determine whether code is running in a signal handler context

[Florian Weimer]

On 11/27/2017 09:42 AM, Yubin Ruan wrote:
> Still remember this thread? It turn out that determining whether or not you
> are currently in a signal handler is trivial with libunwind:

This is incorrect.  libunwind (or any other unwinder) relies on 
information which is not always available.  And since you need to unwind 
the stack completely (if not executing in a signal handler), it is very 
slow.

Thanks,
Florian