1/*	$OpenBSD: pipe.h,v 1.29 2022/07/09 12:48:21 visa Exp $	*/
2
3/*
4 * Copyright (c) 1996 John S. Dyson
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice immediately at the beginning of the file, without modification,
12 *    this list of conditions, and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. Absolutely no warranty of function or purpose is made by the author
17 *    John S. Dyson.
18 * 4. This work was done expressly for inclusion into FreeBSD.  Other use
19 *    is allowed if this notation is included.
20 * 5. Modifications may be freely made to this file if the above conditions
21 *    are met.
22 */
23
24#ifndef _SYS_PIPE_H_
25#define _SYS_PIPE_H_
26
27#ifndef _KERNEL
28#include <sys/time.h>			/* for struct timespec */
29#endif /* _KERNEL */
30
31#include <sys/event.h>			/* for struct klist */
32#include <sys/sigio.h>			/* for struct sigio_ref */
33
34/*
35 * Pipe buffer size, keep moderate in value, pipes take kva space.
36 */
37#ifndef PIPE_SIZE
38#define PIPE_SIZE	16384
39#endif
40
41#ifndef BIG_PIPE_SIZE
42#define BIG_PIPE_SIZE	(64*1024)
43#endif
44
45/*
46 * Pipe buffer information.
47 * Separate in, out, cnt are used to simplify calculations.
48 * Buffered write is active when the buffer.cnt field is set.
49 */
50struct pipebuf {
51	u_int	cnt;		/* number of chars currently in buffer */
52	u_int	in;		/* in pointer */
53	u_int	out;		/* out pointer */
54	u_int	size;		/* size of buffer */
55	caddr_t	buffer;		/* kva of buffer */
56};
57
58/*
59 * Bits in pipe_state.
60 */
61#define PIPE_ASYNC	0x004	/* Async? I/O. */
62#define PIPE_WANTR	0x008	/* Reader wants some characters. */
63#define PIPE_WANTW	0x010	/* Writer wants space to put characters. */
64#define PIPE_WANTD	0x020	/* Pipe is wanted to be run-down. */
65#define PIPE_EOF	0x080	/* Pipe is in EOF condition. */
66#define PIPE_LOCK	0x100	/* Thread has exclusive I/O access. */
67#define PIPE_LWANT	0x200	/* Thread wants exclusive I/O access. */
68
69struct pipe_pair;
70
71/*
72 * Per-pipe data structure.
73 * Two of these are linked together to produce bi-directional pipes.
74 *
75 * Locking:
76 *	I	immutable after creation
77 *	S	sigio_lock
78 *	p	pipe_lock
79 */
80struct pipe {
81	struct	rwlock *pipe_lock;
82	struct	pipebuf pipe_buffer;	/* [p] data storage */
83	struct	klist pipe_klist;	/* [p] list of knotes */
84	struct	timespec pipe_atime;	/* [p] time of last access */
85	struct	timespec pipe_mtime;	/* [p] time of last modify */
86	struct	timespec pipe_ctime;	/* [I] time of status change */
87	struct	sigio_ref pipe_sigio;	/* [S] async I/O registration */
88	struct	pipe *pipe_peer;	/* [p] link with other direction */
89	struct	pipe_pair *pipe_pair;	/* [I] pipe storage */
90	u_int	pipe_state;		/* [p] pipe status info */
91	int	pipe_busy;		/* [p] # readers/writers */
92};
93
94#ifdef _KERNEL
95void	pipe_init(void);
96#endif /* _KERNEL */
97
98#endif /* !_SYS_PIPE_H_ */
99