mq_getattr(2) mq_getattr(2)
NAME [Toc] [Back]
mq_getattr - get status information and attributes associated with a
message queue
SYNOPSIS [Toc] [Back]
#include <sys/mqueue.h>
int mq_getattr(mqd_t mqdes, struct mq_attr *mqstat);
DESCRIPTION [Toc] [Back]
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 [Toc] [Back]
mq_getattr() returns the following values:
0 Successful completion.
-1 Failure. errno is set to indicate the error.
ERRORS [Toc] [Back]
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.
SEE ALSO [Toc] [Back]
mq_open(2), mq_setattr(2).
STANDARDS CONFORMANCE [Toc] [Back]
mq_getattr(): POSIX 1003.1b
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