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SIGPROCMASK(2)           DragonFly System Calls Manual          SIGPROCMASK(2)


NAME

     sigprocmask - manipulate current signal mask


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <signal.h>

     int
     sigprocmask(int how, const sigset_t * restrict set,
         sigset_t * restrict oset);


DESCRIPTION

     The sigprocmask() function examines and/or changes the current signal
     mask (those signals that are blocked from delivery).  Signals are blocked
     if they are members of the current signal mask set.

     If set is not null, the action of sigprocmask() depends on the value of
     the parameter how.  The signal mask is changed as a function of the
     specified set and the current mask.  The function is specified by how
     using one of the following values from <signal.h>:

     SIG_BLOCK        The new mask is the union of the current mask and the
                      specified set.

     SIG_UNBLOCK      The new mask is the intersection of the current mask and
                      the complement of the specified set.

     SIG_SETMASK      The current mask is replaced by the specified set.

     If oset is not null, it is set to the previous value of the signal mask.
     When set is null, the value of how is insignificant and the mask remains
     unset providing a way to examine the signal mask without modification.

     The system quietly disallows SIGKILL or SIGSTOP to be blocked.


RETURN VALUES

     The sigprocmask() function returns the value 0 if successful; otherwise
     the value -1 is returned and the global variable errno is set to indicate
     the error.


ERRORS

     The sigprocmask() call will fail and the signal mask will be unchanged if
     one of the following occurs:

     [EINVAL]           how has a value other than those listed here.


SEE ALSO

     kill(2), sigaction(2), sigsuspend(2), fpsetmask(3), sigblockall(3),
     sigsetops(3), sigunblockall(3)


STANDARDS

     The sigprocmask() function call is expected to conform to IEEE Std
     1003.1-1990 ("POSIX.1").

DragonFly 5.7-DEVELOPMENT      February 22, 2018     DragonFly 5.7-DEVELOPMENT

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