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rec_seq.c revision 1.5 
      1 /*-
      2  * Copyright (c) 1991, 1993
      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 #ifndef lint
     35 static char sccsid[] = "@(#)rec_seq.c	8.2 (Berkeley) 9/7/93";
     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 (ISSET(t, B_SEQINIT)) {
     86 			nrec = t->bt_rcursor + 1;
     87 			break;
     88 		}
     89 		/* FALLTHROUGH */
     90 	case R_FIRST:
     91 		nrec = 1;
     92 		break;
     93 	case R_PREV:
     94 		if (ISSET(t, B_SEQINIT)) {
     95 			if ((nrec = t->bt_rcursor - 1) == 0)
     96 				return (RET_SPECIAL);
     97 			break;
     98 		}
     99 		/* FALLTHROUGH */
    100 	case R_LAST:
    101 		if (!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 (!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 	SET(t, B_SEQINIT);
    123 	t->bt_rcursor = nrec;
    124 
    125 	status = __rec_ret(t, e, nrec, key, data);
    126 	if (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 }
    132