lib/libc/db/recno/rec_seq.c

   1 /*-
   2  * Copyright (c) 1991, 1993, 1994
   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. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * @(#)rec_seq.c        8.3 (Berkeley) 7/14/94
  30  * $DragonFly: src/lib/libc/db/recno/rec_seq.c,v 1.4 2005/11/12 23:01:55 swildner Exp $
  31  */
  32
  33 #include <sys/types.h>
  34
  35 #include <errno.h>
  36 #include <limits.h>
  37 #include <stdio.h>
  38 #include <string.h>
  39
  40 #include <db.h>
  41 #include "recno.h"
  42
  43 /*
  44  * __REC_SEQ -- Recno sequential scan interface.
  45  *
  46  * Parameters:
  47  *      dbp:    pointer to access method
  48  *      key:    key for positioning and return value
  49  *      data:   data return value
  50  *      flags:  R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV.
  51  *
  52  * Returns:
  53  *      RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
  54  */
  55 int
  56 __rec_seq(const DB *dbp, DBT *key, DBT *data, u_int flags)
  57 {
  58         BTREE *t;
  59         EPG *e;
  60         recno_t nrec;
  61         int status;
  62
  63         t = dbp->internal;
  64
  65         /* Toss any page pinned across calls. */
  66         if (t->bt_pinned != NULL) {
  67                 mpool_put(t->bt_mp, t->bt_pinned, 0);
  68                 t->bt_pinned = NULL;
  69         }
  70
  71         switch(flags) {
  72         case R_CURSOR:
  73                 if ((nrec = *(recno_t *)key->data) == 0)
  74                         goto einval;
  75                 break;
  76         case R_NEXT:
  77                 if (F_ISSET(&t->bt_cursor, CURS_INIT)) {
  78                         nrec = t->bt_cursor.rcursor + 1;
  79                         break;
  80                 }
  81                 /* FALLTHROUGH */
  82         case R_FIRST:
  83                 nrec = 1;
  84                 break;
  85         case R_PREV:
  86                 if (F_ISSET(&t->bt_cursor, CURS_INIT)) {
  87                         if ((nrec = t->bt_cursor.rcursor - 1) == 0)
  88                                 return (RET_SPECIAL);
  89                         break;
  90                 }
  91                 /* FALLTHROUGH */
  92         case R_LAST:
  93                 if (!F_ISSET(t, R_EOF | R_INMEM) &&
  94                     t->bt_irec(t, MAX_REC_NUMBER) == RET_ERROR)
  95                         return (RET_ERROR);
  96                 nrec = t->bt_nrecs;
  97                 break;
  98         default:
  99 einval:         errno = EINVAL;
 100                 return (RET_ERROR);
 101         }
 102
 103         if (t->bt_nrecs == 0 || nrec > t->bt_nrecs) {
 104                 if (!F_ISSET(t, R_EOF | R_INMEM) &&
 105                     (status = t->bt_irec(t, nrec)) != RET_SUCCESS)
 106                         return (status);
 107                 if (t->bt_nrecs == 0 || nrec > t->bt_nrecs)
 108                         return (RET_SPECIAL);
 109         }
 110
 111         if ((e = __rec_search(t, nrec - 1, SEARCH)) == NULL)
 112                 return (RET_ERROR);
 113
 114         F_SET(&t->bt_cursor, CURS_INIT);
 115         t->bt_cursor.rcursor = nrec;
 116
 117         status = __rec_ret(t, e, nrec, key, data);
 118         if (F_ISSET(t, B_DB_LOCK))
 119                 mpool_put(t->bt_mp, e->page, 0);
 120         else
 121                 t->bt_pinned = e->page;
 122         return (status);
 123 }