| 1 | /*-
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| 2 |  * Copyright (c) 1991, 1993, 1994
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| 3 |  *      The Regents of the University of California.  All rights reserved.
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| 4 |  *
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| 5 |  * This code is derived from software contributed to Berkeley by
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| 6 |  * Mike Olson.
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| 7 |  *
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| 8 |  * Redistribution and use in source and binary forms, with or without
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| 9 |  * modification, are permitted provided that the following conditions
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| 10 |  * are met:
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| 11 |  * 1. Redistributions of source code must retain the above copyright
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| 12 |  *    notice, this list of conditions and the following disclaimer.
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| 13 |  * 2. Redistributions in binary form must reproduce the above copyright
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| 14 |  *    notice, this list of conditions and the following disclaimer in the
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| 15 |  *    documentation and/or other materials provided with the distribution.
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| 16 |  * 3. All advertising materials mentioning features or use of this software
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| 17 |  *    must display the following acknowledgement:
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| 18 |  *      This product includes software developed by the University of
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| 19 |  *      California, Berkeley and its contributors.
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| 20 |  * 4. Neither the name of the University nor the names of its contributors
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| 21 |  *    may be used to endorse or promote products derived from this software
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| 22 |  *    without specific prior written permission.
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| 23 |  *
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| 24 |  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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| 25 |  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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| 26 |  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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| 27 |  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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| 28 |  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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| 29 |  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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| 30 |  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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| 31 |  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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| 32 |  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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| 33 |  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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| 34 |  * SUCH DAMAGE.
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| 35 |  *
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| 36 |  *      @(#)btree.h     8.11 (Berkeley) 8/17/94
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| 37 |  * $FreeBSD: src/lib/libc/db/btree/btree.h,v 1.3 2002/03/22 23:41:40 obrien Exp $
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| 38 |  */
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| 39 | 
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| 40 | /* Macros to set/clear/test flags. */
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| 41 | #define F_SET(p, f)     (p)->flags |= (f)
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| 42 | #define F_CLR(p, f)     (p)->flags &= ~(f)
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| 43 | #define F_ISSET(p, f)   ((p)->flags & (f))
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| 44 | 
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| 45 | #include <mpool.h>
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| 46 | 
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| 47 | #define DEFMINKEYPAGE   (2)             /* Minimum keys per page */
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| 48 | #define MINCACHE        (5)             /* Minimum cached pages */
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| 49 | #define MINPSIZE        (512)           /* Minimum page size */
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| 50 | 
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| 51 | /*
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| 52 |  * Page 0 of a btree file contains a copy of the meta-data.  This page is also
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| 53 |  * used as an out-of-band page, i.e. page pointers that point to nowhere point
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| 54 |  * to page 0.  Page 1 is the root of the btree.
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| 55 |  */
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| 56 | #define P_INVALID        0              /* Invalid tree page number. */
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| 57 | #define P_META           0              /* Tree metadata page number. */
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| 58 | #define P_ROOT           1              /* Tree root page number. */
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| 59 | 
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| 60 | /*
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| 61 |  * There are five page layouts in the btree: btree internal pages (BINTERNAL),
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| 62 |  * btree leaf pages (BLEAF), recno internal pages (RINTERNAL), recno leaf pages
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| 63 |  * (RLEAF) and overflow pages.  All five page types have a page header (PAGE).
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| 64 |  * This implementation requires that values within structures NOT be padded.
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| 65 |  * (ANSI C permits random padding.)  If your compiler pads randomly you'll have
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| 66 |  * to do some work to get this package to run.
