1 /*- 2 * Copyright (c) 1990, 1993 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 /* from: static char sccsid[] = "@(#)rec_delete.c 8.2 (Berkeley) 9/7/93"; */ 39 static char *rcsid = "$Id: rec_delete.c,v 1.4 1993/09/09 02:42:21 cgd Exp $"; 40 #endif /* LIBC_SCCS and not lint */ 41 42 #include <sys/types.h> 43 44 #include <errno.h> 45 #include <stdio.h> 46 #include <string.h> 47 48 #include <db.h> 49 #include "recno.h" 50 51 static int rec_rdelete __P((BTREE *, recno_t)); 52 53 /* 54 * __REC_DELETE -- Delete the item(s) referenced by a key. 55 * 56 * Parameters: 57 * dbp: pointer to access method 58 * key: key to delete 59 * flags: R_CURSOR if deleting what the cursor references 60 * 61 * Returns: 62 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found. 63 */ 64 int 65 __rec_delete(dbp, key, flags) 66 const DB *dbp; 67 const DBT *key; 68 u_int flags; 69 { 70 BTREE *t; 71 recno_t nrec; 72 int status; 73 74 t = dbp->internal; 75 76 /* Toss any page pinned across calls. */ 77 if (t->bt_pinned != NULL) { 78 mpool_put(t->bt_mp, t->bt_pinned, 0); 79 t->bt_pinned = NULL; 80 } 81 82 switch(flags) { 83 case 0: 84 if ((nrec = *(recno_t *)key->data) == 0) 85 goto einval; 86 if (nrec > t->bt_nrecs) 87 return (RET_SPECIAL); 88 --nrec; 89 status = rec_rdelete(t, nrec); 90 break; 91 case R_CURSOR: 92 if (!ISSET(t, B_SEQINIT)) 93 goto einval; 94 if (t->bt_nrecs == 0) 95 return (RET_SPECIAL); 96 status = rec_rdelete(t, t->bt_rcursor - 1); 97 if (status == RET_SUCCESS) 98 --t->bt_rcursor; 99 break; 100 default: 101 einval: errno = EINVAL; 102 return (RET_ERROR); 103 } 104 105 if (status == RET_SUCCESS) 106 SET(t, B_MODIFIED | R_MODIFIED); 107 return (status); 108 } 109 110 /* 111 * REC_RDELETE -- Delete the data matching the specified key. 112 * 113 * Parameters: 114 * tree: tree 115 * nrec: record to delete 116 * 117 * Returns: 118 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found. 119 */ 120 static int 121 rec_rdelete(t, nrec) 122 BTREE *t; 123 recno_t nrec; 124 { 125 EPG *e; 126 PAGE *h; 127 int status; 128 129 /* Find the record; __rec_search pins the page. */ 130 if ((e = __rec_search(t, nrec, SDELETE)) == NULL) { 131 mpool_put(t->bt_mp, e->page, 0); 132 return (RET_ERROR); 133 } 134 135 /* Delete the record. */ 136 h = e->page; 137 status = __rec_dleaf(t, h, e->index); 138 if (status != RET_SUCCESS) { 139 mpool_put(t->bt_mp, h, 0); 140 return (status); 141 } 142 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 143 return (RET_SUCCESS); 144 } 145 146 /* 147 * __REC_DLEAF -- Delete a single record from a recno leaf page. 148 * 149 * Parameters: 150 * t: tree 151 * index: index on current page to delete 152 * 153 * Returns: 154 * RET_SUCCESS, RET_ERROR. 155 */ 156 int 157 __rec_dleaf(t, h, index) 158 BTREE *t; 159 PAGE *h; 160 int index; 161 { 162 register RLEAF *rl; 163 register indx_t *ip, offset; 164 register size_t nbytes; 165 register int cnt; 166 char *from; 167 void *to; 168 169 /* 170 * Delete a record from a recno leaf page. Internal records are never 171 * deleted from internal pages, regardless of the records that caused 172 * them to be added being deleted. Pages made empty by deletion are 173 * not reclaimed. They are, however, made available for reuse. 174 * 175 * Pack the remaining entries at the end of the page, shift the indices 176 * down, overwriting the deleted record and its index. If the record 177 * uses overflow pages, make them available for reuse. 178 */ 179 to = rl = GETRLEAF(h, index); 180 if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR) 181 return (RET_ERROR); 182 nbytes = NRLEAF(rl); 183 184 /* 185 * Compress the key/data pairs. Compress and adjust the [BR]LEAF 186 * offsets. Reset the headers. 187 */ 188 from = (char *)h + h->upper; 189 memmove(from + nbytes, from, (char *)to - from); 190 h->upper += nbytes; 191 192 offset = h->linp[index]; 193 for (cnt = &h->linp[index] - (ip = &h->linp[0]); cnt--; ++ip) 194 if (ip[0] < offset) 195 ip[0] += nbytes; 196 for (cnt = &h->linp[NEXTINDEX(h)] - ip; --cnt; ++ip) 197 ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1]; 198 h->lower -= sizeof(indx_t); 199 --t->bt_nrecs; 200 return (RET_SUCCESS); 201 } 202