1/* $NetBSD: bt_overflow.c,v 1.22 2016/09/24 21:31:25 christos Exp $ */ 2 3/*- 4 * Copyright (c) 1990, 1993, 1994 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Mike Olson. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35#if HAVE_NBTOOL_CONFIG_H 36#include "nbtool_config.h" 37#endif 38 39#include <sys/cdefs.h> 40__RCSID("$NetBSD: bt_overflow.c,v 1.22 2016/09/24 21:31:25 christos Exp $"); 41 42#include "namespace.h" 43#include <sys/param.h> 44 45#include <assert.h> 46#include <stdio.h> 47#include <stdlib.h> 48#include <string.h> 49 50#include <db.h> 51#include "btree.h" 52 53/* 54 * Big key/data code. 55 * 56 * Big key and data entries are stored on linked lists of pages. The initial 57 * reference is byte string stored with the key or data and is the page number 58 * and size. The actual record is stored in a chain of pages linked by the 59 * nextpg field of the PAGE header. 60 * 61 * The first page of the chain has a special property. If the record is used 62 * by an internal page, it cannot be deleted and the P_PRESERVE bit will be set 63 * in the header. 64 * 65 * XXX 66 * A single DBT is written to each chain, so a lot of space on the last page 67 * is wasted. This is a fairly major bug for some data sets. 68 */ 69 70/* 71 * __OVFL_GET -- Get an overflow key/data item. 72 * 73 * Parameters: 74 * t: tree 75 * p: pointer to { pgno_t, uint32_t } 76 * buf: storage address 77 * bufsz: storage size 78 * 79 * Returns: 80 * RET_ERROR, RET_SUCCESS 81 */ 82int 83__ovfl_get(BTREE *t, void *p, size_t *ssz, void **buf, size_t *bufsz) 84{ 85 PAGE *h; 86 pgno_t pg; 87 uint32_t sz, nb, plen; 88 size_t temp; 89 90 memmove(&pg, p, sizeof(pg)); 91 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(uint32_t)); 92 *ssz = sz; 93 94#ifdef DEBUG 95 if (pg == P_INVALID || sz == 0) 96 abort(); 97#endif 98 /* Make the buffer bigger as necessary. */ 99 if (*bufsz < sz) { 100 void *nbuf = realloc(*buf, sz); 101 if (nbuf == NULL) 102 return (RET_ERROR); 103 *buf = nbuf; 104 *bufsz = sz; 105 } 106 107 /* 108 * Step through the linked list of pages, copying the data on each one 109 * into the buffer. Never copy more than the data's length. 110 */ 111 temp = t->bt_psize - BTDATAOFF; 112 _DBFIT(temp, uint32_t); 113 plen = (uint32_t)temp; 114 for (p = *buf;; p = (char *)p + nb, pg = h->nextpg) { 115 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 116 return (RET_ERROR); 117 118 nb = MIN(sz, plen); 119 memmove(p, (char *)(void *)h + BTDATAOFF, nb); 120 mpool_put(t->bt_mp, h, 0); 121 122 if ((sz -= nb) == 0) 123 break; 124 } 125 return (RET_SUCCESS); 126} 127 128/* 129 * __OVFL_PUT -- Store an overflow key/data item. 130 * 131 * Parameters: 132 * t: tree 133 * data: DBT to store 134 * pgno: storage page number 135 * 136 * Returns: 137 * RET_ERROR, RET_SUCCESS 138 */ 139int 140__ovfl_put(BTREE *t, const DBT *dbt, pgno_t *pg) 141{ 142 PAGE *h, *last; 143 void *p; 144 pgno_t npg; 145 uint32_t sz, nb, plen; 146 size_t temp; 147 148 /* 149 * Allocate pages and copy the key/data record into them. Store the 150 * number of the first page in the chain. 151 */ 152 temp = t->bt_psize - BTDATAOFF; 153 _DBFIT(temp, uint32_t); 154 plen = (uint32_t)temp; 155 last = NULL; 156 p = dbt->data; 157 temp = dbt->size; 158 _DBFIT(temp, uint32_t); 159 sz = (uint32_t)temp; 160 for (;; p = (char *)p + plen, last = h) { 161 if ((h = __bt_new(t, &npg)) == NULL) 162 return (RET_ERROR); 163 164 h->pgno = npg; 165 h->nextpg = h->prevpg = P_INVALID; 166 h->flags = P_OVERFLOW; 167 h->lower = h->upper = 0; 168 169 nb = MIN(sz, plen); 170 (void)memmove((char *)(void *)h + BTDATAOFF, p, (size_t)nb); 171 172 if (last) { 173 last->nextpg = h->pgno; 174 mpool_put(t->bt_mp, last, MPOOL_DIRTY); 175 } else 176 *pg = h->pgno; 177 178 if ((sz -= nb) == 0) { 179 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 180 break; 181 } 182 } 183 return (RET_SUCCESS); 184} 185 186/* 187 * __OVFL_DELETE -- Delete an overflow chain. 188 * 189 * Parameters: 190 * t: tree 191 * p: pointer to { pgno_t, uint32_t } 192 * 193 * Returns: 194 * RET_ERROR, RET_SUCCESS 195 */ 196int 197__ovfl_delete(BTREE *t, void *p) 198{ 199 PAGE *h; 200 pgno_t pg; 201 uint32_t sz, plen; 202 size_t temp; 203 204 (void)memmove(&pg, p, sizeof(pg)); 205 (void)memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(uint32_t)); 206 207#ifdef DEBUG 208 if (pg == P_INVALID || sz == 0) 209 abort(); 210#endif 211 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 212 return (RET_ERROR); 213 214 /* Don't delete chains used by internal pages. */ 215 if (h->flags & P_PRESERVE) { 216 mpool_put(t->bt_mp, h, 0); 217 return (RET_SUCCESS); 218 } 219 220 /* Step through the chain, calling the free routine for each page. */ 221 temp = t->bt_psize - BTDATAOFF; 222 _DBFIT(temp, uint32_t); 223 plen = (uint32_t)temp; 224 for (;; sz -= plen) { 225 pg = h->nextpg; 226 __bt_free(t, h); 227 if (sz <= plen) 228 break; 229 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 230 return (RET_ERROR); 231 } 232 return (RET_SUCCESS); 233} 234