pthread_sigmask(3P)

NAME
     pthread_sigmask - examine and change blocked signals

C SYNOPSIS
     #include <signal.h>

     int pthread_sigmask(int operation, const sigset_t *set, sigset_t *old_set);

DESCRIPTION
     The pthread_sigmask() function manipulates the set of signals which are
     blocked from delivery to the calling thread.

     A non-NULL set specifies the set of signals to use in modifying the
     currently active set.  The incoming signals may be added to, deleted from
     or completely replace the active set, as specified by the operation
     parameter which may have the following values:

     SIG_BLOCK    Add specified signals to those in current mask.

     SIG_UNBLOCK  Remove the specified signals from the current mask.

     SIG_SETMASK  Replace the current mask with set.

     If old_set is not NULL, the current set of blocked signals (before
     modification) is returned in the space to which it points.  In this way,
     with a NULL set the user can determine the current signal mask.

     Routines described in sigsetops() are used to create and examine the set
     and old_set signal masks.

     It is not possible to block SIGKILL or SIGSTOP.  This restriction is
     silently imposed by the system.

DIAGNOSTICS
     On success, pthread_sigmask() returns zero; otherwise, an error number is
     returned:

     [EINVAL]       The value specified by operation is not equal to one of
                    the defined values.

SEE ALSO
     sigaction(2), sigprocmask(2), sigsetops(3), pthread_kill(3P), signal(5).

NOTES
     In IRIX, sigprocmask() it is equivalent to pthread_sigmask().