--- /dev/null
+/*-
+ * 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_seq.c 8.7 (Berkeley) 7/20/94";
+#endif /* LIBC_SCCS and not lint */
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD: src/lib/libc/db/btree/bt_seq.c,v 1.3 2002/03/21 22:46:25 obrien Exp $");
+
+#include <sys/types.h>
+
+#include <errno.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <db.h>
+#include "btree.h"
+
+static int __bt_first(BTREE *, const DBT *, EPG *, int *);
+static int __bt_seqadv(BTREE *, EPG *, int);
+static int __bt_seqset(BTREE *, EPG *, DBT *, int);
+
+/*
+ * Sequential scan support.
+ *
+ * The tree can be scanned sequentially, starting from either end of the
+ * tree or from any specific key. A scan request before any scanning is
+ * done is initialized as starting from the least node.
+ */
+
+/*
+ * __bt_seq --
+ * Btree sequential scan interface.
+ *
+ * Parameters:
+ * dbp: pointer to access method
+ * key: key for positioning and return value
+ * data: data return value
+ * flags: R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV.
+ *
+ * Returns:
+ * RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
+ */
+int
+__bt_seq(dbp, key, data, flags)
+ const DB *dbp;
+ DBT *key, *data;
+ u_int flags;
+{
+ BTREE *t;
+ EPG e;
+ int status;
+
+ t = dbp->internal;
+
+ /* Toss any page pinned across calls. */
+ if (t->bt_pinned != NULL) {
+ mpool_put(t->bt_mp, t->bt_pinned, 0);
+ t->bt_pinned = NULL;
+ }
+
+ /*
+ * If scan unitialized as yet, or starting at a specific record, set
+ * the scan to a specific key. Both __bt_seqset and __bt_seqadv pin
+ * the page the cursor references if they're successful.
+ */
+ switch (flags) {
+ case R_NEXT:
+ case R_PREV:
+ if (F_ISSET(&t->bt_cursor, CURS_INIT)) {
+ status = __bt_seqadv(t, &e, flags);
+ break;
+ }
+ /* FALLTHROUGH */
+ case R_FIRST:
+ case R_LAST:
+ case R_CURSOR:
+ status = __bt_seqset(t, &e, key, flags);
+ break;
+ default:
+ errno = EINVAL;
+ return (RET_ERROR);
+ }
+
+ if (status == RET_SUCCESS) {
+ __bt_setcur(t, e.page->pgno, e.index);
+
+ status =
+ __bt_ret(t, &e, key, &t->bt_rkey, data, &t->bt_rdata, 0);
+
+ /*
+ * If the user is doing concurrent access, we copied the
+ * key/data, toss the page.
+ */
+ if (F_ISSET(t, B_DB_LOCK))
+ mpool_put(t->bt_mp, e.page, 0);
+ else
+ t->bt_pinned = e.page;
+ }
+ return (status);
+}
+
+/*
+ * __bt_seqset --
+ * Set the sequential scan to a specific key.
+ *
+ * Parameters:
+ * t: tree
+ * ep: storage for returned key
+ * key: key for initial scan position
+ * flags: R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV
+ *
+ * Side effects:
+ * Pins the page the cursor references.
+ *
+ * Returns:
+ * RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
+ */
+static int
+__bt_seqset(t, ep, key, flags)
+ BTREE *t;
+ EPG *ep;
+ DBT *key;
+ int flags;
+{
+ PAGE *h;
+ pgno_t pg;
+ int exact;
+
+ /*
+ * Find the first, last or specific key in the tree and point the
+ * cursor at it. The cursor may not be moved until a new key has
+ * been found.
+ */
+ switch (flags) {
+ case R_CURSOR: /* Keyed scan. */
+ /*
+ * Find the first instance of the key or the smallest key
+ * which is greater than or equal to the specified key.
