Throwing an exception from within a signal handler

Answer 1

Signals are totally different than C++ exceptions. You can't use a C++ try/catch block to handle a signal. Specifically, signals are a POSIX concept, not a C++ language concept. Signals are delivered asynchronously to your application by the kernel, whereas C++ exceptions are synchronous events defined by the C++ standard.

You are quite limited in what you can do portably in a POSIX signal handler. A common strategy is to have a global flag of type sig_atomic_t which will be set to 1 in the signal handler, and then possibly longjmp to the appropriate execution path.

See here for help writing proper signal handlers.

Answer 2

I would mask all signals in every thread, except one which would wait signals with sigwait (). This thread can handle signals without restriction, e.g. throw exceptions or use other communication mechanisms.

Answer 3

Throwing out of a signal handler is probably not a good idea as the stack is not nesacerily set up in the same way as for function calls thus unwinding from a signal handler may not work as expected.

Important note must be taken for any register used by the C++ ABI that are saved and re-used by the signal handling mechanism.