xref: /titanic_41/usr/src/lib/krb5/plugins/kdb/db2/libdb2/recno/rec_delete.c (revision 54925bf60766fbb4f1f2d7c843721406a7b7a3fb)
1 #pragma ident	"%Z%%M%	%I%	%E% SMI"
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. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *	This product includes software developed by the University of
21  *	California, Berkeley and its contributors.
22  * 4. Neither the name of the University nor the names of its contributors
23  *    may be used to endorse or promote products derived from this software
24  *    without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36  * SUCH DAMAGE.
37  */
38 
39 #if defined(LIBC_SCCS) && !defined(lint)
40 static char sccsid[] = "@(#)rec_delete.c	8.7 (Berkeley) 7/14/94";
41 #endif /* LIBC_SCCS and not lint */
42 
43 #include <sys/types.h>
44 
45 #include <errno.h>
46 #include <stdio.h>
47 #include <string.h>
48 
49 #include "db-int.h"
50 #include "recno.h"
51 
52 static int rec_rdelete __P((BTREE *, recno_t));
53 
54 /*
55  * __REC_DELETE -- Delete the item(s) referenced by a key.
56  *
57  * Parameters:
58  *	dbp:	pointer to access method
59  *	key:	key to delete
60  *	flags:	R_CURSOR if deleting what the cursor references
61  *
62  * Returns:
63  *	RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
64  */
65 int
__rec_delete(dbp,key,flags)66 __rec_delete(dbp, key, flags)
67 	const DB *dbp;
68 	const DBT *key;
69 	u_int flags;
70 {
71 	BTREE *t;
72 	recno_t nrec;
73 	int status;
74 
75 	t = dbp->internal;
76 
77 	/* Toss any page pinned across calls. */
78 	if (t->bt_pinned != NULL) {
79 		mpool_put(t->bt_mp, t->bt_pinned, 0);
80 		t->bt_pinned = NULL;
81 	}
82 
83 	switch(flags) {
84 	case 0:
85 		if ((nrec = *(recno_t *)key->data) == 0)
86 			goto einval;
87 		if (nrec > t->bt_nrecs)
88 			return (RET_SPECIAL);
89 		--nrec;
90 		status = rec_rdelete(t, nrec);
91 		break;
92 	case R_CURSOR:
93 		if (!F_ISSET(&t->bt_cursor, CURS_INIT))
94 			goto einval;
95 		if (t->bt_nrecs == 0)
96 			return (RET_SPECIAL);
97 		status = rec_rdelete(t, t->bt_cursor.rcursor - 1);
98 		if (status == RET_SUCCESS)
99 			--t->bt_cursor.rcursor;
100 		break;
101 	default:
102 einval:		errno = EINVAL;
103 		return (RET_ERROR);
104 	}
105 
106 	if (status == RET_SUCCESS)
107 		F_SET(t, B_MODIFIED | R_MODIFIED);
108 	return (status);
109 }
110 
111 /*
112  * REC_RDELETE -- Delete the data matching the specified key.
113  *
114  * Parameters:
115  *	tree:	tree
116  *	nrec:	record to delete
117  *
118  * Returns:
119  *	RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
120  */
121 static int
rec_rdelete(t,nrec)122 rec_rdelete(t, nrec)
123 	BTREE *t;
124 	recno_t nrec;
125 {
126 	EPG *e;
127 	PAGE *h;
128 	int status;
129 
130 	/* Find the record; __rec_search pins the page. */
131 	if ((e = __rec_search(t, nrec, SDELETE)) == NULL)
132 		return (RET_ERROR);
133 
134 	/* Delete the record. */
135 	h = e->page;
136 	status = __rec_dleaf(t, h, e->index);
137 	if (status != RET_SUCCESS) {
138 		mpool_put(t->bt_mp, h, 0);
139 		return (status);
140 	}
141 	mpool_put(t->bt_mp, h, MPOOL_DIRTY);
142 	return (RET_SUCCESS);
143 }
144 
145 /*
146  * __REC_DLEAF -- Delete a single record from a recno leaf page.
147  *
148  * Parameters:
149  *	t:	tree
150  *	idx:	index on current page to delete
151  *
152  * Returns:
153  *	RET_SUCCESS, RET_ERROR.
154  */
155 int
__rec_dleaf(t,h,idx)156 __rec_dleaf(t, h, idx)
157 	BTREE *t;
158 	PAGE *h;
159 	u_int32_t idx;
160 {
161 	RLEAF *rl;
162 	indx_t *ip, cnt, offset;
163 	u_int32_t nbytes;
164 	char *from;
165 	void *to;
166 
167 	/*
168 	 * Delete a record from a recno leaf page.  Internal records are never
169 	 * deleted from internal pages, regardless of the records that caused
170 	 * them to be added being deleted.  Pages made empty by deletion are
171 	 * not reclaimed.  They are, however, made available for reuse.
172 	 *
173 	 * Pack the remaining entries at the end of the page, shift the indices
174 	 * down, overwriting the deleted record and its index.  If the record
175 	 * uses overflow pages, make them available for reuse.
176 	 */
177 	to = rl = GETRLEAF(h, idx);
178 	if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR)
179 		return (RET_ERROR);
180 	nbytes = NRLEAF(rl);
181 
182 	/*
183 	 * Compress the key/data pairs.  Compress and adjust the [BR]LEAF
184 	 * offsets.  Reset the headers.
185 	 */
186 	from = (char *)h + h->upper;
187 	memmove(from + nbytes, from, (char *)to - from);
188 	h->upper += nbytes;
189 
190 	offset = h->linp[idx];
191 	for (cnt = &h->linp[idx] - (ip = &h->linp[0]); cnt--; ++ip)
192 		if (ip[0] < offset)
193 			ip[0] += nbytes;
194 	for (cnt = &h->linp[NEXTINDEX(h)] - ip; --cnt; ++ip)
195 		ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1];
196 	h->lower -= sizeof(indx_t);
197 	--t->bt_nrecs;
198 	return (RET_SUCCESS);
199 }
200