1 /* $NetBSD: rec_delete.c,v 1.17 2008/09/11 12:58:00 joerg 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. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #if HAVE_NBTOOL_CONFIG_H
36 #include "nbtool_config.h"
37 #endif
38
39 #include <sys/cdefs.h>
40 __RCSID("$NetBSD: rec_delete.c,v 1.17 2008/09/11 12:58:00 joerg Exp $");
41
42 #include "namespace.h"
43 #include <sys/types.h>
44
45 #include <assert.h>
46 #include <errno.h>
47 #include <stdio.h>
48 #include <string.h>
49
50 #include <db.h>
51 #include "recno.h"
52
53 static int rec_rdelete(BTREE *, recno_t);
54
55 /*
56 * __REC_DELETE -- Delete the item(s) referenced by a key.
57 *
58 * Parameters:
59 * dbp: pointer to access method
60 * key: key to delete
61 * flags: R_CURSOR if deleting what the cursor references
62 *
63 * Returns:
64 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
65 */
66 int
__rec_delete(const DB * dbp,const DBT * key,u_int flags)67 __rec_delete(const DB *dbp, const DBT *key, u_int flags)
68 {
69 BTREE *t;
70 recno_t nrec;
71 int status;
72
73 t = dbp->internal;
74
75 /* Toss any page pinned across calls. */
76 if (t->bt_pinned != NULL) {
77 mpool_put(t->bt_mp, t->bt_pinned, 0);
78 t->bt_pinned = NULL;
79 }
80
81 switch(flags) {
82 case 0:
83 if ((nrec = *(recno_t *)key->data) == 0)
84 goto einval;
85 if (nrec > t->bt_nrecs)
86 return (RET_SPECIAL);
87 --nrec;
88 status = rec_rdelete(t, nrec);
89 break;
90 case R_CURSOR:
91 if (!F_ISSET(&t->bt_cursor, CURS_INIT))
92 goto einval;
93 if (t->bt_nrecs == 0)
94 return (RET_SPECIAL);
95 status = rec_rdelete(t, t->bt_cursor.rcursor - 1);
96 if (status == RET_SUCCESS)
97 --t->bt_cursor.rcursor;
98 break;
99 default:
100 einval: errno = EINVAL;
101 return (RET_ERROR);
102 }
103
104 if (status == RET_SUCCESS)
105 F_SET(t, B_MODIFIED | R_MODIFIED);
106 return (status);
107 }
108
109 /*
110 * REC_RDELETE -- Delete the data matching the specified key.
111 *
112 * Parameters:
113 * tree: tree
114 * nrec: record to delete
115 *
116 * Returns:
117 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
118 */
119 static int
rec_rdelete(BTREE * t,recno_t nrec)120 rec_rdelete(BTREE *t, 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, (uint32_t)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
__rec_dleaf(BTREE * t,PAGE * h,uint32_t idx)152 __rec_dleaf(BTREE *t, PAGE *h, uint32_t idx)
153 {
154 RLEAF *rl;
155 indx_t *ip, cnt, offset;
156 uint32_t nbytes;
157 char *from;
158 void *to;
159 size_t temp;
160
161 /*
162 * Delete a record from a recno leaf page. Internal records are never
163 * deleted from internal pages, regardless of the records that caused
164 * them to be added being deleted. Pages made empty by deletion are
165 * not reclaimed. They are, however, made available for reuse.
166 *
167 * Pack the remaining entries at the end of the page, shift the indices
168 * down, overwriting the deleted record and its index. If the record
169 * uses overflow pages, make them available for reuse.
170 */
171 to = rl = GETRLEAF(h, idx);
172 if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR)
173 return (RET_ERROR);
174 nbytes = NRLEAF(rl);
175
176 /*
177 * Compress the key/data pairs. Compress and adjust the [BR]LEAF
178 * offsets. Reset the headers.
179 */
180 from = (char *)(void *)h + h->upper;
181 memmove(from + nbytes, from, (size_t)((char *)to - from));
182 h->upper += nbytes;
183
184 offset = h->linp[idx];
185 temp = &h->linp[idx] - (ip = &h->linp[0]);
186 _DBFIT(temp, uint16_t);
187 for (cnt = (uint16_t)temp; cnt--; ++ip)
188 if (ip[0] < offset)
189 ip[0] += nbytes;
190 temp = &h->linp[NEXTINDEX(h)] - ip;
191 _DBFIT(temp, uint16_t);
192 for (cnt = (uint16_t)temp; --cnt; ++ip)
193 ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1];
194 h->lower -= sizeof(indx_t);
195 --t->bt_nrecs;
196 return (RET_SUCCESS);
197 }
198