Question

I have build a Ruby extension in Objective-C. Now I want to use @throw/@catch etc. instead of macro based exception handling and self build error handling.

I am using the GNU runtime shipped with the GCC.
When I run my Ruby app with my extension it core dumps as soon as an exception occurs. The abort() comes from the GNU Objective-C runtime (libobjc/exception.c:375):

void
objc_exception_throw (id value)
{
  struct ObjcException *header = calloc (1, sizeof (*header));
  header->base.exception_class = __objc_exception_class;
  header->base.exception_cleanup = __objc_exception_cleanup;
  header->value = value;

#ifdef SJLJ_EXCEPTIONS
  _Unwind_SjLj_RaiseException (&header->base);
#else
  _Unwind_RaiseException (&header->base);
#endif

  /* Some sort of unwinding error.  */
  abort ();
}

Since I compiled with -fobjc-exceptions I think _Unwind_RaiseException is being called.

Is there any way to use the Objective-C exceptions in a Ruby extension?

Answer 1

Problem solved:

The GNU Objective-C runtime does not handle the result of _Unwind_(SjLj_)RaiseException (see code above). In my case it returned 5 which stands for “end of stack” and means that I had forgotten a @try/@catch block.

There really should be some logging or a hook to do it self.

Update:

Unless one compiles Ruby with -fobjc-exceptions the Objective-C exception handling cannot trace the stack through Ruby code. Therefore you must be aware to catch and wrap or translate any Objective-C exception before giving control to Ruby.