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 33 #if defined(LIBC_SCCS) && !defined(lint) 34 static char sccsid[] = "@(#)rec_delete.c 8.7 (Berkeley) 7/14/94"; 35 #endif /* LIBC_SCCS and not lint */ 36 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD$"); 38 39 #include <sys/types.h> 40 41 #include <errno.h> 42 #include <stdio.h> 43 #include <string.h> 44 45 #include <db.h> 46 #include "recno.h" 47 48 static int rec_rdelete(BTREE *, recno_t); 49 50 /* 51 * __REC_DELETE -- Delete the item(s) referenced by a key. 52 * 53 * Parameters: 54 * dbp: pointer to access method 55 * key: key to delete 56 * flags: R_CURSOR if deleting what the cursor references 57 * 58 * Returns: 59 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found. 60 */ 61 int 62 __rec_delete(const DB *dbp, const DBT *key, u_int flags) 63 { 64 BTREE *t; 65 recno_t nrec; 66 int status; 67 68 t = dbp->internal; 69 70 /* Toss any page pinned across calls. */ 71 if (t->bt_pinned != NULL) { 72 mpool_put(t->bt_mp, t->bt_pinned, 0); 73 t->bt_pinned = NULL; 74 } 75 76 switch(flags) { 77 case 0: 78 if ((nrec = *(recno_t *)key->data) == 0) 79 goto einval; 80 if (nrec > t->bt_nrecs) 81 return (RET_SPECIAL); 82 --nrec; 83 status = rec_rdelete(t, nrec); 84 break; 85 case R_CURSOR: 86 if (!F_ISSET(&t->bt_cursor, CURS_INIT)) 87 goto einval; 88 if (t->bt_nrecs == 0) 89 return (RET_SPECIAL); 90 status = rec_rdelete(t, t->bt_cursor.rcursor - 1); 91 if (status == RET_SUCCESS) 92 --t->bt_cursor.rcursor; 93 break; 94 default: 95 einval: errno = EINVAL; 96 return (RET_ERROR); 97 } 98 99 if (status == RET_SUCCESS) 100 F_SET(t, B_MODIFIED | R_MODIFIED); 101 return (status); 102 } 103 104 /* 105 * REC_RDELETE -- Delete the data matching the specified key. 106 * 107 * Parameters: 108 * tree: tree 109 * nrec: record to delete 110 * 111 * Returns: 112 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found. 113 */ 114 static int 115 rec_rdelete(BTREE *t, recno_t nrec) 116 { 117 EPG *e; 118 PAGE *h; 119 int status; 120 121 /* Find the record; __rec_search pins the page. */ 122 if ((e = __rec_search(t, nrec, SDELETE)) == NULL) 123 return (RET_ERROR); 124 125 /* Delete the record. */ 126 h = e->page; 127 status = __rec_dleaf(t, h, e->index); 128 if (status != RET_SUCCESS) { 129 mpool_put(t->bt_mp, h, 0); 130 return (status); 131 } 132 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 133 return (RET_SUCCESS); 134 } 135 136 /* 137 * __REC_DLEAF -- Delete a single record from a recno leaf page. 138 * 139 * Parameters: 140 * t: tree 141 * idx: index on current page to delete 142 * 143 * Returns: 144 * RET_SUCCESS, RET_ERROR. 145 */ 146 int 147 __rec_dleaf(BTREE *t, PAGE *h, u_int32_t idx) 148 { 149 RLEAF *rl; 150 indx_t *ip, cnt, offset; 151 u_int32_t nbytes; 152 char *from; 153 void *to; 154 155 /* 156 * Delete a record from a recno leaf page. Internal records are never 157 * deleted from internal pages, regardless of the records that caused 158 * them to be added being deleted. Pages made empty by deletion are 159 * not reclaimed. They are, however, made available for reuse. 160 * 161 * Pack the remaining entries at the end of the page, shift the indices 162 * down, overwriting the deleted record and its index. If the record 163 * uses overflow pages, make them available for reuse. 164 */ 165 to = rl = GETRLEAF(h, idx); 166 if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR) 167 return (RET_ERROR); 168 nbytes = NRLEAF(rl); 169 170 /* 171 * Compress the key/data pairs. Compress and adjust the [BR]LEAF 172 * offsets. Reset the headers. 173 */ 174 from = (char *)h + h->upper; 175 memmove(from + nbytes, from, (char *)to - from); 176 h->upper += nbytes; 177 178 offset = h->linp[idx]; 179 for (cnt = &h->linp[idx] - (ip = &h->linp[0]); cnt--; ++ip) 180 if (ip[0] < offset) 181 ip[0] += nbytes; 182 for (cnt = &h->linp[NEXTINDEX(h)] - ip; --cnt; ++ip) 183 ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1]; 184 h->lower -= sizeof(indx_t); 185 --t->bt_nrecs; 186 return (RET_SUCCESS); 187 } 188