SIGSUSPEND(P)						     POSIX Programmer's Manual						     SIGSUSPEND(P)

NAME

       sigsuspend - wait for a signal

SYNOPSIS

       #include <signal.h>

       int sigsuspend(const sigset_t *sigmask);

DESCRIPTION

       The  sigsuspend()  function  shall  replace the current signal mask of the calling thread with the set of signals pointed to by sigmask and
       then suspend the thread until delivery of a signal whose action is either to  execute  a  signal-catching  function  or	to  terminate  the
       process. This shall not cause any other signals that may have been pending on the process to become pending on the thread.

       If  the	action	is  to terminate the process then sigsuspend() shall never return. If the action is to execute a signal-catching function,
       then sigsuspend() shall return after the signal-catching function returns, with the signal mask restored to the set that existed  prior	to
       the sigsuspend() call.

       It is not possible to block signals that cannot be ignored. This is enforced by the system without causing an error to be indicated.

RETURN VALUE

       Since  sigsuspend() suspends thread execution indefinitely, there is no successful completion return value. If a return occurs, -1 shall be
       returned and errno set to indicate the error.

ERRORS

       The sigsuspend() function shall fail if:

       EINTR  A signal is caught by the calling process and control is returned from the signal-catching function.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       Normally, at the beginning of a critical code section, a specified set of signals is blocked using the sigprocmask()  function.	 When  the
       thread  has  completed  the critical section and needs to wait for the previously blocked signal(s), it pauses by calling sigsuspend() with
       the mask that was returned by the sigprocmask() call.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       Signal Concepts , pause() , sigaction() , sigaddset() , sigdelset() , sigemptyset()  ,  sigfillset()  ,	the  Base  Definitions	volume	of
       IEEE Std 1003.1-2001, <signal.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical  and	Electronics  Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE
       and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can  be  obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003							     SIGSUSPEND(P)