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

     /*
      * Copyright (c) 1981, 1984, 1993
      *      The Regents of the University of California.  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.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
     *
     *      @(#)msgbuf.h    8.1 (Berkeley) 6/2/93
     * $FreeBSD: releng/5.2/sys/sys/msgbuf.h 116660 2003-06-22 02:18:31Z iedowse $
     */
    
    #ifndef _SYS_MSGBUF_H_
    #define _SYS_MSGBUF_H_
    
    struct msgbuf {
            char    *msg_ptr;               /* pointer to buffer */
    #define MSG_MAGIC       0x063062
            u_int   msg_magic;
            u_int   msg_size;               /* size of buffer area */
            u_int   msg_wseq;               /* write sequence number */
            u_int   msg_rseq;               /* read sequence number */
            u_int   msg_cksum;              /* checksum of contents */
            u_int   msg_seqmod;             /* range for sequence numbers */
    };
    
    /* Normalise a sequence number or a difference between sequence numbers */
    #define MSGBUF_SEQNORM(mbp, seq) (((seq) + (mbp)->msg_seqmod) % \
        (mbp)->msg_seqmod)
    #define MSGBUF_SEQ_TO_POS(mbp, seq) ((seq) % (mbp)->msg_size)
    /* Subtract sequence numbers, but note that only positive values result. */
    #define MSGBUF_SEQSUB(mbp, seq1, seq2) (MSGBUF_SEQNORM((mbp), (seq1) - (seq2)))
    
    #ifdef _KERNEL
    extern int      msgbuftrigger;
    extern struct   msgbuf *msgbufp;
    void    msgbufinit(void *ptr, int size);
    void    msgbuf_addchar(struct msgbuf *mbp, int c);
    void    msgbuf_clear(struct msgbuf *mbp);
    void    msgbuf_copy(struct msgbuf *src, struct msgbuf *dst);
    int     msgbuf_getbytes(struct msgbuf *mbp, char *buf, int buflen);
    int     msgbuf_getchar(struct msgbuf *mbp);
    int     msgbuf_getcount(struct msgbuf *mbp);
    void    msgbuf_init(struct msgbuf *mbp, void *ptr, int size);
    void    msgbuf_reinit(struct msgbuf *mbp, void *ptr, int size);
    int     msgbuf_peekbytes(struct msgbuf *mbp, char *buf, int buflen,
                u_int *seqp);
    
    #if !defined(MSGBUF_SIZE)
    #define MSGBUF_SIZE     32768
    #endif
    
    #endif
    
    #endif

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