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 #if defined(LIBC_SCCS) && !defined(lint) 36 static char sccsid[] = "@(#)rec_delete.c 8.7 (Berkeley) 7/14/94"; 37 #endif /* LIBC_SCCS and not lint */ 38 #include <sys/types.h> 39 40 #include <errno.h> 41 #include <stdio.h> 42 #include <string.h> 43 44 #include <db.h> 45 #include "recno.h" 46 47 static int rec_rdelete(BTREE *, recno_t); 48 49 /* 50 * __REC_DELETE -- Delete the item(s) referenced by a key. 51 * 52 * Parameters: 53 * dbp: pointer to access method 54 * key: key to delete 55 * flags: R_CURSOR if deleting what the cursor references 56 * 57 * Returns: 58 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found. 59 */ 60 int 61 __rec_delete(const DB *dbp, const DBT *key, u_int flags) 62 { 63 BTREE *t; 64 recno_t nrec; 65 int status; 66 67 t = dbp->internal; 68 69 /* Toss any page pinned across calls. */ 70 if (t->bt_pinned != NULL) { 71 mpool_put(t->bt_mp, t->bt_pinned, 0); 72 t->bt_pinned = NULL; 73 } 74 75 switch(flags) { 76 case 0: 77 if ((nrec = *(recno_t *)key->data) == 0) 78 goto einval; 79 if (nrec > t->bt_nrecs) 80 return (RET_SPECIAL); 81 --nrec; 82 status = rec_rdelete(t, nrec); 83 break; 84 case R_CURSOR: 85 if (!F_ISSET(&t->bt_cursor, CURS_INIT)) 86 goto einval; 87 if (t->bt_nrecs == 0) 88 return (RET_SPECIAL); 89 status = rec_rdelete(t, t->bt_cursor.rcursor - 1); 90 if (status == RET_SUCCESS) 91 --t->bt_cursor.rcursor; 92 break; 93 default: 94 einval: errno = EINVAL; 95 return (RET_ERROR); 96 } 97 98 if (status == RET_SUCCESS) 99 F_SET(t, B_MODIFIED | R_MODIFIED); 100 return (status); 101 } 102 103 /* 104 * REC_RDELETE -- Delete the data matching the specified key. 105 * 106 * Parameters: 107 * tree: tree 108 * nrec: record to delete 109 * 110 * Returns: 111 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found. 112 */ 113 static int 114 rec_rdelete(BTREE *t, recno_t nrec) 115 { 116 EPG *e; 117 PAGE *h; 118 int status; 119 120 /* Find the record; __rec_search pins the page. */ 121 if ((e = __rec_search(t, nrec, SDELETE)) == NULL) 122 return (RET_ERROR); 123 124 /* Delete the record. */ 125 h = e->page; 126 status = __rec_dleaf(t, h, e->index); 127 if (status != RET_SUCCESS) { 128 mpool_put(t->bt_mp, h, 0); 129 return (status); 130 } 131 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 132 return (RET_SUCCESS); 133 } 134 135 /* 136 * __REC_DLEAF -- Delete a single record from a recno leaf page. 137 * 138 * Parameters: 139 * t: tree 140 * idx: index on current page to delete 141 * 142 * Returns: 143 * RET_SUCCESS, RET_ERROR. 144 */ 145 int 146 __rec_dleaf(BTREE *t, PAGE *h, u_int32_t idx) 147 { 148 RLEAF *rl; 149 indx_t *ip, cnt, offset; 150 u_int32_t nbytes; 151 char *from; 152 void *to; 153 154 /* 155 * Delete a record from a recno leaf page. Internal records are never 156 * deleted from internal pages, regardless of the records that caused 157 * them to be added being deleted. Pages made empty by deletion are 158 * not reclaimed. They are, however, made available for reuse. 159 * 160 * Pack the remaining entries at the end of the page, shift the indices 161 * down, overwriting the deleted record and its index. If the record 162 * uses overflow pages, make them available for reuse. 163 */ 164 to = rl = GETRLEAF(h, idx); 165 if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR) 166 return (RET_ERROR); 167 nbytes = NRLEAF(rl); 168 169 /* 170 * Compress the key/data pairs. Compress and adjust the [BR]LEAF 171 * offsets. Reset the headers. 172 */ 173 from = (char *)h + h->upper; 174 memmove(from + nbytes, from, (char *)to - from); 175 h->upper += nbytes; 176 177 offset = h->linp[idx]; 178 for (cnt = &h->linp[idx] - (ip = &h->linp[0]); cnt--; ++ip) 179 if (ip[0] < offset) 180 ip[0] += nbytes; 181 for (cnt = &h->linp[NEXTINDEX(h)] - ip; --cnt; ++ip) 182 ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1]; 183 h->lower -= sizeof(indx_t); 184 --t->bt_nrecs; 185 return (RET_SUCCESS); 186 } 187