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 * 4. 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(dbp, key, flags) 63 const DB *dbp; 64 const DBT *key; 65 u_int flags; 66 { 67 BTREE *t; 68 recno_t nrec; 69 int status; 70 71 t = dbp->internal; 72 73 /* Toss any page pinned across calls. */ 74 if (t->bt_pinned != NULL) { 75 mpool_put(t->bt_mp, t->bt_pinned, 0); 76 t->bt_pinned = NULL; 77 } 78 79 switch(flags) { 80 case 0: 81 if ((nrec = *(recno_t *)key->data) == 0) 82 goto einval; 83 if (nrec > t->bt_nrecs) 84 return (RET_SPECIAL); 85 --nrec; 86 status = rec_rdelete(t, nrec); 87 break; 88 case R_CURSOR: 89 if (!F_ISSET(&t->bt_cursor, CURS_INIT)) 90 goto einval; 91 if (t->bt_nrecs == 0) 92 return (RET_SPECIAL); 93 status = rec_rdelete(t, t->bt_cursor.rcursor - 1); 94 if (status == RET_SUCCESS) 95 --t->bt_cursor.rcursor; 96 break; 97 default: 98 einval: errno = EINVAL; 99 return (RET_ERROR); 100 } 101 102 if (status == RET_SUCCESS) 103 F_SET(t, B_MODIFIED | R_MODIFIED); 104 return (status); 105 } 106 107 /* 108 * REC_RDELETE -- Delete the data matching the specified key. 109 * 110 * Parameters: 111 * tree: tree 112 * nrec: record to delete 113 * 114 * Returns: 115 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found. 116 */ 117 static int 118 rec_rdelete(t, nrec) 119 BTREE *t; 120 recno_t nrec; 121 { 122 EPG *e; 123 PAGE *h; 124 int status; 125 126 /* Find the record; __rec_search pins the page. */ 127 if ((e = __rec_search(t, nrec, SDELETE)) == NULL) 128 return (RET_ERROR); 129 130 /* Delete the record. */ 131 h = e->page; 132 status = __rec_dleaf(t, h, e->index); 133 if (status != RET_SUCCESS) { 134 mpool_put(t->bt_mp, h, 0); 135 return (status); 136 } 137 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 138 return (RET_SUCCESS); 139 } 140 141 /* 142 * __REC_DLEAF -- Delete a single record from a recno leaf page. 143 * 144 * Parameters: 145 * t: tree 146 * index: index on current page to delete 147 * 148 * Returns: 149 * RET_SUCCESS, RET_ERROR. 150 */ 151 int 152 __rec_dleaf(t, h, index) 153 BTREE *t; 154 PAGE *h; 155 u_int32_t index; 156 { 157 RLEAF *rl; 158 indx_t *ip, cnt, offset; 159 u_int32_t nbytes; 160 char *from; 161 void *to; 162 163 /* 164 * Delete a record from a recno leaf page. Internal records are never 165 * deleted from internal pages, regardless of the records that caused 166 * them to be added being deleted. Pages made empty by deletion are 167 * not reclaimed. They are, however, made available for reuse. 168 * 169 * Pack the remaining entries at the end of the page, shift the indices 170 * down, overwriting the deleted record and its index. If the record 171 * uses overflow pages, make them available for reuse. 172 */ 173 to = rl = GETRLEAF(h, index); 174 if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR) 175 return (RET_ERROR); 176 nbytes = NRLEAF(rl); 177 178 /* 179 * Compress the key/data pairs. Compress and adjust the [BR]LEAF 180 * offsets. Reset the headers. 181 */ 182 from = (char *)h + h->upper; 183 memmove(from + nbytes, from, (char *)to - from); 184 h->upper += nbytes; 185 186 offset = h->linp[index]; 187 for (cnt = &h->linp[index] - (ip = &h->linp[0]); cnt--; ++ip) 188 if (ip[0] < offset) 189 ip[0] += nbytes; 190 for (cnt = &h->linp[NEXTINDEX(h)] - ip; --cnt; ++ip) 191 ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1]; 192 h->lower -= sizeof(indx_t); 193 --t->bt_nrecs; 194 return (RET_SUCCESS); 195 } 196