change atexit behavior based on program status

Question

I am trying register one function with atexit () that will print different messages based off of the current status of the program. I know that when you register the function with atexit you cannot pass an argument.

So, how can you pass the program status, say an integer, and make that function print different statements?

I know that I can register multiple functions, but I have to only use one.

Answer 1

Instead of using atexit, make use of the on_exit function which takes the status passed into exit() as one argument, and a void * that you can pass in.

int on_exit(void (*function)(int , void *), void *arg);

The on_exit() function registers the given function to be called at normal process termination, whether via exit(3) or via return from the program's main(). The function is passed the status argument given to the last call to exit(3) and the arg argument from on_exit().

The same function may be registered multiple times: it is called once for each registration. When a child process is created via fork(2), it inherits copies of its parent's registrations. Upon a successful call to one of the exec(3) functions, all registrations are removed.