initial import of NetBSD tree

1 files changed, 241 insertions, 0 deletions

diff --git a/lib/libc/db/btree/bt_search.c b/lib/libc/db/btree/bt_search.c
new file mode 100644
index 00000000000..c98fe7346ea
--- /dev/null
+++ b/lib/libc/db/btree/bt_search.c
@@ -0,0 +1,241 @@
+/*	$NetBSD: bt_search.c,v 1.7 1995/02/27 13:20:44 cgd Exp $	*/
+
+/*-
+ * 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)
+#if 0
+static char sccsid[] = "@(#)bt_search.c	8.6 (Berkeley) 3/15/94";
+#else
+static char rcsid[] = "$NetBSD: bt_search.c,v 1.7 1995/02/27 13:20:44 cgd Exp $";
+#endif
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/types.h>
+
+#include <stdio.h>
+
+#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, and duplicates aren't allowed, we're
+		 * done.  If duplicates are allowed, it's possible that there
+		 * were duplicate keys on duplicate pages, and they were later
+		 * deleted, so we could be on a page with no matches while
+		 * there are matches on other pages.  If we're at the start or
+		 * end of a page, check on both sides.
+		 */
+		if (h->flags & P_BLEAF) {
+			t->bt_cur.index = base;
+			*exactp = 0;
+			if (!ISSET(t, B_NODUPS)) {
+				if (base == 0 &&
+				    bt_sprev(t, h, key, exactp))
+					return (&t->bt_cur);
+				if (base == NEXTINDEX(h) &&
+				    bt_snext(t, h, key, exactp))
+					return (&t->bt_cur);
+			}
+			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:		if (__bt_push(t, h->pgno, index) == RET_ERROR)
+			return (NULL);
+		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 to search
+ *	h:	current page.
+ *	key:	key to find
+ *	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;
+	PAGE *tp;
+	pgno_t pg;
+
+	/* Skip until reach the end of the tree or a key. */
+	for (pg = h->nextpg; pg != P_INVALID;) {
+		if ((tp = mpool_get(t->bt_mp, pg, 0)) == NULL) {
+			mpool_put(t->bt_mp, h, 0);
+			return (NULL);
+		}
+		if (NEXTINDEX(tp) != 0)
+			break;
+		pg = tp->prevpg;
+		mpool_put(t->bt_mp, tp, 0);
+	}
+	/*
+	 * The key is either an exact match, or not as good as
+	 * the one we already have.
+	 */
+	if (pg != P_INVALID) {
+		e.page = tp;
+		e.index = NEXTINDEX(tp) - 1;
+		if (__bt_cmp(t, key, &e) == 0) {
+			mpool_put(t->bt_mp, h, 0);
+			t->bt_cur = e;
+			*exactp = 1;
+			return (1);
+		}
+	}
+	return (0);
+}
+
+/*
+ * BT_SPREV -- Check for an exact match before the key.
+ *
+ * Parameters:
+ *	t:	tree to search
+ *	h:	current page.
+ *	key:	key to find
+ *	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;
+	PAGE *tp;
+	pgno_t pg;
+
+	/* Skip until reach the beginning of the tree or a key. */
+	for (pg = h->prevpg; pg != P_INVALID;) {
+		if ((tp = mpool_get(t->bt_mp, pg, 0)) == NULL) {
+			mpool_put(t->bt_mp, h, 0);
+			return (NULL);
+		}
+		if (NEXTINDEX(tp) != 0)
+			break;
+		pg = tp->prevpg;
+		mpool_put(t->bt_mp, tp, 0);
+	}
+	/*
+	 * The key is either an exact match, or not as good as
+	 * the one we already have.
+	 */
+	if (pg != P_INVALID) {
+		e.page = tp;
+		e.index = NEXTINDEX(tp) - 1;
+		if (__bt_cmp(t, key, &e) == 0) {
+			mpool_put(t->bt_mp, h, 0);
+			t->bt_cur = e;
+			*exactp = 1;
+			return (1);
+		}
+	}
+	return (0);
+}