SIGPROCMASK(2) MachTen Programmer’s Manual SIGPROCMASK(2)

NAME
sigprocmask - manipulate current signal mask

SYNOPSIS
#include <signal.h>

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

sigmask(signum)

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 speci-
fied 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 speci-
fied 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
A 0 value indicated that the call succeeded. A -1 return value indicates
an error occurred and errno is set to indicated the reason.

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), sigsetops(3), sigsuspend(2)

STANDARDS
The sigprocmask function call is expected to conform to IEEE
Std1003.1-1988 (‘‘POSIX’’).

4.4BSD June 4, 1993 1