Class pipe

freebsd/sys/pipe.h:108–125

* Per-pipe data structure. * Two of these are linked together to produce bi-directional pipes. */

 * Two of these are linked together to produce bi-directional pipes.
 */
struct pipe {
	struct	pipebuf pipe_buffer;	/* data storage */
	struct	pipemapping pipe_pages;	/* wired pages for direct I/O */
	struct	selinfo pipe_sel;	/* for compat with select */
	struct	timespec pipe_atime;	/* time of last access */
	struct	timespec pipe_mtime;	/* time of last modify */
	struct	timespec pipe_ctime;	/* time of status change */
	struct	sigio *pipe_sigio;	/* information for async I/O */
	struct	pipe *pipe_peer;	/* link with other direction */
	struct	pipepair *pipe_pair;	/* container structure pointer */
	u_short	pipe_state;		/* pipe status info */
	u_char	pipe_type;		/* pipe type info */
	u_char	pipe_present;		/* still present? */
	int	pipe_waiters;		/* pipelock waiters */
	int	pipe_busy;		/* busy flag, mostly to handle rundown sanely */
	int	pipe_wgen;		/* writer generation for named pipe */
	ino_t	pipe_ino;		/* fake inode for stat(2) */
};

/*
 * Values for the pipe_present.