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/5.1/sys/sys/pipe.h 101848 2002-08-14 01:04:43Z rwatson $
   22  */
   23 
   24 #ifndef _SYS_PIPE_H_
   25 #define _SYS_PIPE_H_
   26 
   27 #ifndef _KERNEL
   28 #include <sys/time.h>                   /* for struct timespec */
   29 #include <sys/selinfo.h>                /* for struct selinfo */
   30 #include <vm/vm.h>                      /* for vm_page_t */
   31 #include <sys/_label.h>                 /* for struct label */
   32 #include <machine/param.h>              /* for PAGE_SIZE */
   33 #endif
   34 
   35 /*
   36  * Pipe buffer size, keep moderate in value, pipes take kva space.
   37  */
   38 #ifndef PIPE_SIZE
   39 #define PIPE_SIZE       16384
   40 #endif
   41 
   42 #ifndef BIG_PIPE_SIZE
   43 #define BIG_PIPE_SIZE   (64*1024)
   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  * Pipe buffer information.
   58  * Separate in, out, cnt are used to simplify calculations.
   59  * Buffered write is active when the buffer.cnt field is set.
   60  */
   61 struct pipebuf {
   62         u_int   cnt;            /* number of chars currently in buffer */
   63         u_int   in;             /* in pointer */
   64         u_int   out;            /* out pointer */
   65         u_int   size;           /* size of buffer */
   66         caddr_t buffer;         /* kva of buffer */
   67         struct  vm_object *object;      /* VM object containing buffer */
   68 };
   69 
   70 /*
   71  * Information to support direct transfers between processes for pipes.
   72  */
   73 struct pipemapping {
   74         vm_offset_t     kva;            /* kernel virtual address */
   75         vm_size_t       cnt;            /* number of chars in buffer */
   76         vm_size_t       pos;            /* current position of transfer */
   77         int             npages;         /* number of pages */
   78         vm_page_t       ms[PIPENPAGES]; /* pages in source process */
   79 };
   80 
   81 /*
   82  * Bits in pipe_state.
   83  */
   84 #define PIPE_ASYNC      0x004   /* Async? I/O. */
   85 #define PIPE_WANTR      0x008   /* Reader wants some characters. */
   86 #define PIPE_WANTW      0x010   /* Writer wants space to put characters. */
   87 #define PIPE_WANT       0x020   /* Pipe is wanted to be run-down. */
   88 #define PIPE_SEL        0x040   /* Pipe has a select active. */
   89 #define PIPE_EOF        0x080   /* Pipe is in EOF condition. */
   90 #define PIPE_LOCKFL     0x100   /* Process has exclusive access to pointers/data. */
   91 #define PIPE_LWANT      0x200   /* Process wants exclusive access to pointers/data. */
   92 #define PIPE_DIRECTW    0x400   /* Pipe direct write active. */
   93 #define PIPE_DIRECTOK   0x800   /* Direct mode ok. */
   94 
   95 /*
   96  * Per-pipe data structure.
   97  * Two of these are linked together to produce bi-directional pipes.
   98  */
   99 struct pipe {
  100         struct  pipebuf pipe_buffer;    /* data storage */
  101         struct  pipemapping pipe_map;   /* pipe mapping for direct I/O */
  102         struct  selinfo pipe_sel;       /* for compat with select */
  103         struct  timespec pipe_atime;    /* time of last access */
  104         struct  timespec pipe_mtime;    /* time of last modify */
  105         struct  timespec pipe_ctime;    /* time of status change */
  106         struct  sigio *pipe_sigio;      /* information for async I/O */
  107         struct  pipe *pipe_peer;        /* link with other direction */
  108         u_int   pipe_state;             /* pipe status info */
  109         int     pipe_busy;              /* busy flag, mostly to handle rundown sanely */
  110         struct  label *pipe_label;      /* pipe MAC label - shared */
  111         struct  mtx *pipe_mtxp;         /* shared mutex between both pipes */
  112 };
  113 
  114 #define PIPE_MTX(pipe)          (pipe)->pipe_mtxp
  115 #define PIPE_LOCK(pipe)         mtx_lock(PIPE_MTX(pipe))
  116 #define PIPE_UNLOCK(pipe)       mtx_unlock(PIPE_MTX(pipe))
  117 #define PIPE_LOCK_ASSERT(pipe, type)  mtx_assert(PIPE_MTX(pipe), (type))
  118 
  119 
  120 #endif /* !_SYS_PIPE_H_ */

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