Attribute handling when using multiple threads

We will get a segmentation fault if a thread changes an attribute while another thread is using it.

From SOFTHSM-36:

Rickard Bellgrim added a comment - 2013-10-22 12:26
The problem is that we may have handed out an attribute via ObjectFile::getAttribute() and then the attributes gets erased by ObjectFile::discardAttributes() when there is an update (ObjectFile::refresh()) to the object.

Francis Dupont added a comment - 2013-10-25 16:25
The getAttribute()/discardAttribute() is not really a locking issue: it is just a standard dangling pointer issue…
If we want to keep the value of the time we get the pointer (IMHO the reasonable assumption), I suggest to make getAttribute() to return a unique_ptr (or an auto_ptr on old systems) to a copy of the attribute. Even if compilers should optimise chained calls, I suggest too if we follow this way to factorize accesses.