1/*	$NetBSD: rec_delete.c,v 1.16 2008/09/10 17:52:36 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 1.16 2008/09/10 17:52:36 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
53static 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 */
66int
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:
100einval:		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 */
119static int
120rec_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 */
151int
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