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. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)rec_delete.c 8.7 (Berkeley) 7/14/94 33 * $FreeBSD: head/lib/libc/db/recno/rec_delete.c 189292 2009-03-03 02:16:12Z delphij $ 34 */ 35 36 #include <sys/param.h> 37 38 #include <errno.h> 39 #include <stdio.h> 40 #include <string.h> 41 42 #include <db.h> 43 #include "recno.h" 44 45 static int rec_rdelete(BTREE *, recno_t); 46 47 /* 48 * __REC_DELETE -- Delete the item(s) referenced by a key. 49 * 50 * Parameters: 51 * dbp: pointer to access method 52 * key: key to delete 53 * flags: R_CURSOR if deleting what the cursor references 54 * 55 * Returns: 56 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found. 57 */ 58 int 59 __rec_delete(const DB *dbp, const DBT *key, unsigned int flags) 60 { 61 BTREE *t; 62 recno_t nrec; 63 int status; 64 65 t = dbp->internal; 66 67 /* Toss any page pinned across calls. */ 68 if (t->bt_pinned != NULL) { 69 mpool_put(t->bt_mp, t->bt_pinned, 0); 70 t->bt_pinned = NULL; 71 } 72 73 switch(flags) { 74 case 0: 75 if ((nrec = *(recno_t *)key->data) == 0) 76 goto einval; 77 if (nrec > t->bt_nrecs) 78 return (RET_SPECIAL); 79 --nrec; 80 status = rec_rdelete(t, nrec); 81 break; 82 case R_CURSOR: 83 if (!F_ISSET(&t->bt_cursor, CURS_INIT)) 84 goto einval; 85 if (t->bt_nrecs == 0) 86 return (RET_SPECIAL); 87 status = rec_rdelete(t, t->bt_cursor.rcursor - 1); 88 if (status == RET_SUCCESS) 89 --t->bt_cursor.rcursor; 90 break; 91 default: 92 einval: errno = EINVAL; 93 return (RET_ERROR); 94 } 95 96 if (status == RET_SUCCESS) 97 F_SET(t, B_MODIFIED | R_MODIFIED); 98 return (status); 99 } 100 101 /* 102 * REC_RDELETE -- Delete the data matching the specified key. 103 * 104 * Parameters: 105 * tree: tree 106 * nrec: record to delete 107 * 108 * Returns: 109 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found. 110 */ 111 static int 112 rec_rdelete(BTREE *t, recno_t nrec) 113 { 114 EPG *e; 115 PAGE *h; 116 int status; 117 118 /* Find the record; __rec_search pins the page. */ 119 if ((e = __rec_search(t, nrec, SDELETE)) == NULL) 120 return (RET_ERROR); 121 122 /* Delete the record. */ 123 h = e->page; 124 status = __rec_dleaf(t, h, e->index); 125 if (status != RET_SUCCESS) { 126 mpool_put(t->bt_mp, h, 0); 127 return (status); 128 } 129 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 130 return (RET_SUCCESS); 131 } 132 133 /* 134 * __REC_DLEAF -- Delete a single record from a recno leaf page. 135 * 136 * Parameters: 137 * t: tree 138 * idx: index on current page to delete 139 * 140 * Returns: 141 * RET_SUCCESS, RET_ERROR. 142 */ 143 int 144 __rec_dleaf(BTREE *t, PAGE *h, uint32_t idx) 145 { 146 RLEAF *rl; 147 indx_t *ip, cnt, offset; 148 uint32_t nbytes; 149 char *from; 150 void *to; 151 152 /* 153 * Delete a record from a recno leaf page. Internal records are never 154 * deleted from internal pages, regardless of the records that caused 155 * them to be added being deleted. Pages made empty by deletion are 156 * not reclaimed. They are, however, made available for reuse. 157 * 158 * Pack the remaining entries at the end of the page, shift the indices 159 * down, overwriting the deleted record and its index. If the record 160 * uses overflow pages, make them available for reuse. 161 */ 162 to = rl = GETRLEAF(h, idx); 163 if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR) 164 return (RET_ERROR); 165 nbytes = NRLEAF(rl); 166 167 /* 168 * Compress the key/data pairs. Compress and adjust the [BR]LEAF 169 * offsets. Reset the headers. 170 */ 171 from = (char *)h + h->upper; 172 memmove(from + nbytes, from, (char *)to - from); 173 h->upper += nbytes; 174 175 offset = h->linp[idx]; 176 for (cnt = &h->linp[idx] - (ip = &h->linp[0]); cnt--; ++ip) 177 if (ip[0] < offset) 178 ip[0] += nbytes; 179 for (cnt = &h->linp[NEXTINDEX(h)] - ip; --cnt; ++ip) 180 ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1]; 181 h->lower -= sizeof(indx_t); 182 --t->bt_nrecs; 183 return (RET_SUCCESS); 184 } 185