+ */
+ if (key->data == NULL || key->size == 0) {
+ errno = EINVAL;
+ return (RET_ERROR);
+ }
+ return (__bt_first(t, key, ep, &exact));
+ case R_FIRST: /* First record. */
+ case R_NEXT:
+ /* Walk down the left-hand side of the tree. */
+ for (pg = P_ROOT;;) {
+ if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
+ return (RET_ERROR);
+
+ /* Check for an empty tree. */
+ if (NEXTINDEX(h) == 0) {
+ mpool_put(t->bt_mp, h, 0);
+ return (RET_SPECIAL);
+ }
+
+ if (h->flags & (P_BLEAF | P_RLEAF))
+ break;
+ pg = GETBINTERNAL(h, 0)->pgno;
+ mpool_put(t->bt_mp, h, 0);
+ }
+ ep->page = h;
+ ep->index = 0;
+ break;
+ case R_LAST: /* Last record. */
+ case R_PREV:
+ /* Walk down the right-hand side of the tree. */
+ for (pg = P_ROOT;;) {
+ if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
+ return (RET_ERROR);
+
+ /* Check for an empty tree. */
+ if (NEXTINDEX(h) == 0) {
+ mpool_put(t->bt_mp, h, 0);
+ return (RET_SPECIAL);
+ }
+
+ if (h->flags & (P_BLEAF | P_RLEAF))
+ break;
+ pg = GETBINTERNAL(h, NEXTINDEX(h) - 1)->pgno;
+ mpool_put(t->bt_mp, h, 0);
+ }
+
+ ep->page = h;
+ ep->index = NEXTINDEX(h) - 1;
+ break;
+ }
+ return (RET_SUCCESS);
+}
+
+/*
+ * __bt_seqadvance --
+ * Advance the sequential scan.
+ *
+ * Parameters:
+ * t: tree
+ * flags: R_NEXT, R_PREV
+ *
+ * Side effects:
+ * Pins the page the new key/data record is on.
+ *
+ * Returns:
+ * RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
+ */
+static int
+__bt_seqadv(t, ep, flags)
+ BTREE *t;
+ EPG *ep;
+ int flags;
+{
+ CURSOR *c;
+ PAGE *h;
+ indx_t index;
+ pgno_t pg;
+ int exact;
+
+ /*
+ * There are a couple of states that we can be in. The cursor has
+ * been initialized by the time we get here, but that's all we know.
+ */
+ c = &t->bt_cursor;
+
+ /*
+ * The cursor was deleted where there weren't any duplicate records,
+ * so the key was saved. Find out where that key would go in the
+ * current tree. It doesn't matter if the returned key is an exact
+ * match or not -- if it's an exact match, the record was added after
+ * the delete so we can just return it. If not, as long as there's
+ * a record there, return it.
+ */
+ if (F_ISSET(c, CURS_ACQUIRE))
+ return (__bt_first(t, &c->key, ep, &exact));
+
+ /* Get the page referenced by the cursor. */
+ if ((h = mpool_get(t->bt_mp, c->pg.pgno, 0)) == NULL)
+ return (RET_ERROR);
+
+ /*
+ * Find the next/previous record in the tree and point the cursor at
+ * it. The cursor may not be moved until a new key has been found.
+ */
+ switch (flags) {
+ case R_NEXT: /* Next record. */
+ /*
+ * The cursor was deleted in duplicate records, and moved
+ * forward to a record that has yet to be returned. Clear
+ * that flag, and return the record.
+ */
+ if (F_ISSET(c, CURS_AFTER))
+ goto usecurrent;
+ index = c->pg.index;
+ if (++index == NEXTINDEX(h)) {
+ pg = h->nextpg;
+ mpool_put(t->bt_mp, h, 0);
+ if (pg == P_INVALID)
+ return (RET_SPECIAL);
+ if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
+ return (RET_ERROR);
+ index = 0;
+ }
+ break;
+ case R_PREV: /* Previous record. */
+ /*
+ * The cursor was deleted in duplicate records, and moved
+ * backward to a record that has yet to be returned. Clear
+ * that flag, and return the record.
+ */
+ if (F_ISSET(c, CURS_BEFORE)) {
+usecurrent: F_CLR(c, CURS_AFTER | CURS_BEFORE);
+ ep->page = h;
+ ep->index = c->pg.index;
+ return (RET_SUCCESS);
+ }
+ index = c->pg.index;
+ if (index == 0) {
+ pg = h->prevpg;
+ mpool_put(t->bt_mp, h, 0);
+ if (pg == P_INVALID)
+ return (RET_SPECIAL);
+ if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
+ return (RET_ERROR);
+ index = NEXTINDEX(h) - 1;
+ } else
+ --index;
+ break;
+ }
+
+ ep->page = h;
+ ep->index = index;
+ return (RET_SUCCESS);
+}
+
+/*
+ * __bt_first --
+ * Find the first entry.
