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-rw-r--r--utils/db1-ast/btree/bt_search.c213
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diff --git a/utils/db1-ast/btree/bt_search.c b/utils/db1-ast/btree/bt_search.c
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+/*-
+ * Copyright (c) 1990, 1993, 1994
+ * 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_search.c 8.8 (Berkeley) 7/31/94";
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/types.h>
+
+#include <stdio.h>
+
+#include "../include/db.h"
+#include "btree.h"
+
+static int __bt_snext __P((BTREE *, PAGE *, const DBT *, int *));
+static int __bt_sprev __P((BTREE *, PAGE *, const DBT *, int *));
+
+/*
+ * __bt_search --
+ * Search a btree for a key.
+ *
+ * Parameters:
+ * t: tree to search
+ * key: key to find
+ * exactp: pointer to exact match flag
+ *
+ * Returns:
+ * The EPG for matching record, if any, or the EPG for the location
+ * of the key, if it were inserted into the tree, is entered into
+ * the bt_cur field of the tree. A pointer to the field is returned.
+ */
+EPG *
+__bt_search(t, key, exactp)
+ BTREE *t;
+ const DBT *key;
+ int *exactp;
+{
+ PAGE *h;
+ indx_t base, index, lim;
+ pgno_t pg;
+ int cmp;
+
+ BT_CLR(t);
+ for (pg = P_ROOT;;) {
+ if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
+ return (NULL);
+
+ /* Do a binary search on the current page. */
+ t->bt_cur.page = h;
+ for (base = 0, lim = NEXTINDEX(h); lim; lim >>= 1) {
+ t->bt_cur.index = index = base + (lim >> 1);
+ if ((cmp = __bt_cmp(t, key, &t->bt_cur)) == 0) {
+ if (h->flags & P_BLEAF) {
+ *exactp = 1;
+ return (&t->bt_cur);
+ }
+ goto next;
+ }
+ if (cmp > 0) {
+ base = index + 1;
+ --lim;
+ }
+ }
+
+ /*
+ * If it's a leaf page, we're almost done. If no duplicates
+ * are allowed, or we have an exact match, we're done. Else,
+ * it's possible that there were matching keys on this page,
+ * which later deleted, and we're on a page with no matches
+ * while there are matches on other pages. If at the start or
+ * end of a page, check the adjacent page.
+ */
+ if (h->flags & P_BLEAF) {
+ if (!F_ISSET(t, B_NODUPS)) {
+ if (base == 0 &&
+ h->prevpg != P_INVALID &&
+ __bt_sprev(t, h, key, exactp))
+ return (&t->bt_cur);
+ if (base == NEXTINDEX(h) &&
+ h->nextpg != P_INVALID &&
+ __bt_snext(t, h, key, exactp))
+ return (&t->bt_cur);
+ }
+ *exactp = 0;
+ t->bt_cur.index = base;
+ return (&t->bt_cur);
+ }
+
+ /*
+ * No match found. Base is the smallest index greater than
+ * key and may be zero or a last + 1 index. If it's non-zero,
+ * decrement by one, and record the internal page which should
+ * be a parent page for the key. If a split later occurs, the
+ * inserted page will be to the right of the saved page.
+ */
+ index = base ? base - 1 : base;
+
+next: BT_PUSH(t, h->pgno, index);
+ pg = GETBINTERNAL(h, index)->pgno;
+ mpool_put(t->bt_mp, h, 0);
+ }
+}
+
+/*
+ * __bt_snext --
+ * Check for an exact match after the key.
+ *
+ * Parameters:
+ * t: tree
+ * h: current page
+ * key: key
+ * exactp: pointer to exact match flag
+ *
+ * Returns:
+ * If an exact match found.
+ */
+static int
+__bt_snext(t, h, key, exactp)
+ BTREE *t;
+ PAGE *h;
+ const DBT *key;
+ int *exactp;
+{
+ EPG e;
+
+ /*
+ * Get the next page. The key is either an exact
+ * match, or not as good as the one we already have.
+ */
+ if ((e.page = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL)
+ return (0);
+ e.index = 0;
+ if (__bt_cmp(t, key, &e) == 0) {
+ mpool_put(t->bt_mp, h, 0);
+ t->bt_cur = e;
+ *exactp = 1;
+ return (1);
+ }
+ mpool_put(t->bt_mp, e.page, 0);
+ return (0);
+}
+
+/*
+ * __bt_sprev --
+ * Check for an exact match before the key.
+ *
+ * Parameters:
+ * t: tree
+ * h: current page
+ * key: key
+ * exactp: pointer to exact match flag
+ *
+ * Returns:
+ * If an exact match found.
+ */
+static int
+__bt_sprev(t, h, key, exactp)
+ BTREE *t;
+ PAGE *h;
+ const DBT *key;
+ int *exactp;
+{
+ EPG e;
+
+ /*
+ * Get the previous page. The key is either an exact
+ * match, or not as good as the one we already have.
+ */
+ if ((e.page = mpool_get(t->bt_mp, h->prevpg, 0)) == NULL)
+ return (0);
+ e.index = NEXTINDEX(e.page) - 1;
+ if (__bt_cmp(t, key, &e) == 0) {
+ mpool_put(t->bt_mp, h, 0);
+ t->bt_cur = e;
+ *exactp = 1;
+ return (1);
+ }
+ mpool_put(t->bt_mp, e.page, 0);
+ return (0);
+}