OSF

NAME

sigsuspend − Atomically changes the set of blocked signals and waits for a signal

LIBRARY

Standard C Library (libc.a)

SYNOPSIS

#include <signal.h> int sigsuspend (
sigset_t ∗signal_mask );

PARAMETERS

signal_maskPoints to a set of signals. 

DESCRIPTION

The sigsuspend() function replaces the signal mask of the process with the set of signals pointed to by the signal_mask parameter, and then suspends execution of the process until delivery of a signal whose action is either to execute a signal-catching function or to terminate the process.  The sigsuspend() function does not allow the SIGKILL or SIGSTOP signals to be blocked.  If a program attempts to block one of these signals, the sigsuspend() function gives no indication of the error. 

If delivery of a signal causes the process to terminate, the sigsuspend() function does not return. If delivery of a signal causes a signal-catching function to execute, the sigsuspend() function returns after the signal-catching function returns, with the signal mask restored to the set that existed prior to the call to the sigsuspend() function. 

The sigsuspend() function sets the signal mask and waits for an unblocked signal as one atomic operation. This means that signals cannot occur between the operations of setting the mask and waiting for a signal.  If a program invokes sigprocmask(SIG_SETMASK) and sigpause() separately, a signal that occurs between these functions might not be noticed by sigpause(). 

In normal usage, a signal is blocked by using the sigprocmask(SIG_BLOCK,...) function at the beginning of a critical section. The process then determines whether there is work for it to do. If no work is to be done, the process waits for work by calling the sigsuspend() function with the mask previously returned by the sigprocmask() function. 

NOTES

The sigpause() function is provided for compatibility with older UNIX systems; its function is a subset of the sigsuspend() function. 

AES Support Level:
Full use

RETURN VALUES

If a signal is caught by the calling process and control is returned from the signal handler, the calling process resumes execution after the sigsuspend() function, which always return a value of -1 and sets errno to [EINTR].

RELATED INFORMATION

Functions: pause(3), sigaction(2), sigblock(2), sigprocmask(2), sigvec(2)