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GCC Code Coverage Report

Directory:	./		Exec	Total	Coverage
File:	lib/libc/db/btree/bt_delete.c	Lines:	0	246	0.0 %
Date:	2017-11-13	Branches:	0	201	0.0 %


/*	$OpenBSD: bt_delete.c,v 1.11 2005/08/05 13:02:59 espie Exp $	*/

/*-
 * 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. 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.
 */

#include <sys/types.h>

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

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

static int __bt_bdelete(BTREE *, const DBT *);
static int __bt_curdel(BTREE *, const DBT *, PAGE *, u_int);
static int __bt_pdelete(BTREE *, PAGE *);
static int __bt_relink(BTREE *, PAGE *);
static int __bt_stkacq(BTREE *, PAGE **, CURSOR *);

/*
 * __bt_delete
 *	Delete the item(s) referenced by a key.
 *
 * Return RET_SPECIAL if the key is not found.
 */
int
__bt_delete(const DB *dbp, const DBT *key, u_int flags)
{
	BTREE *t;
	CURSOR *c;
	PAGE *h;
	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;
	}

	/* Check for change to a read-only tree. */
	if (F_ISSET(t, B_RDONLY)) {
		errno = EPERM;
		return (RET_ERROR);
	}

	switch (flags) {
	case 0:
		status = __bt_bdelete(t, key);
		break;
	case R_CURSOR:
		/*
		 * If flags is R_CURSOR, delete the cursor.  Must already
		 * have started a scan and not have already deleted it.
		 */
		c = &t->bt_cursor;
		if (F_ISSET(c, CURS_INIT)) {
			if (F_ISSET(c, CURS_ACQUIRE | CURS_AFTER | CURS_BEFORE))
				return (RET_SPECIAL);
			if ((h = mpool_get(t->bt_mp, c->pg.pgno, 0)) == NULL)
				return (RET_ERROR);

			/*
			 * If the page is about to be emptied, we'll need to
			 * delete it, which means we have to acquire a stack.
			 */
			if (NEXTINDEX(h) == 1)
				if (__bt_stkacq(t, &h, &t->bt_cursor))
					return (RET_ERROR);

			status = __bt_dleaf(t, NULL, h, c->pg.index);

			if (NEXTINDEX(h) == 0 && status == RET_SUCCESS) {
				if (__bt_pdelete(t, h))
					return (RET_ERROR);
			} else
				mpool_put(t->bt_mp,
				    h, status == RET_SUCCESS ? MPOOL_DIRTY : 0);
			break;
		}
		/* FALLTHROUGH */
	default:
		errno = EINVAL;
		return (RET_ERROR);
	}
	if (status == RET_SUCCESS)
		F_SET(t, B_MODIFIED);
	return (status);
}

/*
 * __bt_stkacq --
 *	Acquire a stack so we can delete a cursor entry.
 *
 * Parameters:
 *	  t:	tree
 *	 hp:	pointer to current, pinned PAGE pointer
 *	  c:	pointer to the cursor
 *
 * Returns:
 *	0 on success, 1 on failure
 */
static int
__bt_stkacq(BTREE *t, PAGE **hp, CURSOR *c)
{
	BINTERNAL *bi;
	EPG *e;
	EPGNO *parent;
	PAGE *h;
	indx_t idx;
	pgno_t pgno;
	recno_t nextpg, prevpg;
	int exact, level;

	/*
	 * Find the first occurrence of the key in the tree.  Toss the
	 * currently locked page so we don't hit an already-locked page.
	 */
	h = *hp;
	mpool_put(t->bt_mp, h, 0);
	if ((e = __bt_search(t, &c->key, &exact)) == NULL)
		return (1);
	h = e->page;

	/* See if we got it in one shot. */
	if (h->pgno == c->pg.pgno)
		goto ret;

	/*
	 * Move right, looking for the page.  At each move we have to move
	 * up the stack until we don't have to move to the next page.  If
	 * we have to change pages at an internal level, we have to fix the
	 * stack back up.
	 */
	while (h->pgno != c->pg.pgno) {
		if ((nextpg = h->nextpg) == P_INVALID)
			break;
		mpool_put(t->bt_mp, h, 0);

