db/recno/rec_seq.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Copyright (c) 1991, 1993
  24  *      The Regents of the University of California.  All rights reserved.
  25  *
  26  * Redistribution and use in source and binary forms, with or without
  27  * modification, are permitted provided that the following conditions
  28  * are met:
  29  * 1. Redistributions of source code must retain the above copyright
  30  *    notice, this list of conditions and the following disclaimer.
  31  * 2. Redistributions in binary form must reproduce the above copyright
  32  *    notice, this list of conditions and the following disclaimer in the
  33  *    documentation and/or other materials provided with the distribution.
  34  * 3. All advertising materials mentioning features or use of this software
  35  *    must display the following acknowledgement:
  36  *      This product includes software developed by the University of
  37  *      California, Berkeley and its contributors.
  38  * 4. Neither the name of the University nor the names of its contributors
  39  *    may be used to endorse or promote products derived from this software
  40  *    without specific prior written permission.
  41  *
  42  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  43  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  44  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  45  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  46  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  47  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  48  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  49  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  50  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  51  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  52  * SUCH DAMAGE.
  53  */
  54
  55
  56 #include <sys/types.h>
  57
  58 #include <errno.h>
  59 #include <limits.h>
  60 #include <stdio.h>
  61 #include <string.h>
  62
  63 #include <db.h>
  64 #include "recno.h"
  65
  66 /*
  67  * __REC_SEQ -- Recno sequential scan interface.
  68  *
  69  * Parameters:
  70  *      dbp:    pointer to access method
  71  *      key:    key for positioning and return value
  72  *      data:   data return value
  73  *      flags:  R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV.
  74  *
  75  * Returns:
  76  *      RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
  77  */
  78 int
  79 __rec_seq(dbp, key, data, flags)
  80         const DB *dbp;
  81         DBT *key, *data;
  82         u_int flags;
  83 {
  84         BTREE *t;
  85         EPG *e;
  86         recno_t nrec;
  87         int status;
  88
  89         t = dbp->internal;
  90
  91         /* Toss any page pinned across calls. */
  92         if (t->bt_pinned != NULL) {
  93                 mpool_put(t->bt_mp, t->bt_pinned, 0);
  94                 t->bt_pinned = NULL;
  95         }
  96
  97         switch(flags) {
  98         case R_CURSOR:
  99                 if ((nrec = *(recno_t *)key->data) == 0)
 100                         goto einval;
 101                 break;
 102         case R_NEXT:
 103                 if (ISSET(t, B_SEQINIT)) {
 104                         nrec = t->bt_rcursor + 1;
 105                         break;
 106                 }
 107                 /* FALLTHROUGH */
 108         case R_FIRST:
 109                 nrec = 1;
 110                 break;
 111         case R_PREV:
 112                 if (ISSET(t, B_SEQINIT)) {
 113                         if ((nrec = t->bt_rcursor - 1) == 0)
 114                                 return (RET_SPECIAL);
 115                         break;
 116                 }
 117                 /* FALLTHROUGH */
 118         case R_LAST:
 119                 if (!ISSET(t, R_EOF | R_INMEM) &&
 120                     t->bt_irec(t, MAX_REC_NUMBER) == RET_ERROR)
 121                         return (RET_ERROR);
 122                 nrec = t->bt_nrecs;
 123                 break;
 124         default:
 125 einval:         errno = EINVAL;
 126                 return (RET_ERROR);
 127         }
 128
 129         if (t->bt_nrecs == 0 || nrec > t->bt_nrecs) {
 130                 if (!ISSET(t, R_EOF | R_INMEM) &&
 131                     (status = t->bt_irec(t, nrec)) != RET_SUCCESS)
 132                         return (status);
 133                 if (t->bt_nrecs == 0 || nrec > t->bt_nrecs)
 134                         return (RET_SPECIAL);
 135         }
 136
 137         if ((e = __rec_search(t, nrec - 1, SEARCH)) == NULL)
 138                 return (RET_ERROR);
 139
 140         SET(t, B_SEQINIT);
 141         t->bt_rcursor = nrec;
 142
 143         status = __rec_ret(t, e, nrec, key, data);
 144         if (ISSET(t, B_DB_LOCK))
 145                 mpool_put(t->bt_mp, e->page, 0);
 146         else
 147                 t->bt_pinned = e->page;
 148         return (status);
 149 }