Coroutine: How to tell if a windows fiber has finished execution?

Question

I have the following function that I use as an entry point for a windows fiber.

void foo(void*) {
    for(int i =0; i < 10; ++i) { doStuff(); }
}

Now I call SwitchToFiber in my main in a for loop; something like the following.

int main() {
    ... create the fiber and stuff

    for (int i = 0; i < 50; ++i) {
        SwitchToFiber(foo_fiber_ptr);
        // how do I tell if foo has already finished execution?
        // (without passing in a state variable to communicate.)
        if (someCondition) { break; }
    }

    ... do stuff
}

So my question is: how do I tell if foo has already finished execution?(without passing in a state variable or declaring a global state variable to communicate.)

Answer 1

Declare a global variable. After executing the foo function, change the state of the global variable in foo.

In main check for the state change. If the state of the global variable is changed, means foo has already been executed.

Answer 2

how do I tell if foo has already finished execution?

You tell that seeing your whole program's termination - see Fibers:

If your fiber function returns, the thread running the fiber exits.