int sigblock(int mask);
int sigsetmask(int mask);
This interface is made obsolete by sigprocmask(2).
The sigblock system call adds the signals specified in mask to the set of signals currently being blocked from delivery.
The sigsetmask system call replaces the set of blocked signals totally with a new set specified in mask. Signals are blocked if the corresponding bit in mask is a 1.
The current set of blocked signals can be obtained using siggetmask.
siggetmask returns the current set of masked signals.
Prototypes for these functions are only available if _BSD_SOURCE is defined before the inclusion of any system header file.