I'm debugging a sort of weird issue where it looks like a thread that's killed in an atexit handler is accessing a shared library, and is segfaulting because that shared library is unloaded before the exit handler runs. I'm not sure this is actually the issue, but it's a hunch on what might be happening.
When a process terminates (main exits or exit() is called), is the atexit handler the immediate next thing to run? My mind says so, but the segfault I'm seeing seems to say otherwise.
Is there any difference (with regards to exit handling) between main returning (either end of function or with return) and calling exit() directly?
When a process terminates (main exits or exit() is called), is the atexit handler the immediate next thing to run? My mind says so, but the segfault I'm seeing seems to say otherwise.
Not necessarily, you're guaranteed that atexit handlers will run. But that's it, atexit handlers may even be called concurrently with other things. While you're using c remember that c++ may be in the same process. C++ says that atexit may be called concurrently to destructors being run for objects of static duration. This means that atexit is very dangerous and you need to ensure you're being very careful what you call.
Is there any difference (with regards to exit handling) between main returning (either end of function or with return) and calling exit() directly?
According to the documentation: No.
The safest thing to do when tearing down the house: Nothing. Just get out and let the house be torn down. Closing the drapes on the way out isn't worth the time so to speak.