1 | /*- |
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2 | * Copyright (c) 1990, 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 | * 4. Neither the name of the University nor the names of its contributors |
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17 | * may be used to endorse or promote products derived from this software |
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18 | * without specific prior written permission. |
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19 | * |
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20 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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21 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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22 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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23 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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24 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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25 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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26 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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27 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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28 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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29 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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30 | * SUCH DAMAGE. |
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31 | */ |
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32 | |
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33 | #if defined(LIBC_SCCS) && !defined(lint) |
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34 | static char sccsid[] = "@(#)bt_overflow.c 8.5 (Berkeley) 7/16/94"; |
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35 | #endif /* LIBC_SCCS and not lint */ |
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36 | #include <sys/cdefs.h> |
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37 | __FBSDID("$FreeBSD$"); |
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38 | |
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39 | #include <rtems/bsd/sys/param.h> |
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40 | |
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41 | #include <stdio.h> |
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42 | #include <stdlib.h> |
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43 | #include <string.h> |
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44 | |
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45 | #include <db.h> |
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46 | #include "btree.h" |
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47 | |
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48 | /* |
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49 | * Big key/data code. |
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50 | * |
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51 | * Big key and data entries are stored on linked lists of pages. The initial |
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52 | * reference is byte string stored with the key or data and is the page number |
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53 | * and size. The actual record is stored in a chain of pages linked by the |
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54 | * nextpg field of the PAGE header. |
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55 | * |
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56 | * The first page of the chain has a special property. If the record is used |
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57 | * by an internal page, it cannot be deleted and the P_PRESERVE bit will be set |
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58 | * in the header. |
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59 | * |
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60 | * XXX |
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61 | * A single DBT is written to each chain, so a lot of space on the last page |
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62 | * is wasted. This is a fairly major bug for some data sets. |
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63 | */ |
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64 | |
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65 | /* |
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66 | * __OVFL_GET -- Get an overflow key/data item. |
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67 | * |
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68 | * Parameters: |
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69 | * t: tree |
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70 | * p: pointer to { pgno_t, u_int32_t } |
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71 | * buf: storage address |
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72 | * bufsz: storage size |
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73 | * |
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74 | * Returns: |
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75 | * RET_ERROR, RET_SUCCESS |
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76 | */ |
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77 | int |
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78 | __ovfl_get(BTREE *t, void *p, size_t *ssz, void **buf, size_t *bufsz) |
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79 | { |
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80 | PAGE *h; |
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81 | pgno_t pg; |
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82 | size_t nb, plen; |
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83 | u_int32_t sz; |
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84 | |
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85 | memmove(&pg, p, sizeof(pgno_t)); |
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86 | memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); |
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87 | *ssz = sz; |
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88 | |
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89 | #ifdef DEBUG |
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90 | if (pg == P_INVALID || sz == 0) |
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91 | abort(); |
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92 | #endif |
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93 | /* Make the buffer bigger as necessary. */ |
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94 | if (*bufsz < sz) { |
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95 | *buf = reallocf(*buf, sz); |
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96 | if (*buf == NULL) |
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97 | return (RET_ERROR); |
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98 | *bufsz = sz; |
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99 | } |
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100 | |
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101 | /* |
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102 | * Step through the linked list of pages, copying the data on each one |
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103 | * into the buffer. Never copy more than the data's length. |
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104 | */ |
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105 | plen = t->bt_psize - BTDATAOFF; |
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106 | for (p = *buf;; p = (char *)p + nb, pg = h->nextpg) { |
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107 | if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) |
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108 | return (RET_ERROR); |
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109 | |
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110 | nb = MIN(sz, plen); |
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111 | memmove(p, (char *)h + BTDATAOFF, nb); |
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112 | mpool_put(t->bt_mp, h, 0); |
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113 | |
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114 | if ((sz -= nb) == 0) |
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115 | break; |
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116 | } |
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117 | return (RET_SUCCESS); |
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118 | } |
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119 | |
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120 | /* |
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121 | * __OVFL_PUT -- Store an overflow key/data item. |
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122 | * |
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123 | * Parameters: |
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124 | * t: tree |
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125 | * data: DBT to store |
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126 | * pgno: storage page number |
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127 | * |
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128 | * Returns: |
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129 | * RET_ERROR, RET_SUCCESS |
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130 | */ |
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131 | int |
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132 | __ovfl_put(BTREE *t, const DBT *dbt, pgno_t *pg) |
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133 | { |
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134 | PAGE *h, *last; |
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135 | void *p; |
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136 | pgno_t npg; |
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137 | size_t nb, plen; |
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138 | u_int32_t sz; |
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139 | |
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140 | /* |
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141 | * Allocate pages and copy the key/data record into them. Store the |
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142 | * number of the first page in the chain. |
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143 | */ |
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144 | plen = t->bt_psize - BTDATAOFF; |
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145 | for (last = NULL, p = dbt->data, sz = dbt->size;; |
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146 | p = (char *)p + plen, last = h) { |
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147 | if ((h = __bt_new(t, &npg)) == NULL) |
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148 | return (RET_ERROR); |
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149 | |
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150 | h->pgno = npg; |
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151 | h->nextpg = h->prevpg = P_INVALID; |
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152 | h->flags = P_OVERFLOW; |
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153 | h->lower = h->upper = 0; |
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154 | |
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155 | nb = MIN(sz, plen); |
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156 | memmove((char *)h + BTDATAOFF, p, nb); |
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157 | |
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158 | if (last) { |
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159 | last->nextpg = h->pgno; |
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160 | mpool_put(t->bt_mp, last, MPOOL_DIRTY); |
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161 | } else |
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162 | *pg = h->pgno; |
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163 | |
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164 | if ((sz -= nb) == 0) { |
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165 | mpool_put(t->bt_mp, h, MPOOL_DIRTY); |
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166 | break; |
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167 | } |
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168 | } |
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169 | return (RET_SUCCESS); |
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170 | } |
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171 | |
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172 | /* |
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173 | * __OVFL_DELETE -- Delete an overflow chain. |
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174 | * |
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175 | * Parameters: |
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176 | * t: tree |
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177 | * p: pointer to { pgno_t, u_int32_t } |
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178 | * |
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179 | * Returns: |
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180 | * RET_ERROR, RET_SUCCESS |
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181 | */ |
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182 | int |
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183 | __ovfl_delete(BTREE *t, void *p) |
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184 | { |
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185 | PAGE *h; |
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186 | pgno_t pg; |
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187 | size_t plen; |
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188 | u_int32_t sz; |
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189 | |
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190 | memmove(&pg, p, sizeof(pgno_t)); |
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191 | memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); |
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192 | |
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193 | #ifdef DEBUG |
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194 | if (pg == P_INVALID || sz == 0) |
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195 | abort(); |
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196 | #endif |
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197 | if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) |
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198 | return (RET_ERROR); |
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199 | |
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200 | /* Don't delete chains used by internal pages. */ |
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201 | if (h->flags & P_PRESERVE) { |
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202 | mpool_put(t->bt_mp, h, 0); |
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203 | return (RET_SUCCESS); |
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204 | } |
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205 | |
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206 | /* Step through the chain, calling the free routine for each page. */ |
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207 | for (plen = t->bt_psize - BTDATAOFF;; sz -= plen) { |
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208 | pg = h->nextpg; |
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209 | __bt_free(t, h); |
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210 | if (sz <= plen) |
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211 | break; |
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212 | if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) |
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213 | return (RET_ERROR); |
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214 | } |
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215 | return (RET_SUCCESS); |
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216 | } |
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