db/recno/rec_seq.c

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