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. 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[] = "@(#)rec_seq.c   8.3 (Berkeley) 7/14/94";
  36 #endif /* not lint */
  37
  38 #include <sys/types.h>
  39
  40 #include <errno.h>
  41 #include <limits.h>
  42 #include <stdio.h>
  43 #include <string.h>
  44
  45 #include <db.h>
  46 #include "recno.h"
  47
  48 /*
  49  * __REC_SEQ -- Recno sequential scan interface.
  50  *
  51  * Parameters:
  52  *      dbp:    pointer to access method
  53  *      key:    key for positioning and return value
  54  *      data:   data return value
  55  *      flags:  R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV.
  56  *
  57  * Returns:
  58  *      RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
  59  */
  60 int
  61 __rec_seq(dbp, key, data, flags)
  62         const DB *dbp;
  63         DBT *key, *data;
  64         u_int flags;
  65 {
  66         BTREE *t;
  67         EPG *e;
  68         recno_t nrec;
  69         int status;
  70
  71         t = dbp->internal;
  72
  73         /* Toss any page pinned across calls. */
  74         if (t->bt_pinned != NULL) {
  75                 mpool_put(t->bt_mp, t->bt_pinned, 0);
  76                 t->bt_pinned = NULL;
  77         }
  78
  79         switch(flags) {
  80         case R_CURSOR:
  81                 if ((nrec = *(recno_t *)key->data) == 0)
  82                         goto einval;
  83                 break;
  84         case R_NEXT:
  85                 if (F_ISSET(&t->bt_cursor, CURS_INIT)) {
  86                         nrec = t->bt_cursor.rcursor + 1;
  87                         break;
  88                 }
  89                 /* FALLTHROUGH */
  90         case R_FIRST:
  91                 nrec = 1;
  92                 break;
  93         case R_PREV:
  94                 if (F_ISSET(&t->bt_cursor, CURS_INIT)) {
  95                         if ((nrec = t->bt_cursor.rcursor - 1) == 0)
  96                                 return (RET_SPECIAL);
  97                         break;
  98                 }
  99                 /* FALLTHROUGH */
 100         case R_LAST:
 101                 if (!F_ISSET(t, R_EOF | R_INMEM) &&
 102                     t->bt_irec(t, MAX_REC_NUMBER) == RET_ERROR)
 103                         return (RET_ERROR);
 104                 nrec = t->bt_nrecs;
 105                 break;
 106         default:
 107 einval:         errno = EINVAL;
 108                 return (RET_ERROR);
 109         }
 110
 111         if (t->bt_nrecs == 0 || nrec > t->bt_nrecs) {
 112                 if (!F_ISSET(t, R_EOF | R_INMEM) &&
 113                     (status = t->bt_irec(t, nrec)) != RET_SUCCESS)
 114                         return (status);
 115                 if (t->bt_nrecs == 0 || nrec > t->bt_nrecs)
 116                         return (RET_SPECIAL);
 117         }
 118
 119         if ((e = __rec_search(t, nrec - 1, SEARCH)) == NULL)
 120                 return (RET_ERROR);
 121
 122         F_SET(&t->bt_cursor, CURS_INIT);
 123         t->bt_cursor.rcursor = nrec;
 124
 125         status = __rec_ret(t, e, nrec, key, data);
 126         if (F_ISSET(t, B_DB_LOCK))
 127                 mpool_put(t->bt_mp, e->page, 0);
 128         else
 129                 t->bt_pinned = e->page;
 130         return (status);
 131 }