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

     /* $FreeBSD: releng/5.0/sys/sys/msg.h 101971 2002-08-16 07:42:18Z alfred $ */
     /*      $NetBSD: msg.h,v 1.4 1994/06/29 06:44:43 cgd Exp $      */
     
     /*
      * SVID compatible msg.h file
      *
      * Author:  Daniel Boulet
      *
      * Copyright 1993 Daniel Boulet and RTMX Inc.
     *
     * This system call was implemented by Daniel Boulet under contract from RTMX.
     *
     * Redistribution and use in source forms, with and without modification,
     * are permitted provided that this entire comment appears intact.
     *
     * Redistribution in binary form may occur without any restrictions.
     * Obviously, it would be nice if you gave credit where credit is due
     * but requiring it would be too onerous.
     *
     * This software is provided ``AS IS'' without any warranties of any kind.
     */
    
    #ifndef _SYS_MSG_H_
    #define _SYS_MSG_H_
    
    #include <sys/ipc.h>
    
    /*
     * The MSG_NOERROR identifier value, the msqid_ds struct and the msg struct
     * are as defined by the SV API Intel 386 Processor Supplement.
     */
    
    #define MSG_NOERROR     010000          /* don't complain about too long msgs */
    
    struct msg;
    
    struct msqid_ds {
            struct  ipc_perm msg_perm;      /* msg queue permission bits */
            struct  msg *msg_first; /* first message in the queue */
            struct  msg *msg_last;  /* last message in the queue */
            u_long  msg_cbytes;     /* number of bytes in use on the queue */
            u_long  msg_qnum;       /* number of msgs in the queue */
            u_long  msg_qbytes;     /* max # of bytes on the queue */
            pid_t   msg_lspid;      /* pid of last msgsnd() */
            pid_t   msg_lrpid;      /* pid of last msgrcv() */
            time_t  msg_stime;      /* time of last msgsnd() */
            long    msg_pad1;
            time_t  msg_rtime;      /* time of last msgrcv() */
            long    msg_pad2;
            time_t  msg_ctime;      /* time of last msgctl() */
            long    msg_pad3;
            long    msg_pad4[4];
    };
    
    /*
     * Structure describing a message.  The SVID doesn't suggest any
     * particular name for this structure.  There is a reference in the
     * msgop man page that reads "The structure mymsg is an example of what
     * this user defined buffer might look like, and includes the following
     * members:".  This sentence is followed by two lines equivalent
     * to the mtype and mtext field declarations below.  It isn't clear
     * if "mymsg" refers to the name of the structure type or the name of an
     * instance of the structure...
     */
    struct mymsg {
            long    mtype;          /* message type (+ve integer) */
            char    mtext[1];       /* message body */
    };
    
    #ifdef _KERNEL
    
    /*
     * Based on the configuration parameters described in an SVR2 (yes, two)
     * config(1m) man page.
     *
     * Each message is broken up and stored in segments that are msgssz bytes
     * long.  For efficiency reasons, this should be a power of two.  Also,
     * it doesn't make sense if it is less than 8 or greater than about 256.
     * Consequently, msginit in kern/sysv_msg.c checks that msgssz is a power of
     * two between 8 and 1024 inclusive (and panic's if it isn't).
     */
    struct msginfo {
            int     msgmax,         /* max chars in a message */
                    msgmni,         /* max message queue identifiers */
                    msgmnb,         /* max chars in a queue */
                    msgtql,         /* max messages in system */
                    msgssz,         /* size of a message segment (see notes above) */
                    msgseg;         /* number of message segments */
    };
    extern struct msginfo   msginfo;
    #endif
    
    #ifndef _KERNEL
    
    #include <sys/cdefs.h>
    
    __BEGIN_DECLS
    int msgsys(int, ...);
    int msgctl(int, int, struct msqid_ds *);
   int msgget(key_t, int);
   int msgsnd(int, void *, size_t, int);
   int msgrcv(int, void*, size_t, long, int);
   __END_DECLS
   #endif
   
   #endif /* !_SYS_MSG_H_ */

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