How to determine if code is running in signal-handler context?

Question

I just found out that someone is calling - from a signal handler - a definitely not async-signal-safe function that I wrote.

So, now I\'m curious: how to circumvent this

Answer 1

for code optimized at -O2 or better (istr) have found need to add -fno-omit-frame-pointer

else gcc will optimize out the stack context information