		/* Move up the stack. */
		for (level = 0; (parent = BT_POP(t)) != NULL; ++level) {
			/* Get the parent page. */
			if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
				return (1);

			/* Move to the next index. */
			if (parent->index != NEXTINDEX(h) - 1) {
				idx = parent->index + 1;
				BT_PUSH(t, h->pgno, idx);
				break;
			}
			mpool_put(t->bt_mp, h, 0);
		}

		/* Restore the stack. */
		while (level--) {
			/* Push the next level down onto the stack. */
			bi = GETBINTERNAL(h, idx);
			pgno = bi->pgno;
			BT_PUSH(t, pgno, 0);

			/* Lose the currently pinned page. */
			mpool_put(t->bt_mp, h, 0);

			/* Get the next level down. */
			if ((h = mpool_get(t->bt_mp, pgno, 0)) == NULL)
				return (1);
			idx = 0;
		}
		mpool_put(t->bt_mp, h, 0);
		if ((h = mpool_get(t->bt_mp, nextpg, 0)) == NULL)
			return (1);
	}

	if (h->pgno == c->pg.pgno)
		goto ret;

	/* Reacquire the original stack. */
	mpool_put(t->bt_mp, h, 0);
	if ((e = __bt_search(t, &c->key, &exact)) == NULL)
		return (1);
	h = e->page;

	/*
	 * Move left, looking for the page.  At each move we have to move
	 * up the stack until we don't have to change pages to move to the
	 * next page.  If we have to change pages at an internal level, we
	 * have to fix the stack back up.
	 */
	while (h->pgno != c->pg.pgno) {
		if ((prevpg = h->prevpg) == P_INVALID)
			break;
		mpool_put(t->bt_mp, h, 0);

		/* Move up the stack. */
		for (level = 0; (parent = BT_POP(t)) != NULL; ++level) {
			/* Get the parent page. */
			if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
				return (1);

			/* Move to the next index. */
			if (parent->index != 0) {
				idx = parent->index - 1;
				BT_PUSH(t, h->pgno, idx);
				break;
			}
			mpool_put(t->bt_mp, h, 0);
		}

		/* Restore the stack. */
		while (level--) {
			/* Push the next level down onto the stack. */
			bi = GETBINTERNAL(h, idx);
			pgno = bi->pgno;

			/* Lose the currently pinned page. */
			mpool_put(t->bt_mp, h, 0);

			/* Get the next level down. */
			if ((h = mpool_get(t->bt_mp, pgno, 0)) == NULL)
				return (1);

			idx = NEXTINDEX(h) - 1;
			BT_PUSH(t, pgno, idx);
		}
		mpool_put(t->bt_mp, h, 0);
		if ((h = mpool_get(t->bt_mp, prevpg, 0)) == NULL)
			return (1);
	}


ret:	mpool_put(t->bt_mp, h, 0);
	return ((*hp = mpool_get(t->bt_mp, c->pg.pgno, 0)) == NULL);
}

/*
 * __bt_bdelete --
 *	Delete all key/data pairs matching the specified key.
 *
 * Parameters:
 *	  t:	tree
 *	key:	key to delete
 *
 * Returns:
 *	RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
 */
static int
__bt_bdelete(BTREE *t, const DBT *key)
{
	EPG *e;
	PAGE *h;
	int deleted, exact, redo;

	deleted = 0;

	/* Find any matching record; __bt_search pins the page. */
loop:	if ((e = __bt_search(t, key, &exact)) == NULL)
		return (deleted ? RET_SUCCESS : RET_ERROR);
	if (!exact) {
		mpool_put(t->bt_mp, e->page, 0);
		return (deleted ? RET_SUCCESS : RET_SPECIAL);
	}

