FreeBSD/Linux Kernel Cross Reference
sys/sys/pipe.h

     /*
      * 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 1.16 1999/12/29 04:24:45 peter Exp $
     * $DragonFly: src/sys/sys/pipe.h,v 1.10 2006/06/10 20:00:17 dillon Exp $
     */
    
    #ifndef _SYS_PIPE_H_
    #define _SYS_PIPE_H_
    
    #if defined(_KERNEL) || defined(_KERNEL_STRUCTURES)
    
    #ifndef _SYS_TYPES_H_
    #include <sys/types.h>
    #endif
    #ifndef _SYS_TIME_H_
    #include <sys/time.h>                   /* for struct timespec */
    #endif
    #ifndef _SYS_EVENT_H_
    #include <sys/event.h>                  /* for struct kqinfo */
    #endif
    #ifndef _SYS_XIO_H_
    #include <sys/xio.h>                    /* for struct xio */
    #endif
    #ifndef _SYS_THREAD_H_
    #include <sys/thread.h>                 /* for struct lwkt_token */
    #endif
    #ifndef _MACHINE_PARAM_H_
    #include <machine/param.h>              /* for PAGE_SIZE */
    #endif
    
    /*
     * Pipe buffer size, keep moderate in value, pipes take kva space.
     * Must be a multiple of PAGE_SIZE.
     */
    #ifndef PIPE_SIZE
    #define PIPE_SIZE       16384
    #endif
    
    #ifndef BIG_PIPE_SIZE
    #define BIG_PIPE_SIZE   (64*1024)
    #endif
    
    #if PIPE_SIZE < PAGE_SIZE
    #error "PIPE_SIZE is too small for this architecture"
    #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   rindex;         /* FIFO read index */
            u_int   dummy1[3];      /* cache-align */
            u_int   windex;         /* FIFO write index */
            u_int   dummy2[3];      /* cache-align */
            u_int   size;           /* size of buffer */
            caddr_t buffer;         /* kva of buffer */
            struct  vm_object *object;      /* VM object containing buffer */
    };
    
    /*
     * Bits in pipe_state.
     */
    #define PIPE_ASYNC      0x0004  /* Async? I/O */
    #define PIPE_WANTR      0x0008  /* Reader wants some characters */
    #define PIPE_WANTW      0x0010  /* Writer wants space to put characters */
    #define PIPE_REOF       0x0040  /* Pipe is in EOF condition (read EOF) */
    #define PIPE_WEOF       0x0080  /* Pipe is in EOF condition (write shutdown) */
    #define PIPE_CLOSED     0x1000  /* Pipe has been closed */
    
    /*
     * Per-pipe data structure.
     * Two of these are linked together to produce bi-directional pipes.
     */
    struct pipe {
            struct  pipebuf pipe_buffer;    /* data storage */
            struct  kqinfo pipe_kq;         /* for compat with select/poll/kq */
            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 */
           u_int   pipe_state;             /* pipe status info */
           int     pipe_rip;               /* read uio in-progress */
           int     pipe_wip;               /* write uio in-progress */
           u_int   pipe_wantwcnt;          /* for resize */
           struct  lwkt_token pipe_rlock;  /* rindex locked */
           struct  lwkt_token pipe_wlock;  /* windex locked */
           struct  lock *pipe_slock;       /* state locked (shared w/peer) */
   };
   
   #endif  /* _KERNEL || _KERNEL_STRUCTURES */
   #endif /* !_SYS_PIPE_H_ */

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