1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
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 #include <sys/types.h>
36
37 #include <errno.h>
38 #include <stdio.h>
39 #include <string.h>
40
41 #include <db.h>
42 #include "recno.h"
43
44 static int rec_rdelete(BTREE *, recno_t);
45
46 /*
47 * __REC_DELETE -- Delete the item(s) referenced by a key.
48 *
49 * Parameters:
50 * dbp: pointer to access method
51 * key: key to delete
52 * flags: R_CURSOR if deleting what the cursor references
53 *
54 * Returns:
55 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
56 */
57 int
__rec_delete(const DB * dbp,const DBT * key,u_int flags)58 __rec_delete(const DB *dbp, const DBT *key, u_int flags)
59 {
60 BTREE *t;
61 recno_t nrec;
62 int status;
63
64 t = dbp->internal;
65
66 /* Toss any page pinned across calls. */
67 if (t->bt_pinned != NULL) {
68 mpool_put(t->bt_mp, t->bt_pinned, 0);
69 t->bt_pinned = NULL;
70 }
71
72 switch(flags) {
73 case 0:
74 if ((nrec = *(recno_t *)key->data) == 0)
75 goto einval;
76 if (nrec > t->bt_nrecs)
77 return (RET_SPECIAL);
78 --nrec;
79 status = rec_rdelete(t, nrec);
80 break;
81 case R_CURSOR:
82 if (!F_ISSET(&t->bt_cursor, CURS_INIT))
83 goto einval;
84 if (t->bt_nrecs == 0)
85 return (RET_SPECIAL);
86 status = rec_rdelete(t, t->bt_cursor.rcursor - 1);
87 if (status == RET_SUCCESS)
88 --t->bt_cursor.rcursor;
89 break;
90 default:
91 einval: errno = EINVAL;
92 return (RET_ERROR);
93 }
94
95 if (status == RET_SUCCESS)
96 F_SET(t, B_MODIFIED | R_MODIFIED);
97 return (status);
98 }
99
100 /*
101 * REC_RDELETE -- Delete the data matching the specified key.
102 *
103 * Parameters:
104 * tree: tree
105 * nrec: record to delete
106 *
107 * Returns:
108 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
109 */
110 static int
rec_rdelete(BTREE * t,recno_t nrec)111 rec_rdelete(BTREE *t, recno_t nrec)
112 {
113 EPG *e;
114 PAGE *h;
115 int status;
116
117 /* Find the record; __rec_search pins the page. */
118 if ((e = __rec_search(t, nrec, SDELETE)) == NULL)
119 return (RET_ERROR);
120
121 /* Delete the record. */
122 h = e->page;
123 status = __rec_dleaf(t, h, e->index);
124 if (status != RET_SUCCESS) {
125 mpool_put(t->bt_mp, h, 0);
126 return (status);
127 }
128 mpool_put(t->bt_mp, h, MPOOL_DIRTY);
129 return (RET_SUCCESS);
130 }
131
132 /*
133 * __REC_DLEAF -- Delete a single record from a recno leaf page.
134 *
135 * Parameters:
136 * t: tree
137 * idx: index on current page to delete
138 *
139 * Returns:
140 * RET_SUCCESS, RET_ERROR.
141 */
142 int
__rec_dleaf(BTREE * t,PAGE * h,u_int32_t idx)143 __rec_dleaf(BTREE *t, PAGE *h, u_int32_t idx)
144 {
145 RLEAF *rl;
146 indx_t *ip, cnt, offset;
147 u_int32_t nbytes;
148 char *from;
149 void *to;
150
151 /*
152 * Delete a record from a recno leaf page. Internal records are never
153 * deleted from internal pages, regardless of the records that caused
154 * them to be added being deleted. Pages made empty by deletion are
155 * not reclaimed. They are, however, made available for reuse.
156 *
157 * Pack the remaining entries at the end of the page, shift the indices
158 * down, overwriting the deleted record and its index. If the record
159 * uses overflow pages, make them available for reuse.
160 */
161 to = rl = GETRLEAF(h, idx);
162 if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR)
163 return (RET_ERROR);
164 nbytes = NRLEAF(rl);
165
166 /*
167 * Compress the key/data pairs. Compress and adjust the [BR]LEAF
168 * offsets. Reset the headers.
169 */
170 from = (char *)h + h->upper;
171 memmove(from + nbytes, from, (char *)to - from);
172 h->upper += nbytes;
173
174 offset = h->linp[idx];
175 for (cnt = &h->linp[idx] - (ip = &h->linp[0]); cnt--; ++ip)
176 if (ip[0] < offset)
177 ip[0] += nbytes;
178 for (cnt = &h->linp[NEXTINDEX(h)] - ip; --cnt; ++ip)
179 ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1];
180 h->lower -= sizeof(indx_t);
181 --t->bt_nrecs;
182 return (RET_SUCCESS);
183 }
184