	/*
	 * Delete forward, then delete backward, from the found key.  If
	 * there are duplicates and we reach either side of the page, do
	 * the key search again, so that we get them all.
	 */
	redo = 0;
	h = e->page;
	do {
		if (__bt_dleaf(t, key, h, e->index)) {
			mpool_put(t->bt_mp, h, 0);
			return (RET_ERROR);
		}
		if (F_ISSET(t, B_NODUPS)) {
			if (NEXTINDEX(h) == 0) {
				if (__bt_pdelete(t, h))
					return (RET_ERROR);
			} else
				mpool_put(t->bt_mp, h, MPOOL_DIRTY);
			return (RET_SUCCESS);
		}
		deleted = 1;
	} while (e->index < NEXTINDEX(h) && __bt_cmp(t, key, e) == 0);

	/* Check for right-hand edge of the page. */
	if (e->index == NEXTINDEX(h))
		redo = 1;

	/* Delete from the key to the beginning of the page. */
	while (e->index-- > 0) {
		if (__bt_cmp(t, key, e) != 0)
			break;
		if (__bt_dleaf(t, key, h, e->index) == RET_ERROR) {
			mpool_put(t->bt_mp, h, 0);
			return (RET_ERROR);
		}
		if (e->index == 0)
			redo = 1;
	}

	/* Check for an empty page. */
	if (NEXTINDEX(h) == 0) {
		if (__bt_pdelete(t, h))
			return (RET_ERROR);
		goto loop;
	}

	/* Put the page. */
	mpool_put(t->bt_mp, h, MPOOL_DIRTY);

	if (redo)
		goto loop;
	return (RET_SUCCESS);
}

/*
 * __bt_pdelete --
 *	Delete a single page from the tree.
 *
 * Parameters:
 *	t:	tree
 *	h:	leaf page
 *
 * Returns:
 *	RET_SUCCESS, RET_ERROR.
 *
 * Side-effects:
 *	mpool_put's the page
 */
static int
__bt_pdelete(BTREE *t, PAGE *h)
{
	BINTERNAL *bi;
	PAGE *pg;
	EPGNO *parent;
	indx_t cnt, idx, *ip, offset;
	u_int32_t nksize;
	char *from;

	/*
	 * Walk the parent page stack -- a LIFO stack of the pages that were
	 * traversed when we searched for the page where the delete occurred.
	 * Each stack entry is a page number and a page index offset.  The
	 * offset is for the page traversed on the search.  We've just deleted
	 * a page, so we have to delete the key from the parent page.
	 *
	 * If the delete from the parent page makes it empty, this process may
	 * continue all the way up the tree.  We stop if we reach the root page
	 * (which is never deleted, it's just not worth the effort) or if the
	 * delete does not empty the page.
	 */
	while ((parent = BT_POP(t)) != NULL) {
		/* Get the parent page. */
		if ((pg = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
			return (RET_ERROR);

		idx = parent->index;
		bi = GETBINTERNAL(pg, idx);

		/* Free any overflow pages. */
		if (bi->flags & P_BIGKEY &&
		    __ovfl_delete(t, bi->bytes) == RET_ERROR) {
			mpool_put(t->bt_mp, pg, 0);
			return (RET_ERROR);
		}

		/*
		 * Free the parent if it has only the one key and it's not the
		 * root page. If it's the rootpage, turn it back into an empty
		 * leaf page.
		 */
		if (NEXTINDEX(pg) == 1) {
			if (pg->pgno == P_ROOT) {
				pg->lower = BTDATAOFF;
				pg->upper = t->bt_psize;
				pg->flags = P_BLEAF;
			} else {
				if (__bt_relink(t, pg) || __bt_free(t, pg))
					return (RET_ERROR);
				continue;
			}
		} else {
			/* Pack remaining key items at the end of the page. */
			nksize = NBINTERNAL(bi->ksize);
			from = (char *)pg + pg->upper;
			memmove(from + nksize, from, (char *)bi - from);
			pg->upper += nksize;

