Asterisk - The Open Source Telephony Project  21.4.1
rec_search.c
1 /*-
2  * Copyright (c) 1990, 1993
3  * The Regents of the University of California. All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  * notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  * notice, this list of conditions and the following disclaimer in the
12  * documentation and/or other materials provided with the distribution.
13  * 3. All advertising materials mentioning features or use of this software
14  * must display the following acknowledgement:
15  * This product includes software developed by the University of
16  * California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  * may be used to endorse or promote products derived from this software
19  * without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #if defined(LIBC_SCCS) && !defined(lint)
35 static char sccsid[] = "@(#)rec_search.c 8.4 (Berkeley) 7/14/94";
36 #endif /* LIBC_SCCS and not lint */
37 
38 #include <sys/types.h>
39 
40 #include <errno.h>
41 #include <stdio.h>
42 
43 #include "../include/db.h"
44 #include "recno.h"
45 
46 /*
47  * __REC_SEARCH -- Search a btree for a key.
48  *
49  * Parameters:
50  * t: tree to search
51  * recno: key to find
52  * op: search operation
53  *
54  * Returns:
55  * EPG for matching record, if any, or the EPG for the location of the
56  * key, if it were inserted into the tree.
57  *
58  * Returns:
59  * The EPG for matching record, if any, or the EPG for the location
60  * of the key, if it were inserted into the tree, is entered into
61  * the bt_cur field of the tree. A pointer to the field is returned.
62  */
63 EPG *
64 __rec_search(t, recno, op)
65  BTREE *t;
66  recno_t recno;
67  enum SRCHOP op;
68 {
69  register indx_t index;
70  register PAGE *h;
71  EPGNO *parent;
72  RINTERNAL *r;
73  pgno_t pg;
74  indx_t top;
75  recno_t total;
76  int sverrno;
77 
78  BT_CLR(t);
79  for (pg = P_ROOT, total = 0;;) {
80  if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
81  goto err;
82  if (h->flags & P_RLEAF) {
83  t->bt_cur.page = h;
84  t->bt_cur.index = recno - total;
85  return (&t->bt_cur);
86  }
87  for (index = 0, top = NEXTINDEX(h);;) {
88  r = GETRINTERNAL(h, index);
89  if (++index == top || total + r->nrecs > recno)
90  break;
91  total += r->nrecs;
92  }
93 
94  BT_PUSH(t, pg, index - 1);
95 
96  pg = r->pgno;
97  switch (op) {
98  case SDELETE:
99  --GETRINTERNAL(h, (index - 1))->nrecs;
100  mpool_put(t->bt_mp, h, MPOOL_DIRTY);
101  break;
102  case SINSERT:
103  ++GETRINTERNAL(h, (index - 1))->nrecs;
104  mpool_put(t->bt_mp, h, MPOOL_DIRTY);
105  break;
106  case SEARCH:
107  mpool_put(t->bt_mp, h, 0);
108  break;
109  }
110 
111  }
112  /* Try and recover the tree. */
113 err: sverrno = errno;
114  if (op != SEARCH)
115  while ((parent = BT_POP(t)) != NULL) {
116  if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
117  break;
118  if (op == SINSERT)
119  --GETRINTERNAL(h, parent->index)->nrecs;
120  else
121  ++GETRINTERNAL(h, parent->index)->nrecs;
122  mpool_put(t->bt_mp, h, MPOOL_DIRTY);
123  }
124  errno = sverrno;
125  return (NULL);
126 }
Definition: btree.h:75
Definition: btree.h:254
Definition: btree.h:249
Definition: btree.h:312