signal-readme.txt

Plausible CrashReporter now provides support for executing your own code in the context of the
crash reporter's signal handler, after the crash report has been written to disk. This was a
regularly requested feature, and provides a convenient point for performing application finalization.
However, there is an important caveat to be aware to  when writing code intended for execution inside
of a signal handler -- specifically, your code must be async-safe.
 
Program Flow and Signal Handlers
 
When the signal handler is called, the normal flow of the program is interrupted, and your program is
an entirely unknown state. Locks may be held, the heap may be corrupt (or in the process of being updated),
and your signal handler may invoke a function that was being executed at the time of the signal. This may
result in deadlocks, data corruption, and program termination.
 
Async-Safe Functions 
 
A subset of functions are defined to be async-safe by the OS, and are safely callable from within a
signal handler. If  you do implement a custom post-crash handler, it must be async-safe. A table of
POSIX-defined async-safe functions and additional information is available from the CERT programming
guide - SIG30-C:

https://www.securecoding.cert.org/confluence/display/seccode/SIG30-C.+Call+only+asynchronous-safe+functions+within+signal+handlers