/* $FreeBSD: src/sys/kern/sysv_msg.c,v 1.23.2.5 2002/12/31 08:54:53 maxim Exp $ */

/*
 * Implementation of SVID messages
 *
 * Author:  Daniel Boulet
 *
 * Copyright 1993 Daniel Boulet and RTMX Inc.
 * Copyright (c) 2013 Larisa Grigore <larisagrigore@gmail.com>
 *
 * 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 _SYSVIPC_MSG_H_
#define _SYSVIPC_MSG_H_

#include <sys/msg.h>
#include "sysvipc_lock.h"
#include "sysvipc_lock_generic.h"

struct msg {
        short   msg_next;       /* next msg in the chain */
        long    msg_type;       /* type of this message */
                                /* >0 -> type of this message */
                                /* 0 -> free header */
        u_short msg_ts;         /* size of this message */
        short   msg_spot;       /* location of start of msg in buffer */
};

/* Intarnal structure defined to keep compatbility with
 * th kernel implementation.
 */
struct msqid_ds_internal {
        struct  ipc_perm msg_perm;      /* msg queue permission bits */
        union {
                struct  msg *msg_first;
                int msg_first_index;
        } first;
        union {
                struct  msg *msg_last;
                int msg_last_index;
        } last;
        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];
};

#ifndef MSGSSZ
#define MSGSSZ  8               /* Each segment must be 2^N long */
#endif
#ifndef MSGSEG
#define MSGSEG  256             /* must be calculated such that all
                                        structure fits in PAGE_SIZE. */
#endif
#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  10//40
#endif

 /* 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 */
};

struct msgmap {
        short   next;           /* next segment in buffer */
                                /* -1 -> available */
                                /* 0..(MSGSEG-1) -> index of next segment */
};

struct msqid_pool {
#ifdef SYSV_RWLOCK
        struct sysv_rwlock rwlock;
#else
        struct sysv_mutex mutex;
#endif
        struct msqid_ds_internal ds;
        char gen;
        int nfree_msgmaps;      /* # of free map entries */
        short free_msgmaps;     /* head of linked list of free map entries */
        short free_msghdrs;/* list of free msg headers */
        struct msg msghdrs[MSGTQL];     /* MSGTQL msg headers */
        struct msgmap msgmaps[MSGSEG];  /* MSGSEG msgmap structures */
        char msgpool[MSGMAX];           /* MSGMAX byte long msg buffer pool */
};

int sysvipc_msgctl(int, int, struct msqid_ds *);
int sysvipc_msgget(key_t, int);
int sysvipc_msgsnd(int, const void *, size_t, int);
int sysvipc_msgrcv(int, void *, size_t, long, int);

#endif /* !_SYSVIPC_MSG_H_ */