[Mono-dev] NullReferenceException thrown inside catch

[Robert Jordan]

Robert Jordan wrote:
> Robert Jordan wrote:
>> Hi,
>>
>> Janne Rantala wrote:
>>> I found out that when NullReferenceException is thrown inside catch
>>> clause in embedded environment, Mono crashes. Normally when method is
>>> invoked with mono_runtime_invoke, exceptions are stored in MonoObject
>>> but somehow this does not happen in this case.
>>> This happened when I tried to print out message from InnerException
>>> which didn't exist.
>>>
>>> Here is the code, without that Console.WriteLine it works ok
>>> (exception is stored in MonoObject).
>>
>> Here is another simple sample:
>>
>> public void CrashMe ()
>> {
>> 	null.Equals (null);
>> }
>>
>>
>> It seems that a "true" SIGSEGV (generated by native JIT code)
>> cannot be caught by mono_runtime_invoke ().
>>
>> Please file a bug, if no one objects (it could be by design).
> 
> Oh, it's a Windows problem. I cannot reproduce it under Linux.


The Windows port seems to use SEH. Maybe a SEH handler
could be able to catch the exception:

#include <windows.h>

MonoException *ex;

__try {
	mono_runtime_invoke ( ..., &ex);
}
__except (EXCEPTION_EXECUTE_HANDLER) {

	/* simulate a NRE */
	ex = mono_get_exception_null_reference ();
}

if (ex != NULL) {
	handle the exception
}

The code is for VC++ in C mode (not C++).

Robert