[cxx-abi-dev] How to detect a forced unwind in a catch block?

[Thiago Macieira]

Em sábado, 3 de setembro de 2016, às 10:21:07 CEST, Richard Smith escreveu:
> When trying to implement this requirement for QThread, we've run into a
> snag:
> with glibc's pthread implementation on Linux, pthread_exit() as well as all
> POSIX asynchronous cancellations happen by way of a forced stack unwinding.
> This means the obvious solution to implement the requirement from the
> standard
> fails:
> 
>         try {
>                 thr->run();
>         } catch (...) {
>                 std::terminate();
>         }
> 
> That catch (...) block is run by the forced stack unwinding started with
> _Unwind_ForcedUnwind.
> 
> 
> What does std::current_exception() return here?

$1 = {_M_exception_object = 0x0}

This suggests a solution:

    try {
        thr->run();
    } catch (...) {
        if (std::current_exception())
            std::terminate();
        throw;
    }

This code allows a thread to exit cleanly if the run() function above did 
pthread_exit(0).

Is this what would be recommended?

-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
   Software Architect - Intel Open Source Technology Center