backtrace() vs. _Unwind_Backtrace()

Mon Dec 8 20:15:00 GMT 2003

On Dec 9, 2003, at 12:33 AM, Andrew Haley wrote:
> Bryce McKinlay writes:
>> On Dec 7, 2003, at 12:21 AM, Andrew Haley wrote:
>>>>> I don't want it to sound like I'm opposed to the approach of calling
>>> _Unwind_Backtrace() directly. It sounds quite a clean idea. 
>>> However,
>>> not every architecture supports DWARF2, and if we have a new
>>> architecture for unwinding we need to support those targets too.
>>>> The thing is, backtrace() alone doesn't help us much. Without DWARF2,
>> we can't find the start of the function, and can't lookup the
>> Class/Method. So why bother?
>> All we need is a method that maps pc->name. We know that we can use
> addr2line to do that, and we are about to get a demangler that we can
> link into libgcj.

It needs to map pc->Class/_Jv_Method, not just a name. Mapping to a 
name (eg symbol lookup/demangling) is insufficient because different 
classes, with different privileges, can have the same name. Someone 
could, for example, name their class java.lang.Whatever and potentially 
bypass security checks.
Admittedly this problem only really applies to security checks and not 
diagnostic stack traces, but I think its better to pursue a solution 
that works for everything.
Regards
Bryce.