1 /* $NetBSD: bt_overflow.c,v 1.13 2007/02/03 23:46:09 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 #include <sys/cdefs.h> 36 #if defined(LIBC_SCCS) && !defined(lint) 37 #if 0 38 static char sccsid[] = "@(#)bt_overflow.c 8.5 (Berkeley) 7/16/94"; 39 #else 40 __RCSID("$NetBSD: bt_overflow.c,v 1.13 2007/02/03 23:46:09 christos Exp $"); 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include "namespace.h" 45 #include <sys/param.h> 46 47 #include <assert.h> 48 #include <stdio.h> 49 #include <stdlib.h> 50 #include <string.h> 51 52 #include <db.h> 53 #include "btree.h" 54 55 /* 56 * Big key/data code. 57 * 58 * Big key and data entries are stored on linked lists of pages. The initial 59 * reference is byte string stored with the key or data and is the page number 60 * and size. The actual record is stored in a chain of pages linked by the 61 * nextpg field of the PAGE header. 62 * 63 * The first page of the chain has a special property. If the record is used 64 * by an internal page, it cannot be deleted and the P_PRESERVE bit will be set 65 * in the header. 66 * 67 * XXX 68 * A single DBT is written to each chain, so a lot of space on the last page 69 * is wasted. This is a fairly major bug for some data sets. 70 */ 71 72 /* 73 * __OVFL_GET -- Get an overflow key/data item. 74 * 75 * Parameters: 76 * t: tree 77 * p: pointer to { pgno_t, u_int32_t } 78 * buf: storage address 79 * bufsz: storage size 80 * 81 * Returns: 82 * RET_ERROR, RET_SUCCESS 83 */ 84 int 85 __ovfl_get(BTREE *t, void *p, size_t *ssz, void **buf, size_t *bufsz) 86 { 87 PAGE *h; 88 pgno_t pg; 89 u_int32_t sz, nb, plen; 90 size_t temp; 91 92 memmove(&pg, p, sizeof(pgno_t)); 93 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); 94 *ssz = sz; 95 96 #ifdef DEBUG 97 if (pg == P_INVALID || sz == 0) 98 abort(); 99 #endif 100 /* Make the buffer bigger as necessary. */ 101 if (*bufsz < sz) { 102 *buf = (char *)(*buf == NULL ? malloc(sz) : realloc(*buf, sz)); 103 if (*buf == NULL) 104 return (RET_ERROR); 105 *bufsz = sz; 106 } 107 108 /* 109 * Step through the linked list of pages, copying the data on each one 110 * into the buffer. Never copy more than the data's length. 111 */ 112 temp = t->bt_psize - BTDATAOFF; 113 _DBFIT(temp, u_int32_t); 114 plen = (u_int32_t)temp; 115 for (p = *buf;; p = (char *)p + nb, pg = h->nextpg) { 116 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 117 return (RET_ERROR); 118 119 nb = MIN(sz, plen); 120 memmove(p, (char *)(void *)h + BTDATAOFF, nb); 121 mpool_put(t->bt_mp, h, 0); 122 123 if ((sz -= nb) == 0) 124 break; 125 } 126 return (RET_SUCCESS); 127 } 128 129 /* 130 * __OVFL_PUT -- Store an overflow key/data item. 131 * 132 * Parameters: 133 * t: tree 134 * data: DBT to store 135 * pgno: storage page number 136 * 137 * Returns: 138 * RET_ERROR, RET_SUCCESS 139 */ 140 int 141 __ovfl_put(BTREE *t, const DBT *dbt, pgno_t *pg) 142 { 143 PAGE *h, *last; 144 void *p; 145 pgno_t npg; 146 u_int32_t sz, nb, plen; 147 size_t temp; 148 149 /* 150 * Allocate pages and copy the key/data record into them. Store the 151 * number of the first page in the chain. 152 */ 153 temp = t->bt_psize - BTDATAOFF; 154 _DBFIT(temp, u_int32_t); 155 plen = (u_int32_t)temp; 156 last = NULL; 157 p = dbt->data; 158 temp = dbt->size; 159 _DBFIT(temp, u_int32_t); 160 sz = temp; 161 for (;; p = (char *)p + plen, last = h) { 162 if ((h = __bt_new(t, &npg)) == NULL) 163 return (RET_ERROR); 164 165 h->pgno = npg; 166 h->nextpg = h->prevpg = P_INVALID; 167 h->flags = P_OVERFLOW; 168 h->lower = h->upper = 0; 169 170 nb = MIN(sz, plen); 171 (void)memmove((char *)(void *)h + BTDATAOFF, p, (size_t)nb); 172 173 if (last) { 174 last->nextpg = h->pgno; 175 mpool_put(t->bt_mp, last, MPOOL_DIRTY); 176 } else 177 *pg = h->pgno; 178 179 if ((sz -= nb) == 0) { 180 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 181 break; 182 } 183 } 184 return (RET_SUCCESS); 185 } 186 187 /* 188 * __OVFL_DELETE -- Delete an overflow chain. 189 * 190 * Parameters: 191 * t: tree 192 * p: pointer to { pgno_t, u_int32_t } 193 * 194 * Returns: 195 * RET_ERROR, RET_SUCCESS 196 */ 197 int 198 __ovfl_delete(BTREE *t, void *p) 199 { 200 PAGE *h; 201 pgno_t pg; 202 u_int32_t sz, plen; 203 size_t temp; 204 205 (void)memmove(&pg, p, sizeof(pgno_t)); 206 (void)memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); 207 208 #ifdef DEBUG 209 if (pg == P_INVALID || sz == 0) 210 abort(); 211 #endif 212 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 213 return (RET_ERROR); 214 215 /* Don't delete chains used by internal pages. */ 216 if (h->flags & P_PRESERVE) { 217 mpool_put(t->bt_mp, h, 0); 218 return (RET_SUCCESS); 219 } 220 221 /* Step through the chain, calling the free routine for each page. */ 222 temp = t->bt_psize - BTDATAOFF; 223 _DBFIT(temp, u_int32_t); 224 plen = (u_int32_t)temp; 225 for (;; sz -= plen) { 226 pg = h->nextpg; 227 __bt_free(t, h); 228 if (sz <= plen) 229 break; 230 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 231 return (RET_ERROR); 232 } 233 return (RET_SUCCESS); 234 } 235