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

     /*      $OpenBSD: msg.h,v 1.20 2022/09/16 15:57:23 mbuhl Exp $  */
     /*      $NetBSD: msg.h,v 1.9 1996/02/09 18:25:18 christos 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 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 */
            unsigned long   msg_cbytes;     /* number of bytes in use on the queue */
            unsigned long   msg_qnum;       /* number of msgs in the queue */
            unsigned 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];
    };
    
    #ifdef _KERNEL
    #include <sys/queue.h>
    
    struct msg {
            long             msg_type;
            size_t           msg_len;
            struct mbuf     *msg_data;
    
            TAILQ_ENTRY(msg)        msg_next;
    };
    
    struct que {
            struct msqid_ds msqid_ds;
            int             que_ix;         /* pseudo-index */
            int             que_flags;
            int             que_references;
    
            TAILQ_ENTRY(que)        que_next;
            TAILQ_HEAD(, msg) que_msgs;
    };
    
    /* for que_flags */
    #define MSGQ_READERS    0x01
    #define MSGQ_WRITERS    0x02
    #define MSGQ_DYING      0x04
    
    #define QREF(q) (q)->que_references++
    
    #define QRELE(q) do {                                                   \
            if (--(q)->que_references == 0 && (q)->que_flags & MSGQ_DYING)  \
                    wakeup_one(&(q)->que_references);                       \
    } while (0)
    #endif
    
    /*
     * 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 */
   };
   #ifdef SYSVMSG
   extern struct msginfo   msginfo;
   #endif
   
   int sysctl_sysvmsg(int *, u_int, void *, size_t *);
   
   struct msg_sysctl_info {
           struct msginfo msginfo;
           struct msqid_ds msgids[1];
   };
   
   #ifndef MSGSSZ
   #define MSGSSZ  8               /* Each segment must be 2^N long */
   #endif
   #ifndef MSGSEG
   #define MSGSEG  2048            /* must be less than 32767 */
   #endif
   #undef MSGMAX                   /* ALWAYS compute MSGMAX! */
   #define MSGMAX  (MSGSSZ*MSGSEG)
   #ifndef MSGMNB
   #define MSGMNB  2048            /* max # of bytes in a queue */
   #endif
   #ifndef MSGMNI
   #define MSGMNI  40
   #endif
   #ifndef MSGTQL
   #define MSGTQL  40
   #endif
   
   /*
    * macros to convert between msqid_ds's and msqid's.
    * XXX unused, going away
    */
   #define MSQID(ix,ds)    ((ix) & 0xffff | (((ds).msg_perm.seq << 16) & 0xffff0000))
   #define MSQID_IX(id)    ((id) & 0xffff)
   #define MSQID_SEQ(id)   (((id) >> 16) & 0xffff)
   #endif
   
   
   #ifndef _KERNEL
   __BEGIN_DECLS
   int msgctl(int, int, struct msqid_ds *);
   int msgget(key_t, int);
   int msgsnd(int, const void *, size_t, int);
   int msgrcv(int, void *, size_t, long, int);
   __END_DECLS
   #else
   struct proc;
   
   void    msginit(void);
   #endif /* !_KERNEL */
   
   #endif /* !_SYS_MSG_H_ */

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