Content-type: text/html Man page of mq_send

mq_send

Section: C Library Functions (3)
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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 message in the queue at the position indicated by the msg_prio argument. A message with a relatively large numeric value for the msg_prio argument 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 order. 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 becomes 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 indicate the error.  

ERRORS

The mq_send function fails under the following conditions:

[EAGAIN]
The O_NONBLOCK flag is set in the message queue description associated with mqdes, and the specified message queue is full.
[EBADF]
The mqdes argument is not a valid message queue descriptor 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 message 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


 

Index

NAME
SYNOPSIS
PARAMETERS
DESCRIPTION
RETURN VALUES
ERRORS
RELATED INFORMATION

This document was created by man2html, using the manual pages.
Time: 02:41:42 GMT, October 02, 2010