#ifndef _LINUX_MSG_H
  #define _LINUX_MSG_H
  
  #include <linux/list.h>
  #include <uapi/linux/msg.h>
  
  /* one msg_msg structure for each message */
  struct msg_msg {
  	struct list_head m_list;
  	long m_type;
  	size_t m_ts;		/* message text size */
  	struct msg_msgseg *next;
  	void *security;
  	/* the actual message follows immediately */
  };
  
  /* one msq_queue structure for each present queue on the system */
  struct msg_queue {
  	struct kern_ipc_perm q_perm;
  	time_t q_stime;			/* last msgsnd time */
  	time_t q_rtime;			/* last msgrcv time */
  	time_t q_ctime;			/* last change time */
  	unsigned long q_cbytes;		/* current number of bytes on queue */
  	unsigned long q_qnum;		/* number of messages in queue */
  	unsigned long q_qbytes;		/* max number of bytes on queue */
  	pid_t q_lspid;			/* pid of last msgsnd */
  	pid_t q_lrpid;			/* last receive pid */
  
  	struct list_head q_messages;
  	struct list_head q_receivers;
  	struct list_head q_senders;
  };
  
  /* Helper routines for sys_msgsnd and sys_msgrcv */
  extern long do_msgsnd(int msqid, long mtype, void __user *mtext,
  			size_t msgsz, int msgflg);
  extern long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp,
  		      int msgflg,
  		      long (*msg_fill)(void __user *, struct msg_msg *,
  				       size_t));
  
  #endif /* _LINUX_MSG_H */