13.18. Data Definitions for librt

This section defines global identifiers and their values that are associated with interfaces contained in librt. These definitions are organized into groups that correspond to system headers. This convention is used as a convenience for the reader, and does not imply the existence of these headers, or their content. Where an interface is defined as requiring a particular system header file all of the data definitions for that system header file presented here shall be in effect.

This section gives data definitions to promote binary application portability, not to repeat source interface definitions available elsewhere. System providers and application developers should use this ABI to supplement - not to replace - source interface definition specifications.

This specification uses the ISO C (1999) C Language as the reference programming language, and data definitions are specified in ISO C format. The C language is used here as a convenient notation. Using a C language description of these data objects does not preclude their use by other programming languages.

typedef int mqd_t;
struct mq_attr {
    long int mq_flags;
    long int mq_maxmsg;
    long int mq_msgsize;
    long int mq_curmsgs;
    long int __pad[4];
};
extern int mq_close(mqd_t);
extern int mq_getattr(mqd_t, struct mq_attr *);
extern int mq_notify(mqd_t, const struct sigevent *);
extern mqd_t mq_open(const char *, int, ...);
extern ssize_t mq_receive(mqd_t, char *, size_t, unsigned int *);
extern int mq_send(mqd_t, const char *, size_t, unsigned int);
extern int mq_setattr(mqd_t, const struct mq_attr *, struct mq_attr *);
extern ssize_t mq_timedreceive(mqd_t, char *, size_t, unsigned int *,
			       const struct timespec *);
extern int mq_timedsend(mqd_t, const char *, size_t, unsigned int,
			const struct timespec *);
extern int mq_unlink(const char *);