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sigprocmask(2) [freebsd man page]

SIGPROCMASK(2)						      BSD System Calls Manual						    SIGPROCMASK(2)

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() system call 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 how argument. 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. In threaded applications, pthread_sigmask(3) must be used instead of sigprocmask(). 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() system call will fail and the signal mask will be unchanged if one of the following occurs: [EINVAL] The how argument has a value other than those listed here. SEE ALSO
kill(2), sigaction(2), sigpending(2), sigsuspend(2), fpsetmask(3), pthread_sigmask(3), sigsetops(3) STANDARDS
The sigprocmask() system call is expected to conform to ISO/IEC 9945-1:1990 (``POSIX.1''). BSD
May 7, 2010 BSD

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sigprocmask(2)							   System Calls 						    sigprocmask(2)

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); DESCRIPTION
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. RETURN VALUES
Upon successful completion, 0 is returned. Otherwise, -1 is returned and errno is set to indicate the error. ERRORS
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. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |Async-Signal-Safe | +-----------------------------+-----------------------------+ SEE ALSO
sigaction(2), pthread_cancel(3C), pthread_sigmask(3C), signal(3C), signal.h(3HEAD), sigsetops(3C), attributes(5), cancellation(5) NOTES
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. SunOS 5.11 23 Mar 2005 sigprocmask(2)
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