1 /* $NetBSD: bt_overflow.c,v 1.12 2003/08/07 16:42:41 agc 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 1.12 2003/08/07 16:42:41 agc Exp $"); 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include "namespace.h" 45 #include <sys/param.h> 46 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include <string.h> 50 51 #include <db.h> 52 #include "btree.h" 53 54 /* 55 * Big key/data code. 56 * 57 * Big key and data entries are stored on linked lists of pages. The initial 58 * reference is byte string stored with the key or data and is the page number 59 * and size. The actual record is stored in a chain of pages linked by the 60 * nextpg field of the PAGE header. 61 * 62 * The first page of the chain has a special property. If the record is used 63 * by an internal page, it cannot be deleted and the P_PRESERVE bit will be set 64 * in the header. 65 * 66 * XXX 67 * A single DBT is written to each chain, so a lot of space on the last page 68 * is wasted. This is a fairly major bug for some data sets. 69 */ 70 71 /* 72 * __OVFL_GET -- Get an overflow key/data item. 73 * 74 * Parameters: 75 * t: tree 76 * p: pointer to { pgno_t, u_int32_t } 77 * buf: storage address 78 * bufsz: storage size 79 * 80 * Returns: 81 * RET_ERROR, RET_SUCCESS 82 */ 83 int 84 __ovfl_get(t, p, ssz, buf, bufsz) 85 BTREE *t; 86 void *p; 87 size_t *ssz; 88 void **buf; 89 size_t *bufsz; 90 { 91 PAGE *h; 92 pgno_t pg; 93 size_t nb, plen; 94 u_int32_t sz; 95 96 memmove(&pg, p, sizeof(pgno_t)); 97 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); 98 *ssz = sz; 99 100 #ifdef DEBUG 101 if (pg == P_INVALID || sz == 0) 102 abort(); 103 #endif 104 /* Make the buffer bigger as necessary. */ 105 if (*bufsz < sz) { 106 *buf = (char *)(*buf == NULL ? malloc(sz) : realloc(*buf, sz)); 107 if (*buf == NULL) 108 return (RET_ERROR); 109 *bufsz = sz; 110 } 111 112 /* 113 * Step through the linked list of pages, copying the data on each one 114 * into the buffer. Never copy more than the data's length. 115 */ 116 plen = t->bt_psize - BTDATAOFF; 117 for (p = *buf;; p = (char *)p + nb, pg = h->nextpg) { 118 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 119 return (RET_ERROR); 120 121 nb = MIN(sz, plen); 122 memmove(p, (char *)(void *)h + BTDATAOFF, nb); 123 mpool_put(t->bt_mp, h, 0); 124 125 if ((sz -= nb) == 0) 126 break; 127 } 128 return (RET_SUCCESS); 129 } 130 131 /* 132 * __OVFL_PUT -- Store an overflow key/data item. 133 * 134 * Parameters: 135 * t: tree 136 * data: DBT to store 137 * pgno: storage page number 138 * 139 * Returns: 140 * RET_ERROR, RET_SUCCESS 141 */ 142 int 143 __ovfl_put(t, dbt, pg) 144 BTREE *t; 145 const DBT *dbt; 146 pgno_t *pg; 147 { 148 PAGE *h, *last; 149 void *p; 150 pgno_t npg; 151 size_t nb, plen; 152 u_int32_t sz; 153 154 /* 155 * Allocate pages and copy the key/data record into them. Store the 156 * number of the first page in the chain. 157 */ 158 plen = t->bt_psize - BTDATAOFF; 159 for (last = NULL, p = dbt->data, sz = dbt->size;; 160 p = (char *)p + plen, last = h) { 161 if ((h = __bt_new(t, &npg)) == NULL) 162 return (RET_ERROR); 163 164 h->pgno = npg; 165 h->nextpg = h->prevpg = P_INVALID; 166 h->flags = P_OVERFLOW; 167 h->lower = h->upper = 0; 168 169 nb = MIN(sz, plen); 170 memmove((char *)(void *)h + BTDATAOFF, p, nb); 171 172 if (last) { 173 last->nextpg = h->pgno; 174 mpool_put(t->bt_mp, last, MPOOL_DIRTY); 175 } else 176 *pg = h->pgno; 177 178 if ((sz -= nb) == 0) { 179 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 180 break; 181 } 182 } 183 return (RET_SUCCESS); 184 } 185 186 /* 187 * __OVFL_DELETE -- Delete an overflow chain. 188 * 189 * Parameters: 190 * t: tree 191 * p: pointer to { pgno_t, u_int32_t } 192 * 193 * Returns: 194 * RET_ERROR, RET_SUCCESS 195 */ 196 int 197 __ovfl_delete(t, p) 198 BTREE *t; 199 void *p; 200 { 201 PAGE *h; 202 pgno_t pg; 203 size_t plen; 204 u_int32_t sz; 205 206 memmove(&pg, p, sizeof(pgno_t)); 207 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); 208 209 #ifdef DEBUG 210 if (pg == P_INVALID || sz == 0) 211 abort(); 212 #endif 213 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 214 return (RET_ERROR); 215 216 /* Don't delete chains used by internal pages. */ 217 if (h->flags & P_PRESERVE) { 218 mpool_put(t->bt_mp, h, 0); 219 return (RET_SUCCESS); 220 } 221 222 /* Step through the chain, calling the free routine for each page. */ 223 for (plen = t->bt_psize - BTDATAOFF;; sz -= plen) { 224 pg = h->nextpg; 225 __bt_free(t, h); 226 if (sz <= plen) 227 break; 228 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 229 return (RET_ERROR); 230 } 231 return (RET_SUCCESS); 232 } 233