1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 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/types.h> 36 37 #include <errno.h> 38 #include <stdio.h> 39 #include <string.h> 40 41 #include <db.h> 42 #include "recno.h" 43 44 static int rec_rdelete(BTREE *, recno_t); 45 46 /* 47 * __REC_DELETE -- Delete the item(s) referenced by a key. 48 * 49 * Parameters: 50 * dbp: pointer to access method 51 * key: key to delete 52 * flags: R_CURSOR if deleting what the cursor references 53 * 54 * Returns: 55 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found. 56 */ 57 int 58 __rec_delete(const DB *dbp, const DBT *key, u_int flags) 59 { 60 BTREE *t; 61 recno_t nrec; 62 int status; 63 64 t = dbp->internal; 65 66 /* Toss any page pinned across calls. */ 67 if (t->bt_pinned != NULL) { 68 mpool_put(t->bt_mp, t->bt_pinned, 0); 69 t->bt_pinned = NULL; 70 } 71 72 switch(flags) { 73 case 0: 74 if ((nrec = *(recno_t *)key->data) == 0) 75 goto einval; 76 if (nrec > t->bt_nrecs) 77 return (RET_SPECIAL); 78 --nrec; 79 status = rec_rdelete(t, nrec); 80 break; 81 case R_CURSOR: 82 if (!F_ISSET(&t->bt_cursor, CURS_INIT)) 83 goto einval; 84 if (t->bt_nrecs == 0) 85 return (RET_SPECIAL); 86 status = rec_rdelete(t, t->bt_cursor.rcursor - 1); 87 if (status == RET_SUCCESS) 88 --t->bt_cursor.rcursor; 89 break; 90 default: 91 einval: errno = EINVAL; 92 return (RET_ERROR); 93 } 94 95 if (status == RET_SUCCESS) 96 F_SET(t, B_MODIFIED | R_MODIFIED); 97 return (status); 98 } 99 100 /* 101 * REC_RDELETE -- Delete the data matching the specified key. 102 * 103 * Parameters: 104 * tree: tree 105 * nrec: record to delete 106 * 107 * Returns: 108 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found. 109 */ 110 static int 111 rec_rdelete(BTREE *t, recno_t nrec) 112 { 113 EPG *e; 114 PAGE *h; 115 int status; 116 117 /* Find the record; __rec_search pins the page. */ 118 if ((e = __rec_search(t, nrec, SDELETE)) == NULL) 119 return (RET_ERROR); 120 121 /* Delete the record. */ 122 h = e->page; 123 status = __rec_dleaf(t, h, e->index); 124 if (status != RET_SUCCESS) { 125 mpool_put(t->bt_mp, h, 0); 126 return (status); 127 } 128 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 129 return (RET_SUCCESS); 130 } 131 132 /* 133 * __REC_DLEAF -- Delete a single record from a recno leaf page. 134 * 135 * Parameters: 136 * t: tree 137 * idx: index on current page to delete 138 * 139 * Returns: 140 * RET_SUCCESS, RET_ERROR. 141 */ 142 int 143 __rec_dleaf(BTREE *t, PAGE *h, u_int32_t idx) 144 { 145 RLEAF *rl; 146 indx_t *ip, cnt, offset; 147 u_int32_t nbytes; 148 char *from; 149 void *to; 150 151 /* 152 * Delete a record from a recno leaf page. Internal records are never 153 * deleted from internal pages, regardless of the records that caused 154 * them to be added being deleted. Pages made empty by deletion are 155 * not reclaimed. They are, however, made available for reuse. 156 * 157 * Pack the remaining entries at the end of the page, shift the indices 158 * down, overwriting the deleted record and its index. If the record 159 * uses overflow pages, make them available for reuse. 160 */ 161 to = rl = GETRLEAF(h, idx); 162 if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR) 163 return (RET_ERROR); 164 nbytes = NRLEAF(rl); 165 166 /* 167 * Compress the key/data pairs. Compress and adjust the [BR]LEAF 168 * offsets. Reset the headers. 169 */ 170 from = (char *)h + h->upper; 171 memmove(from + nbytes, from, (char *)to - from); 172 h->upper += nbytes; 173 174 offset = h->linp[idx]; 175 for (cnt = &h->linp[idx] - (ip = &h->linp[0]); cnt--; ++ip) 176 if (ip[0] < offset) 177 ip[0] += nbytes; 178 for (cnt = &h->linp[NEXTINDEX(h)] - ip; --cnt; ++ip) 179 ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1]; 180 h->lower -= sizeof(indx_t); 181 --t->bt_nrecs; 182 return (RET_SUCCESS); 183 } 184