#include <mqueue.h>
int mq_setattr(mqd_t mqdes, const struct mq_attr *restrict
mqstat,
struct mq_attr *restrict omqstat);
The mq_setattr() function shall set 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 shall be set to the specified values upon successful completion of mq_setattr():
The values of the mq_maxmsg, mq_msgsize, and mq_curmsgs members of the mq_attr structure shall be ignored by mq_setattr().
If omqstat is non-NULL, the mq_setattr() function shall store, in the location referenced by omqstat, the previous message queue attributes and the current queue status. These values shall be the same as would be returned by a call to mq_getattr() at that point.
Upon successful completion, the function shall return a value of zero and the attributes of the message queue shall have been changed as specified.
Otherwise, the message queue attributes shall be unchanged, and the function shall return a value of -1 and set errno to indicate the error.
The mq_setattr() function shall fail if:
The following sections are informative.
mq_open() , mq_send() , mq_timedsend() , msgctl() , msgget() , msgrcv() , msgsnd() , the Base Definitions volume of IEEE Std 1003.1-2001, <mqueue.h>