#include <signal.h>

     int
     pthread_sigmask(int how, const sigset_t *set, sigset_t *oset);

DESCRIPTION

     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.

     SIG_SETMASK  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.

RETURN VALUES

     If successful, pthread_sigmask() returns 0.  Otherwise, an error is
     returned.

ERRORS

     pthread_sigmask() will fail if:

     [EINVAL]           how is not one of the defined values.

SEE ALSO

     sigaction(2), sigpending(2), sigprocmask(2), sigsuspend(2), sigsetops(3)

STANDARDS

     pthread_sigmask() conforms to ISO/IEC 9945-1:1996 (``POSIX.1'')

BSD                             April 27, 2000                             BSD