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| 67 |  */
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| 68 | typedef struct _page {
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| 69 |         pgno_t  pgno;                   /* this page's page number */
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| 70 |         pgno_t  prevpg;                 /* left sibling */
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| 71 |         pgno_t  nextpg;                 /* right sibling */
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| 72 | 
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| 73 | #define P_BINTERNAL     0x01            /* btree internal page */
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| 74 | #define P_BLEAF         0x02            /* leaf page */
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| 75 | #define P_OVERFLOW      0x04            /* overflow page */
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| 76 | #define P_RINTERNAL     0x08            /* recno internal page */
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| 77 | #define P_RLEAF         0x10            /* leaf page */
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| 78 | #define P_TYPE          0x1f            /* type mask */
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| 79 | #define P_PRESERVE      0x20            /* never delete this chain of pages */
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| 80 |         u_int32_t flags;
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| 81 | 
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| 82 |         indx_t  lower;                  /* lower bound of free space on page */
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| 83 |         indx_t  upper;                  /* upper bound of free space on page */
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| 84 |         indx_t  linp[1];                /* indx_t-aligned VAR. LENGTH DATA */
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| 85 | } PAGE;
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| 86 | 
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| 87 | /* First and next index. */
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| 88 | #define BTDATAOFF                                                       \
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| 89 |         (sizeof(pgno_t) + sizeof(pgno_t) + sizeof(pgno_t) +             \
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| 90 |             sizeof(u_int32_t) + sizeof(indx_t) + sizeof(indx_t))
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| 91 | #define NEXTINDEX(p)    (((p)->lower - BTDATAOFF) / sizeof(indx_t))
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| 92 | 
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| 93 | /*
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| 94 |  * For pages other than overflow pages, there is an array of offsets into the
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| 95 |  * rest of the page immediately following the page header.  Each offset is to
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| 96 |  * an item which is unique to the type of page.  The h_lower offset is just
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| 97 |  * past the last filled-in index.  The h_upper offset is the first item on the
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| 98 |  * page.  Offsets are from the beginning of the page.
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| 99 |  *
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| 100 |  * If an item is too big to store on a single page, a flag is set and the item
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| 101 |  * is a { page, size } pair such that the page is the first page of an overflow
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| 102 |  * chain with size bytes of item.  Overflow pages are simply bytes without any
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| 103 |  * external structure.
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| 104 |  *
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| 105 |  * The page number and size fields in the items are pgno_t-aligned so they can
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| 106 |  * be manipulated without copying.  (This presumes that 32 bit items can be
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| 107 |  * manipulated on this system.)
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| 108 |  */
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| 109 | #define LALIGN(n)       (((n) + sizeof(pgno_t) - 1) & ~(sizeof(pgno_t) - 1))
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| 110 | #define NOVFLSIZE       (sizeof(pgno_t) + sizeof(u_int32_t))
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| 111 | 
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| 112 | /*
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| 113 |  * For the btree internal pages, the item is a key.  BINTERNALs are {key, pgno}
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| 114 |  * pairs, such that the key compares less than or equal to all of the records
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| 115 |  * on that page.  For a tree without duplicate keys, an internal page with two
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| 116 |  * consecutive keys, a and b, will have all records greater than or equal to a
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| 117 |  * and less than b stored on the page associated with a.  Duplicate keys are
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| 118 |  * somewhat special and can cause duplicate internal and leaf page records and
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| 119 |  * some minor modifications of the above rule.
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| 120 |  */
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| 121 | typedef struct _binternal {
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| 122 |         u_int32_t ksize;                /* key size */
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| 123 |         pgno_t  pgno;                   /* page number stored on */
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| 124 | #define P_BIGDATA       0x01            /* overflow data */
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| 125 | #define P_BIGKEY        0x02            /* overflow key */
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| 126 |         u_char  flags;
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| 127 |         char    bytes[1];               /* data */
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| 128 | } BINTERNAL;
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| 129 | 
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| 130 | /* Get the page's BINTERNAL structure at index indx. */
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| 131 | #define GETBINTERNAL(pg, indx)                                          \
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| 132 |         ((BINTERNAL *)((char *)(pg) + (pg)->linp[indx]))
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| 133 | 
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| 134 | /* Get the number of bytes in the entry. */
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| 135 | #define NBINTERNAL(len)                                                 \
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| 136 |         LALIGN(sizeof(u_int32_t) + sizeof(pgno_t) + sizeof(u_char) + (len))
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| 137 | 
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| 138 | /* Copy a BINTERNAL entry to the page. */
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| 139 | #define WR_BINTERNAL(p, size, pgno, flags) {                            \
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| 140 |         *(u_int32_t *)p = size;                                         \
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| 141 |         p += sizeof(u_int32_t);                                         \
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| 142 |         *(pgno_t *)p = pgno;                                            \
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| 143 |         p += sizeof(pgno_t);                                            \
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| 144 |         *(u_char *)p = flags;                                           \
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| 145 |         p += sizeof(u_char);                                            \
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| 146 | }
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| 147 | 
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| 148 | /*
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| 149 |  * For the recno internal pages, the item is a page number with the number of
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| 150 |  * keys found on that page and below.
