The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*      $OpenBSD: msg.h,v 1.20 2022/09/16 15:57:23 mbuhl Exp $  */
    2 /*      $NetBSD: msg.h,v 1.9 1996/02/09 18:25:18 christos Exp $ */
    3 
    4 /*
    5  * SVID compatible msg.h file
    6  *
    7  * Author:  Daniel Boulet
    8  *
    9  * Copyright 1993 Daniel Boulet and RTMX Inc.
   10  *
   11  * This system call was implemented by Daniel Boulet under contract from RTMX.
   12  *
   13  * Redistribution and use in source forms, with and without modification,
   14  * are permitted provided that this entire comment appears intact.
   15  *
   16  * Redistribution in binary form may occur without any restrictions.
   17  * Obviously, it would be nice if you gave credit where credit is due
   18  * but requiring it would be too onerous.
   19  *
   20  * This software is provided ``AS IS'' without any warranties of any kind.
   21  */
   22 
   23 #ifndef _SYS_MSG_H_
   24 #define _SYS_MSG_H_
   25 
   26 #include <sys/ipc.h>
   27 
   28 /*
   29  * The MSG_NOERROR identifier value, the msqid_ds struct and the msg struct
   30  * are as defined by the SV API Intel 386 Processor Supplement.
   31  */
   32 
   33 #define MSG_NOERROR     010000          /* don't complain about too long msgs */
   34 
   35 struct msqid_ds {
   36         struct ipc_perm msg_perm;       /* msg queue permission bits */
   37         struct msg      *msg_first;     /* first message in the queue */
   38         struct msg      *msg_last;      /* last message in the queue */
   39         unsigned long   msg_cbytes;     /* number of bytes in use on the queue */
   40         unsigned long   msg_qnum;       /* number of msgs in the queue */
   41         unsigned long   msg_qbytes;     /* max # of bytes on the queue */
   42         pid_t           msg_lspid;      /* pid of last msgsnd() */
   43         pid_t           msg_lrpid;      /* pid of last msgrcv() */
   44         time_t          msg_stime;      /* time of last msgsnd() */
   45         long            msg_pad1;
   46         time_t          msg_rtime;      /* time of last msgrcv() */
   47         long            msg_pad2;
   48         time_t          msg_ctime;      /* time of last msgctl() */
   49         long            msg_pad3;
   50         long            msg_pad4[4];
   51 };
   52 
   53 #ifdef _KERNEL
   54 #include <sys/queue.h>
   55 
   56 struct msg {
   57         long             msg_type;
   58         size_t           msg_len;
   59         struct mbuf     *msg_data;
   60 
   61         TAILQ_ENTRY(msg)        msg_next;
   62 };
   63 
   64 struct que {
   65         struct msqid_ds msqid_ds;
   66         int             que_ix;         /* pseudo-index */
   67         int             que_flags;
   68         int             que_references;
   69 
   70         TAILQ_ENTRY(que)        que_next;
   71         TAILQ_HEAD(, msg) que_msgs;
   72 };
   73 
   74 /* for que_flags */
   75 #define MSGQ_READERS    0x01
   76 #define MSGQ_WRITERS    0x02
   77 #define MSGQ_DYING      0x04
   78 
   79 #define QREF(q) (q)->que_references++
   80 
   81 #define QRELE(q) do {                                                   \
   82         if (--(q)->que_references == 0 && (q)->que_flags & MSGQ_DYING)  \
   83                 wakeup_one(&(q)->que_references);                       \
   84 } while (0)
   85 #endif
   86 
   87 /*
   88  * Structure describing a message.  The SVID doesn't suggest any
   89  * particular name for this structure.  There is a reference in the
   90  * msgop man page that reads "The structure mymsg is an example of what
   91  * this user defined buffer might look like, and includes the following
   92  * members:".  This sentence is followed by two lines equivalent
   93  * to the mtype and mtext field declarations below.  It isn't clear
   94  * if "mymsg" refers to the name of the structure type or the name of an
   95  * instance of the structure...
   96  */
   97 struct mymsg {
   98         long    mtype;          /* message type (+ve integer) */
   99         char    mtext[1];       /* message body */
  100 };
  101 
  102 
  103 #ifdef _KERNEL
  104 /*
  105  * Based on the configuration parameters described in an SVR2 (yes, two)
  106  * config(1m) man page.
  107  *
  108  * Each message is broken up and stored in segments that are msgssz bytes
  109  * long.  For efficiency reasons, this should be a power of two.  Also,
  110  * it doesn't make sense if it is less than 8 or greater than about 256.
  111  * Consequently, msginit in kern/sysv_msg.c checks that msgssz is a power of
  112  * two between 8 and 1024 inclusive (and panic's if it isn't).
  113  */
  114 struct msginfo {
  115         int     msgmax,         /* max chars in a message */
  116                 msgmni,         /* max message queue identifiers */
  117                 msgmnb,         /* max chars in a queue */
  118                 msgtql,         /* max messages in system */
  119                 msgssz,         /* size of a message segment (see notes above) */
  120                 msgseg;         /* number of message segments */
  121 };
  122 #ifdef SYSVMSG
  123 extern struct msginfo   msginfo;
  124 #endif
  125 
  126 int sysctl_sysvmsg(int *, u_int, void *, size_t *);
  127 
  128 struct msg_sysctl_info {
  129         struct msginfo msginfo;
  130         struct msqid_ds msgids[1];
  131 };
  132 
  133 #ifndef MSGSSZ
  134 #define MSGSSZ  8               /* Each segment must be 2^N long */
  135 #endif
  136 #ifndef MSGSEG
  137 #define MSGSEG  2048            /* must be less than 32767 */
  138 #endif
  139 #undef MSGMAX                   /* ALWAYS compute MSGMAX! */
  140 #define MSGMAX  (MSGSSZ*MSGSEG)
  141 #ifndef MSGMNB
  142 #define MSGMNB  2048            /* max # of bytes in a queue */
  143 #endif
  144 #ifndef MSGMNI
  145 #define MSGMNI  40
  146 #endif
  147 #ifndef MSGTQL
  148 #define MSGTQL  40
  149 #endif
  150 
  151 /*
  152  * macros to convert between msqid_ds's and msqid's.
  153  * XXX unused, going away
  154  */
  155 #define MSQID(ix,ds)    ((ix) & 0xffff | (((ds).msg_perm.seq << 16) & 0xffff0000))
  156 #define MSQID_IX(id)    ((id) & 0xffff)
  157 #define MSQID_SEQ(id)   (((id) >> 16) & 0xffff)
  158 #endif
  159 
  160 
  161 #ifndef _KERNEL
  162 __BEGIN_DECLS
  163 int msgctl(int, int, struct msqid_ds *);
  164 int msgget(key_t, int);
  165 int msgsnd(int, const void *, size_t, int);
  166 int msgrcv(int, void *, size_t, long, int);
  167 __END_DECLS
  168 #else
  169 struct proc;
  170 
  171 void    msginit(void);
  172 #endif /* !_KERNEL */
  173 
  174 #endif /* !_SYS_MSG_H_ */

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