1 /*- 2 * Copyright (c) 1990, 1993, 1994 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Mike Olson. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #if defined(LIBC_SCCS) && !defined(lint) 34 static char sccsid[] = "@(#)bt_overflow.c 8.5 (Berkeley) 7/16/94"; 35 #endif /* LIBC_SCCS and not lint */ 36 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD$"); 38 39 #include <sys/param.h> 40 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include <string.h> 44 45 #include <db.h> 46 #include "btree.h" 47 48 /* 49 * Big key/data code. 50 * 51 * Big key and data entries are stored on linked lists of pages. The initial 52 * reference is byte string stored with the key or data and is the page number 53 * and size. The actual record is stored in a chain of pages linked by the 54 * nextpg field of the PAGE header. 55 * 56 * The first page of the chain has a special property. If the record is used 57 * by an internal page, it cannot be deleted and the P_PRESERVE bit will be set 58 * in the header. 59 * 60 * XXX 61 * A single DBT is written to each chain, so a lot of space on the last page 62 * is wasted. This is a fairly major bug for some data sets. 63 */ 64 65 /* 66 * __OVFL_GET -- Get an overflow key/data item. 67 * 68 * Parameters: 69 * t: tree 70 * p: pointer to { pgno_t, u_int32_t } 71 * buf: storage address 72 * bufsz: storage size 73 * 74 * Returns: 75 * RET_ERROR, RET_SUCCESS 76 */ 77 int 78 __ovfl_get(BTREE *t, void *p, size_t *ssz, void **buf, size_t *bufsz) 79 { 80 PAGE *h; 81 pgno_t pg; 82 size_t nb, plen; 83 u_int32_t sz; 84 85 memmove(&pg, p, sizeof(pgno_t)); 86 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); 87 *ssz = sz; 88 89 #ifdef DEBUG 90 if (pg == P_INVALID || sz == 0) 91 abort(); 92 #endif 93 /* Make the buffer bigger as necessary. */ 94 if (*bufsz < sz) { 95 *buf = reallocf(*buf, sz); 96 if (*buf == NULL) 97 return (RET_ERROR); 98 *bufsz = sz; 99 } 100 101 /* 102 * Step through the linked list of pages, copying the data on each one 103 * into the buffer. Never copy more than the data's length. 104 */ 105 plen = t->bt_psize - BTDATAOFF; 106 for (p = *buf;; p = (char *)p + nb, pg = h->nextpg) { 107 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 108 return (RET_ERROR); 109 110 nb = MIN(sz, plen); 111 memmove(p, (char *)h + BTDATAOFF, nb); 112 mpool_put(t->bt_mp, h, 0); 113 114 if ((sz -= nb) == 0) 115 break; 116 } 117 return (RET_SUCCESS); 118 } 119 120 /* 121 * __OVFL_PUT -- Store an overflow key/data item. 122 * 123 * Parameters: 124 * t: tree 125 * data: DBT to store 126 * pgno: storage page number 127 * 128 * Returns: 129 * RET_ERROR, RET_SUCCESS 130 */ 131 int 132 __ovfl_put(BTREE *t, const DBT *dbt, pgno_t *pg) 133 { 134 PAGE *h, *last; 135 void *p; 136 pgno_t npg; 137 size_t nb, plen; 138 u_int32_t sz; 139 140 /* 141 * Allocate pages and copy the key/data record into them. Store the 142 * number of the first page in the chain. 143 */ 144 plen = t->bt_psize - BTDATAOFF; 145 for (last = NULL, p = dbt->data, sz = dbt->size;; 146 p = (char *)p + plen, last = h) { 147 if ((h = __bt_new(t, &npg)) == NULL) 148 return (RET_ERROR); 149 150 h->pgno = npg; 151 h->nextpg = h->prevpg = P_INVALID; 152 h->flags = P_OVERFLOW; 153 h->lower = h->upper = 0; 154 155 nb = MIN(sz, plen); 156 memmove((char *)h + BTDATAOFF, p, nb); 157 158 if (last) { 159 last->nextpg = h->pgno; 160 mpool_put(t->bt_mp, last, MPOOL_DIRTY); 161 } else 162 *pg = h->pgno; 163 164 if ((sz -= nb) == 0) { 165 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 166 break; 167 } 168 } 169 return (RET_SUCCESS); 170 } 171 172 /* 173 * __OVFL_DELETE -- Delete an overflow chain. 174 * 175 * Parameters: 176 * t: tree 177 * p: pointer to { pgno_t, u_int32_t } 178 * 179 * Returns: 180 * RET_ERROR, RET_SUCCESS 181 */ 182 int 183 __ovfl_delete(BTREE *t, void *p) 184 { 185 PAGE *h; 186 pgno_t pg; 187 size_t plen; 188 u_int32_t sz; 189 190 memmove(&pg, p, sizeof(pgno_t)); 191 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); 192 193 #ifdef DEBUG 194 if (pg == P_INVALID || sz == 0) 195 abort(); 196 #endif 197 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 198 return (RET_ERROR); 199 200 /* Don't delete chains used by internal pages. */ 201 if (h->flags & P_PRESERVE) { 202 mpool_put(t->bt_mp, h, 0); 203 return (RET_SUCCESS); 204 } 205 206 /* Step through the chain, calling the free routine for each page. */ 207 for (plen = t->bt_psize - BTDATAOFF;; sz -= plen) { 208 pg = h->nextpg; 209 __bt_free(t, h); 210 if (sz <= plen) 211 break; 212 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 213 return (RET_ERROR); 214 } 215 return (RET_SUCCESS); 216 } 217