/*-
 * Copyright (c) 1996 John S. Dyson
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice immediately at the beginning of the file, without modification,
 *    this list of conditions, and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Absolutely no warranty of function or purpose is made by the author
 *    John S. Dyson.
 * 4. This work was done expressly for inclusion into FreeBSD.  Other use
 *    is allowed if this notation is included.
 * 5. Modifications may be freely made to this file if the above conditions
 *    are met.
 *
 * $FreeBSD: releng/12.0/sys/sys/pipe.h 312235 2017-01-15 18:00:45Z cem $
 */

#ifndef _SYS_PIPE_H_
#define _SYS_PIPE_H_

#ifndef _KERNEL
#error "no user-serviceable parts inside"
#endif

/*
 * Pipe buffer size, keep moderate in value, pipes take kva space.
 */
#ifndef PIPE_SIZE
#define PIPE_SIZE	16384
#endif

#ifndef BIG_PIPE_SIZE
#define BIG_PIPE_SIZE	(64*1024)
#endif

#ifndef SMALL_PIPE_SIZE
#define SMALL_PIPE_SIZE	PAGE_SIZE
#endif

/*
 * PIPE_MINDIRECT MUST be smaller than PIPE_SIZE and MUST be bigger
 * than PIPE_BUF.
 */
#ifndef PIPE_MINDIRECT
#define PIPE_MINDIRECT	8192
#endif

#define PIPENPAGES	(BIG_PIPE_SIZE / PAGE_SIZE + 1)

/*
 * See sys_pipe.c for info on what these limits mean. 
 */
extern long	maxpipekva;
extern struct	fileops pipeops;

/*
 * Pipe buffer information.
 * Separate in, out, cnt are used to simplify calculations.
 * Buffered write is active when the buffer.cnt field is set.
 */
struct pipebuf {
	u_int	cnt;		/* number of chars currently in buffer */
	u_int	in;		/* in pointer */
	u_int	out;		/* out pointer */
	u_int	size;		/* size of buffer */
	caddr_t	buffer;		/* kva of buffer */
};

/*
 * Information to support direct transfers between processes for pipes.
 */
struct pipemapping {
	vm_size_t	cnt;		/* number of chars in buffer */
	vm_size_t	pos;		/* current position of transfer */
	int		npages;		/* number of pages */
	vm_page_t	ms[PIPENPAGES];	/* pages in source process */
};

/*
 * Bits in pipe_state.
 */
#define PIPE_ASYNC	0x004	/* Async? I/O. */
#define PIPE_WANTR	0x008	/* Reader wants some characters. */
#define PIPE_WANTW	0x010	/* Writer wants space to put characters. */
#define PIPE_WANT	0x020	/* Pipe is wanted to be run-down. */
#define PIPE_SEL	0x040	/* Pipe has a select active. */
#define PIPE_EOF	0x080	/* Pipe is in EOF condition. */
#define PIPE_LOCKFL	0x100	/* Process has exclusive access to pointers/data. */
#define PIPE_LWANT	0x200	/* Process wants exclusive access to pointers/data. */
#define PIPE_DIRECTW	0x400	/* Pipe direct write active. */
#define PIPE_DIRECTOK	0x800	/* Direct mode ok. */
#define PIPE_NAMED	0x1000	/* Is a named pipe. */

/*
 * Per-pipe data structure.
 * Two of these are linked together to produce bi-directional pipes.
 */
struct pipe {
	struct	pipebuf pipe_buffer;	/* data storage */
	struct	pipemapping pipe_map;	/* pipe mapping 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_int	pipe_state;		/* pipe status info */
	int	pipe_busy;		/* busy flag, mostly to handle rundown sanely */
	int	pipe_present;		/* still present? */
	int	pipe_wgen;		/* writer generation for named pipe */
	ino_t	pipe_ino;		/* fake inode for stat(2) */
};

/*
 * Values for the pipe_present.
 */
#define PIPE_ACTIVE		1
#define	PIPE_CLOSING		2
#define	PIPE_FINALIZED		3

/*
 * Container structure to hold the two pipe endpoints, mutex, and label
 * pointer.
 */
struct pipepair {
	struct pipe	pp_rpipe;
	struct pipe	pp_wpipe;
	struct mtx	pp_mtx;
	struct label	*pp_label;
};

#define PIPE_MTX(pipe)		(&(pipe)->pipe_pair->pp_mtx)
#define PIPE_LOCK(pipe)		mtx_lock(PIPE_MTX(pipe))
#define PIPE_UNLOCK(pipe)	mtx_unlock(PIPE_MTX(pipe))
#define PIPE_LOCK_ASSERT(pipe, type)  mtx_assert(PIPE_MTX(pipe), (type))

void	pipe_dtor(struct pipe *dpipe);
void	pipe_named_ctor(struct pipe **ppipe, struct thread *td);
void	pipeselwakeup(struct pipe *cpipe);
#endif /* !_SYS_PIPE_H_ */
