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MQ_GETATTR(3) | Linux Programmer's Manual | MQ_GETATTR(3) |
NAME¶
mq_getattr, mq_setattr - get/set message queue attributesSYNOPSIS¶
#include <mqueue.h>int mq_getattr(mqd_t mqdes, struct mq_attr *attr); int mq_setattr(mqd_t mqdes, struct mq_attr *newattr, struct mq_attr *oldattr);
DESCRIPTION¶
mq_getattr() and mq_setattr() respectively retrieve and modify attributes of the message queue referred to by the descriptor mqdes.struct mq_attr { long mq_flags; /* Flags: 0 or O_NONBLOCK */ long mq_maxmsg; /* Max. # of messages on queue */ long mq_msgsize; /* Max. message size (bytes) */ long mq_curmsgs; /* # of messages currently in queue */ };
The mq_flags field contains flags associated with the open message queue description. This field is initialized when the queue is created by mq_open(3). The only flag that can appear in this field is O_NONBLOCK.
RETURN VALUE¶
On success mq_getattr() and mq_setattr() return 0; on error, -1 is returned, with errno set to indicate the error.ERRORS¶
- EBADF
- The descriptor specified in mqdes is invalid.
- EINVAL
- newattr->mq_flags contained set bits other than O_NONBLOCK.
CONFORMING TO¶
POSIX.1-2001.NOTES¶
On Linux, mq_getattr() and mq_setattr() are library functions layered on top of the mq_getsetattr(2) system call.SEE ALSO¶
mq_close(3), mq_notify(3), mq_open(3), mq_receive(3), mq_send(3), mq_unlink(3), mq_overview(7)COLOPHON¶
This page is part of release 3.44 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.2010-08-29 | Linux |