mirror of https://github.com/mkerrisk/man-pages
89 lines
3.1 KiB
Plaintext
89 lines
3.1 KiB
Plaintext
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "MQ_NOTIFY" 3P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" mq_notify
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.SH NAME
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mq_notify \- notify process that a message is available (\fBREALTIME\fP)
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.SH SYNOPSIS
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.LP
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\fB#include <mqueue.h>
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.br
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.sp
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int mq_notify(mqd_t\fP \fImqdes\fP\fB, const struct sigevent *\fP\fInotification\fP\fB);
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\fP
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\fB
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.br
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\fP
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.SH DESCRIPTION
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.LP
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If the argument \fInotification\fP is not NULL, this function shall
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register the calling process to be notified of message
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arrival at an empty message queue associated with the specified message
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queue descriptor, \fImqdes\fP. The notification specified
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by the \fInotification\fP argument shall be sent to the process when
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the message queue transitions from empty to non-empty. At any
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time, only one process may be registered for notification by a message
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queue. If the calling process or any other process has
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already registered for notification of message arrival at the specified
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message queue, subsequent attempts to register for that
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message queue shall fail.
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.LP
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If \fInotification\fP is NULL and the process is currently registered
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for notification by the specified message queue, the
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existing registration shall be removed.
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.LP
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When the notification is sent to the registered process, its registration
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shall be removed. The message queue shall then be
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available for registration.
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.LP
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If a process has registered for notification of message arrival at
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a message queue and some thread is blocked in \fImq_receive\fP() waiting
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to receive a message when a message arrives at the queue, the
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arriving message shall satisfy the appropriate \fImq_receive\fP().
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The resulting
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behavior is as if the message queue remains empty, and no notification
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shall be sent.
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.SH RETURN VALUE
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.LP
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Upon successful completion, the \fImq_notify\fP() function shall return
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a value of zero; otherwise, the function shall return a
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value of -1 and set \fIerrno\fP to indicate the error.
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.SH ERRORS
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.LP
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The \fImq_notify\fP() function shall fail if:
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.TP 7
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.B EBADF
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The \fImqdes\fP argument is not a valid message queue descriptor.
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.TP 7
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.B EBUSY
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A process is already registered for notification by the message queue.
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.sp
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.LP
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\fIThe following sections are informative.\fP
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.SH EXAMPLES
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.LP
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None.
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.SH APPLICATION USAGE
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.LP
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None.
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.SH RATIONALE
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.LP
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None.
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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\fImq_open\fP() , \fImq_send\fP() , \fImq_timedsend\fP() , \fImsgctl\fP()
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, \fImsgget\fP() , \fImsgrcv\fP() , \fImsgsnd\fP() , the
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Base Definitions volume of IEEE\ Std\ 1003.1-2001, \fI<mqueue.h>\fP
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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