pipe.h revision 268335 
1/*-
2 * Copyright (c) 1996 John S. Dyson
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice immediately at the beginning of the file, without modification,
10 *    this list of conditions, and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. Absolutely no warranty of function or purpose is made by the author
15 *    John S. Dyson.
16 * 4. This work was done expressly for inclusion into FreeBSD.  Other use
17 *    is allowed if this notation is included.
18 * 5. Modifications may be freely made to this file if the above conditions
19 *    are met.
20 *
21 * $FreeBSD: stable/10/sys/sys/pipe.h 268335 2014-07-06 22:47:18Z mjg $
22 */
23
24#ifndef _SYS_PIPE_H_
25#define _SYS_PIPE_H_
26
27#ifndef _KERNEL
28#error "no user-servicable parts inside"
29#endif
30
31/*
32 * Pipe buffer size, keep moderate in value, pipes take kva space.
33 */
34#ifndef PIPE_SIZE
35#define PIPE_SIZE	16384
36#endif
37
38#ifndef BIG_PIPE_SIZE
39#define BIG_PIPE_SIZE	(64*1024)
40#endif
41
42#ifndef SMALL_PIPE_SIZE
43#define SMALL_PIPE_SIZE	PAGE_SIZE
44#endif
45
46/*
47 * PIPE_MINDIRECT MUST be smaller than PIPE_SIZE and MUST be bigger
48 * than PIPE_BUF.
49 */
50#ifndef PIPE_MINDIRECT
51#define PIPE_MINDIRECT	8192
52#endif
53
54#define PIPENPAGES	(BIG_PIPE_SIZE / PAGE_SIZE + 1)
55
56/*
57 * See sys_pipe.c for info on what these limits mean.
58 */
59extern long	maxpipekva;
60extern struct	fileops pipeops;
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	u_int	cnt;		/* number of chars currently in buffer */
69	u_int	in;		/* in pointer */
70	u_int	out;		/* out pointer */
71	u_int	size;		/* size of buffer */
72	caddr_t	buffer;		/* kva of buffer */
73};
74
75/*
76 * Information to support direct transfers between processes for pipes.
77 */
78struct pipemapping {
79	vm_size_t	cnt;		/* number of chars in buffer */
80	vm_size_t	pos;		/* current position of transfer */
81	int		npages;		/* number of pages */
82	vm_page_t	ms[PIPENPAGES];	/* pages in source process */
83};
84
85/*
86 * Bits in pipe_state.
87 */
88#define PIPE_ASYNC	0x004	/* Async? I/O. */
89#define PIPE_WANTR	0x008	/* Reader wants some characters. */
90#define PIPE_WANTW	0x010	/* Writer wants space to put characters. */
91#define PIPE_WANT	0x020	/* Pipe is wanted to be run-down. */
92#define PIPE_SEL	0x040	/* Pipe has a select active. */
93#define PIPE_EOF	0x080	/* Pipe is in EOF condition. */
94#define PIPE_LOCKFL	0x100	/* Process has exclusive access to pointers/data. */
95#define PIPE_LWANT	0x200	/* Process wants exclusive access to pointers/data. */
96#define PIPE_DIRECTW	0x400	/* Pipe direct write active. */
97#define PIPE_DIRECTOK	0x800	/* Direct mode ok. */
98#define PIPE_NAMED	0x1000	/* Is a named pipe. */
99
100/*
101 * Per-pipe data structure.
102 * Two of these are linked together to produce bi-directional pipes.
103 */
104struct pipe {
105	struct	pipebuf pipe_buffer;	/* data storage */
106	struct	pipemapping pipe_map;	/* pipe mapping for direct I/O */
107	struct	selinfo pipe_sel;	/* for compat with select */
108	struct	timespec pipe_atime;	/* time of last access */
109	struct	timespec pipe_mtime;	/* time of last modify */
110	struct	timespec pipe_ctime;	/* time of status change */
111	struct	sigio *pipe_sigio;	/* information for async I/O */
112	struct	pipe *pipe_peer;	/* link with other direction */
113	struct	pipepair *pipe_pair;	/* container structure pointer */
114	u_int	pipe_state;		/* pipe status info */
115	int	pipe_busy;		/* busy flag, mostly to handle rundown sanely */
116	int	pipe_present;		/* still present? */
117	int	pipe_wgen;		/* writer generation for named pipe */
118	ino_t	pipe_ino;		/* fake inode for stat(2) */
119};
120
121/*
122 * Values for the pipe_present.
123 */
124#define PIPE_ACTIVE		1
125#define	PIPE_CLOSING		2
126#define	PIPE_FINALIZED		3
127
128/*
129 * Container structure to hold the two pipe endpoints, mutex, and label
130 * pointer.
131 */
132struct pipepair {
133	struct pipe	pp_rpipe;
134	struct pipe	pp_wpipe;
135	struct mtx	pp_mtx;
136	struct label	*pp_label;
137};
138
139#define PIPE_MTX(pipe)		(&(pipe)->pipe_pair->pp_mtx)
140#define PIPE_LOCK(pipe)		mtx_lock(PIPE_MTX(pipe))
141#define PIPE_UNLOCK(pipe)	mtx_unlock(PIPE_MTX(pipe))
142#define PIPE_LOCK_ASSERT(pipe, type)  mtx_assert(PIPE_MTX(pipe), (type))
143
144void	pipe_dtor(struct pipe *dpipe);
145void	pipe_named_ctor(struct pipe **ppipe, struct thread *td);
146void	pipeselwakeup(struct pipe *cpipe);
147#endif /* !_SYS_PIPE_H_ */
148