/* $NetBSD: pipe.h,v 1.43 2026/03/11 21:54:22 andvar Exp $ */

/*
 * 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: src/sys/sys/pipe.h,v 1.18 2002/02/27 07:35:59 alfred Exp $
 */

#ifndef _SYS_PIPE_H_
#define _SYS_PIPE_H_

#include <sys/selinfo.h>                /* for struct selinfo */
#include <sys/time.h>                   /* for struct timespec */

#include <uvm/uvm_extern.h>

/*
 * 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   (4*PIPE_SIZE)
#endif

/*
 * Maximum size of transfer for direct write transfer. If the amount
 * of data in buffer is larger, it would be transferred in chunks of this
 * size.
 */
#ifndef PIPE_DIRECT_CHUNK
#define PIPE_DIRECT_CHUNK       (1*1024*1024)
#endif

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

/*
 * 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 {
        size_t  cnt;            /* number of chars currently in buffer */
        u_int   in;             /* in pointer */
        u_int   out;            /* out pointer */
        size_t  size;           /* size of buffer */
        void *  buffer;         /* kva of buffer */
};

/*
 * Bits in pipe_state.
 */
#define PIPE_ASYNC      0x001   /* Async I/O */
#define PIPE_EOF        0x010   /* Pipe is in EOF condition */
#define PIPE_SIGNALR    0x020   /* Do selwakeup() on read(2) */
#define PIPE_LOCKFL     0x100   /* Process has exclusive access to
                                   pointers/data. */
/*      unused          0x200   */
#define PIPE_RESTART    0x400   /* Return ERESTART to blocked syscalls */

/*
 * Per-pipe data structure.
 * Two of these are linked together to produce bi-directional pipes.
 */
struct pipe {
        kmutex_t *pipe_lock;            /* pipe mutex */
        kcondvar_t pipe_rcv;            /* cv for readers */
        kcondvar_t pipe_wcv;            /* cv for writers */
        kcondvar_t pipe_draincv;        /* cv for close */
        kcondvar_t pipe_lkcv;           /* locking */
        struct  pipebuf pipe_buffer;    /* data storage */
        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_btime;    /* time of creation */
        struct  pipe *pipe_peer;        /* link with other direction */
        pid_t   pipe_pgid;              /* process group for sigio */
        u_int   pipe_state;             /* pipe status info */
        int     pipe_busy;              /* busy flag, to handle rundown */
        vaddr_t pipe_kmem;              /* preallocated PIPE_SIZE buffer */
};

/*
 * KERN_PIPE subtypes
 */
#define KERN_PIPE_MAXKVASZ              1       /* maximum kva size (obsolete) */
#define KERN_PIPE_LIMITKVA              2       /* limit kva for loans (obsolete) */
#define KERN_PIPE_MAXBIGPIPES           3       /* maximum # of "big" pipes */
#define KERN_PIPE_NBIGPIPES             4       /* current number of "big" p. */
#define KERN_PIPE_KVASIZE               5       /* current pipe kva size */

#ifdef _KERNEL
int     sysctl_dopipe(int *, u_int, void *, size_t *, void *, size_t);
void    pipe_init(void);
#endif /* _KERNEL */

#endif /* !_SYS_PIPE_H_ */