NAME
mq_getattr — get status information and attributes associated with a message queue
SYNOPSIS
#include <sys/mqueue.h>
int mq_getattr(mqd_t mqdes, struct mq_attr *mqstat);
DESCRIPTION
The
mq_getattr()
system call collects status information and attributes associated with the
message queue specified by
mqdes
which is copied into the
mq_attr
structure referenced by
mqstat.
Upon a successful return, the
mq_msgsize
and
mq_maxmsg
fields within the
mq_attr
structure contain the maximum size of a message for this queue and the
maximum number of messages that can be queued at any time. The
mq_curmsgs
field contains the number of messages currently on the queue. In addition, the
mq_flags
field contains the message queue blocking status
associated with this
mqdes.
To use this function, link in the realtime library by specifying
-lrt
on the compiler or linker command line.
RETURN VALUE
mq_getattr()
returns the following values:
- 0
Successful completion.
- -1
Failure.
errno
is set to indicate the error.
ERRORS
If
mq_getattr()
fails,
errno
is set to one of the following values:
- [EBADF]
mqdes
is not a valid message queue descriptor.
- [EINVAL]
mqstat
does not point to a valid
mq_attr
structure.
- [ENOSYS]
mq_getattr()
is not supported by the implementation.
STANDARDS CONFORMANCE
mq_getattr(): POSIX 1003.1b
Printable version
