rec_delete.c revision 331722 
1/*-
2 * Copyright (c) 1990, 1993, 1994
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Mike Olson.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#if defined(LIBC_SCCS) && !defined(lint)
34static char sccsid[] = "@(#)rec_delete.c	8.7 (Berkeley) 7/14/94";
35#endif /* LIBC_SCCS and not lint */
36#include <sys/cdefs.h>
37__FBSDID("$FreeBSD: stable/11/lib/libc/db/recno/rec_delete.c 331722 2018-03-29 02:50:57Z eadler $");
38
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
48static 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 */
61int
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:
95einval:		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 */
114static int
115rec_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 */
146int
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