windows/c++: how can I get a useful stack trace from a signal handler?

Question

I've got a Windows/C++ app (using JUCE) and I'd like to dump a stack trace to a file when the app crashes. In my initialization code, I've got:

signal(SIGABRT, abortHandler);
signal(SIGSEGV, abortHandler);
signal(SIGILL, abortHandler);
signal(SIGFPE, abortHandler);

And then my handler looks like:

void abortHandler(int signum)
{
    juce::File log("stacktrace.txt");

    log.appendText(juce::SystemStats::getStackBacktrace());

    exit(signum);
}

However, the resulting stack trace is not the thread where the crash occurred:

0: AudulusDebug32: juce::SystemStats::getStackBacktrace + 0x7f
1: AudulusDebug32: abortHandler + 0x61
2: AudulusDebug32: _XcptFilter + 0x1e3
3: AudulusDebug32: __tmainCRTStartup + 0x15f
4: AudulusDebug32: WinMainCRTStartup + 0xd
5: BaseThreadInitThunk + 0xe
6: RtlInitializeExceptionChain + 0x84
7: RtlInitializeExceptionChain + 0x5a

Internally, getStackBacktrace does the following:

    HANDLE process = GetCurrentProcess();
    SymInitialize (process, nullptr, TRUE);

    void* stack[128];
    int frames = (int) CaptureStackBackTrace (0, numElementsInArray (stack), stack, nullptr);

Is there a way I could get the stack trace for the thread where the crash occurred (or all threads)?

https://msdn.microsoft.com/en-us/library/windows/desktop/ms680634%28v=vs.85%29.aspx — Hans Passant, Jan 22 '15 at 22:52
Doesn't happen in x64. I'm not sure whether this is because x86 uses stack-based rather than table-based exceptions, or because WOW64 is confusing things. (I don't have a 32-bit machine handy to try it on.) — Harry Johnston, Jan 23 '15 at 03:36

score 8 · Answer 1 · answered Jan 23 '15 at 17:39

My solution was, as @HansPassant suggested, to use:

SetUnhandledExceptionFilter(TopLevelExceptionHandler);

And in TopLevelExceptionHandler, instead of calling CaptureStackBackTrace, I use StackWalk64, which allows you to specify which stack to walk (as opposed to the just assuming the current stack).

Here is the code:

LONG WINAPI TopLevelExceptionHandler(PEXCEPTION_POINTERS pExceptionInfo)
{
    std::ofstream f;
    f.open("stacktrace.txt", std::ios::out | std::ios::trunc);

    HANDLE process = GetCurrentProcess();
    SymInitialize(process, NULL, TRUE);

    // StackWalk64() may modify context record passed to it, so we will
    // use a copy.
    CONTEXT context_record = *pExceptionInfo->ContextRecord;
    // Initialize stack walking.
    STACKFRAME64 stack_frame;
    memset(&stack_frame, 0, sizeof(stack_frame));
    #if defined(_WIN64)
    int machine_type = IMAGE_FILE_MACHINE_AMD64;
    stack_frame.AddrPC.Offset = context_record.Rip;
    stack_frame.AddrFrame.Offset = context_record.Rbp;
    stack_frame.AddrStack.Offset = context_record.Rsp;
    #else
    int machine_type = IMAGE_FILE_MACHINE_I386;
    stack_frame.AddrPC.Offset = context_record.Eip;
    stack_frame.AddrFrame.Offset = context_record.Ebp;
    stack_frame.AddrStack.Offset = context_record.Esp;
    #endif
    stack_frame.AddrPC.Mode = AddrModeFlat;
    stack_frame.AddrFrame.Mode = AddrModeFlat;
    stack_frame.AddrStack.Mode = AddrModeFlat;

    juce::HeapBlock<SYMBOL_INFO> symbol;
    symbol.calloc(sizeof(SYMBOL_INFO) + 256, 1);
    symbol->MaxNameLen = 255;
    symbol->SizeOfStruct = sizeof(SYMBOL_INFO);

    while (StackWalk64(machine_type,
        GetCurrentProcess(),
        GetCurrentThread(),
        &stack_frame,
        &context_record,
        NULL,
        &SymFunctionTableAccess64,
        &SymGetModuleBase64,
        NULL)) {

        DWORD64 displacement = 0;

        if (SymFromAddr(process, (DWORD64)stack_frame.AddrPC.Offset, &displacement, symbol))
        {
            IMAGEHLP_MODULE64 moduleInfo;
            juce::zerostruct(moduleInfo);
            moduleInfo.SizeOfStruct = sizeof(moduleInfo);

            if (::SymGetModuleInfo64(process, symbol->ModBase, &moduleInfo))
                f << moduleInfo.ModuleName << ": ";

            f << symbol->Name << " + 0x" << String::toHexString((juce::int64)displacement) << std::endl;
        }

    }

    return EXCEPTION_CONTINUE_SEARCH;
}

Having the same problem here. I wonder why do you pass GetCurrentThread() as third argument to StackWalk64()? Don't we need to pass a handle to the thread that we are examining, do we? If yes, then how to obtain the handle to the crashed thread? — Anton Jebrak, Jul 11 '15 at 16:41

windows/c++: how can I get a useful stack trace from a signal handler?

1 Answers1