MQUEUE.H(7) Miscellaneous Information Manual MQUEUE.H(7)

NAME

mqueue.h — message queues (REALTIME)

SYNOPSIS

#include <mqueue.h>

DESCRIPTION

The <mqueue.h> header defines the mqd_t type, which is used for message queue descriptors. This will not be an array type. A message queue descriptor may be implemented using a file descriptor, in which case applications can open up to at least {OPEN_MAX} file and message queues.

The <mqueue.h> header defines the sigevent structure (as described in <signal.h>) and the mq_attr structure, which is used in getting and setting the attributes of a message queue. Attributes are initially set when the message queue is created. A mq_attr structure will have at least the following fields: long mq_flags message queue flags long mq_maxmsg maximum number of messages long mq_msgsize maximum message size long mq_curmsgs number of messages currently queued

The following are declared as functions and may also be declared as macros. Function prototypes must be provided for use with an ISO C compiler. int mq_close(mqd_t); int mq_getattr(mqd_t, struct mq_attr *); int mq_notify(mqd_t, const struct sigevent *); mqd_t mq_open(const char *, int, ...); ssize_t mq_receive(mqd_t, char *, size_t, unsigned int *); int mq_send(mqd_t, const char *, size_t, unsigned int); int mq_setattr(mqd_t, const struct mq_attr *, struct mq_attr *); int mq_unlink(const char *);

Inclusion of the <mqueue.h> header may make visible symbols defined in the headers <fcntl.h>, <signal.h>, <sys/types.h> and <time.h>.

APPLICATION USAGE

None.

FUTURE DIRECTIONS