The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*-
    2  * Copyright (c) 1996 John S. Dyson
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice immediately at the beginning of the file, without modification,
   10  *    this list of conditions, and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  * 3. Absolutely no warranty of function or purpose is made by the author
   15  *    John S. Dyson.
   16  * 4. This work was done expressly for inclusion into FreeBSD.  Other use
   17  *    is allowed if this notation is included.
   18  * 5. Modifications may be freely made to this file if the above conditions
   19  *    are met.
   20  *
   21  * $FreeBSD: releng/10.2/sys/sys/pipe.h 268335 2014-07-06 22:47:18Z mjg $
   22  */
   23 
   24 #ifndef _SYS_PIPE_H_
   25 #define _SYS_PIPE_H_
   26 
   27 #ifndef _KERNEL
   28 #error "no user-servicable parts inside"
   29 #endif
   30 
   31 /*
   32  * Pipe buffer size, keep moderate in value, pipes take kva space.
   33  */
   34 #ifndef PIPE_SIZE
   35 #define PIPE_SIZE       16384
   36 #endif
   37 
   38 #ifndef BIG_PIPE_SIZE
   39 #define BIG_PIPE_SIZE   (64*1024)
   40 #endif
   41 
   42 #ifndef SMALL_PIPE_SIZE
   43 #define SMALL_PIPE_SIZE PAGE_SIZE
   44 #endif
   45 
   46 /*
   47  * PIPE_MINDIRECT MUST be smaller than PIPE_SIZE and MUST be bigger
   48  * than PIPE_BUF.
   49  */
   50 #ifndef PIPE_MINDIRECT
   51 #define PIPE_MINDIRECT  8192
   52 #endif
   53 
   54 #define PIPENPAGES      (BIG_PIPE_SIZE / PAGE_SIZE + 1)
   55 
   56 /*
   57  * See sys_pipe.c for info on what these limits mean. 
   58  */
   59 extern long     maxpipekva;
   60 extern struct   fileops pipeops;
   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         u_int   cnt;            /* number of chars currently in buffer */
   69         u_int   in;             /* in pointer */
   70         u_int   out;            /* out pointer */
   71         u_int   size;           /* size of buffer */
   72         caddr_t buffer;         /* kva of buffer */
   73 };
   74 
   75 /*
   76  * Information to support direct transfers between processes for pipes.
   77  */
   78 struct pipemapping {
   79         vm_size_t       cnt;            /* number of chars in buffer */
   80         vm_size_t       pos;            /* current position of transfer */
   81         int             npages;         /* number of pages */
   82         vm_page_t       ms[PIPENPAGES]; /* pages in source process */
   83 };
   84 
   85 /*
   86  * Bits in pipe_state.
   87  */
   88 #define PIPE_ASYNC      0x004   /* Async? I/O. */
   89 #define PIPE_WANTR      0x008   /* Reader wants some characters. */
   90 #define PIPE_WANTW      0x010   /* Writer wants space to put characters. */
   91 #define PIPE_WANT       0x020   /* Pipe is wanted to be run-down. */
   92 #define PIPE_SEL        0x040   /* Pipe has a select active. */
   93 #define PIPE_EOF        0x080   /* Pipe is in EOF condition. */
   94 #define PIPE_LOCKFL     0x100   /* Process has exclusive access to pointers/data. */
   95 #define PIPE_LWANT      0x200   /* Process wants exclusive access to pointers/data. */
   96 #define PIPE_DIRECTW    0x400   /* Pipe direct write active. */
   97 #define PIPE_DIRECTOK   0x800   /* Direct mode ok. */
   98 #define PIPE_NAMED      0x1000  /* Is a named pipe. */
   99 
  100 /*
  101  * Per-pipe data structure.
  102  * Two of these are linked together to produce bi-directional pipes.
  103  */
  104 struct pipe {
  105         struct  pipebuf pipe_buffer;    /* data storage */
  106         struct  pipemapping pipe_map;   /* pipe mapping for direct I/O */
  107         struct  selinfo pipe_sel;       /* for compat with select */
  108         struct  timespec pipe_atime;    /* time of last access */
  109         struct  timespec pipe_mtime;    /* time of last modify */
  110         struct  timespec pipe_ctime;    /* time of status change */
  111         struct  sigio *pipe_sigio;      /* information for async I/O */
  112         struct  pipe *pipe_peer;        /* link with other direction */
  113         struct  pipepair *pipe_pair;    /* container structure pointer */
  114         u_int   pipe_state;             /* pipe status info */
  115         int     pipe_busy;              /* busy flag, mostly to handle rundown sanely */
  116         int     pipe_present;           /* still present? */
  117         int     pipe_wgen;              /* writer generation for named pipe */
  118         ino_t   pipe_ino;               /* fake inode for stat(2) */
  119 };
  120 
  121 /*
  122  * Values for the pipe_present.
  123  */
  124 #define PIPE_ACTIVE             1
  125 #define PIPE_CLOSING            2
  126 #define PIPE_FINALIZED          3
  127 
  128 /*
  129  * Container structure to hold the two pipe endpoints, mutex, and label
  130  * pointer.
  131  */
  132 struct pipepair {
  133         struct pipe     pp_rpipe;
  134         struct pipe     pp_wpipe;
  135         struct mtx      pp_mtx;
  136         struct label    *pp_label;
  137 };
  138 
  139 #define PIPE_MTX(pipe)          (&(pipe)->pipe_pair->pp_mtx)
  140 #define PIPE_LOCK(pipe)         mtx_lock(PIPE_MTX(pipe))
  141 #define PIPE_UNLOCK(pipe)       mtx_unlock(PIPE_MTX(pipe))
  142 #define PIPE_LOCK_ASSERT(pipe, type)  mtx_assert(PIPE_MTX(pipe), (type))
  143 
  144 void    pipe_dtor(struct pipe *dpipe);
  145 void    pipe_named_ctor(struct pipe **ppipe, struct thread *td);
  146 void    pipeselwakeup(struct pipe *cpipe);
  147 #endif /* !_SYS_PIPE_H_ */

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