This data type is the BSD equivalent of struct sigaction (see Advanced Signal Handling); it is used to specify signal actions to the sigvec function. It contains the following members:

sighandler_t sv_handler

This is the handler function.

int sv_mask

This is the mask of additional signals to be blocked while the handler function is being called.

int sv_flags

This is a bit mask used to specify various flags which affect the behavior of the signal. You can also refer to this field as sv_onstack.

If this bit is set in the sv_flags field of a sigvec structure, it means to use the signal stack when delivering the signal.

If this bit is set in the sv_flags field of a sigvec structure, it means that system calls interrupted by this kind of signal should not be restarted if the handler returns; instead, the system calls should return with a EINTR error status. See Interrupted Primitives.

If this bit is set in the sv_flags field of a sigvec structure, it means to reset the action for the signal back to SIG_DFL when the signal is received.

This function is the equivalent of sigaction (see Advanced Signal Handling); it installs the action action for the signal signum, returning information about the previous action in effect for that signal in old-action.

This function specifies which approach to use when certain primitives are interrupted by handling signal signum. If failflag is false, signal signum restarts primitives. If failflag is true, handling signum causes these primitives to fail with error code EINTR. See Interrupted Primitives.