/*      $NetBSD: mqueue.h,v 1.7 2009/04/11 15:47:34 christos Exp $      */

/*
 * Copyright (c) 2007, Mindaugas Rasiukevicius <rmind at NetBSD 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, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, 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 AUTHOR AND CONTRIBUTORS ``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 AUTHOR OR CONTRIBUTORS 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.
 */

#ifndef _SYS_MQUEUE_H_
#define _SYS_MQUEUE_H_

/* Maximal number of mqueue descriptors, that process could open */
#define MQ_OPEN_MAX             512

/* Maximal priority of the message */
#define MQ_PRIO_MAX             32

typedef int             mqd_t;          /* message queue descriptor */

struct mq_attr {
        long    mq_flags;       /* Flags of message queue */
        long    mq_maxmsg;      /* Maximum number of messages */
        long    mq_msgsize;     /* Maximum size of the message */
        long    mq_curmsgs;     /* Count of the queued messages */
};

/* Internal kernel data */
#if defined(_KERNEL) || defined(_KERNEL_STRUCTURES)

#include <sys/types.h>
#include <sys/lock.h>
#include <sys/queue.h>
#include <sys/event.h>
#include <sys/signal.h>

/*
 * Flags below are used in mq_flags for internal
 * purposes, this is appropriate according to POSIX.
 */

/* Message queue is unlinking */
#define MQ_UNLINK               0x10000000
/* There are receive-waiters */
#define MQ_RECEIVE              0x20000000

/* Maximal length of mqueue name */
#define MQ_NAMELEN              (NAME_MAX + 1)

/* Default size of the message */
#define MQ_DEF_MSGSIZE          1024

/* Size/bits and index of reserved queue */
#define MQ_PQSIZE               32
#define MQ_PQRESQ               0

/* Structure of the message queue */
struct mqueue {
        char                    mq_name[MQ_NAMELEN];
        struct lock             mq_mtx;
        int                     mq_send_cv;     /* Condition variables for tsleep() */
        int                     mq_recv_cv;
        struct mq_attr          mq_attrib;
        /* Notification */
        struct kqinfo           mq_rkq;
        struct kqinfo           mq_wkq;
        struct sigevent         mq_sig_notify;
        struct proc *           mq_notify_proc;
        /* Permissions */
        mode_t                  mq_mode;
        uid_t                   mq_euid;
        gid_t                   mq_egid;
        /*
         * Reference counter, heads of the message queue
         *
         * Every message queue has `MQ_PQSIZE' priority queues that guarantee
         * constant-time insertion of messages. If `mq_prio_max' is increased
         * via sysctl, then the reserved queue (MQ_PQRESQ) is used which
         * performs linear insertion.
         */
        u_int                   mq_refcnt;
        TAILQ_HEAD(, mq_msg)    mq_head[1 + MQ_PQSIZE];
        uint32_t                mq_bitmap;
        /* Entry of the global list */
        LIST_ENTRY(mqueue)      mq_list;
        struct timespec         mq_atime;
        struct timespec         mq_mtime;
        struct timespec         mq_btime;
};

/* Structure of the message */
struct mq_msg {
        TAILQ_ENTRY(mq_msg)     msg_queue;
        size_t                  msg_len;
        u_int                   msg_prio;
        int8_t                  msg_ptr[1];
};

/* Prototypes */
void    mqueue_sysinit(void);
int     abstimeout2timo(struct timespec *, int *);
int     mq_send1(struct lwp *, mqd_t, const char *, size_t, unsigned, struct timespec *);
int     mq_receive1(struct lwp *, mqd_t, void *, size_t, unsigned *, struct timespec *,
    ssize_t *);

#endif  /* _KERNEL || _KERNEL_STRUCTURES */

#endif  /* _SYS_MQUEUE_H_ */