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/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include <sys/param.h> 42 43 #include <stdio.h> 44 #include <stdlib.h> 45 #include <string.h> 46 47 #include <db.h> 48 #include "btree.h" 49 50 /* 51 * Big key/data code. 52 * 53 * Big key and data entries are stored on linked lists of pages. The initial 54 * reference is byte string stored with the key or data and is the page number 55 * and size. The actual record is stored in a chain of pages linked by the 56 * nextpg field of the PAGE header. 57 * 58 * The first page of the chain has a special property. If the record is used 59 * by an internal page, it cannot be deleted and the P_PRESERVE bit will be set 60 * in the header. 61 * 62 * XXX 63 * A single DBT is written to each chain, so a lot of space on the last page 64 * is wasted. This is a fairly major bug for some data sets. 65 */ 66 67 /* 68 * __OVFL_GET -- Get an overflow key/data item. 69 * 70 * Parameters: 71 * t: tree 72 * p: pointer to { pgno_t, u_int32_t } 73 * buf: storage address 74 * bufsz: storage size 75 * 76 * Returns: 77 * RET_ERROR, RET_SUCCESS 78 */ 79 int 80 __ovfl_get(BTREE *t, void *p, size_t *ssz, void **buf, size_t *bufsz) 81 { 82 PAGE *h; 83 pgno_t pg; 84 size_t nb, plen; 85 u_int32_t sz; 86 87 memmove(&pg, p, sizeof(pgno_t)); 88 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); 89 *ssz = sz; 90 91 #ifdef DEBUG 92 if (pg == P_INVALID || sz == 0) 93 abort(); 94 #endif 95 /* Make the buffer bigger as necessary. */ 96 if (*bufsz < sz) { 97 *buf = reallocf(*buf, sz); 98 if (*buf == NULL) 99 return (RET_ERROR); 100 *bufsz = sz; 101 } 102 103 /* 104 * Step through the linked list of pages, copying the data on each one 105 * into the buffer. Never copy more than the data's length. 106 */ 107 plen = t->bt_psize - BTDATAOFF; 108 for (p = *buf;; p = (char *)p + nb, pg = h->nextpg) { 109 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 110 return (RET_ERROR); 111 112 nb = MIN(sz, plen); 113 memmove(p, (char *)h + BTDATAOFF, nb); 114 mpool_put(t->bt_mp, h, 0); 115 116 if ((sz -= nb) == 0) 117 break; 118 } 119 return (RET_SUCCESS); 120 } 121 122 /* 123 * __OVFL_PUT -- Store an overflow key/data item. 124 * 125 * Parameters: 126 * t: tree 127 * data: DBT to store 128 * pgno: storage page number 129 * 130 * Returns: 131 * RET_ERROR, RET_SUCCESS 132 */ 133 int 134 __ovfl_put(BTREE *t, const DBT *dbt, pgno_t *pg) 135 { 136 PAGE *h, *last; 137 void *p; 138 pgno_t npg; 139 size_t nb, plen; 140 u_int32_t sz; 141 142 /* 143 * Allocate pages and copy the key/data record into them. Store the 144 * number of the first page in the chain. 145 */ 146 plen = t->bt_psize - BTDATAOFF; 147 for (last = NULL, p = dbt->data, sz = dbt->size;; 148 p = (char *)p + plen, last = h) { 149 if ((h = __bt_new(t, &npg)) == NULL) 150 return (RET_ERROR); 151 152 h->pgno = npg; 153 h->nextpg = h->prevpg = P_INVALID; 154 h->flags = P_OVERFLOW; 155 h->lower = h->upper = 0; 156 157 nb = MIN(sz, plen); 158 memmove((char *)h + BTDATAOFF, p, nb); 159 160 if (last) { 161 last->nextpg = h->pgno; 162 mpool_put(t->bt_mp, last, MPOOL_DIRTY); 163 } else 164 *pg = h->pgno; 165 166 if ((sz -= nb) == 0) { 167 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 168 break; 169 } 170 } 171 return (RET_SUCCESS); 172 } 173 174 /* 175 * __OVFL_DELETE -- Delete an overflow chain. 176 * 177 * Parameters: 178 * t: tree 179 * p: pointer to { pgno_t, u_int32_t } 180 * 181 * Returns: 182 * RET_ERROR, RET_SUCCESS 183 */ 184 int 185 __ovfl_delete(BTREE *t, void *p) 186 { 187 PAGE *h; 188 pgno_t pg; 189 size_t plen; 190 u_int32_t sz; 191 192 memmove(&pg, p, sizeof(pgno_t)); 193 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); 194 195 #ifdef DEBUG 196 if (pg == P_INVALID || sz == 0) 197 abort(); 198 #endif 199 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 200 return (RET_ERROR); 201 202 /* Don't delete chains used by internal pages. */ 203 if (h->flags & P_PRESERVE) { 204 mpool_put(t->bt_mp, h, 0); 205 return (RET_SUCCESS); 206 } 207 208 /* Step through the chain, calling the free routine for each page. */ 209 for (plen = t->bt_psize - BTDATAOFF;; sz -= plen) { 210 pg = h->nextpg; 211 __bt_free(t, h); 212 if (sz <= plen) 213 break; 214 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 215 return (RET_ERROR); 216 } 217 return (RET_SUCCESS); 218 } 219