/*-
 * 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.
 */

#ifndef _SYS_PIPE_H_
#define _SYS_PIPE_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   (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)

#ifdef _KERNEL
/*
 * See sys_pipe.c for info on what these limits mean. 
 */
extern long     maxpipekva;
extern const struct fileops pipeops;
#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 {
        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 {
        u_int           cnt;            /* number of chars in buffer */
        u_int           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_DIRECTW    0x400   /* Pipe direct write active. */
#define PIPE_DIRECTOK   0x800   /* Direct mode ok. */

/*
 * Bits in pipe_type.
 */
#define PIPE_TYPE_NAMED 0x001   /* 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_pages; /* wired pages 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_short pipe_state;             /* pipe status info */
        u_char  pipe_type;              /* pipe type info */
        u_char  pipe_present;           /* still present? */
        int     pipe_waiters;           /* pipelock waiters */
        int     pipe_busy;              /* busy flag, mostly to handle rundown sanely */
        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;
        struct ucred    *pp_owner;      /* to dec pipe usage count */
};

#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))

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