			/* Adjust indices' offsets, shift the indices down. */
			offset = pg->linp[idx];
			for (cnt = idx, ip = &pg->linp[0]; cnt--; ++ip)
				if (ip[0] < offset)
					ip[0] += nksize;
			for (cnt = NEXTINDEX(pg) - idx; --cnt; ++ip)
				ip[0] = ip[1] < offset ? ip[1] + nksize : ip[1];
			pg->lower -= sizeof(indx_t);
		}

		mpool_put(t->bt_mp, pg, MPOOL_DIRTY);
		break;
	}

	/* Free the leaf page, as long as it wasn't the root. */
	if (h->pgno == P_ROOT) {
		mpool_put(t->bt_mp, h, MPOOL_DIRTY);
		return (RET_SUCCESS);
	}
	return (__bt_relink(t, h) || __bt_free(t, h));
}

/*
 * __bt_dleaf --
 *	Delete a single record from a leaf page.
 *
 * Parameters:
 *	t:	tree
 *    key:	referenced key
 *	h:	page
 *	idx:	index on page to delete
 *
 * Returns:
 *	RET_SUCCESS, RET_ERROR.
 */
int
__bt_dleaf(BTREE *t, const DBT *key, PAGE *h, u_int idx)
{
	BLEAF *bl;
	indx_t cnt, *ip, offset;
	u_int32_t nbytes;
	void *to;
	char *from;

	/* If this record is referenced by the cursor, delete the cursor. */
	if (F_ISSET(&t->bt_cursor, CURS_INIT) &&
	    !F_ISSET(&t->bt_cursor, CURS_ACQUIRE) &&
	    t->bt_cursor.pg.pgno == h->pgno && t->bt_cursor.pg.index == idx &&
	    __bt_curdel(t, key, h, idx))
		return (RET_ERROR);

	/* If the entry uses overflow pages, make them available for reuse. */
	to = bl = GETBLEAF(h, idx);
	if (bl->flags & P_BIGKEY && __ovfl_delete(t, bl->bytes) == RET_ERROR)
		return (RET_ERROR);
	if (bl->flags & P_BIGDATA &&
	    __ovfl_delete(t, bl->bytes + bl->ksize) == RET_ERROR)
		return (RET_ERROR);

	/* Pack the remaining key/data items at the end of the page. */
	nbytes = NBLEAF(bl);
	from = (char *)h + h->upper;
	memmove(from + nbytes, from, (char *)to - from);
	h->upper += nbytes;

	/* Adjust the indices' offsets, shift the indices down. */
	offset = h->linp[idx];
	for (cnt = idx, ip = &h->linp[0]; cnt--; ++ip)
		if (ip[0] < offset)
			ip[0] += nbytes;
	for (cnt = NEXTINDEX(h) - idx; --cnt; ++ip)
		ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1];
	h->lower -= sizeof(indx_t);

	/* If the cursor is on this page, adjust it as necessary. */
	if (F_ISSET(&t->bt_cursor, CURS_INIT) &&
	    !F_ISSET(&t->bt_cursor, CURS_ACQUIRE) &&
	    t->bt_cursor.pg.pgno == h->pgno && t->bt_cursor.pg.index > idx)
		--t->bt_cursor.pg.index;

	return (RET_SUCCESS);
}

/*
 * __bt_curdel --
 *	Delete the cursor.
 *
 * Parameters:
 *	t:	tree
 *    key:	referenced key (or NULL)
 *	h:	page
 *    idx:	index on page to delete
 *
 * Returns:
 *	RET_SUCCESS, RET_ERROR.
 */
static int
__bt_curdel(BTREE *t, const DBT *key, PAGE *h, u_int idx)
{
	CURSOR *c;
	EPG e;
	PAGE *pg;
	int curcopy, status;

	/*
	 * If there are duplicates, move forward or backward to one.
	 * Otherwise, copy the key into the cursor area.
	 */
	c = &t->bt_cursor;
	F_CLR(c, CURS_AFTER | CURS_BEFORE | CURS_ACQUIRE);

