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 #if defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)rec_delete.c 8.7 (Berkeley) 7/14/94";
37 #endif /* LIBC_SCCS and not lint */
38 #include <sys/cdefs.h>
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
__rec_delete(const DB * dbp,const DBT * key,u_int flags)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
rec_rdelete(BTREE * t,recno_t nrec)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
__rec_dleaf(BTREE * t,PAGE * h,u_int32_t idx)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