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Интерактивная система просмотра системных руководств (man-ов)

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sigwait (2)
  • >> sigwait (2) ( Solaris man: Системные вызовы )
  • sigwait (2) ( FreeBSD man: Системные вызовы )
  • sigwait (3) ( Linux man: Библиотечные вызовы )
  • sigwait (3) ( POSIX man: Библиотечные вызовы )
  •  

    NAME

    sigwait - wait until a signal is
    posted
     
    

    SYNOPSIS

    #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);
    

     

    DESCRIPTION

    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 signals 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 synchronously 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.  

    RETURN VALUES

    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 location pointed to by sig. Otherwise, -1 is returned and errno is set to indicate an error.  

    ERRORS

    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.

     

    EXAMPLES

    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 *
    main(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("##################\n");
       printf("press CTRL-C to deliver SIGINT to sigint thread\n");
       printf("##################\n");
       
       pthread_exit((void *)0);
    }
    static void *
    threadTwo(void *arg)
    {
       printf("hello world, from threadTwo [tid: %d]\n",
                               pthread_self());
       printf("threadTwo [tid: %d] is now complete and exiting\n",
                               pthread_self());
       pthread_exit((void *)0);
    }
    
    static void *
    threadThree(void *arg)
    {
       printf("hello world, from threadThree [tid: %d]\n",
                               pthread_self());
       printf("threadThree [tid: %d] is now complete and exiting\n",
                               pthread_self());
       pthread_exit((void *)0);
    }
    
    void *
    sigint(void *arg)
    {
       int    sig;
       int    err;
       
       printf("thread sigint [tid: %d] awaiting SIGINT\n",
                               pthread_self());
       
       /*
       /* use standard-conforming sigwait() -- 2 args: signal set, signum
        */
       err = sigwait ( &signalSet, &sig );
       
       /* test for SIGINT; could catch other signals */
       if (err || sig != SIGINT)
           abort();
       
       printf("\nSIGINT signal %d caught by sigint thread [tid: %d]\n",
                               sig, pthread_self());
       pthread_exit((void *)0);
    }
    

     

    ATTRIBUTES

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

    ATTRIBUTE TYPEATTRIBUTE VALUE

    Interface StabilityStandard

    MT-Level

     

    SEE ALSO

    sigaction(2), signal.h(3HEAD), sigpending(2), sigprocmask(2), sigsuspend(2), pthread_create(3C), pthread_sigmask(3C), thr_create(3C), thr_sigsetmask(3C), attributes(5), standards(5)  

    NOTES

    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 interface.


     

    Index

    NAME
    SYNOPSIS
    Standard conforming
    DESCRIPTION
    RETURN VALUES
    ERRORS
    EXAMPLES
    ATTRIBUTES
    SEE ALSO
    NOTES


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