NAME

mq_setattr — set message queue attributes (REALTIME)

LIBRARY

POSIX Real-time Library (librt, -lrt)

SYNOPSIS

#include <mqueue.h>

int
mq_setattr(mqd_t mqdes, const struct mq_attr *restrict mqstat, struct mq_attr *restrict omqstat);

DESCRIPTION

The mq_setattr() function sets attributes associated with the open message queue description referenced by the message queue descriptor specified by mqdes.

The message queue attributes corresponding to the following members defined in the mq_attr structure will be set to the specified values upon successful completion of mq_setattr():

mq_flags

The value of this member is the bitwise-logical OR of zero or more of O_NONBLOCK and any implementation-defined flags.

The values of the mq_maxmsg, mq_msgsize, and mq_curmsgs members of the mq_attr structure will be ignored by mq_setattr().

If omqstat is non-NULL, the mq_setattr() function will store, in the location referenced by omqstat the previous message queue attributes and the current queue status. These values are the same as would be returned by a call to mq_getattr(3) at that point.

RETURN VALUES

Upon successful completion, the mq_setattr() function returns zero and the attributes of the message queue will have been changed as specified. Otherwise, the message queue attributes are unchanged, and the function returns a value of -1 and sets the global variable errno to indicate the error.

ERRORS

The mq_setattr() function fails if:

[EBADF]

The mqdes argument is not a valid message queue descriptor.

SEE ALSO

mq(3), mq_getattr(3)

STANDARDS

This function conforms to the IEEE Std 1003.1-2001 (“POSIX.1”) standard.

HISTORY

This function first appeared in NetBSD 5.0.

COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html.