изучить и изменить сигнальное действие (examine and change a signal action)
Ошибки (баги) (Bugs)
When delivering a signal with a SA_SIGINFO handler, the kernel
does not always provide meaningful values for all of the fields
of the siginfo_t that are relevant for that signal.
In kernels up to and including 2.6.13, specifying SA_NODEFER in
sa_flags prevents not only the delivered signal from being masked
during execution of the handler, but also the signals specified
in sa_mask. This bug was fixed in kernel 2.6.14.
