Unix/Linux Go Back    

OpenSolaris 2009.06 - man page for sigwait (opensolaris section 2)

Linux & Unix Commands - Search Man Pages
Man Page or Keyword Search:   man
Select Man Page Set:       apropos Keyword Search (sections above)

sigwait(2)				   System Calls 			       sigwait(2)

       sigwait - wait until a signal is posted

       #include <signal.h>

       int sigwait(sigset_t *set);

   Standard conforming
       cc [ flag ... ] file ... -D_POSIX_PTHREAD_SEMANTICS [ library...]
       #include <signal.h>

       int sigwait(const sigset_t *set, int *sig);

       The  sigwait() function selects a signal in set that is pending on the calling thread (see
       thr_create(3C) and pthread_create(3C).) If no signal in set is pending,	sigwait()  blocks
       until a signal in set becomes pending. The selected signal is cleared from the set of sig-
       nals pending on the calling thread and the number of the signal is  returned,  or  in  the
       standard-conforming version (see standards(5)) placed in sig. The selection of a signal in
       set is independent of the signal mask of the calling thread. This means a thread can  syn-
       chronously  wait  for  signals  that  are  being blocked by the signal mask of the calling
       thread . To ensure that only the caller receives the signals defined in set,  all  threads
       should have signals in set masked including the calling thread. If the set argument points
       to an invalid address, the behavior is undefined and errno may be set to EFAULT.

       If sigwait() is called on an ignored signal, then the occurrence of  the  signal  will  be
       ignored, unless sigaction() changes the disposition. If more than one thread waits for the
       same signal, only one is unblocked when the signal arrives.

       Upon successful completion, the default version of sigwait() returns a signal number;  the
       standard-conforming  version  returns 0 and stores the received signal number at the loca-
       tion pointed to by sig. Otherwise, -1 is returned and errno is set to indicate an error.

       The sigwait() function will fail if:

       EINTR	 The wait was interrupted by an unblocked, caught signal.

       EINVAL	 The set argument contains an unsupported signal number.

       The sigwait() function may fail if:

       EFAULT	 The set argument points to an invalid address.

       Example 1 Creating a thread to handle receipt of a signal

       The following sample C code creates a thread to handle  the  receipt  of  a  signal.  More
       specifically, it catches the asynchronously generated signal, SIGINT.

	 * compile with -D_POSIX_PTHREAD_SEMANTICS switch;
	 * required by sigwait()
	 * sigint thread handles delivery of signal. uses sigwait() to wait
	 * for SIGINT signal.
	 #include <pthread.h>
	 #include <stdlib.h>
	 #include <stdio.h>
	 #include <string.h>
	 #include <unistd.h>
	 #include <signal.h>
	 #include <synch.h>

	 static void	*threadTwo(void *);
	 static void	*threadThree(void *);
	 static void	*sigint(void *);

	 sigset_t	signalSet;

	 void *
	     pthread_t	  t;
	     pthread_t	  t2;
	     pthread_t	  t3;

	     sigfillset ( &signalSet );
	      * Block signals in initial thread. New threads will
	      * inherit this signal mask.
	     pthread_sigmask ( SIG_BLOCK, &signalSet, NULL );

	     printf("Creating threads\n");

	     pthread_create(&t, NULL, sigint, NULL);
	     pthread_create(&t2, NULL, threadTwo, NULL);
	     pthread_create(&t3, NULL, threadThree, NULL);

	     printf("press CTRL-C to deliver SIGINT to sigint thread\n");

	     pthread_exit((void *)0);
	 static void *
	 threadTwo(void *arg)
	     printf("hello world, from threadTwo [tid: %d]\n",
	     printf("threadTwo [tid: %d] is now complete and exiting\n",
	     pthread_exit((void *)0);

	 static void *
	 threadThree(void *arg)
	     printf("hello world, from threadThree [tid: %d]\n",
	     printf("threadThree [tid: %d] is now complete and exiting\n",
	     pthread_exit((void *)0);

	 void *
	 sigint(void *arg)
	     int    sig;
	     int    err;

	     printf("thread sigint [tid: %d] awaiting SIGINT\n",

	     /* use standard-conforming sigwait() -- 2 args: signal set, signum
	     err = sigwait ( &signalSet, &sig );

	     /* test for SIGINT; could catch other signals */
	     if (err || sig != SIGINT)

	     printf("\nSIGINT signal %d caught by sigint thread [tid: %d]\n",
				     sig, pthread_self());
	     pthread_exit((void *)0);

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

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

       sigaction(2),  signal.h(3HEAD), sigpending(2), sigprocmask(2), sigsuspend(2), pthread_cre-
       ate(3C), pthread_sigmask(3C),  thr_create(3C),  thr_sigsetmask(3C),  attributes(5),  stan-

       The  sigwait()  function  cannot  be  used  to wait for signals that cannot be caught (see
       sigaction(2)). This restriction is silently imposed by the system.

       Solaris 2.4 and earlier releases provided a sigwait() facility as  specified  in  POSIX.1c
       Draft 6. The final POSIX.1c standard changed the interface as described above. Support for
       the Draft 6 interface is provided for compatibility only  and  may  not	be  supported  in
       future  releases. New applications and libraries should use the standard-conforming inter-

SunOS 5.11				   24 Jun 2002				       sigwait(2)
Unix & Linux Commands & Man Pages : ©2000 - 2018 Unix and Linux Forums

All times are GMT -4. The time now is 03:50 PM.