	curcopy = 0;
	if (!F_ISSET(t, B_NODUPS)) {
		/*
		 * We're going to have to do comparisons.  If we weren't
		 * provided a copy of the key, i.e. the user is deleting
		 * the current cursor position, get one.
		 */
		if (key == NULL) {
			e.page = h;
			e.index = idx;
			if ((status = __bt_ret(t, &e,
			    &c->key, &c->key, NULL, NULL, 1)) != RET_SUCCESS)
				return (status);
			curcopy = 1;
			key = &c->key;
		}
		/* Check previous key, if not at the beginning of the page. */
		if (idx > 0) {
			e.page = h;
			e.index = idx - 1;
			if (__bt_cmp(t, key, &e) == 0) {
				F_SET(c, CURS_BEFORE);
				goto dup2;
			}
		}
		/* Check next key, if not at the end of the page. */
		if (idx < NEXTINDEX(h) - 1) {
			e.page = h;
			e.index = idx + 1;
			if (__bt_cmp(t, key, &e) == 0) {
				F_SET(c, CURS_AFTER);
				goto dup2;
			}
		}
		/* Check previous key if at the beginning of the page. */
		if (idx == 0 && h->prevpg != P_INVALID) {
			if ((pg = mpool_get(t->bt_mp, h->prevpg, 0)) == NULL)
				return (RET_ERROR);
			e.page = pg;
			e.index = NEXTINDEX(pg) - 1;
			if (__bt_cmp(t, key, &e) == 0) {
				F_SET(c, CURS_BEFORE);
				goto dup1;
			}
			mpool_put(t->bt_mp, pg, 0);
		}
		/* Check next key if at the end of the page. */
		if (idx == NEXTINDEX(h) - 1 && h->nextpg != P_INVALID) {
			if ((pg = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL)
				return (RET_ERROR);
			e.page = pg;
			e.index = 0;
			if (__bt_cmp(t, key, &e) == 0) {
				F_SET(c, CURS_AFTER);
dup1:				mpool_put(t->bt_mp, pg, 0);
dup2:				c->pg.pgno = e.page->pgno;
				c->pg.index = e.index;
				return (RET_SUCCESS);
			}
			mpool_put(t->bt_mp, pg, 0);
		}
	}
	e.page = h;
	e.index = idx;
	if (curcopy || (status =
	    __bt_ret(t, &e, &c->key, &c->key, NULL, NULL, 1)) == RET_SUCCESS) {
		F_SET(c, CURS_ACQUIRE);
		return (RET_SUCCESS);
	}
	return (status);
}

/*
 * __bt_relink --
 *	Link around a deleted page.
 *
 * Parameters:
 *	t:	tree
 *	h:	page to be deleted
 */
static int
__bt_relink(BTREE *t, PAGE *h)
{
	PAGE *pg;

	if (h->nextpg != P_INVALID) {
		if ((pg = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL)
			return (RET_ERROR);
		pg->prevpg = h->prevpg;
		mpool_put(t->bt_mp, pg, MPOOL_DIRTY);
	}
	if (h->prevpg != P_INVALID) {
		if ((pg = mpool_get(t->bt_mp, h->prevpg, 0)) == NULL)
			return (RET_ERROR);
		pg->nextpg = h->nextpg;
		mpool_put(t->bt_mp, pg, MPOOL_DIRTY);
	}
	return (0);
}


Generated by: GCOVR (Version 3.3)

