sigprocmask(3) [ultrix man page]

sigprocmask(3)						     Library Functions Manual						    sigprocmask(3)

Name
       sigprocmask - examine and change blocked signals (POSIX)

Syntax
       #include <signal.h>

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

Description
       The system call is used to examine and/or change the calling process's signal mask. If the value of the argument set is not NULL, it points
       to a set of signals that will be used to change the currently blocked set.

       The value of the argument how indicates the manner in which the set is changed as defined by the following values, defined in <signal.h>:

       SIG_BLOCK
	      The resulting signal set is the union of the current set and the signal set pointed to by the argument set.

       SIG_UNBLOCK
	      The resulting signal set is the intersection of the current set and the complement of the signal set pointed to by the argument set.

       SIG_SETMASK
	      The resulting signal set is the signal set pointed to by the argument set.

       If the argument oset is not NULL, the previous mask is stored in the space pointed to by oset.  If the value of the argument set  is  NULL,
       the process's signal mask is unchanged; thus, the function can be used to enquire about currently blocked signals.

       The signal masks used as arguments to this function are manipulated using the functions.

       As a system restriction, SIGKILL and SIGSTOP cannot be blocked.

Return Values
       A 0 return value indicates a successful call.  A -1 return value indicates an error and errno is set to indicated the reason.

Diagnostics
       The function fails and the signal mask remains unchanged if the follow occurs:

       [EINVAL]       The value of the how argument is not equal to one of the defined values.

See Also
       kill(2), sigsetmask(2), sigvec(2), sigblock(2), sigsetops(3)

																    sigprocmask(3)

sigprocmask(2)															    sigprocmask(2)

NAME

       sigprocmask - change or examine caller's signal mask

SYNOPSIS

       #include <signal.h>

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

       The sigprocmask() function is used to examine and/or change the caller's signal mask. If the value is  SIG_BLOCK, the set pointed to by the
       set argument is added to the current signal mask. If the value is  SIG_UNBLOCK, the set pointed by the  set argument is	removed  from  the
       current	signal	mask. If the value is  SIG_SETMASK, the current signal mask is replaced by the set pointed to by the  set argument. If the
       oset argument is not  NULL, the previous mask is stored in the space pointed to by oset. If the value of the  set argument  is	NULL,  the
       value  how is not significant and the caller's signal mask is unchanged; thus, the call can be used to inquire about currently blocked sig-
       nals. If the set or oset argument points to an invalid address, the behavior is undefined and errno may be set to EFAULT.

       If there are any pending unblocked signals after the call to sigprocmask(), at least one of those signals will be delivered before the call
       to sigprocmask() returns.

       It  is  not possible to block signals that cannot be caught or ignored (see sigaction(2)). It is also not possible to block or unblock SIG-
       CANCEL, as SIGCANCEL is reserved for the implementation of POSIX thread cancellation (see  pthread_cancel(3C)  and  cancellation(5)).  This
       restriction is silently enforced by the standard C library.

       If sigprocmask() fails, the caller's signal mask is not changed.

       Upon successful completion, 0 is returned. Otherwise, -1 is returned and errno is set to indicate the error.

       The sigprocmask() function will fail if:

       EINVAL	       The value of the how argument is not equal to one of the defined values.

       The sigprocmask() function may fail if:

       EFAULT	       The set or oset argument points to an illegal address.

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Async-Signal-Safe 	   |
       +-----------------------------+-----------------------------+

       sigaction(2), pthread_cancel(3C), pthread_sigmask(3C), signal(3C), signal.h(3HEAD), sigsetops(3C), attributes(5), cancellation(5)

       The call to sigprocmask() affects only the calling thread's signal mask. It is identical to a call to pthread_sigmask(3C).

       Signals that are generated synchronously should not be masked. If such a signal is blocked and delivered, the receiving process is killed.

								    23 Mar 2005 						    sigprocmask(2)