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author | davidxu <davidxu@FreeBSD.org> | 2005-11-30 04:12:37 +0000 |
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committer | davidxu <davidxu@FreeBSD.org> | 2005-11-30 04:12:37 +0000 |
commit | da7f33853459e213d6c82d736324b88e2d5f0e5a (patch) | |
tree | ae6875a0f56c5bb79497f1eb2ebd3c79bad06423 /lib/libc/sys/mq_notify.2 | |
parent | 1ecc8e42ea795ea1c6eed93d1135654efb7f9f4e (diff) | |
download | FreeBSD-src-da7f33853459e213d6c82d736324b88e2d5f0e5a.zip FreeBSD-src-da7f33853459e213d6c82d736324b88e2d5f0e5a.tar.gz |
Add manuals for POSIX message queue.
Diffstat (limited to 'lib/libc/sys/mq_notify.2')
-rw-r--r-- | lib/libc/sys/mq_notify.2 | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/lib/libc/sys/mq_notify.2 b/lib/libc/sys/mq_notify.2 new file mode 100644 index 0000000..3046618 --- /dev/null +++ b/lib/libc/sys/mq_notify.2 @@ -0,0 +1,103 @@ +.\" Copyright (c) 2005 David Xu <davidxu@FreeBSD.org> +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice(s), this list of conditions and the following disclaimer as +.\" the first lines of this file unmodified other than the possible +.\" addition of one or more copyright notices. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice(s), this list of conditions and the following disclaimer in +.\" the documentation and/or other materials provided with the +.\" distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY +.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR +.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE +.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR +.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF +.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR +.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, +.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE +.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, +.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +.\" +.\" $FreeBSD$ +.\" +.Dd November 29, 2005 +.Dt MQ_NOTIFY 2 +.Os +.Sh NAME +.Nm mq_notify +.Nd "notify process that a message is available (REALTIME)" +.Sh LIBRARY +.Lb libc +.Sh SYNOPSIS +.In mqueue.h +.Ft int +.Fn mq_notify "mqd_t mqdes" "const struct sigevent *notification" +.Sh DESCRIPTION +If the argument notification is not +.Dv NULL , +this syscall will register the calling process to be notified of message +arrival at an empty message queue associated with the specified message +queue descriptor, +.Fa mqdes. +The notification specified by the notification argument will be sent to +the process when the message queue transitions from empty to non-empty. +At any time, only one process may be registered for notification by a +message queue. If the calling process or any other process has already +registered for notification of message arrival at the specified message +queue, subsequent attempts to register for that message queue will fail. +.Pp +If notification is +.Dv NULL +and the process is currently registered for notification by the specified +message queue, the existing registration will be removed. +.Pp +When the notification is sent to the registered process, its registration +is removed. The message queue then is available for registration. +.Pp +If a process has registered for notification of message arrival at a +message queue and some thread is blocked in +.Fn mq_receive +waiting to receive a message when a message arrives at the queue, the +arriving message will satisfy the appropriate +.Fn mq_receive . +The resulting behavior is as if the message queue remains empty, and no +notification will be sent. +.Sh RETURN VALUES +Upon successful completion, the +.Fn mq_notify +syscall returns a value of zero; otherwise, the function returns a value +of -1 and set +.Va errno +to indicate the error. +.Sh ERRORS +The +.Fn mq_notify +syscall call +will fail if: +.Bl -tag -width Er +.It Bq Er EBADF +The +.Fa mqdes +argument is not a valid message queue descriptor. +.It Bq Er EBUSY +process is already registered for notification by the message queue. +.El +.Sh SEE ALSO +.Xr mq_open 2 , +.Xr mq_send 2 , +.Xr mq_timedsend 2 +.Sh STANDARDS +The +.Fn mq_notify +system call conform to +.St -p1003.1-2004 . +.Sh HISTORY +Support for POSIX message queue first appeared in +.Fx 7.0 . |