204 lines
5.4 KiB
HTML
204 lines
5.4 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of SIGEVENT</TITLE>
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</HEAD><BODY>
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<H1>SIGEVENT</H1>
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Section: Linux Programmer's Manual (7)<BR>Updated: 2017-07-13<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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sigevent - structure for notification from asynchronous routines
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<PRE>
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#include <<A HREF="file:///usr/include/signal.h">signal.h</A>>
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union sigval { /* Data passed with notification */
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int sival_int; /* Integer value */
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void *sival_ptr; /* Pointer value */
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};
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struct sigevent {
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int sigev_notify; /* Notification method */
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int sigev_signo; /* Notification signal */
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union sigval sigev_value; /* Data passed with
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notification */
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void (*sigev_notify_function) (union sigval);
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/* Function used for thread
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notification (SIGEV_THREAD) */
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void *sigev_notify_attributes;
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/* Attributes for notification thread
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(SIGEV_THREAD) */
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pid_t sigev_notify_thread_id;
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/* ID of thread to signal (SIGEV_THREAD_ID) */
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};
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</PRE>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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<P>
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The
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<I>sigevent</I>
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structure is used by various APIs
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to describe the way a process is to be notified about an event
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(e.g., completion of an asynchronous request, expiration of a timer,
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or the arrival of a message).
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<P>
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The definition shown in the SYNOPSIS is approximate:
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some of the fields in the
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<I>sigevent</I>
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structure may be defined as part of a union.
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Programs should employ only those fields relevant
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to the value specified in
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<I>sigev_notify</I>.
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<P>
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The
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<I>sigev_notify</I>
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field specifies how notification is to be performed.
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This field can have one of the following values:
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<DL COMPACT>
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<DT id="1"><B>SIGEV_NONE</B>
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<DD>
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A "null" notification: don't do anything when the event occurs.
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<DT id="2"><B>SIGEV_SIGNAL</B>
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<DD>
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Notify the process by sending the signal specified in
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<I>sigev_signo</I>.
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<DT id="3"><DD>
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If the signal is caught with a signal handler that was registered using the
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<B><A HREF="/cgi-bin/man/man2html?2+sigaction">sigaction</A></B>(2)
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<B>SA_SIGINFO</B>
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flag, then the following fields are set in the
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<I>siginfo_t</I>
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structure that is passed as the second argument of the handler:
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<DL COMPACT><DT id="4"><DD>
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<DL COMPACT>
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<DT id="5"><I>si_code</I>
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<DD>
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This field is set to a value that depends on the API
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delivering the notification.
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<DT id="6"><I>si_signo</I>
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<DD>
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This field is set to the signal number (i.e., the same value as in
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<I>sigev_signo</I>).
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<DT id="7"><I>si_value</I>
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<DD>
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This field is set to the value specified in
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<I>sigev_value</I>.
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</DL>
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</DL>
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<DT id="8"><DD>
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Depending on the API, other fields may also be set in the
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<I>siginfo_t</I>
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structure.
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<DT id="9"><DD>
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The same information is also available if the signal is accepted using
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<B><A HREF="/cgi-bin/man/man2html?2+sigwaitinfo">sigwaitinfo</A></B>(2).
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<DT id="10"><B>SIGEV_THREAD</B>
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<DD>
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Notify the process by invoking
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<I>sigev_notify_function</I>
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"as if" it were the start function of a new thread.
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(Among the implementation possibilities here are that
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each timer notification could result in the creation of a new thread,
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or that a single thread is created to receive all notifications.)
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The function is invoked with
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<I>sigev_value</I>
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as its sole argument.
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If
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<I>sigev_notify_attributes</I>
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is not NULL, it should point to a
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<I>pthread_attr_t</I>
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structure that defines attributes for the new thread (see
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<B><A HREF="/cgi-bin/man/man2html?3+pthread_attr_init">pthread_attr_init</A></B>(3)).
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<DT id="11"><B>SIGEV_THREAD_ID</B> (Linux-specific)
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<DD>
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Currently used only by POSIX timers; see
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<B><A HREF="/cgi-bin/man/man2html?2+timer_create">timer_create</A></B>(2).
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</DL>
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<A NAME="lbAE"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?2+timer_create">timer_create</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?3+aio_fsync">aio_fsync</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+aio_read">aio_read</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+aio_write">aio_write</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+getaddrinfo_a">getaddrinfo_a</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+lio_listio">lio_listio</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+mq_notify">mq_notify</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?7+aio">aio</A></B>(7),
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<B><A HREF="/cgi-bin/man/man2html?7+pthreads">pthreads</A></B>(7)
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<A NAME="lbAF"> </A>
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<H2>COLOPHON</H2>
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This page is part of release 5.05 of the Linux
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<I>man-pages</I>
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="12"><A HREF="#lbAB">NAME</A><DD>
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<DT id="13"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="14"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="15"><A HREF="#lbAE">SEE ALSO</A><DD>
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<DT id="16"><A HREF="#lbAF">COLOPHON</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:06:09 GMT, March 31, 2021
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</BODY>
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</HTML>
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