1/* $NetBSD: pipe.h,v 1.42 2023/11/02 10:31:55 martin 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 * $FreeBSD: src/sys/sys/pipe.h,v 1.18 2002/02/27 07:35:59 alfred Exp $
24 */
25
26#ifndef _SYS_PIPE_H_
27#define _SYS_PIPE_H_
28
29#include <sys/selinfo.h> /* for struct selinfo */
30#include <sys/time.h> /* for struct timespec */
31
32#include <uvm/uvm_extern.h>
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 (4*PIPE_SIZE)
43#endif
44
45/*
46 * Maximum size of transfer for direct write transfer. If the amount
47 * of data in buffer is larger, it would be transferred in chunks of this
48 * size.
49 */
50#ifndef PIPE_DIRECT_CHUNK
51#define PIPE_DIRECT_CHUNK (1*1024*1024)
52#endif
53
54/*
55 * PIPE_MINDIRECT MUST be smaller than PIPE_SIZE and MUST be bigger
56 * than PIPE_BUF.
57 */
58#ifndef PIPE_MINDIRECT
59#define PIPE_MINDIRECT 8192
60#endif
61
62/*
63 * Pipe buffer information.
64 * Separate in, out, cnt are used to simplify calculations.
65 * Buffered write is active when the buffer.cnt field is set.
66 */
67struct pipebuf {
68 size_t cnt; /* number of chars currently in buffer */
69 u_int in; /* in pointer */
70 u_int out; /* out pointer */
71 size_t size; /* size of buffer */
72 void * buffer; /* kva of buffer */
73};
74
75/*
76 * Bits in pipe_state.
77 */
78#define PIPE_ASYNC 0x001 /* Async I/O */
79#define PIPE_EOF 0x010 /* Pipe is in EOF condition */
80#define PIPE_SIGNALR 0x020 /* Do selwakeup() on read(2) */
81#define PIPE_LOCKFL 0x100 /* Process has exclusive access to
82 pointers/data. */
83/* unused 0x200 */
84#define PIPE_RESTART 0x400 /* Return ERESTART to blocked syscalls */
85
86/*
87 * Per-pipe data structure.
88 * Two of these are linked together to produce bi-directional pipes.
89 */
90struct pipe {
91 kmutex_t *pipe_lock; /* pipe mutex */
92 kcondvar_t pipe_rcv; /* cv for readers */
93 kcondvar_t pipe_wcv; /* cv for writers */
94 kcondvar_t pipe_draincv; /* cv for close */
95 kcondvar_t pipe_lkcv; /* locking */
96 struct pipebuf pipe_buffer; /* data storage */
97 struct selinfo pipe_sel; /* for compat with select */
98 struct timespec pipe_atime; /* time of last access */
99 struct timespec pipe_mtime; /* time of last modify */
100 struct timespec pipe_btime; /* time of creation */
101 struct pipe *pipe_peer; /* link with other direction */
102 pid_t pipe_pgid; /* process group for sigio */
103 u_int pipe_state; /* pipe status info */
104 int pipe_busy; /* busy flag, to handle rundown */
105 vaddr_t pipe_kmem; /* preallocated PIPE_SIZE buffer */
106};
107
108/*
109 * KERN_PIPE subtypes
110 */
111#define KERN_PIPE_MAXKVASZ 1 /* maximum kva size (obsolete) */
112#define KERN_PIPE_LIMITKVA 2 /* limit kva for laons (obsolete) */
113#define KERN_PIPE_MAXBIGPIPES 3 /* maximum # of "big" pipes */
114#define KERN_PIPE_NBIGPIPES 4 /* current number of "big" p. */
115#define KERN_PIPE_KVASIZE 5 /* current pipe kva size */
116
117#ifdef _KERNEL
118int sysctl_dopipe(int *, u_int, void *, size_t *, void *, size_t);
119void pipe_init(void);
120#endif /* _KERNEL */
121
122#endif /* !_SYS_PIPE_H_ */