printing_ruby_stack_trace_via_c_api.c

static VALUE callback_exception(VALUE did_raise, VALUE exception) {
  VALUE ret = rb_funcall(exception, rb_intern("message"), 0);
  VALUE trace = rb_funcall(exception, rb_intern("backtrace"), 0);
  if (RB_TYPE_P(trace, T_ARRAY) && RARRAY_LEN(trace) > 0) {
    printf("we got an exception: %s:%d\n", StringValueCStr(ret), RARRAY_LEN(trace));
    VALUE sep = rb_str_new_cstr("\n");
    VALUE trace_lines = rb_ary_join(trace, sep);
    if (RB_TYPE_P(trace_lines, T_STRING)) {
      printf("%s\n", StringValueCStr(trace_lines));
    } else {
      printf("trace is not a string??\n");
    }
  } else {
    printf("we got an exception: %s\nno stack available\n", StringValueCStr(ret));
  }
  rb_hash_aset(did_raise, rb_easy_hkey("error"), Qtrue);
  return exception;
}

  VALUE did_raise = rb_hash_new();
    rb_rescue(call_status_handler1, callargs, callback_exception, did_raise);