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      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  */
     67 struct 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  */
     90 struct 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
    118 int	sysctl_dopipe(int *, u_int, void *, size_t *, void *, size_t);
    119 void	pipe_init(void);
    120 #endif /* _KERNEL */
    121 
    122 #endif /* !_SYS_PIPE_H_ */
    123