include/linux/mqueue.h

   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