xref: /linux-6.15/include/uapi/linux/mqueue.h (revision 607ca46e)
1*607ca46eSDavid Howells /* Copyright (C) 2003 Krzysztof Benedyczak & Michal Wronski
2*607ca46eSDavid Howells 
3*607ca46eSDavid Howells    This program is free software; you can redistribute it and/or
4*607ca46eSDavid Howells    modify it under the terms of the GNU Lesser General Public
5*607ca46eSDavid Howells    License as published by the Free Software Foundation; either
6*607ca46eSDavid Howells    version 2.1 of the License, or (at your option) any later version.
7*607ca46eSDavid Howells 
8*607ca46eSDavid Howells    It is distributed in the hope that it will be useful,
9*607ca46eSDavid Howells    but WITHOUT ANY WARRANTY; without even the implied warranty of
10*607ca46eSDavid Howells    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11*607ca46eSDavid Howells    Lesser General Public License for more details.
12*607ca46eSDavid Howells 
13*607ca46eSDavid Howells    You should have received a copy of the GNU Lesser General Public
14*607ca46eSDavid Howells    License along with this software; if not, write to the Free
15*607ca46eSDavid Howells    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
16*607ca46eSDavid Howells    02111-1307 USA.  */
17*607ca46eSDavid Howells 
18*607ca46eSDavid Howells #ifndef _LINUX_MQUEUE_H
19*607ca46eSDavid Howells #define _LINUX_MQUEUE_H
20*607ca46eSDavid Howells 
21*607ca46eSDavid Howells #define MQ_PRIO_MAX 	32768
22*607ca46eSDavid Howells /* per-uid limit of kernel memory used by mqueue, in bytes */
23*607ca46eSDavid Howells #define MQ_BYTES_MAX	819200
24*607ca46eSDavid Howells 
25*607ca46eSDavid Howells struct mq_attr {
26*607ca46eSDavid Howells 	long	mq_flags;	/* message queue flags			*/
27*607ca46eSDavid Howells 	long	mq_maxmsg;	/* maximum number of messages		*/
28*607ca46eSDavid Howells 	long	mq_msgsize;	/* maximum message size			*/
29*607ca46eSDavid Howells 	long	mq_curmsgs;	/* number of messages currently queued	*/
30*607ca46eSDavid Howells 	long	__reserved[4];	/* ignored for input, zeroed for output */
31*607ca46eSDavid Howells };
32*607ca46eSDavid Howells 
33*607ca46eSDavid Howells /*
34*607ca46eSDavid Howells  * SIGEV_THREAD implementation:
35*607ca46eSDavid Howells  * SIGEV_THREAD must be implemented in user space. If SIGEV_THREAD is passed
36*607ca46eSDavid Howells  * to mq_notify, then
37*607ca46eSDavid Howells  * - sigev_signo must be the file descriptor of an AF_NETLINK socket. It's not
38*607ca46eSDavid Howells  *   necessary that the socket is bound.
39*607ca46eSDavid Howells  * - sigev_value.sival_ptr must point to a cookie that is NOTIFY_COOKIE_LEN
40*607ca46eSDavid Howells  *   bytes long.
41*607ca46eSDavid Howells  * If the notification is triggered, then the cookie is sent to the netlink
42*607ca46eSDavid Howells  * socket. The last byte of the cookie is replaced with the NOTIFY_?? codes:
43*607ca46eSDavid Howells  * NOTIFY_WOKENUP if the notification got triggered, NOTIFY_REMOVED if it was
44*607ca46eSDavid Howells  * removed, either due to a close() on the message queue fd or due to a
45*607ca46eSDavid Howells  * mq_notify() that removed the notification.
46*607ca46eSDavid Howells  */
47*607ca46eSDavid Howells #define NOTIFY_NONE	0
48*607ca46eSDavid Howells #define NOTIFY_WOKENUP	1
49*607ca46eSDavid Howells #define NOTIFY_REMOVED	2
50*607ca46eSDavid Howells 
51*607ca46eSDavid Howells #define NOTIFY_COOKIE_LEN	32
52*607ca46eSDavid Howells 
53*607ca46eSDavid Howells #endif
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