db/recno/rec_seq.c

   1 /*
   2  * Copyright (c) 2003 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*-
  26  * Copyright (c) 1991, 1993, 1994
  27  *      The Regents of the University of California.  All rights reserved.
  28  *
  29  * Redistribution and use in source and binary forms, with or without
  30  * modification, are permitted provided that the following conditions
  31  * are met:
  32  * 1. Redistributions of source code must retain the above copyright
  33  *    notice, this list of conditions and the following disclaimer.
  34  * 2. Redistributions in binary form must reproduce the above copyright
  35  *    notice, this list of conditions and the following disclaimer in the
  36  *    documentation and/or other materials provided with the distribution.
  37  * 3. All advertising materials mentioning features or use of this software
  38  *    must display the following acknowledgement:
  39  *      This product includes software developed by the University of
  40  *      California, Berkeley and its contributors.
  41  * 4. Neither the name of the University nor the names of its contributors
  42  *    may be used to endorse or promote products derived from this software
  43  *    without specific prior written permission.
  44  *
  45  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  46  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  47  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  48  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  49  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  50  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  51  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  52  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  53  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  54  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  55  * SUCH DAMAGE.
  56  */
  57
  58 #include <sys/cdefs.h>
  59 #include <sys/types.h>
  60
  61 #include <errno.h>
  62 #include <limits.h>
  63 #include <stdio.h>
  64 #include <string.h>
  65
  66 #include <db.h>
  67 #include "recno.h"
  68
  69 /*
  70  * __REC_SEQ -- Recno sequential scan interface.
  71  *
  72  * Parameters:
  73  *      dbp:    pointer to access method
  74  *      key:    key for positioning and return value
  75  *      data:   data return value
  76  *      flags:  R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV.
  77  *
  78  * Returns:
  79  *      RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
  80  */
  81 int
  82 __rec_seq(dbp, key, data, flags)
  83         const DB *dbp;
  84         DBT *key, *data;
  85         u_int flags;
  86 {
  87         BTREE *t;
  88         EPG *e;
  89         recno_t nrec;
  90         int status;
  91
  92         t = dbp->internal;
  93
  94         /* Toss any page pinned across calls. */
  95         if (t->bt_pinned != NULL) {
  96                 mpool_put(t->bt_mp, t->bt_pinned, 0);
  97                 t->bt_pinned = NULL;
  98         }
  99
 100         switch(flags) {
 101         case R_CURSOR:
 102                 if ((nrec = *(recno_t *)key->data) == 0)
 103                         goto einval;
 104                 break;
 105         case R_NEXT:
 106                 if (F_ISSET(&t->bt_cursor, CURS_INIT)) {
 107                         nrec = t->bt_cursor.rcursor + 1;
 108                         break;
 109                 }
 110                 /* FALLTHROUGH */
 111         case R_FIRST:
 112                 nrec = 1;
 113                 break;
 114         case R_PREV:
 115                 if (F_ISSET(&t->bt_cursor, CURS_INIT)) {
 116                         if ((nrec = t->bt_cursor.rcursor - 1) == 0)
 117                                 return (RET_SPECIAL);
 118                         break;
 119                 }
 120                 /* FALLTHROUGH */
 121         case R_LAST:
 122                 if (!F_ISSET(t, R_EOF | R_INMEM) &&
 123                     t->bt_irec(t, MAX_REC_NUMBER) == RET_ERROR)
 124                         return (RET_ERROR);
 125                 nrec = t->bt_nrecs;
 126                 break;
 127         default:
 128 einval:         errno = EINVAL;
 129                 return (RET_ERROR);
 130         }
 131
 132         if (t->bt_nrecs == 0 || nrec > t->bt_nrecs) {
 133                 if (!F_ISSET(t, R_EOF | R_INMEM) &&
 134                     (status = t->bt_irec(t, nrec)) != RET_SUCCESS)
 135                         return (status);
 136                 if (t->bt_nrecs == 0 || nrec > t->bt_nrecs)
 137                         return (RET_SPECIAL);
 138         }
 139
 140         if ((e = __rec_search(t, nrec - 1, SEARCH)) == NULL)
 141                 return (RET_ERROR);
 142
 143         F_SET(&t->bt_cursor, CURS_INIT);
 144         t->bt_cursor.rcursor = nrec;
 145
 146         status = __rec_ret(t, e, nrec, key, data);
 147         if (F_ISSET(t, B_DB_LOCK))
 148                 mpool_put(t->bt_mp, e->page, 0);
 149         else
 150                 t->bt_pinned = e->page;
 151         return (status);
 152 }