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| 151 |  */
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| 152 | typedef struct _rinternal {
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| 153 |         recno_t nrecs;                  /* number of records */
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| 154 |         pgno_t  pgno;                   /* page number stored below */
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| 155 | } RINTERNAL;
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| 156 | 
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| 157 | /* Get the page's RINTERNAL structure at index indx. */
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| 158 | #define GETRINTERNAL(pg, indx)                                          \
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| 159 |         ((RINTERNAL *)((char *)(pg) + (pg)->linp[indx]))
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| 160 | 
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| 161 | /* Get the number of bytes in the entry. */
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| 162 | #define NRINTERNAL                                                      \
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| 163 |         LALIGN(sizeof(recno_t) + sizeof(pgno_t))
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| 164 | 
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| 165 | /* Copy a RINTERAL entry to the page. */
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| 166 | #define WR_RINTERNAL(p, nrecs, pgno) {                                  \
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| 167 |         *(recno_t *)p = nrecs;                                          \
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| 168 |         p += sizeof(recno_t);                                           \
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| 169 |         *(pgno_t *)p = pgno;                                            \
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| 170 | }
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| 171 | 
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| 172 | /* For the btree leaf pages, the item is a key and data pair. */
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| 173 | typedef struct _bleaf {
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| 174 |         u_int32_t       ksize;          /* size of key */
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| 175 |         u_int32_t       dsize;          /* size of data */
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| 176 |         u_char  flags;                  /* P_BIGDATA, P_BIGKEY */
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| 177 |         char    bytes[1];               /* data */
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| 178 | } BLEAF;
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| 179 | 
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| 180 | /* Get the page's BLEAF structure at index indx. */
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| 181 | #define GETBLEAF(pg, indx)                                              \
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| 182 |         ((BLEAF *)((char *)(pg) + (pg)->linp[indx]))
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| 183 | 
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| 184 | /* Get the number of bytes in the entry. */
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| 185 | #define NBLEAF(p)       NBLEAFDBT((p)->ksize, (p)->dsize)
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| 186 | 
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| 187 | /* Get the number of bytes in the user's key/data pair. */
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| 188 | #define NBLEAFDBT(ksize, dsize)                                         \
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| 189 |         LALIGN(sizeof(u_int32_t) + sizeof(u_int32_t) + sizeof(u_char) + \
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| 190 |             (ksize) + (dsize))
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| 191 | 
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| 192 | /* Copy a BLEAF entry to the page. */
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| 193 | #define WR_BLEAF(p, key, data, flags) {                                 \
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| 194 |         *(u_int32_t *)p = key->size;                                    \
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| 195 |         p += sizeof(u_int32_t);                                         \
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| 196 |         *(u_int32_t *)p = data->size;                                   \
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| 197 |         p += sizeof(u_int32_t);                                         \
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| 198 |         *(u_char *)p = flags;                                           \
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| 199 |         p += sizeof(u_char);                                            \
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| 200 |         memmove(p, key->data, key->size);                               \
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| 201 |         p += key->size;                                                 \
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| 202 |         memmove(p, data->data, data->size);                             \
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| 203 | }
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| 204 | 
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| 205 | /* For the recno leaf pages, the item is a data entry. */
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| 206 | typedef struct _rleaf {
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| 207 |         u_int32_t       dsize;          /* size of data */
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| 208 |         u_char  flags;                  /* P_BIGDATA */
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| 209 |         char    bytes[1];
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| 210 | } RLEAF;
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| 211 | 
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| 212 | /* Get the page's RLEAF structure at index indx. */
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| 213 | #define GETRLEAF(pg, indx)                                              \
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| 214 |         ((RLEAF *)((char *)(pg) + (pg)->linp[indx]))
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| 215 | 
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| 216 | /* Get the number of bytes in the entry. */
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| 217 | #define NRLEAF(p)       NRLEAFDBT((p)->dsize)
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| 218 | 
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| 219 | /* Get the number of bytes from the user's data. */
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| 220 | #define NRLEAFDBT(dsize)                                                \
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| 221 |         LALIGN(sizeof(u_int32_t) + sizeof(u_char) + (dsize))
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| 222 | 
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| 223 | /* Copy a RLEAF entry to the page. */
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| 224 | #define WR_RLEAF(p, data, flags) {                                      \
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| 225 |         *(u_int32_t *)p = data->size;                                   \
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| 226 |         p += sizeof(u_int32_t);                                         \
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| 227 |         *(u_char *)p = flags;                                           \
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| 228 |         p += sizeof(u_char);                                            \
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| 229 |         memmove(p, data->data, data->size);                             \
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| 230 | }
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| 231 | 
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| 232 | /*
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| 233 |  * A record in the tree is either a pointer to a page and an index in the page
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| 234 |  * or a page number and an index.  These structures are used as a cursor, stack
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| 235 |  * entry and search returns as well as to pass records to other routines.
