From: barabba <igor.sarzisartori@...>
Date: 2007-04-07T03:20:04+09:00
Subject: Ruby C extension crash: how to create a stack trace?

Hi,

I am using ruby to test and develop  my legacy C code. I packed it
inside  a ruby extension as dll under windows. I am using visual
studio 6 to debug my extension.
The process works very well, but when I make a mistake in my C code
ruby abort  without stack trace and it is difficult for me to find the
reason.
Here a trivial example. I have exported the buggy function
foo_thread_handler to ruby:

void foo_thread_handler()
{
    while(1)
    {
         //  a thread task
         mystruct* pCrash = 0; // null pointer usage
         pCrash->len = 555;     // crash with 0xC0000005: Access
Violation.
         do_realstuff(); // do real stuff
         // call a function inside ruby to get back to the scheduler
         rb_something()
    }
}

and in ruby:
require 'myextension'
 Thread.new {
      begin
        Myextension::foo_thread_handler()
      rescue Exception => detail
        puts " c extension code  error"
      end
}

def rb_something
  puts "I am alive"
end

How can avoid ruby to silent  abort when pCrash->len = 555; is
executed?
I am interested on stack trace, because it is not created, or an
assert to identify the code that make a crash.
Usually such exceptions are handled inside visual studio, but if I run
ruby inside it, in order to debug my extension, this doesn't happens.
I think to rebuild ruby and modify error.c  to avoid abort() call
inside rb_bug(), but I am looking for a better solution.

Regards,
Igor