1 /* $NetBSD: bt_overflow.c,v 1.7 1997/07/13 18:51:54 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. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 #if 0 42 static char sccsid[] = "@(#)bt_overflow.c 8.5 (Berkeley) 7/16/94"; 43 #else 44 __RCSID("$NetBSD: bt_overflow.c,v 1.7 1997/07/13 18:51:54 christos Exp $"); 45 #endif 46 #endif /* LIBC_SCCS and not lint */ 47 48 #include <sys/param.h> 49 50 #include <stdio.h> 51 #include <stdlib.h> 52 #include <string.h> 53 54 #include <db.h> 55 #include "btree.h" 56 57 /* 58 * Big key/data code. 59 * 60 * Big key and data entries are stored on linked lists of pages. The initial 61 * reference is byte string stored with the key or data and is the page number 62 * and size. The actual record is stored in a chain of pages linked by the 63 * nextpg field of the PAGE header. 64 * 65 * The first page of the chain has a special property. If the record is used 66 * by an internal page, it cannot be deleted and the P_PRESERVE bit will be set 67 * in the header. 68 * 69 * XXX 70 * A single DBT is written to each chain, so a lot of space on the last page 71 * is wasted. This is a fairly major bug for some data sets. 72 */ 73 74 /* 75 * __OVFL_GET -- Get an overflow key/data item. 76 * 77 * Parameters: 78 * t: tree 79 * p: pointer to { pgno_t, u_int32_t } 80 * buf: storage address 81 * bufsz: storage size 82 * 83 * Returns: 84 * RET_ERROR, RET_SUCCESS 85 */ 86 int 87 __ovfl_get(t, p, ssz, buf, bufsz) 88 BTREE *t; 89 void *p; 90 size_t *ssz; 91 void **buf; 92 size_t *bufsz; 93 { 94 PAGE *h; 95 pgno_t pg; 96 size_t nb, plen; 97 u_int32_t sz; 98 99 memmove(&pg, p, sizeof(pgno_t)); 100 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); 101 *ssz = sz; 102 103 #ifdef DEBUG 104 if (pg == P_INVALID || sz == 0) 105 abort(); 106 #endif 107 /* Make the buffer bigger as necessary. */ 108 if (*bufsz < sz) { 109 *buf = (char *)(*buf == NULL ? malloc(sz) : realloc(*buf, sz)); 110 if (*buf == NULL) 111 return (RET_ERROR); 112 *bufsz = sz; 113 } 114 115 /* 116 * Step through the linked list of pages, copying the data on each one 117 * into the buffer. Never copy more than the data's length. 118 */ 119 plen = t->bt_psize - BTDATAOFF; 120 for (p = *buf;; p = (char *)p + nb, pg = h->nextpg) { 121 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 122 return (RET_ERROR); 123 124 nb = MIN(sz, plen); 125 memmove(p, (char *)h + BTDATAOFF, nb); 126 mpool_put(t->bt_mp, h, 0); 127 128 if ((sz -= nb) == 0) 129 break; 130 } 131 return (RET_SUCCESS); 132 } 133 134 /* 135 * __OVFL_PUT -- Store an overflow key/data item. 136 * 137 * Parameters: 138 * t: tree 139 * data: DBT to store 140 * pgno: storage page number 141 * 142 * Returns: 143 * RET_ERROR, RET_SUCCESS 144 */ 145 int 146 __ovfl_put(t, dbt, pg) 147 BTREE *t; 148 const DBT *dbt; 149 pgno_t *pg; 150 { 151 PAGE *h, *last; 152 void *p; 153 pgno_t npg; 154 size_t nb, plen; 155 u_int32_t sz; 156 157 /* 158 * Allocate pages and copy the key/data record into them. Store the 159 * number of the first page in the chain. 160 */ 161 plen = t->bt_psize - BTDATAOFF; 162 for (last = NULL, p = dbt->data, sz = dbt->size;; 163 p = (char *)p + plen, last = h) { 164 if ((h = __bt_new(t, &npg)) == NULL) 165 return (RET_ERROR); 166 167 h->pgno = npg; 168 h->nextpg = h->prevpg = P_INVALID; 169 h->flags = P_OVERFLOW; 170 h->lower = h->upper = 0; 171 172 nb = MIN(sz, plen); 173 memmove((char *)h + BTDATAOFF, p, nb); 174 175 if (last) { 176 last->nextpg = h->pgno; 177 mpool_put(t->bt_mp, last, MPOOL_DIRTY); 178 } else 179 *pg = h->pgno; 180 181 if ((sz -= nb) == 0) { 182 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 183 break; 184 } 185 } 186 return (RET_SUCCESS); 187 } 188 189 /* 190 * __OVFL_DELETE -- Delete an overflow chain. 191 * 192 * Parameters: 193 * t: tree 194 * p: pointer to { pgno_t, u_int32_t } 195 * 196 * Returns: 197 * RET_ERROR, RET_SUCCESS 198 */ 199 int 200 __ovfl_delete(t, p) 201 BTREE *t; 202 void *p; 203 { 204 PAGE *h; 205 pgno_t pg; 206 size_t plen; 207 u_int32_t sz; 208 209 memmove(&pg, p, sizeof(pgno_t)); 210 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); 211 212 #ifdef DEBUG 213 if (pg == P_INVALID || sz == 0) 214 abort(); 215 #endif 216 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 217 return (RET_ERROR); 218 219 /* Don't delete chains used by internal pages. */ 220 if (h->flags & P_PRESERVE) { 221 mpool_put(t->bt_mp, h, 0); 222 return (RET_SUCCESS); 223 } 224 225 /* Step through the chain, calling the free routine for each page. */ 226 for (plen = t->bt_psize - BTDATAOFF;; sz -= plen) { 227 pg = h->nextpg; 228 __bt_free(t, h); 229 if (sz <= plen) 230 break; 231 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 232 return (RET_ERROR); 233 } 234 return (RET_SUCCESS); 235 } 236