Display backtrace at runtime

cpp_backtrace.cpp

// "-rdynamic" must be enabled and symbols mustn't be hidden

#include <execinfo.h>
#include <cxxabi.h>

#include <iostream>
#include <iterator>
#include <cstdlib>
#include <cstring>
#include <thread>

static void displayBacktrace(const char *text, const int traceSize = 8)
{
    void **trace = new void *[traceSize];
    const int realTraceSize = backtrace(trace, traceSize);
    char **symbols = backtrace_symbols(trace, realTraceSize);
    if (realTraceSize > 1)
    {
        const auto oldFlags = std::cerr.flags();
        std::cerr << "Backtrace ";
        if (text)
            std::cerr << text << ' ';
        std::cerr << "[thread: " << std::hex << "0x" << std::this_thread::get_id() << "]:\n";
        std::cerr.flags(oldFlags);
    }
    for (int i = 1; i < realTraceSize; ++i)
    {
        bool displayed = false;
        if (char *symbol = std::strrchr(symbols[i], '('))
        {
            char *endOfSymbol = std::strchr(symbol += 1, '+');
            const size_t mangledSize = endOfSymbol - symbol;
            if (endOfSymbol && mangledSize > 0)
            {
                char *mangled = new char[mangledSize + 1];
                std::strncpy(mangled, symbol, mangledSize);
                mangled[mangledSize] = '\0';
                if (char *demangled = __cxxabiv1::__cxa_demangle(mangled, nullptr, nullptr, nullptr))
                {
                    const int pathLength = symbol - symbols[i];
                    std::cerr << "  ";
                    std::copy(symbols[i], symbols[i] + pathLength, std::ostream_iterator<char>(std::cerr));
                    std::cerr << demangled << endOfSymbol << '\n';
                    std::free(demangled);
                    displayed = true;
                }
                delete[] mangled;
            }
        }
        if (!displayed)
            std::cerr << "  " << symbols[i] << '\n';
    }
    std::cerr << std::flush;
    std::free(symbols);
    delete[] trace;
}