usr/src/lib/libc/db/btree/bt_utils.c

/*-
 * Copyright (c) 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Mike Olson.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)bt_utils.c  8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */

#include <sys/param.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <db.h>
#include "btree.h"

/*
 * __BT_RET -- Build return key/data pair as a result of search or scan.
 *
 * Parameters:
 *      t:      tree
 *      d:      LEAF to be returned to the user.
 *      key:    user's key structure (NULL if not to be filled in)
 *      data:   user's data structure
 *
 * Returns:
 *      RET_SUCCESS, RET_ERROR.
 */
int
__bt_ret(t, e, key, data)
        BTREE *t;
        EPG *e;
        DBT *key, *data;
{
        register BLEAF *bl;
        register void *p;

        bl = GETBLEAF(e->page, e->index);

        if (bl->flags & P_BIGDATA) {
                if (__ovfl_get(t, bl->bytes + bl->ksize,
                    &data->size, &t->bt_dbuf, &t->bt_dbufsz))
                        return (RET_ERROR);
        } else {
                /* Use +1 in case the first record retrieved is 0 length. */
                if (bl->dsize + 1 > t->bt_dbufsz) {
                        if ((p = realloc(t->bt_dbuf, bl->dsize + 1)) == NULL)
                                return (RET_ERROR);
                        t->bt_dbuf = p;
                        t->bt_dbufsz = bl->dsize + 1;
                }
                memmove(t->bt_dbuf, bl->bytes + bl->ksize, bl->dsize);
                data->size = bl->dsize;
        }
        data->data = t->bt_dbuf;

        if (key == NULL)
                return (RET_SUCCESS);

        if (bl->flags & P_BIGKEY) {
                if (__ovfl_get(t, bl->bytes,
                    &key->size, &t->bt_kbuf, &t->bt_kbufsz))
                        return (RET_ERROR);
        } else {
                if (bl->ksize > t->bt_kbufsz) {
                        if ((p = realloc(t->bt_kbuf, bl->ksize)) == NULL)
                                return (RET_ERROR);
                        t->bt_kbuf = p;
                        t->bt_kbufsz = bl->ksize;
                }
                memmove(t->bt_kbuf, bl->bytes, bl->ksize);
                key->size = bl->ksize;
        }
        key->data = t->bt_kbuf;
        return (RET_SUCCESS);
}

/*
 * __BT_CMP -- Compare a key to a given record.
 *
 * Parameters:
 *      t:      tree
 *      k1:     DBT pointer of first arg to comparison
 *      e:      pointer to EPG for comparison
 *
 * Returns:
 *      < 0 if k1 is < record
 *      = 0 if k1 is = record
 *      > 0 if k1 is > record
 */
int
__bt_cmp(t, k1, e)
        BTREE *t;
        const DBT *k1;
        EPG *e;
{
        BINTERNAL *bi;
        BLEAF *bl;
        DBT k2;
        PAGE *h;
        void *bigkey;

        /*
         * The left-most key on internal pages, at any level of the tree, is
         * guaranteed by the following code to be less than any user key.
         * This saves us from having to update the leftmost key on an internal
         * page when the user inserts a new key in the tree smaller than
         * anything we've yet seen.
         */
        h = e->page;
        if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & P_BLEAF))
                return (1);

        bigkey = NULL;
        if (h->flags & P_BLEAF) {
                bl = GETBLEAF(h, e->index);
                if (bl->flags & P_BIGKEY)
                        bigkey = bl->bytes;
                else {
                        k2.data = bl->bytes;
                        k2.size = bl->ksize;
                }
        } else {
                bi = GETBINTERNAL(h, e->index);
                if (bi->flags & P_BIGKEY)
                        bigkey = bi->bytes;
                else {
                        k2.data = bi->bytes;
                        k2.size = bi->ksize;
                }
        }

        if (bigkey) {
                if (__ovfl_get(t, bigkey,
                    &k2.size, &t->bt_dbuf, &t->bt_dbufsz))
                        return (RET_ERROR);
                k2.data = t->bt_dbuf;
        }
        return ((*t->bt_cmp)(k1, &k2));
}

/*
 * __BT_DEFCMP -- Default comparison routine.
 *
 * Parameters:
 *      a:      DBT #1
 *      b:      DBT #2
 *
 * Returns:
 *      < 0 if a is < b
 *      = 0 if a is = b
 *      > 0 if a is > b
 */
int
__bt_defcmp(a, b)
        const DBT *a, *b;
{
        register u_char *p1, *p2;
        register int diff, len;

        len = MIN(a->size, b->size);
        for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2)
                if (diff = *p1 - *p2)
                        return (diff);
        return (a->size - b->size);
}

/*
 * __BT_DEFPFX -- Default prefix routine.
 *
 * Parameters:
 *      a:      DBT #1
 *      b:      DBT #2
 *
 * Returns:
 *      Number of bytes needed to distinguish b from a.
 */
int
__bt_defpfx(a, b)
        const DBT *a, *b;
{
        register u_char *p1, *p2;
        register int len;
        int cnt;

        cnt = 1;
        len = MIN(a->size, b->size);
        for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt)
                if (*p1 != *p2)
                        return (cnt);

        /* a->size must be <= b->size, or they wouldn't be in this order. */
        return (a->size < b->size ? a->size + 1 : a->size);
}