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 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #if defined(LIBC_SCCS) && !defined(lint) 38 static char sccsid[] = "@(#)bt_overflow.c 8.5 (Berkeley) 7/16/94"; 39 #endif /* LIBC_SCCS and not lint */ 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(t, p, ssz, buf, bufsz) 81 BTREE *t; 82 void *p; 83 size_t *ssz; 84 void **buf; 85 size_t *bufsz; 86 { 87 PAGE *h; 88 pgno_t pg; 89 size_t nb, plen; 90 u_int32_t sz; 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) : reallocf(*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 plen = t->bt_psize - BTDATAOFF; 113 for (p = *buf;; p = (char *)p + nb, pg = h->nextpg) { 114 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 115 return (RET_ERROR); 116 117 nb = MIN(sz, plen); 118 memmove(p, (char *)h + BTDATAOFF, nb); 119 mpool_put(t->bt_mp, h, 0); 120 121 if ((sz -= nb) == 0) 122 break; 123 } 124 return (RET_SUCCESS); 125 } 126 127 /* 128 * __OVFL_PUT -- Store an overflow key/data item. 129 * 130 * Parameters: 131 * t: tree 132 * data: DBT to store 133 * pgno: storage page number 134 * 135 * Returns: 136 * RET_ERROR, RET_SUCCESS 137 */ 138 int 139 __ovfl_put(t, dbt, pg) 140 BTREE *t; 141 const DBT *dbt; 142 pgno_t *pg; 143 { 144 PAGE *h, *last; 145 void *p; 146 pgno_t npg; 147 size_t nb, plen; 148 u_int32_t sz; 149 150 /* 151 * Allocate pages and copy the key/data record into them. Store the 152 * number of the first page in the chain. 153 */ 154 plen = t->bt_psize - BTDATAOFF; 155 for (last = NULL, p = dbt->data, sz = dbt->size;; 156 p = (char *)p + plen, last = h) { 157 if ((h = __bt_new(t, &npg)) == NULL) 158 return (RET_ERROR); 159 160 h->pgno = npg; 161 h->nextpg = h->prevpg = P_INVALID; 162 h->flags = P_OVERFLOW; 163 h->lower = h->upper = 0; 164 165 nb = MIN(sz, plen); 166 memmove((char *)h + BTDATAOFF, p, nb); 167 168 if (last) { 169 last->nextpg = h->pgno; 170 mpool_put(t->bt_mp, last, MPOOL_DIRTY); 171 } else 172 *pg = h->pgno; 173 174 if ((sz -= nb) == 0) { 175 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 176 break; 177 } 178 } 179 return (RET_SUCCESS); 180 } 181 182 /* 183 * __OVFL_DELETE -- Delete an overflow chain. 184 * 185 * Parameters: 186 * t: tree 187 * p: pointer to { pgno_t, u_int32_t } 188 * 189 * Returns: 190 * RET_ERROR, RET_SUCCESS 191 */ 192 int 193 __ovfl_delete(t, p) 194 BTREE *t; 195 void *p; 196 { 197 PAGE *h; 198 pgno_t pg; 199 size_t plen; 200 u_int32_t sz; 201 202 memmove(&pg, p, sizeof(pgno_t)); 203 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); 204 205 #ifdef DEBUG 206 if (pg == P_INVALID || sz == 0) 207 abort(); 208 #endif 209 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 210 return (RET_ERROR); 211 212 /* Don't delete chains used by internal pages. */ 213 if (h->flags & P_PRESERVE) { 214 mpool_put(t->bt_mp, h, 0); 215 return (RET_SUCCESS); 216 } 217 218 /* Step through the chain, calling the free routine for each page. */ 219 for (plen = t->bt_psize - BTDATAOFF;; sz -= plen) { 220 pg = h->nextpg; 221 __bt_free(t, h); 222 if (sz <= plen) 223 break; 224 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 225 return (RET_ERROR); 226 } 227 return (RET_SUCCESS); 228 } 229