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 rcsid[] = "$OpenBSD: bt_overflow.c,v 1.4 1998/08/14 21:39:18 deraadt Exp $"; 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 void *tp; 92 93 memmove(&pg, p, sizeof(pgno_t)); 94 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); 95 *ssz = sz; 96 97 #ifdef DEBUG 98 if (pg == P_INVALID || sz == 0) 99 abort(); 100 #endif 101 /* Make the buffer bigger as necessary. */ 102 if (*bufsz < sz) { 103 tp = (char *)(*buf == NULL ? malloc(sz) : realloc(*buf, sz)); 104 if (tp == NULL) 105 return (RET_ERROR); 106 *buf = tp; 107 *bufsz = sz; 108 } 109 110 /* 111 * Step through the linked list of pages, copying the data on each one 112 * into the buffer. Never copy more than the data's length. 113 */ 114 plen = t->bt_psize - BTDATAOFF; 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 *)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(t, dbt, pg) 142 BTREE *t; 143 const DBT *dbt; 144 pgno_t *pg; 145 { 146 PAGE *h, *last; 147 void *p; 148 pgno_t npg; 149 size_t nb, plen; 150 u_int32_t sz; 151 152 /* 153 * Allocate pages and copy the key/data record into them. Store the 154 * number of the first page in the chain. 155 */ 156 plen = t->bt_psize - BTDATAOFF; 157 for (last = NULL, p = dbt->data, sz = dbt->size;; 158 p = (char *)p + plen, last = h) { 159 if ((h = __bt_new(t, &npg)) == NULL) 160 return (RET_ERROR); 161 162 h->pgno = npg; 163 h->nextpg = h->prevpg = P_INVALID; 164 h->flags = P_OVERFLOW; 165 h->lower = h->upper = 0; 166 167 nb = MIN(sz, plen); 168 memmove((char *)h + BTDATAOFF, p, nb); 169 170 if (last) { 171 last->nextpg = h->pgno; 172 mpool_put(t->bt_mp, last, MPOOL_DIRTY); 173 } else 174 *pg = h->pgno; 175 176 if ((sz -= nb) == 0) { 177 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 178 break; 179 } 180 } 181 return (RET_SUCCESS); 182 } 183 184 /* 185 * __OVFL_DELETE -- Delete an overflow chain. 186 * 187 * Parameters: 188 * t: tree 189 * p: pointer to { pgno_t, u_int32_t } 190 * 191 * Returns: 192 * RET_ERROR, RET_SUCCESS 193 */ 194 int 195 __ovfl_delete(t, p) 196 BTREE *t; 197 void *p; 198 { 199 PAGE *h; 200 pgno_t pg; 201 size_t plen; 202 u_int32_t sz; 203 204 memmove(&pg, p, sizeof(pgno_t)); 205 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); 206 207 #ifdef DEBUG 208 if (pg == P_INVALID || sz == 0) 209 abort(); 210 #endif 211 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 212 return (RET_ERROR); 213 214 /* Don't delete chains used by internal pages. */ 215 if (h->flags & P_PRESERVE) { 216 mpool_put(t->bt_mp, h, 0); 217 return (RET_SUCCESS); 218 } 219 220 /* Step through the chain, calling the free routine for each page. */ 221 for (plen = t->bt_psize - BTDATAOFF;; sz -= plen) { 222 pg = h->nextpg; 223 __bt_free(t, h); 224 if (sz <= plen) 225 break; 226 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 227 return (RET_ERROR); 228 } 229 return (RET_SUCCESS); 230 } 231