Linux Kernel  3.7.1
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mqueue.h
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1 /* Copyright (C) 2003 Krzysztof Benedyczak & Michal Wronski
2 
3  This program is free software; you can redistribute it and/or
4  modify it under the terms of the GNU Lesser General Public
5  License as published by the Free Software Foundation; either
6  version 2.1 of the License, or (at your option) any later version.
7 
8  It is distributed in the hope that it will be useful,
9  but WITHOUT ANY WARRANTY; without even the implied warranty of
10  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11  Lesser General Public License for more details.
12 
13  You should have received a copy of the GNU Lesser General Public
14  License along with this software; if not, write to the Free
15  Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
16  02111-1307 USA. */
17 
18 #ifndef _LINUX_MQUEUE_H
19 #define _LINUX_MQUEUE_H
20 
21 #define MQ_PRIO_MAX 32768
22 /* per-uid limit of kernel memory used by mqueue, in bytes */
23 #define MQ_BYTES_MAX 819200
24 
25 struct mq_attr {
26  long mq_flags; /* message queue flags */
27  long mq_maxmsg; /* maximum number of messages */
28  long mq_msgsize; /* maximum message size */
29  long mq_curmsgs; /* number of messages currently queued */
30  long __reserved[4]; /* ignored for input, zeroed for output */
31 };
32 
33 /*
34  * SIGEV_THREAD implementation:
35  * SIGEV_THREAD must be implemented in user space. If SIGEV_THREAD is passed
36  * to mq_notify, then
37  * - sigev_signo must be the file descriptor of an AF_NETLINK socket. It's not
38  * necessary that the socket is bound.
39  * - sigev_value.sival_ptr must point to a cookie that is NOTIFY_COOKIE_LEN
40  * bytes long.
41  * If the notification is triggered, then the cookie is sent to the netlink
42  * socket. The last byte of the cookie is replaced with the NOTIFY_?? codes:
43  * NOTIFY_WOKENUP if the notification got triggered, NOTIFY_REMOVED if it was
44  * removed, either due to a close() on the message queue fd or due to a
45  * mq_notify() that removed the notification.
46  */
47 #define NOTIFY_NONE 0
48 #define NOTIFY_WOKENUP 1
49 #define NOTIFY_REMOVED 2
50 
51 #define NOTIFY_COOKIE_LEN 32
52 
53 #endif