bt_get.c

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00001 /*-
00002  * Copyright (c) 1990, 1993, 1994
00003  * The Regents of the University of California.  All rights reserved.
00004  *
00005  * This code is derived from software contributed to Berkeley by
00006  * Mike Olson.
00007  *
00008  * Redistribution and use in source and binary forms, with or without
00009  * modification, are permitted provided that the following conditions
00010  * are met:
00011  * 1. Redistributions of source code must retain the above copyright
00012  *    notice, this list of conditions and the following disclaimer.
00013  * 2. Redistributions in binary form must reproduce the above copyright
00014  *    notice, this list of conditions and the following disclaimer in the
00015  *    documentation and/or other materials provided with the distribution.
00016  * 3. All advertising materials mentioning features or use of this software
00017  *    must display the following acknowledgement:
00018  * This product includes software developed by the University of
00019  * California, Berkeley and its contributors.
00020  * 4. Neither the name of the University nor the names of its contributors
00021  *    may be used to endorse or promote products derived from this software
00022  *    without specific prior written permission.
00023  *
00024  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
00025  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00026  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
00027  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
00028  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
00029  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
00030  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
00031  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00032  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
00033  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
00034  * SUCH DAMAGE.
00035  */
00036 
00037 #if defined(LIBC_SCCS) && !defined(lint)
00038 static char sccsid[] = "@(#)bt_get.c   8.6 (Berkeley) 7/20/94";
00039 #endif /* LIBC_SCCS and not lint */
00040 
00041 #include <sys/types.h>
00042 
00043 #include <errno.h>
00044 #include <stddef.h>
00045 #include <stdio.h>
00046 
00047 #include "../include/db.h"
00048 #include "btree.h"
00049 
00050 /*
00051  * __BT_GET -- Get a record from the btree.
00052  *
00053  * Parameters:
00054  * dbp:  pointer to access method
00055  * key:  key to find
00056  * data: data to return
00057  * flag: currently unused
00058  *
00059  * Returns:
00060  * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
00061  */
00062 int
00063 __bt_get(dbp, key, data, flags)
00064    const DB *dbp;
00065    const DBT *key;
00066    DBT *data;
00067    u_int flags;
00068 {
00069    BTREE *t;
00070    EPG *e;
00071    int exact, status;
00072 
00073    t = dbp->internal;
00074 
00075    /* Toss any page pinned across calls. */
00076    if (t->bt_pinned != NULL) {
00077       mpool_put(t->bt_mp, t->bt_pinned, 0);
00078       t->bt_pinned = NULL;
00079    }
00080 
00081    /* Get currently doesn't take any flags. */
00082    if (flags) {
00083       errno = EINVAL;
00084       return (RET_ERROR);
00085    }
00086 
00087    if ((e = __bt_search(t, key, &exact)) == NULL)
00088       return (RET_ERROR);
00089    if (!exact) {
00090       mpool_put(t->bt_mp, e->page, 0);
00091       return (RET_SPECIAL);
00092    }
00093 
00094    status = __bt_ret(t, e, NULL, NULL, data, &t->bt_rdata, 0);
00095 
00096    /*
00097     * If the user is doing concurrent access, we copied the
00098     * key/data, toss the page.
00099     */
00100    if (F_ISSET(t, B_DB_LOCK))
00101       mpool_put(t->bt_mp, e->page, 0);
00102    else
00103       t->bt_pinned = e->page;
00104    return (status);
00105 }

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