1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 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 #include <sys/param.h> 36 37 #include <stdio.h> 38 #include <stdlib.h> 39 #include <string.h> 40 41 #include <db.h> 42 #include "btree.h" 43 44 /* 45 * Big key/data code. 46 * 47 * Big key and data entries are stored on linked lists of pages. The initial 48 * reference is byte string stored with the key or data and is the page number 49 * and size. The actual record is stored in a chain of pages linked by the 50 * nextpg field of the PAGE header. 51 * 52 * The first page of the chain has a special property. If the record is used 53 * by an internal page, it cannot be deleted and the P_PRESERVE bit will be set 54 * in the header. 55 * 56 * XXX 57 * A single DBT is written to each chain, so a lot of space on the last page 58 * is wasted. This is a fairly major bug for some data sets. 59 */ 60 61 /* 62 * __OVFL_GET -- Get an overflow key/data item. 63 * 64 * Parameters: 65 * t: tree 66 * p: pointer to { pgno_t, u_int32_t } 67 * buf: storage address 68 * bufsz: storage size 69 * 70 * Returns: 71 * RET_ERROR, RET_SUCCESS 72 */ 73 int 74 __ovfl_get(BTREE *t, void *p, size_t *ssz, void **buf, size_t *bufsz) 75 { 76 PAGE *h; 77 pgno_t pg; 78 size_t nb, plen; 79 u_int32_t sz; 80 81 memmove(&pg, p, sizeof(pgno_t)); 82 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); 83 *ssz = sz; 84 85 #ifdef DEBUG 86 if (pg == P_INVALID || sz == 0) 87 abort(); 88 #endif 89 /* Make the buffer bigger as necessary. */ 90 if (*bufsz < sz) { 91 *buf = reallocf(*buf, sz); 92 if (*buf == NULL) 93 return (RET_ERROR); 94 *bufsz = sz; 95 } 96 97 /* 98 * Step through the linked list of pages, copying the data on each one 99 * into the buffer. Never copy more than the data's length. 100 */ 101 plen = t->bt_psize - BTDATAOFF; 102 for (p = *buf;; p = (char *)p + nb, pg = h->nextpg) { 103 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 104 return (RET_ERROR); 105 106 nb = MIN(sz, plen); 107 memmove(p, (char *)h + BTDATAOFF, nb); 108 mpool_put(t->bt_mp, h, 0); 109 110 if ((sz -= nb) == 0) 111 break; 112 } 113 return (RET_SUCCESS); 114 } 115 116 /* 117 * __OVFL_PUT -- Store an overflow key/data item. 118 * 119 * Parameters: 120 * t: tree 121 * data: DBT to store 122 * pgno: storage page number 123 * 124 * Returns: 125 * RET_ERROR, RET_SUCCESS 126 */ 127 int 128 __ovfl_put(BTREE *t, const DBT *dbt, pgno_t *pg) 129 { 130 PAGE *h, *last; 131 void *p; 132 pgno_t npg; 133 size_t nb, plen; 134 u_int32_t sz; 135 136 /* 137 * Allocate pages and copy the key/data record into them. Store the 138 * number of the first page in the chain. 139 */ 140 plen = t->bt_psize - BTDATAOFF; 141 for (last = NULL, p = dbt->data, sz = dbt->size;; 142 p = (char *)p + plen, last = h) { 143 if ((h = __bt_new(t, &npg)) == NULL) 144 return (RET_ERROR); 145 146 h->pgno = npg; 147 h->nextpg = h->prevpg = P_INVALID; 148 h->flags = P_OVERFLOW; 149 h->lower = h->upper = 0; 150 151 nb = MIN(sz, plen); 152 memmove((char *)h + BTDATAOFF, p, nb); 153 154 if (last) { 155 last->nextpg = h->pgno; 156 mpool_put(t->bt_mp, last, MPOOL_DIRTY); 157 } else 158 *pg = h->pgno; 159 160 if ((sz -= nb) == 0) { 161 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 162 break; 163 } 164 } 165 return (RET_SUCCESS); 166 } 167 168 /* 169 * __OVFL_DELETE -- Delete an overflow chain. 170 * 171 * Parameters: 172 * t: tree 173 * p: pointer to { pgno_t, u_int32_t } 174 * 175 * Returns: 176 * RET_ERROR, RET_SUCCESS 177 */ 178 int 179 __ovfl_delete(BTREE *t, void *p) 180 { 181 PAGE *h; 182 pgno_t pg; 183 size_t plen; 184 u_int32_t sz; 185 186 memmove(&pg, p, sizeof(pgno_t)); 187 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); 188 189 #ifdef DEBUG 190 if (pg == P_INVALID || sz == 0) 191 abort(); 192 #endif 193 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 194 return (RET_ERROR); 195 196 /* Don't delete chains used by internal pages. */ 197 if (h->flags & P_PRESERVE) { 198 mpool_put(t->bt_mp, h, 0); 199 return (RET_SUCCESS); 200 } 201 202 /* Step through the chain, calling the free routine for each page. */ 203 for (plen = t->bt_psize - BTDATAOFF;; sz -= plen) { 204 pg = h->nextpg; 205 __bt_free(t, h); 206 if (sz <= plen) 207 break; 208 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 209 return (RET_ERROR); 210 } 211 return (RET_SUCCESS); 212 } 213