*** UNIX MANUAL PAGE BROWSER ***

mq_send(3) Library Functions Manual mq_send(3) NAME mq_send - Places a message in the message queue (P1003.1b) SYNOPSIS #include <mqueue.h> int mq_send ( mqd_t mqdes, const char *msg_ptr, size_t msg_len, unsigned int msg_prio); PARAMETERS mqdes Specifies a message queue descriptor. *msg_ptr A pointer to a buffer containing the message to be sent. msg_len Indicates the number of bytes of the message to be sent. msg_prio Indicates the priority of the message being sent. DESCRIPTION Places a message in the message queue. This function inserts the mes- sage in the queue at the position indicated by the msg_prio argument. A message with a relatively large numeric value for the msg_prio argu- ment has a high priority, and it is therefore inserted before messages with lower values for the msg_prio argument. This function inserts messages with equal priority into the queue in first-in/first-out or- der. Thus the function inserts a message with a given priority after already-queued messages that have the same priority. If the message queue is full, and the O_NONBLOCK flag associated with it is not set, the mq_send function blocks until either sufficient space in the message queue becomes available or a signal interrupts the mq_send function. If two or more processes are waiting to send messages when space be- comes available in the queue, the highest priority process that has been waiting the longest sends the message first. The mq_send function returns an error indication if the specified queue is full and the O_NONBLOCK flag is set for that queue. RETURN VALUES On successful completion, the mq_send function returns a value of zero. Otherwise, no message is sent, -1 is returned, and errno is set to in- dicate the error. ERRORS The mq_send function fails under the following conditions: [EAGAIN] The O_NONBLOCK flag is set in the message queue descrip- tion associated with mqdes, and the specified message queue is full. [EBADF] The mqdes argument is not a valid message queue descrip- tor open for writing. [EFAULT] Internal virtual memory error. [EINTR] A signal interrupted the call to mq_send. [EINVAL] The value of msg_prio is outside the valid range. [EMSGSIZE] The specified message length, msg_len, exceeds the mes- sage size attribute of the message queue. Note that a zero length message is valid. RELATED INFORMATION Functions: mq_receive(3), mq_setattr(3) delim off mq_send(3)