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       mqueue.h - message queues (REALTIME)


       #include <mqueue.h>


       The  <mqueue.h>  header  shall define the mqd_t type, which is used for
       message queue descriptors. This is not an array type.

       The <mqueue.h> header shall define the sigevent structure (as described
       in <signal.h> ) and the mq_attr structure, which is used in getting and
       setting the attributes of a message queue. Attributes are initially set
       when  the  message queue is created. An mq_attr structure shall have at
       least the following fields:

              long    mq_flags    Message queue flags.
              long    mq_maxmsg   Maximum number of messages.
              long    mq_msgsize  Maximum message size.
              long    mq_curmsgs  Number of messages currently queued.

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

              int      mq_close(mqd_t);
              int      mq_getattr(mqd_t, struct mq_attr *);
              int      mq_notify(mqd_t, const struct sigevent *);
              mqd_t    mq_open(const char *, int, ...);
              ssize_t  mq_receive(mqd_t, char *, size_t, unsigned *);
              int      mq_send(mqd_t, const char *, size_t, unsigned );
              int      mq_setattr(mqd_t, const struct mq_attr *restrict,
                           struct mq_attr *restrict);

              ssize_t  mq_timedreceive(mqd_t, char *restrict, size_t,
                           unsigned *restrict, const struct timespec *restrict);
              int      mq_timedsend(mqd_t, const char *, size_t, unsigned ,
                           const struct timespec *);

              int      mq_unlink(const char *);

       Inclusion  of the <mqueue.h> header may make visible symbols defined in
       the headers <fcntl.h>, <signal.h>, <sys/types.h>, and <time.h>.

       The following sections are informative.








       <fcntl.h>  ,  <signal.h>  ,  <sys/types.h>  ,  <time.h>  ,  the  System
       Interfaces  volume  of  IEEE Std 1003.1-2001, mq_close(), mq_getattr(),
       mq_notify(),   mq_open(),   mq_receive(),   mq_send(),    mq_setattr(),
       mq_timedreceive(), mq_timedsend(), mq_unlink()


       Portions  of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       --  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 .