msg.h

<sys/msg.h>(P)						       <sys/msg.h>(P)



NAME
       sys/msg.h - XSI message queue structures

SYNOPSIS
       #include <sys/msg.h>

DESCRIPTION
       The  <sys/msg.h>	 header shall define the following data types through
       typedef:

       msgqnum_t
	      Used for the number of messages in the message queue.

       msglen_t
	      Used for the number of bytes allowed in a message queue.


       These types shall be unsigned integer types that	 are  able  to	store
       values at least as large as a type unsigned short.

       The  <sys/msg.h>	 header shall define the following constant as a mes-
       sage operation flag:

       MSG_NOERROR
	      No error if big message.


       The msqid_ds structure shall contain the following members:


	      struct ipc_perm msg_perm	 Operation permission structure.
	      msgqnum_t	      msg_qnum	 Number of messages currently on queue.
	      msglen_t	      msg_qbytes Maximum number of bytes allowed on queue.
	      pid_t	      msg_lspid	 Process ID of last msgsnd
	       ().
	      pid_t	      msg_lrpid	 Process ID of last msgrcv
	       ().
	      time_t	      msg_stime	 Time of last msgsnd
	       ().
	      time_t	      msg_rtime	 Time of last msgrcv
	       ().
	      time_t	      msg_ctime	 Time of last change.

       The pid_t, time_t, key_t, size_t, and ssize_t types shall  be  defined
       as described in <sys/types.h> .

       The  following  shall be declared as functions and may also be defined
       as macros. Function prototypes shall be provided.


	      int	msgctl(int, int, struct msqid_ds *);
	      int	msgget(key_t, int);
	      ssize_t	msgrcv(int, void *, size_t, long, int);
	      int	msgsnd(int, const void *, size_t, int);

       In addition, all of the symbols from <sys/ipc.h> shall be defined when
       this header is included.

       The following sections are informative.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       <sys/ipc.h> , <sys/types.h> , msgctl(), msgget(), msgrcv(), msgsnd()

COPYRIGHT
       Portions	 of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information  Technol-
       ogy  --	Portable  Operating  System Interface (POSIX), The Open Group
       Base Specifications Issue 6, Copyright (C) 2001-2003 by the  Institute
       of  Electrical  and  Electronics Engineers, Inc and The Open Group. In
       the event of any discrepancy between this  version  and	the  original
       IEEE and The Open Group Standard, the original IEEE and The Open Group
       Standard is  the	 referee  document.  The  original  Standard  can  be
       obtained online at http://www.opengroup.org/unix/online.html .



POSIX				     2003		       <sys/msg.h>(P)