hpux man page for mq_open

mq_open(2)							System Calls Manual							mq_open(2)

NAME
       mq_open - create or open a message queue

SYNOPSIS
   Remarks
       The ANSI C "" construct specifies a variable length argument list whose optional members are given in the associated comment

DESCRIPTION
       The system call establishes a connection between a process and a message queue.	It returns a new message queue descriptor which is used by
       other message queue system calls to refer to that queue.

       The name argument points to the message queue name, and must conform to the rules listed in

       The oflag argument is the bitwise inclusive OR of the flags listed in and below.

       The new message queue descriptor returned, remains open across the system call and is inherited by the child process.

   Read-Write Flags
       The value of oflag must be composed by taking the inclusive OR of exactly one of the following flags:

	      Open for receiving only.

	      Open for sending only.

	      Open for sending and receiving.

   General Flags
       Any combination of the following flags may also be used in setting the value of oflag.

	      This flag must be used to create a message queue, and it uses two additional
			     arguments: mode which is of type and attr which is a pointer to a structure.  If a message  queue	with  name,  name,
			     exists,  this flag has no effect, except as noted under Otherwise a new message queue is created.	The user ID of the
			     queue will be set to the effective user ID of the process, and the group ID of the queue will be set to the effective
			     group  ID of the process.	The "file permission bits" will be set to the value of mode.  If attr is NULL, the message
			     queue is created with default attributes - and (defined in If attr is non-NULL and the message  queue  mq_maxmsg  and
			     mq_msgsize attributes are set to the values of the corresponding members in the structure referred to by attr.

	      If	     and are set in oflag and the named message queue exists, will fail.  The flag is ignored if is not set in oflag.

	      This flag is used to specify the blocking status of the message queue
			     descriptor  and  determines  whether  a or a will wait for resources or messages respectively, that are not currently
			     available, or fail with set to

   Message Queue Naming Convention
       A valid message queue name string, must conform to path name construction rules.  In addition it must also meet	the  following	specifica-
       tions:

	      a.   Begin with a slash character.

	      b.   Contain no path name component consisting of a dot or dot-dot.  For example, and are invalid.

	      c.   Contain no illegal characters.

	      d.   Contain no path name components longer that

	      e.   Entire name should not be longer that

       To use this function, link in the realtime library by specifying on the compiler or linker command line.

   Security Restrictions
       Some or all of the actions associated with this system call are subject to compartmental restrictions.  See compartments(5) for more infor-
       mation about compartmentalization on systems that support that feature.

       Compartmental restrictions can be overridden if the process possesses the privilege Processes owned by the  superuser  may  not	have  this
       privilege.  Processes owned by any user may have this privilege, depending on system configuration.

       Some  or  all  of  the actions associated with this system call require the privilege Processes owned by the superuser have this privilege.
       Processes owned by other users may have this privilege, depending on system configuration.

       See privileges(5) for more information about privileged access on systems that support fine-grained privileges.

RETURN VALUE
       returns the following values:

	      n    Successful completion.  n is a message queue descriptor for the opened message queue and is greater than or equal to

	      Failure.
		   is set to indicate the error.

ERRORS
       If fails, is set to one of the following values:

	      The message queue exists and the permissions specified by
			     oflag are denied, or the message queue does not exist and permission to create the queue is denied.

	      The	     and flags are set in oflag and the named message queue exists.

	      was interrupted by a signal.

	      The argument   name, does not conform to the

			     has been specified in oflag, the value of attr is not NULL, and either mq_maxmsg or mq_msgsize is less than or  equal
			     to zero.

	      Too many message queue descriptors are currently in use by this process.

	      The length of the
			     name  string  exceeds  bytes,  or	the length of a (path name) component of the name string exceeds bytes while is in
			     effect.

	      Too many message queues are currently open in the system.

	      The	     flag is not set in oflag and the named message queue does not exist.

	      There are insufficient resources for the creation of the new message queue.

	      is not supported by the implementation.

SEE ALSO
       mq_close(2), mq_getattr(2), mq_receive(2), mq_send(2), mq_setattr(2), mq_unlink(2), privileges(5).

STANDARDS CONFORMANCE
																	mq_open(2)