How do I exit thee? Let me count the ways (original) (raw)

How do I exit thee? Let me count the ways

[**reading:** Tom Holt, "Alexander at the World's End"]

Today I've been trying to sort out the interactions between the various different mechanisms for generating and catching errors in Windows. With the help of a noddy test program, I ended up with:

Type	No handler	atexit	signal	catch (...)	set_terminate	__except (EXCEPTION_EXECUTE_HANDLER)
exit(0)	No message	Hit
abort()	Visual C++ Runtime Error dialog	Hit (SIGABRT)
c=(char)0	'Encountered a problem and needs to close' dialog	Hit (SIGSEGV)	Hit	Hit	Hit, generates infinite loop	Hit
i=1/0	'Encountered a problem and needs to close' dialog	Hit	Hit	Hit, generates infinite loop	Hit
raise()	No message	Hit, execution continues from the raise
throw	Visual C++ Runtime Error dialog	Hit	Hit	Hit
RaiseException(0xE0000001,EXCEPTION_NONCONTINUABLE, 0, NULL)	'Encountered a problem and needs to close' dialog	Hit	Hit	Hit	Hit
RaiseException(0xE0000001, 0, 0, NULL)	'Encountered a problem and needs to close' dialog	Hit	Hit	Hit, execution continues from the RaiseException	Hit

Other key points to note:

All catchers only see errors from the same thread, with the exception of the SEH unhandled exception filter set by SetUnhandledExceptionFilter().
For (say) a null dereference, the order that various handlers get to see things is:
- Vectored Exception Handler (VEH)
- C++ exception handler or Structured Exception Handler (SEH), whichever has the narrower enclosing scope
- SIGSEGV signal handler /* FALLTHRU */
- SEH unhandled exception filter installed by SetUnhandledExceptionFilter
- C++ unhandled exception handler installed by set_terminate
I've no idea why a null dereference does appear as a C++ exception in a catch (...) block, but_doesn't_ hit the unhandled-C++-exception-handler installed by set_terminate.