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| 236 |  *
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| 237 |  * One comment about searches.  Internal page searches must find the largest
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| 238 |  * record less than key in the tree so that descents work.  Leaf page searches
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| 239 |  * must find the smallest record greater than key so that the returned index
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| 240 |  * is the record's correct position for insertion.
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| 241 |  */
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| 242 | typedef struct _epgno {
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| 243 |         pgno_t  pgno;                   /* the page number */
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| 244 |         indx_t  index;                  /* the index on the page */
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| 245 | } EPGNO;
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| 246 | 
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| 247 | typedef struct _epg {
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| 248 |         PAGE    *page;                  /* the (pinned) page */
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| 249 |         indx_t   index;                 /* the index on the page */
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| 250 | } EPG;
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| 251 | 
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| 252 | /*
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| 253 |  * About cursors.  The cursor (and the page that contained the key/data pair
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| 254 |  * that it referenced) can be deleted, which makes things a bit tricky.  If
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| 255 |  * there are no duplicates of the cursor key in the tree (i.e. B_NODUPS is set
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| 256 |  * or there simply aren't any duplicates of the key) we copy the key that it
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| 257 |  * referenced when it's deleted, and reacquire a new cursor key if the cursor
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| 258 |  * is used again.  If there are duplicates keys, we move to the next/previous
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| 259 |  * key, and set a flag so that we know what happened.  NOTE: if duplicate (to
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| 260 |  * the cursor) keys are added to the tree during this process, it is undefined
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| 261 |  * if they will be returned or not in a cursor scan.
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| 262 |  *
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| 263 |  * The flags determine the possible states of the cursor:
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| 264 |  *
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| 265 |  * CURS_INIT    The cursor references *something*.
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| 266 |  * CURS_ACQUIRE The cursor was deleted, and a key has been saved so that
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| 267 |  *              we can reacquire the right position in the tree.
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| 268 |  * CURS_AFTER, CURS_BEFORE
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| 269 |  *              The cursor was deleted, and now references a key/data pair
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| 270 |  *              that has not yet been returned, either before or after the
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| 271 |  *              deleted key/data pair.
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| 272 |  * XXX
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| 273 |  * This structure is broken out so that we can eventually offer multiple
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| 274 |  * cursors as part of the DB interface.
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| 275 |  */
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| 276 | typedef struct _cursor {
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| 277 |         EPGNO    pg;                    /* B: Saved tree reference. */
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| 278 |         DBT      key;                   /* B: Saved key, or key.data == NULL. */
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| 279 |         recno_t  rcursor;               /* R: recno cursor (1-based) */
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| 280 | 
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| 281 | #define CURS_ACQUIRE    0x01            /*  B: Cursor needs to be reacquired. */
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| 282 | #define CURS_AFTER      0x02            /*  B: Unreturned cursor after key. */
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| 283 | #define CURS_BEFORE     0x04            /*  B: Unreturned cursor before key. */
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| 284 | #define CURS_INIT       0x08            /* RB: Cursor initialized. */
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| 285 |         u_int8_t flags;
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| 286 | } CURSOR;
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| 287 | 
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| 288 | /*
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| 289 |  * The metadata of the tree.  The nrecs field is used only by the RECNO code.
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| 290 |  * This is because the btree doesn't really need it and it requires that every
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| 291 |  * put or delete call modify the metadata.
