posix ipc message queue Post: 302072068

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mq_receive

mq_receive(2)							System Calls Manual						     mq_receive(2)

NAME

       mq_receive - receive a message from a message queue

SYNOPSIS

DESCRIPTION

       The  system  call  receives  the oldest of the highest priority message from the message queue specified by mqdes.  The selected message is
       removed from the queue and copied to the buffer pointed to by the msg_ptr argument. The argument, msg_len, specifies the size of the buffer
       in bytes. The value of msg_len should be greater than or equal to the mq_msgsize attribute of the message queue, or will fail.

       If the argument msg_prio is not NULL, the priority of the message removed from the queue is stored in the location pointed to by msg_prio.

       If  the	specified message queue is empty and the flag is not set in the message queue blocking status associated with mqdes, will block in
       priority order, until it can receive a message from the queue, or until is interrupted by a signal. If the specified message queue is empty
       and  the  flag  is  set	in the message queue blocking status associated with mqdes, will not wait for a message to arrive on the queue and
       will return with an error.

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

RETURN VALUE

       returns the following values:

	      n    Successful completion.  n is the size of the selected message in bytes and the message is removed from the queue.

	      Failure.
		   is set to indicate the error and no message is removed from the queue.

ERRORS

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

	      [EAGAIN]	     The flag is set in the message queue blocking status associated with mqdes, and the message queue is empty.

	      [EBADF]	     mqdes is not a valid message queue descriptor open for reading.

	      [EINTR]	     A signal interrupted the call to

	      [EINVAL]	     msg_ptr points to an invalid address.

	      [EMSGSIZE]     The specified message buffer size, msg_len, is less than the message size attribute of the message queue.

	      [ENOSYS]	     is not supported by the implementation.

SEE ALSO

       mq_send(2).

STANDARDS CONFORMANCE

																     mq_receive(2)