visual c++ - Windows C++ stack trace from a running app

Question

All,

I saw an app, an SVN Visual Studio plugin, that displayed a beautiful readable stack trace, when it crashed.

I would love to add that to my application. How do I provide that? No emailing of the information, just a visual display is enough.

Answer 1

The core of the necessary code is StackWalk64. To get much from that, you'll also want/need to get symbol names with SymGetSymFromAddr64 (which requires SymLoadModule64) and (probably) SymGetLineFromAddr64 and GetThreadContext. If the target was written in C++, you'll probably also want to use UnDecorateSymbolName. Along with those you'll need a few ancillaries like SymInitialize, SymCleanup, and probably SymSetOptions.

Here's a fairly minimal demo. The stack dump it produces is more utilitarian than beautiful, but presumably with the basics of doing the stack trace, you can display the results as you see fit:

#include <windows.h>
#include <winnt.h>

#include <string>
#include <vector>
#include <Psapi.h>
#include <algorithm>
#include <iomanip>
#include <iostream>
#include <stdexcept>
#include <iterator>

#pragma comment(lib, "psapi.lib")
#pragma comment(lib, "dbghelp.lib")

// Some versions of imagehlp.dll lack the proper packing directives themselves
// so we need to do it.
#pragma pack( push, before_imagehlp, 8 )
#include <imagehlp.h>
#pragma pack( pop, before_imagehlp )

struct module_data {
    std::string image_name;
    std::string module_name;
    void *base_address;
    DWORD load_size;
};
typedef std::vector<module_data> ModuleList;

HANDLE thread_ready;

bool show_stack(std::ostream &, HANDLE hThread, CONTEXT& c);
DWORD __stdcall TargetThread( void *arg );
void ThreadFunc1();
void ThreadFunc2();
DWORD Filter( EXCEPTION_POINTERS *ep );
void *load_modules_symbols( HANDLE hProcess, DWORD pid );

int main( void ) {
    DWORD thread_id;

    thread_ready = CreateEvent( NULL, false, false, NULL );

    HANDLE thread = CreateThread( NULL, 0, TargetThread, NULL, 0, &thread_id );

    WaitForSingleObject( thread_ready, INFINITE );
    CloseHandle(thread_ready);
    return 0;
}

// if you use C++ exception handling: install a translator function
// with set_se_translator(). In the context of that function (but *not*
// afterwards), you can either do your stack dump, or save the CONTEXT
// record as a local copy. Note that you must do the stack dump at the
// earliest opportunity, to avoid the interesting stack-frames being gone
// by the time you do the dump.
DWORD Filter(EXCEPTION_POINTERS *ep) {
    HANDLE thread;

    DuplicateHandle(GetCurrentProcess(), GetCurrentThread(),
        GetCurrentProcess(), &thread, 0, false, DUPLICATE_SAME_ACCESS);
    std::cout << "Walking stack.";
    show_stack(std::cout, thread, *(ep->ContextRecord));
    std::cout << "
End of stack walk.
";
    CloseHandle(thread);

    return EXCEPTION_EXECUTE_HANDLER;
}

void ThreadFunc2() {
    __try { DebugBreak(); }
    __except (Filter(GetExceptionInformation())) {  }
    SetEvent(thread_ready);
}

void ThreadFunc1(void (*f)()) {
    f();
}

// We'll do a few levels of calls from our thread function so 
//     there's something on the stack to walk...
//
DWORD __stdcall TargetThread(void *) {
    ThreadFunc1(ThreadFunc2);
    return 0;
}

class SymHandler { 
    HANDLE p;
public:
    SymHandler(HANDLE process, char const *path=NULL, bool intrude = false) : p(process) { 
        if (!SymInitialize(p, path, intrude)) 
            throw(std::logic_error("Unable to initialize symbol handler"));
    }
    ~SymHandler() { SymCleanup(p); }
};

