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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