Function signal_handler 

unsafe extern "C" fn signal_handler(
    signum: c_int,
    info: *mut siginfo_t,
    _data: *mut c_void,
)

Available on non-miri and (Linux or FreeBSD or target_os=hurd or macOS or NetBSD or OpenBSD or Solaris or illumos) only.

SIGSEGV/SIGBUS entry point

Safety

Rust doesn’t call this, it gets called.