1 /* $NetBSD: rec_delete.c,v 1.12 2001/11/04 13:57:29 lukem Exp $ */ 2 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. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 #if 0 42 static char sccsid[] = "@(#)rec_delete.c 8.7 (Berkeley) 7/14/94"; 43 #else 44 __RCSID("$NetBSD: rec_delete.c,v 1.12 2001/11/04 13:57:29 lukem Exp $"); 45 #endif 46 #endif /* LIBC_SCCS and not lint */ 47 48 #include "namespace.h" 49 #include <sys/types.h> 50 51 #include <errno.h> 52 #include <stdio.h> 53 #include <string.h> 54 55 #include <db.h> 56 #include "recno.h" 57 58 static int rec_rdelete __P((BTREE *, recno_t)); 59 60 /* 61 * __REC_DELETE -- Delete the item(s) referenced by a key. 62 * 63 * Parameters: 64 * dbp: pointer to access method 65 * key: key to delete 66 * flags: R_CURSOR if deleting what the cursor references 67 * 68 * Returns: 69 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found. 70 */ 71 int 72 __rec_delete(dbp, key, flags) 73 const DB *dbp; 74 const DBT *key; 75 u_int flags; 76 { 77 BTREE *t; 78 recno_t nrec; 79 int status; 80 81 t = dbp->internal; 82 83 /* Toss any page pinned across calls. */ 84 if (t->bt_pinned != NULL) { 85 mpool_put(t->bt_mp, t->bt_pinned, 0); 86 t->bt_pinned = NULL; 87 } 88 89 switch(flags) { 90 case 0: 91 if ((nrec = *(recno_t *)key->data) == 0) 92 goto einval; 93 if (nrec > t->bt_nrecs) 94 return (RET_SPECIAL); 95 --nrec; 96 status = rec_rdelete(t, nrec); 97 break; 98 case R_CURSOR: 99 if (!F_ISSET(&t->bt_cursor, CURS_INIT)) 100 goto einval; 101 if (t->bt_nrecs == 0) 102 return (RET_SPECIAL); 103 status = rec_rdelete(t, t->bt_cursor.rcursor - 1); 104 if (status == RET_SUCCESS) 105 --t->bt_cursor.rcursor; 106 break; 107 default: 108 einval: errno = EINVAL; 109 return (RET_ERROR); 110 } 111 112 if (status == RET_SUCCESS) 113 F_SET(t, B_MODIFIED | R_MODIFIED); 114 return (status); 115 } 116 117 /* 118 * REC_RDELETE -- Delete the data matching the specified key. 119 * 120 * Parameters: 121 * tree: tree 122 * nrec: record to delete 123 * 124 * Returns: 125 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found. 126 */ 127 static int 128 rec_rdelete(t, nrec) 129 BTREE *t; 130 recno_t nrec; 131 { 132 EPG *e; 133 PAGE *h; 134 int status; 135 136 /* Find the record; __rec_search pins the page. */ 137 if ((e = __rec_search(t, nrec, SDELETE)) == NULL) 138 return (RET_ERROR); 139 140 /* Delete the record. */ 141 h = e->page; 142 status = __rec_dleaf(t, h, (u_int32_t)e->index); 143 if (status != RET_SUCCESS) { 144 mpool_put(t->bt_mp, h, 0); 145 return (status); 146 } 147 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 148 return (RET_SUCCESS); 149 } 150 151 /* 152 * __REC_DLEAF -- Delete a single record from a recno leaf page. 153 * 154 * Parameters: 155 * t: tree 156 * index: index on current page to delete 157 * 158 * Returns: 159 * RET_SUCCESS, RET_ERROR. 160 */ 161 int 162 __rec_dleaf(t, h, idx) 163 BTREE *t; 164 PAGE *h; 165 u_int32_t idx; 166 { 167 RLEAF *rl; 168 indx_t *ip, cnt, offset; 169 u_int32_t nbytes; 170 char *from; 171 void *to; 172 173 /* 174 * Delete a record from a recno leaf page. Internal records are never 175 * deleted from internal pages, regardless of the records that caused 176 * them to be added being deleted. Pages made empty by deletion are 177 * not reclaimed. They are, however, made available for reuse. 178 * 179 * Pack the remaining entries at the end of the page, shift the indices 180 * down, overwriting the deleted record and its index. If the record 181 * uses overflow pages, make them available for reuse. 182 */ 183 to = rl = GETRLEAF(h, idx); 184 if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR) 185 return (RET_ERROR); 186 nbytes = NRLEAF(rl); 187 188 /* 189 * Compress the key/data pairs. Compress and adjust the [BR]LEAF 190 * offsets. Reset the headers. 191 */ 192 from = (char *)(void *)h + h->upper; 193 memmove(from + nbytes, from, (size_t)((char *)to - from)); 194 h->upper += nbytes; 195 196 offset = h->linp[idx]; 197 for (cnt = &h->linp[idx] - (ip = &h->linp[0]); cnt--; ++ip) 198 if (ip[0] < offset) 199 ip[0] += nbytes; 200 for (cnt = &h->linp[NEXTINDEX(h)] - ip; --cnt; ++ip) 201 ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1]; 202 h->lower -= sizeof(indx_t); 203 --t->bt_nrecs; 204 return (RET_SUCCESS); 205 } 206