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
44static 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 */
57int
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:
91einval:		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 */
110static int
111rec_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 */
142int
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