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 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37 #if defined(LIBC_SCCS) && !defined(lint)
38 static char sccsid[] = "@(#)rec_delete.c 8.7 (Berkeley) 7/14/94";
39 #endif /* LIBC_SCCS and not lint */
40
41 #include <sys/types.h>
42
43 #include <errno.h>
44 #include <stdio.h>
45 #include <string.h>
46
47 #include "db-int.h"
48 #include "recno.h"
49
50 static int rec_rdelete __P((BTREE *, recno_t));
51
52 /*
53 * __REC_DELETE -- Delete the item(s) referenced by a key.
54 *
55 * Parameters:
56 * dbp: pointer to access method
57 * key: key to delete
58 * flags: R_CURSOR if deleting what the cursor references
59 *
60 * Returns:
61 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
62 */
63 int
__rec_delete(dbp,key,flags)64 __rec_delete(dbp, key, flags)
65 const DB *dbp;
66 const DBT *key;
67 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:
100 einval: 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 */
119 static int
rec_rdelete(t,nrec)120 rec_rdelete(t, nrec)
121 BTREE *t;
122 recno_t nrec;
123 {
124 EPG *e;
125 PAGE *h;
126 int status;
127
128 /* Find the record; __rec_search pins the page. */
129 if ((e = __rec_search(t, nrec, SDELETE)) == NULL)
130 return (RET_ERROR);
131
132 /* Delete the record. */
133 h = e->page;
134 status = __rec_dleaf(t, h, e->index);
135 if (status != RET_SUCCESS) {
136 mpool_put(t->bt_mp, h, 0);
137 return (status);
138 }
139 mpool_put(t->bt_mp, h, MPOOL_DIRTY);
140 return (RET_SUCCESS);
141 }
142
143 /*
144 * __REC_DLEAF -- Delete a single record from a recno leaf page.
145 *
146 * Parameters:
147 * t: tree
148 * idx: index on current page to delete
149 *
150 * Returns:
151 * RET_SUCCESS, RET_ERROR.
152 */
153 int
__rec_dleaf(t,h,idx)154 __rec_dleaf(t, h, idx)
155 BTREE *t;
156 PAGE *h;
157 u_int32_t idx;
158 {
159 RLEAF *rl;
160 indx_t *ip, cnt, offset;
161 u_int32_t nbytes;
162 char *from;
163 void *to;
164
165 /*
166 * Delete a record from a recno leaf page. Internal records are never
167 * deleted from internal pages, regardless of the records that caused
168 * them to be added being deleted. Pages made empty by deletion are
169 * not reclaimed. They are, however, made available for reuse.
170 *
171 * Pack the remaining entries at the end of the page, shift the indices
172 * down, overwriting the deleted record and its index. If the record
173 * uses overflow pages, make them available for reuse.
174 */
175 to = rl = GETRLEAF(h, idx);
176 if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR)
177 return (RET_ERROR);
178 nbytes = NRLEAF(rl);
179
180 /*
181 * Compress the key/data pairs. Compress and adjust the [BR]LEAF
182 * offsets. Reset the headers.
183 */
184 from = (char *)h + h->upper;
185 memmove(from + nbytes, from, (char *)to - from);
186 h->upper += nbytes;
187
188 offset = h->linp[idx];
189 for (cnt = &h->linp[idx] - (ip = &h->linp[0]); cnt--; ++ip)
190 if (ip[0] < offset)
191 ip[0] += nbytes;
192 for (cnt = &h->linp[NEXTINDEX(h)] - ip; --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