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| 292 |  */
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| 293 | typedef struct _btmeta {
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| 294 |         u_int32_t       magic;          /* magic number */
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| 295 |         u_int32_t       version;        /* version */
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| 296 |         u_int32_t       psize;          /* page size */
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| 297 |         u_int32_t       free;           /* page number of first free page */
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| 298 |         u_int32_t       nrecs;          /* R: number of records */
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| 299 | 
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| 300 | #define SAVEMETA        (B_NODUPS | R_RECNO)
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| 301 |         u_int32_t       flags;          /* bt_flags & SAVEMETA */
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| 302 | } BTMETA;
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| 303 | 
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| 304 | /* The in-memory btree/recno data structure. */
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| 305 | typedef struct _btree {
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| 306 |         MPOOL    *bt_mp;                /* memory pool cookie */
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| 307 | 
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| 308 |         DB       *bt_dbp;               /* pointer to enclosing DB */
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| 309 | 
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| 310 |         EPG       bt_cur;               /* current (pinned) page */
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| 311 |         PAGE     *bt_pinned;            /* page pinned across calls */
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| 312 | 
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| 313 |         CURSOR    bt_cursor;            /* cursor */
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| 314 | 
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| 315 | #define BT_PUSH(t, p, i) {                                              \
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| 316 |         t->bt_sp->pgno = p;                                             \
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| 317 |         t->bt_sp->index = i;                                            \
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| 318 |         ++t->bt_sp;                                                     \
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| 319 | }
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| 320 | #define BT_POP(t)       (t->bt_sp == t->bt_stack ? NULL : --t->bt_sp)
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| 321 | #define BT_CLR(t)       (t->bt_sp = t->bt_stack)
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| 322 |         EPGNO     bt_stack[50];         /* stack of parent pages */
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| 323 |         EPGNO    *bt_sp;                /* current stack pointer */
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| 324 | 
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| 325 |         DBT       bt_rkey;              /* returned key */
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| 326 |         DBT       bt_rdata;             /* returned data */
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| 327 | 
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| 328 |         int       bt_fd;                /* tree file descriptor */
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| 329 | 
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| 330 |         pgno_t    bt_free;              /* next free page */
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| 331 |         u_int32_t bt_psize;             /* page size */
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| 332 |         indx_t    bt_ovflsize;          /* cut-off for key/data overflow */
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| 333 |         int       bt_lorder;            /* byte order */
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| 334 |                                         /* sorted order */
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| 335 |         enum { NOT, BACK, FORWARD } bt_order;
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| 336 |         EPGNO     bt_last;              /* last insert */
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| 337 | 
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| 338 |                                         /* B: key comparison function */
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| 339 |         int     (*bt_cmp)(const DBT *, const DBT *);
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| 340 |                                         /* B: prefix comparison function */
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| 341 |         size_t  (*bt_pfx)(const DBT *, const DBT *);
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| 342 |                                         /* R: recno input function */
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| 343 |         int     (*bt_irec)(struct _btree *, recno_t);
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| 344 | 
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| 345 |         FILE     *bt_rfp;               /* R: record FILE pointer */
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| 346 |         int       bt_rfd;               /* R: record file descriptor */
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| 347 | 
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| 348 |         caddr_t   bt_cmap;              /* R: current point in mapped space */
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| 349 |         caddr_t   bt_smap;              /* R: start of mapped space */
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| 350 |         caddr_t   bt_emap;              /* R: end of mapped space */
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| 351 |         size_t    bt_msize;             /* R: size of mapped region. */
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| 352 | 
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| 353 |         recno_t   bt_nrecs;             /* R: number of records */
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| 354 |         size_t    bt_reclen;            /* R: fixed record length */
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| 355 |         u_char    bt_bval;              /* R: delimiting byte/pad character */
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| 356 | 
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| 357 | /*
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| 358 |  * NB:
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| 359 |  * B_NODUPS and R_RECNO are stored on disk, and may not be changed.
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| 360 |  */
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| 361 | #define B_INMEM         0x00001         /* in-memory tree */
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| 362 | #define B_METADIRTY     0x00002         /* need to write metadata */
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| 363 | #define B_MODIFIED      0x00004         /* tree modified */
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| 364 | #define B_NEEDSWAP      0x00008         /* if byte order requires swapping */
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| 365 | #define B_RDONLY        0x00010         /* read-only tree */
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| 366 | 
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| 367 | #define B_NODUPS        0x00020         /* no duplicate keys permitted */
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| 368 | #define R_RECNO         0x00080         /* record oriented tree */
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| 369 | 
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| 370 | #define R_CLOSEFP       0x00040         /* opened a file pointer */
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| 371 | #define R_EOF           0x00100         /* end of input file reached. */
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| 372 | #define R_FIXLEN        0x00200         /* fixed length records */
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| 373 | #define R_MEMMAPPED     0x00400         /* memory mapped file. */
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| 374 | #define R_INMEM         0x00800         /* in-memory file */
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| 375 | #define R_MODIFIED      0x01000         /* modified file */
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| 376 | #define R_RDONLY        0x02000         /* read-only file */
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| 377 | 
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| 378 | #define B_DB_LOCK       0x04000         /* DB_LOCK specified. */
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| 379 | #define B_DB_SHMEM      0x08000         /* DB_SHMEM specified. */
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| 380 | #define B_DB_TXN        0x10000         /* DB_TXN specified. */
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| 381 |         u_int32_t flags;
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| 382 | } BTREE;
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| 383 | 
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| 384 | #include "extern.h"
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