How to get what() and back trace at the same time for an uncaught exception?

Question

When an uncaught exception happens in my application, I can get the what() string of the exception by adding a global catch to my main() function, something like:

catch (std::exception& ex)
{
    std::cerr << "Error: " << ex.what() << "\n";
}

I can also get the stack trace of the location where the exception was thrown by calling backtrace() and backtrace_symbol() from inside a std::terminate() handler (set by calling std::set_terminate()). For example (ignore the memory leak):

void terminate_handler()
{
    void** buffer = new void*[15];
    int count = backtrace(buffer, 15);
    backtrace_symbols_fd(buffer, count, STDERR_FILENO);
}

…

std::set_terminate(terminate_handler);

But when I try to combine the two approaches by rethrowing the exception using throw; in my global catch, I'm getting stack trace to that catch, not to the location where the exception was originally thrown.

Is there some way I can do both (get the stack trace for the location where the exception was originally thrown and also get the value of its what()) at the same time?

Answer 1

This should work:

void terminate_handler()
{
    void** buffer = new void*[15];
    int count = backtrace(buffer, 15);
    backtrace_symbols_fd(buffer, count, STDERR_FILENO);

    //etc.
    auto ptr = std::current_exception();
    try { std::rethrow_exception(ptr); }
    catch (std::exception & p) { std::cout << p.what() << std::endl;}
}