mq_getattr(3) Library Functions Manual mq_getattr(3)
NAME
mq_getattr - Returns the status and attributes of a message queue (P1003.1b)
LIBRARY
Realtime Library (librt.so, librt.a)
SYNOPSIS
#include <mqueue.h>
int mq_getattr (
mqd_t mqdes,
struct mq_attr *mqstat);
PARAMETERS
mqdes Specifies the message queue descriptor whose attributes are obtained.
*mqstat Specifies a pointer to a structure that is updated to contain the values that were set when the message queue was created or
modified by a call to the mq_setattr function.
When the mq_getattr function returns, the following three members of the mq_attr structure specified by mqstat will have the values that
were set when the message queue was created, but with modifications made by subsequent calls to the mq_setattr function:
o The mq_maxmsg member specifies the maximum number of messages that can be held in the queue specified by the mqdes argument.
o The mq_msgsize member specifies the maximum size of any message in the queue.
o The mq_flags member specifies whether the message operation is blocking or nonblocking (MQ_NONBLOCK).
The mq_curmsgs member of the mq_attr structure indicates the number of messages currently on the queue.
DESCRIPTION
The mq_getattr function returns the status and attributes of a message queue. Use the mq_setattr function to set message queue attributes.
RETURN VALUES
On successful completion, the function returns the value 0 (zero); otherwise, the function returns the value -1 and sets errno to indicate
the error.
ERRORS
The mq_getattr function fails under the following conditions:
[EBADF] The fildes argument is an invalid file descriptor.
[EINVAL] The mqstat argument is a null pointer.
RELATED INFORMATION
Functions: mq_open(3), mq_receive(3), mq_send(3), mq_setattr(3)
Guide to Realtime Programming delim off
mq_getattr(3)
