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_ */