The
pthread_sigmask() function examines and/or changes the calling thread's signal mask.
If
set is not
NULL, it specifies a set of signals to be modified, and
how specifies what to set the signal mask to:
SIG_BLOCK
Union of the current mask and set.
SIG_UNBLOCK
Intersection of the current mask and the complement of set.
If
oset is not
NULL, the previous signal mask is stored in the location pointed to by
oset.
SIGKILL and
SIGSTOP cannot be blocked, and will be silently ignored if included in the signal mask.