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[] = "from: @(#)rec_search.c 8.1 (Berkeley) 6/4/93";*/ 36 static char rcsid[] = "$Id: rec_search.c,v 1.2 1993/08/01 18:43:12 mycroft Exp $"; 37 #endif /* LIBC_SCCS and not lint */ 38 39 #include <sys/types.h> 40 41 #include <errno.h> 42 #include <stdio.h> 43 44 #include <db.h> 45 #include "recno.h" 46 47 /* 48 * __REC_SEARCH -- Search a btree for a key. 49 * 50 * Parameters: 51 * t: tree to search 52 * recno: key to find 53 * op: search operation 54 * 55 * Returns: 56 * EPG for matching record, if any, or the EPG for the location of the 57 * key, if it were inserted into the tree. 58 * 59 * Warnings: 60 * The EPG returned is in static memory, and will be overwritten by the 61 * next search of any kind in any tree. 62 */ 63 EPG * 64 __rec_search(t, recno, op) 65 BTREE *t; 66 recno_t recno; 67 enum SRCHOP op; 68 { 69 static EPG e; 70 register indx_t index; 71 register PAGE *h; 72 EPGNO *parent; 73 RINTERNAL *r; 74 pgno_t pg; 75 indx_t top; 76 recno_t total; 77 int serrno; 78 79 BT_CLR(t); 80 for (pg = P_ROOT, total = 0;;) { 81 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 82 goto err; 83 if (h->flags & P_RLEAF) { 84 e.page = h; 85 e.index = recno - total; 86 return (&e); 87 } 88 for (index = 0, top = NEXTINDEX(h);;) { 89 r = GETRINTERNAL(h, index); 90 if (++index == top || total + r->nrecs > recno) 91 break; 92 total += r->nrecs; 93 } 94 95 if (__bt_push(t, pg, index - 1) == RET_ERROR) 96 return (NULL); 97 98 pg = r->pgno; 99 switch (op) { 100 case SDELETE: 101 --GETRINTERNAL(h, (index - 1))->nrecs; 102 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 103 break; 104 case SINSERT: 105 ++GETRINTERNAL(h, (index - 1))->nrecs; 106 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 107 break; 108 case SEARCH: 109 mpool_put(t->bt_mp, h, 0); 110 break; 111 } 112 113 } 114 /* Try and recover the tree. */ 115 err: serrno = errno; 116 if (op != SEARCH) 117 while ((parent = BT_POP(t)) != NULL) { 118 if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL) 119 break; 120 if (op == SINSERT) 121 --GETRINTERNAL(h, parent->index)->nrecs; 122 else 123 ++GETRINTERNAL(h, parent->index)->nrecs; 124 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 125 } 126 errno = serrno; 127 return (NULL); 128 } 129