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 #if defined(LIBC_SCCS) && !defined(lint) 36 static char sccsid[] = "@(#)bt_overflow.c 8.5 (Berkeley) 7/16/94"; 37 #endif /* LIBC_SCCS and not lint */ 38 #include <sys/param.h> 39 40 #include <stdio.h> 41 #include <stdlib.h> 42 #include <string.h> 43 44 #include <db.h> 45 #include "btree.h" 46 47 /* 48 * Big key/data code. 49 * 50 * Big key and data entries are stored on linked lists of pages. The initial 51 * reference is byte string stored with the key or data and is the page number 52 * and size. The actual record is stored in a chain of pages linked by the 53 * nextpg field of the PAGE header. 54 * 55 * The first page of the chain has a special property. If the record is used 56 * by an internal page, it cannot be deleted and the P_PRESERVE bit will be set 57 * in the header. 58 * 59 * XXX 60 * A single DBT is written to each chain, so a lot of space on the last page 61 * is wasted. This is a fairly major bug for some data sets. 62 */ 63 64 /* 65 * __OVFL_GET -- Get an overflow key/data item. 66 * 67 * Parameters: 68 * t: tree 69 * p: pointer to { pgno_t, u_int32_t } 70 * buf: storage address 71 * bufsz: storage size 72 * 73 * Returns: 74 * RET_ERROR, RET_SUCCESS 75 */ 76 int 77 __ovfl_get(BTREE *t, void *p, size_t *ssz, void **buf, size_t *bufsz) 78 { 79 PAGE *h; 80 pgno_t pg; 81 size_t nb, plen; 82 u_int32_t sz; 83 84 memmove(&pg, p, sizeof(pgno_t)); 85 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); 86 *ssz = sz; 87 88 #ifdef DEBUG 89 if (pg == P_INVALID || sz == 0) 90 abort(); 91 #endif 92 /* Make the buffer bigger as necessary. */ 93 if (*bufsz < sz) { 94 *buf = reallocf(*buf, sz); 95 if (*buf == NULL) 96 return (RET_ERROR); 97 *bufsz = sz; 98 } 99 100 /* 101 * Step through the linked list of pages, copying the data on each one 102 * into the buffer. Never copy more than the data's length. 103 */ 104 plen = t->bt_psize - BTDATAOFF; 105 for (p = *buf;; p = (char *)p + nb, pg = h->nextpg) { 106 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 107 return (RET_ERROR); 108 109 nb = MIN(sz, plen); 110 memmove(p, (char *)h + BTDATAOFF, nb); 111 mpool_put(t->bt_mp, h, 0); 112 113 if ((sz -= nb) == 0) 114 break; 115 } 116 return (RET_SUCCESS); 117 } 118 119 /* 120 * __OVFL_PUT -- Store an overflow key/data item. 121 * 122 * Parameters: 123 * t: tree 124 * data: DBT to store 125 * pgno: storage page number 126 * 127 * Returns: 128 * RET_ERROR, RET_SUCCESS 129 */ 130 int 131 __ovfl_put(BTREE *t, const DBT *dbt, pgno_t *pg) 132 { 133 PAGE *h, *last; 134 void *p; 135 pgno_t npg; 136 size_t nb, plen; 137 u_int32_t sz; 138 139 /* 140 * Allocate pages and copy the key/data record into them. Store the 141 * number of the first page in the chain. 142 */ 143 plen = t->bt_psize - BTDATAOFF; 144 for (last = NULL, p = dbt->data, sz = dbt->size;; 145 p = (char *)p + plen, last = h) { 146 if ((h = __bt_new(t, &npg)) == NULL) 147 return (RET_ERROR); 148 149 h->pgno = npg; 150 h->nextpg = h->prevpg = P_INVALID; 151 h->flags = P_OVERFLOW; 152 h->lower = h->upper = 0; 153 154 nb = MIN(sz, plen); 155 memmove((char *)h + BTDATAOFF, p, nb); 156 157 if (last) { 158 last->nextpg = h->pgno; 159 mpool_put(t->bt_mp, last, MPOOL_DIRTY); 160 } else 161 *pg = h->pgno; 162 163 if ((sz -= nb) == 0) { 164 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 165 break; 166 } 167 } 168 return (RET_SUCCESS); 169 } 170 171 /* 172 * __OVFL_DELETE -- Delete an overflow chain. 173 * 174 * Parameters: 175 * t: tree 176 * p: pointer to { pgno_t, u_int32_t } 177 * 178 * Returns: 179 * RET_ERROR, RET_SUCCESS 180 */ 181 int 182 __ovfl_delete(BTREE *t, void *p) 183 { 184 PAGE *h; 185 pgno_t pg; 186 size_t plen; 187 u_int32_t sz; 188 189 memmove(&pg, p, sizeof(pgno_t)); 190 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); 191 192 #ifdef DEBUG 193 if (pg == P_INVALID || sz == 0) 194 abort(); 195 #endif 196 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 197 return (RET_ERROR); 198 199 /* Don't delete chains used by internal pages. */ 200 if (h->flags & P_PRESERVE) { 201 mpool_put(t->bt_mp, h, 0); 202 return (RET_SUCCESS); 203 } 204 205 /* Step through the chain, calling the free routine for each page. */ 206 for (plen = t->bt_psize - BTDATAOFF;; sz -= plen) { 207 pg = h->nextpg; 208 __bt_free(t, h); 209 if (sz <= plen) 210 break; 211 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 212 return (RET_ERROR); 213 } 214 return (RET_SUCCESS); 215 } 216