int
pthread_sigmask(int how, const sigset_t * restrict set, sigset_t * restrict oset)
)
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_BLOCKset.
SIG_UNBLOCKset.
SIG_SETMASKset.
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.
)
returns 0.
Otherwise, an error is returned.
)
shall fail if:
EINVAL]how
is not one of the defined values.
)
conforms to
ISO/IEC 9945-1:1996 (``POSIX.1'')