+ *
+ * Parameters:
+ * t: the tree
+ * key: the key
+ * erval: return EPG
+ * exactp: pointer to exact match flag
+ *
+ * Returns:
+ * The first entry in the tree greater than or equal to key,
+ * or RET_SPECIAL if no such key exists.
+ */
+static int
+__bt_first(t, key, erval, exactp)
+ BTREE *t;
+ const DBT *key;
+ EPG *erval;
+ int *exactp;
+{
+ PAGE *h;
+ EPG *ep, save;
+ pgno_t pg;
+
+ /*
+ * Find any matching record; __bt_search pins the page.
+ *
+ * If it's an exact match and duplicates are possible, walk backwards
+ * in the tree until we find the first one. Otherwise, make sure it's
+ * a valid key (__bt_search may return an index just past the end of a
+ * page) and return it.
+ */
+ if ((ep = __bt_search(t, key, exactp)) == NULL)
+ return (0);
+ if (*exactp) {
+ if (F_ISSET(t, B_NODUPS)) {
+ *erval = *ep;
+ return (RET_SUCCESS);
+ }
+
+ /*
+ * Walk backwards, as long as the entry matches and there are
+ * keys left in the tree. Save a copy of each match in case
+ * we go too far.
+ */
+ save = *ep;
+ h = ep->page;
+ do {
+ if (save.page->pgno != ep->page->pgno) {
+ mpool_put(t->bt_mp, save.page, 0);
+ save = *ep;
+ } else
+ save.index = ep->index;
+
+ /*
+ * Don't unpin the page the last (or original) match
+ * was on, but make sure it's unpinned if an error
+ * occurs.
+ */
+ if (ep->index == 0) {
+ PAGE *hprev;
+ if (h->prevpg == P_INVALID)
+ break;
+ if (h->pgno != save.page->pgno)
+ mpool_put(t->bt_mp, h, 0);
+ if ((hprev = mpool_get(t->bt_mp,
+ h->prevpg, 0)) == NULL) {
+ if (h->pgno == save.page->pgno)
+ mpool_put(t->bt_mp,
+ save.page, 0);
+ return (RET_ERROR);
+ }
+ ep->page = h = hprev;
+ ep->index = NEXTINDEX(h);
+ }
+ --ep->index;
+ } while (__bt_cmp(t, key, ep) == 0);
+
+ /*
+ * Reach here with the last page that was looked at pinned,
+ * which may or may not be the same as the last (or original)
+ * match page. If it's not useful, release it.
+ */
+ if (h->pgno != save.page->pgno)
+ mpool_put(t->bt_mp, h, 0);
+
+ *erval = save;
+ return (RET_SUCCESS);
+ }
+
+ /* If at the end of a page, find the next entry. */
+ if (ep->index == NEXTINDEX(ep->page)) {
+ h = ep->page;
+ pg = h->nextpg;
+ mpool_put(t->bt_mp, h, 0);
+ if (pg == P_INVALID)
+ return (RET_SPECIAL);
+ if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
+ return (RET_ERROR);
+ ep->index = 0;
+ ep->page = h;
+ }
+ *erval = *ep;
+ return (RET_SUCCESS);
+}
+
+/*
+ * __bt_setcur --
+ * Set the cursor to an entry in the tree.
+ *
+ * Parameters:
+ * t: the tree
+ * pgno: page number
+ * index: page index
+ */
+void
+__bt_setcur(t, pgno, index)
+ BTREE *t;
+ pgno_t pgno;
+ u_int index;
+{
+ /* Lose any already deleted key. */
+ if (t->bt_cursor.key.data != NULL) {
+ free(t->bt_cursor.key.data);
+ t->bt_cursor.key.size = 0;
+ t->bt_cursor.key.data = NULL;
+ }
+ F_CLR(&t->bt_cursor, CURS_ACQUIRE | CURS_AFTER | CURS_BEFORE);
+
+ /* Update the cursor. */
+ t->bt_cursor.pg.pgno = pgno;
+ t->bt_cursor.pg.index = index;
+ F_SET(&t->bt_cursor, CURS_INIT);
+}
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