uapi/linux/mqueue.h

0001 /* SPDX-License-Identifier: LGPL-2.1+ WITH Linux-syscall-note */
0002 /* Copyright (C) 2003 Krzysztof Benedyczak & Michal Wronski
0003
0004    This program is free software; you can redistribute it and/or
0005    modify it under the terms of the GNU Lesser General Public
0006    License as published by the Free Software Foundation; either
0007    version 2.1 of the License, or (at your option) any later version.
0008
0009    It is distributed in the hope that it will be useful,
0010    but WITHOUT ANY WARRANTY; without even the implied warranty of
0011    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
0012    Lesser General Public License for more details.
0013
0014    You should have received a copy of the GNU Lesser General Public
0015    License along with this software; if not, write to the Free
0016    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
0017    02111-1307 USA.  */
0018
0019 #ifndef _LINUX_MQUEUE_H
0020 #define _LINUX_MQUEUE_H
0021
0022 #include <linux/types.h>
0023
0024 #define MQ_PRIO_MAX     32768
0025 /* per-uid limit of kernel memory used by mqueue, in bytes */
0026 #define MQ_BYTES_MAX    819200
0027
0028 struct mq_attr {
0029     __kernel_long_t mq_flags;   /* message queue flags          */
0030     __kernel_long_t mq_maxmsg;  /* maximum number of messages       */
0031     __kernel_long_t mq_msgsize; /* maximum message size         */
0032     __kernel_long_t mq_curmsgs; /* number of messages currently queued  */
0033     __kernel_long_t __reserved[4];  /* ignored for input, zeroed for output */
0034 };
0035
0036 /*
0037  * SIGEV_THREAD implementation:
0038  * SIGEV_THREAD must be implemented in user space. If SIGEV_THREAD is passed
0039  * to mq_notify, then
0040  * - sigev_signo must be the file descriptor of an AF_NETLINK socket. It's not
0041  *   necessary that the socket is bound.
0042  * - sigev_value.sival_ptr must point to a cookie that is NOTIFY_COOKIE_LEN
0043  *   bytes long.
0044  * If the notification is triggered, then the cookie is sent to the netlink
0045  * socket. The last byte of the cookie is replaced with the NOTIFY_?? codes:
0046  * NOTIFY_WOKENUP if the notification got triggered, NOTIFY_REMOVED if it was
0047  * removed, either due to a close() on the message queue fd or due to a
0048  * mq_notify() that removed the notification.
0049  */
0050 #define NOTIFY_NONE 0
0051 #define NOTIFY_WOKENUP  1
0052 #define NOTIFY_REMOVED  2
0053
0054 #define NOTIFY_COOKIE_LEN   32
0055
0056 #endif