#ifdef _M_X64
STACKFRAME64 init_stack_frame(CONTEXT c) {
    STACKFRAME64 s;
    s.AddrPC.Offset = c.Rip;
    s.AddrPC.Mode = AddrModeFlat;
    s.AddrStack.Offset = c.Rsp;
    s.AddrStack.Mode = AddrModeFlat;    
    s.AddrFrame.Offset = c.Rbp;
    s.AddrFrame.Mode = AddrModeFlat;
    return s;
}
#else
STACKFRAME64 init_stack_frame(CONTEXT c) {
    STACKFRAME64 s;
    s.AddrPC.Offset = c.Eip;
    s.AddrPC.Mode = AddrModeFlat;
    s.AddrStack.Offset = c.Esp;
    s.AddrStack.Mode = AddrModeFlat;    
    s.AddrFrame.Offset = c.Ebp;
    s.AddrFrame.Mode = AddrModeFlat;
    return s;
}
#endif

void sym_options(DWORD add, DWORD remove=0) {
    DWORD symOptions = SymGetOptions();
    symOptions |= add;
    symOptions &= ~remove;
    SymSetOptions(symOptions);
}

class symbol { 
    typedef IMAGEHLP_SYMBOL64 sym_type;
    sym_type *sym;
    static const int max_name_len = 1024;
public:
    symbol(HANDLE process, DWORD64 address) : sym((sym_type *)::operator new(sizeof(*sym) + max_name_len)) {
        memset(sym, '', sizeof(*sym) + max_name_len);
        sym->SizeOfStruct = sizeof(*sym);
        sym->MaxNameLength = max_name_len;
        DWORD64 displacement;

        if (!SymGetSymFromAddr64(process, address, &displacement, sym))
            throw(std::logic_error("Bad symbol"));
    }

    std::string name() { return std::string(sym->Name); }
    std::string undecorated_name() { 
        std::vector<char> und_name(max_name_len);
        UnDecorateSymbolName(sym->Name, &und_name[0], max_name_len, UNDNAME_COMPLETE);
        return std::string(&und_name[0], strlen(&und_name[0]));
    }
};

bool show_stack(std::ostream &os, HANDLE hThread, CONTEXT& c) {
    HANDLE process = GetCurrentProcess();
    int frame_number=0;
    DWORD offset_from_symbol=0;
    IMAGEHLP_LINE64 line = {0};

    SymHandler handler(process);

    sym_options(SYMOPT_LOAD_LINES | SYMOPT_UNDNAME);

    void *base = load_modules_symbols(process, GetCurrentProcessId());

    STACKFRAME64 s = init_stack_frame(c);

    line.SizeOfStruct = sizeof line;

    IMAGE_NT_HEADERS *h = ImageNtHeader(base);
    DWORD image_type = h->FileHeader.Machine;

    do {
        if (!StackWalk64(image_type, process, hThread, &s, &c, NULL, SymFunctionTableAccess64, SymGetModuleBase64, NULL))
            return false;

        os << std::setw(3) << "
" << frame_number << "";
        if ( s.AddrPC.Offset != 0 ) {
            std::cout << symbol(process, s.AddrPC.Offset).undecorated_name();

            if (SymGetLineFromAddr64( process, s.AddrPC.Offset, &offset_from_symbol, &line ) ) 
                    os << "" << line.FileName << "(" << line.LineNumber << ")";
        }
        else
            os << "(No Symbols: PC == 0)";
        ++frame_number;
    } while (s.AddrReturn.Offset != 0);
    return true;
}

class get_mod_info {
    HANDLE process;
    static const int buffer_length = 4096;
public:
    get_mod_info(HANDLE h) : process(h) {}

    module_data operator()(HMODULE module) { 
        module_data ret;
        char temp[buffer_length];
        MODULEINFO mi;

        GetModuleInformation(process, module, &mi, sizeof(mi));
        ret.base_address = mi.lpBaseOfDll;
        ret.load_size = mi.SizeOfImage;

        GetModuleFileNameEx(process, module, temp, sizeof(temp));
        ret.image_name = temp;
        GetModuleBaseName(process, module, temp, sizeof(temp));
        ret.module_name = temp;
        std::vector<char> img(ret.image_name.begin(), ret.image_name.end());
        std::vector<char> mod(ret.module_name.begin(), ret.module_name.end());
        SymLoadModule64(process, 0, &img[0], &mod[0], (DWORD64)ret.base_address, ret.load_size);
        return ret;
    }
};

void *load_modules_symbols(HANDLE process, DWORD pid) {
    ModuleList modules;

    DWORD cbNeeded;
    std::vector<HMODULE> module_handles(1);

    EnumProcessModules(process, &module_handles[0], module_handles.size() * sizeof(HMODULE), &cbNeeded);
    module_handles.resize(cbNeeded/sizeof(HMODULE));
    EnumProcessModules(process, &module_handles[0], module_handles.size() * sizeof(HMODULE), &cbNeeded);

    std::transform(module_handles.begin(), module_handles.end(), std::back_inserter(modules), get_mod_info(process));
    return modules[0].base_address;
}