text: /*-
   * 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: soc2013/dpl/head/sys/sys/pipe.h 239945 2012-07-31 05:48:35Z davidxu $
   */
  
  #ifndef _SYS_PIPE_H_
  #define _SYS_PIPE_H_
  
  #ifndef _KERNEL
  #error "no user-servicable 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);
  int	pipe_named_ctor(struct pipe **ppipe, struct thread *td);
  void	pipeselwakeup(struct pipe *cpipe);
  #endif /* !_SYS_PIPE_H_ */
  