mqueue.h(7posix) [posix man page]

<mqueue.h>(P)						     POSIX Programmer's Manual						     <mqueue.h>(P)

NAME

       mqueue.h - message queues (REALTIME)

SYNOPSIS

       #include <mqueue.h>

DESCRIPTION

       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.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       <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()

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 .

IEEE
/The Open Group						       2003							     <mqueue.h>(P)

MQ_SETATTR(3P)						     POSIX Programmer's Manual						    MQ_SETATTR(3P)

PROLOG

       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME

       mq_setattr - set message queue attributes (REALTIME)

SYNOPSIS

       #include <mqueue.h>

       int mq_setattr(mqd_t mqdes, const struct mq_attr *restrict mqstat,
	      struct mq_attr *restrict omqstat);

DESCRIPTION

       The mq_setattr() function shall set attributes associated with the open message queue description referenced by the message queue  descrip-
       tor specified by mqdes.

       The  message  queue attributes corresponding to the following members defined in the mq_attr structure shall be set to the specified values
       upon successful completion of mq_setattr():

       mq_flags
	      The value of this member is the bitwise-logical OR of zero or more of O_NONBLOCK and any implementation-defined flags.

       The values of the mq_maxmsg, mq_msgsize, and mq_curmsgs members of the mq_attr structure shall be ignored by mq_setattr().

       If omqstat is non-NULL, the mq_setattr() function shall store, in the location referenced by omqstat, the previous message queue attributes
       and the current queue status. These values shall be the same as would be returned by a call to mq_getattr() at that point.

RETURN VALUE

       Upon  successful  completion,  the function shall return a value of zero and the attributes of the message queue shall have been changed as
       specified.

       Otherwise, the message queue attributes shall be unchanged, and the function shall return a value of -1	and  set  errno  to  indicate  the
       error.

ERRORS

       The mq_setattr() function shall fail if:

       EBADF  The mqdes argument is not a valid message queue descriptor.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       mq_open(),  mq_send(),  mq_timedsend(),	msgctl(),  msgget(),  msgrcv(),  msgsnd(),  the  Base  Definitions volume of IEEE Std 1003.1-2001,
       <mqueue.h>

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 .

IEEE
/The Open Group						       2003							    MQ_SETATTR(3P)