Re: [PATCH 2/2] Testsuite for varobj updation after symbol removal

[Taimoor <tmirza@codesourcery.com>]

On 04/27/2015 11:46 PM, Vladimir Prus wrote:
>
> thanks, so the issue is that removing a symbol file recreates
> *all* global varobjs, and in the process clears any change of value
> since the last update. I agree the patch is fixing that.
>
> There's a second change, it seems - to invalidate varobj that refers to types in unloaded objfile - is there a test for that?
>

Hi Vladimir,

Sorry for delayed response. There are no separate tests for invalidation 
of varobjs in unloaded objfile as it gets tested by existing varobj 
tests. If we don't invalidate varobjs in unloaded objfile, a lot GDB 
tests will fail. This is because while trying to retrieve old varobj 
value for already removed objfile (to compare with current value), it 
will try to access pointers that are no longer valid and that will 
result in failure.
Marking varobjs that refers to types in unloaded objfile invalid makes 
sure we do not accidentally use dangling pointers to obtain varobj value 
for unloaded objfile.

IMO, GDB should avoid using pointers whose target has been already freed 
and this change specifically marks var->type to NULL to make sure no 
dangling pointers remain after objfile is unloaded so any subsequent 
call to varobj_get_value does not result in segmentation fault.


Thanks,
Taimoor