FreeBSD/Linux Kernel Cross Reference
sys/sys/mqueue.h

     /*      $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
    
    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_ */
   

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