I am doing SetUnhandledExceptionFilter(MyUnhandledExceptionFilter); from the main entry point of my app ( I am not setting it for each thread though). After this to test this code I did the following to generate an access violation: int* p = 0; *p = 0; The dump file did get generated. Then I used windbg and opened the dump file and used .ecxr command to get the exception record. However, no information is coming there (i.e. I am not getting the call stack). Also if I use !analyze -v command then it is able to show the line where the crash occured. Does anybody know what I am missing and how to solve this?

BTW, I am using VC7 compiler with /EHa (asynchronuos exception model) flag.

Answer 1

Your code creating minidump is OK, the problem is post-mortem debugging. Debugger must have access to the program source code, .pdb files (which should be pdb files created when this program executable was built), and OS debugging symbols. Only having all this information, debugger can show exception place in the source code and call stack.

Post-mortem debugging process using Visual Studio debugger is described in details here: http://www.codeproject.com/KB/debug/postmortemdebug_standalone1.aspx For WinDbg, use Symbol, Source and Image file path to provide the same information for debugger.