sigevent(3type) - Linux manual page (original) (raw)

sigevent(3type) sigevent(3type)

NAME top

   sigevent, sigval - structure for notification from asynchronous
   routines

SYNOPSIS top

   **#include <signal.h>**

   **struct sigevent {**
       **int             sigev_notify;** /* Notification type */
       **int             sigev_signo;** /* Signal number */
       **union sigval    sigev_value;** /* Data passed with notification */

       **typeof(void (union sigval))  *sigev_notify_function;**
                                      /* Notification function
                                         (SIGEV_THREAD) */
       **pthread_attr_t *sigev_notify_attributes;**
                                      /* Notification attributes */

       /* Linux only: */
       **pid_t           sigev_notify_thread_id;**
                                      /* ID of thread to signal
                                         (SIGEV_THREAD_ID) */
   **};**

   **union sigval {** /* Data passed with notification */
       **int             sival_int;** /* Integer value */
       **void           *sival_ptr;** /* Pointer value */
   **};**

DESCRIPTION top

sigevent The sigevent structure is used by various APIs to describe the way a process is to be notified about an event (e.g., completion of an asynchronous request, expiration of a timer, or the arrival of a message).

   The definition shown in the SYNOPSIS is approximate: some of the
   fields in the _sigevent_ structure may be defined as part of a
   union.  Programs should employ only those fields relevant to the
   value specified in _sigevnotify_.

   The _sigevnotify_ field specifies how notification is to be
   performed.  This field can have one of the following values:

   **SIGEV_NONE**
          A "null" notification: don't do anything when the event
          occurs.

   **SIGEV_SIGNAL**
          Notify the process by sending the signal specified in
          _sigevsigno_.

          If the signal is caught with a signal handler that was
          registered using the [sigaction(2)](../man2/sigaction.2.html) **SA_SIGINFO** flag, then the
          following fields are set in the _siginfot_ structure that is
          passed as the second argument of the handler:

          _sicode_
                 This field is set to a value that depends on the API
                 delivering the notification.

          _sisigno_
                 This field is set to the signal number (i.e., the
                 same value as in _sigevsigno_).

          _sivalue_
                 This field is set to the value specified in
                 _sigevvalue_.

          Depending on the API, other fields may also be set in the
          _siginfot_ structure.

          The same information is also available if the signal is
          accepted using [sigwaitinfo(2)](../man2/sigwaitinfo.2.html).

   **SIGEV_THREAD**
          Notify the process by invoking _sigevnotifyfunction_ "as
          if" it were the start function of a new thread.  (Among the
          implementation possibilities here are that each timer
          notification could result in the creation of a new thread,
          or that a single thread is created to receive all
          notifications.)  The function is invoked with _sigevvalue_
          as its sole argument.  If _sigevnotifyattributes_ is not
          NULL, it should point to a _pthreadattrt_ structure that
          defines attributes for the new thread (see
          [pthread_attr_init(3)](../man3/pthread%5Fattr%5Finit.3.html)).

   **SIGEV_THREAD_ID** (Linux-specific)
          Currently used only by POSIX timers; see [timer_create(2)](../man2/timer%5Fcreate.2.html).

sigval Data passed with a signal.

STANDARDS top

   POSIX.1-2008.

HISTORY top

   POSIX.1-2001.

   _<aio.h>_ and _<time.h>_ define _sigevent_ since POSIX.1-2008.

NOTES top

   The following headers also provide _sigevent_: _<aio.h>_, _<mqueue.h>_,
   and _<time.h>_.

SEE ALSO top

   [timer_create(2)](../man2/timer%5Fcreate.2.html), [getaddrinfo_a(3)](../man3/getaddrinfo%5Fa.3.html), [lio_listio(3)](../man3/lio%5Flistio.3.html), [mq_notify(3)](../man3/mq%5Fnotify.3.html),
   [pthread_sigqueue(3)](../man3/pthread%5Fsigqueue.3.html), [sigqueue(3)](../man3/sigqueue.3.html), [aiocb(3type)](../man3/aiocb.3type.html), [siginfo_t(3type)](../man3/siginfo%5Ft.3type.html)

COLOPHON top

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Linux man-pages 6.10 2024-12-13 sigevent(3type)

Pages that refer to this page:timer_create(2), aio_cancel(3), aio_fsync(3), aio_read(3), aio_write(3), getaddrinfo_a(3), lio_listio(3), mq_notify(3), aio(7), pthreads(7), signal(7)