Line	Branch	Exec	Source
1			/* $OpenBSD: bt_delete.c,v 1.11 2005/08/05 13:02:59 espie Exp $ */
2
3			/*-
4			* Copyright (c) 1990, 1993, 1994
5			* The Regents of the University of California. All rights reserved.
6			*
7			* This code is derived from software contributed to Berkeley by
8			* Mike Olson.
9			*
10			* Redistribution and use in source and binary forms, with or without
11			* modification, are permitted provided that the following conditions
12			* are met:
13			* 1. Redistributions of source code must retain the above copyright
14			* notice, this list of conditions and the following disclaimer.
15			* 2. Redistributions in binary form must reproduce the above copyright
16			* notice, this list of conditions and the following disclaimer in the
17			* documentation and/or other materials provided with the distribution.
18			* 3. Neither the name of the University nor the names of its contributors
19			* may be used to endorse or promote products derived from this software
20			* without specific prior written permission.
21			*
22			* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23			* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24			* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25			* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26			* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27			* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28			* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29			* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30			* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31			* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32			* SUCH DAMAGE.
33			*/
34
35			#include <sys/types.h>
36
37			#include <errno.h>
38			#include <stdio.h>
39			#include <string.h>
40
41			#include <db.h>
42			#include "btree.h"
43
44			static int __bt_bdelete(BTREE , const DBT );
45			static int __bt_curdel(BTREE , const DBT , PAGE *, u_int);
46			static int __bt_pdelete(BTREE , PAGE );
47			static int __bt_relink(BTREE , PAGE );
48			static int __bt_stkacq(BTREE , PAGE , CURSOR );
49
50			/*
51			* __bt_delete
52			* Delete the item(s) referenced by a key.
53			*
54			* Return RET_SPECIAL if the key is not found.
55			*/
56			int
57			__bt_delete(const DB dbp, const DBT key, u_int flags)
58			{
59			BTREE *t;
60			CURSOR *c;
61			PAGE *h;
62			int status;
63
64			t = dbp->internal;
65
66			/* Toss any page pinned across calls. */
67			if (t->bt_pinned != NULL) {
68			mpool_put(t->bt_mp, t->bt_pinned, 0);
69			t->bt_pinned = NULL;
70			}
71
72			/* Check for change to a read-only tree. */
73			if (F_ISSET(t, B_RDONLY)) {
74			errno = EPERM;
75			return (RET_ERROR);
76			}
77
78			switch (flags) {
79			case 0:
80			status = __bt_bdelete(t, key);
81			break;
82			case R_CURSOR:
83			/*
84			* If flags is R_CURSOR, delete the cursor. Must already
85			* have started a scan and not have already deleted it.
86			*/
87			c = &t->bt_cursor;
88			if (F_ISSET(c, CURS_INIT)) {
89			if (F_ISSET(c, CURS_ACQUIRE \| CURS_AFTER \| CURS_BEFORE))
90			return (RET_SPECIAL);
91			if ((h = mpool_get(t->bt_mp, c->pg.pgno, 0)) == NULL)
92			return (RET_ERROR);
93
94			/*
95			* If the page is about to be emptied, we'll need to
96			* delete it, which means we have to acquire a stack.
97			*/
98			if (NEXTINDEX(h) == 1)
99			if (__bt_stkacq(t, &h, &t->bt_cursor))
100			return (RET_ERROR);
101
102			status = __bt_dleaf(t, NULL, h, c->pg.index);
103
104			if (NEXTINDEX(h) == 0 && status == RET_SUCCESS) {
105			if (__bt_pdelete(t, h))
106			return (RET_ERROR);
107			} else
108			mpool_put(t->bt_mp,
109			h, status == RET_SUCCESS ? MPOOL_DIRTY : 0);
110			break;
111			}
112			/* FALLTHROUGH */
113			default:
114			errno = EINVAL;
115			return (RET_ERROR);
116			}
117			if (status == RET_SUCCESS)
118			F_SET(t, B_MODIFIED);
119			return (status);
120			}
121
122			/*
123			* __bt_stkacq --
124			* Acquire a stack so we can delete a cursor entry.
125			*
126			* Parameters:
127			* t: tree
128			* hp: pointer to current, pinned PAGE pointer
129			* c: pointer to the cursor
130			*
131			* Returns:
132			* 0 on success, 1 on failure
133			*/
134			static int
135			__bt_stkacq(BTREE t, PAGE hp, CURSOR c)
136			{
137			BINTERNAL *bi;
138			EPG *e;
139			EPGNO *parent;
140			PAGE *h;
141			indx_t idx;
142			pgno_t pgno;
143			recno_t nextpg, prevpg;
144			int exact, level;
145
146			/*
147			* Find the first occurrence of the key in the tree. Toss the
148			* currently locked page so we don't hit an already-locked page.
149			*/
150			h = *hp;
151			mpool_put(t->bt_mp, h, 0);
152			if ((e = __bt_search(t, &c->key, &exact)) == NULL)
153			return (1);
154			h = e->page;
155
156			/* See if we got it in one shot. */
157			if (h->pgno == c->pg.pgno)
158			goto ret;
159
160			/*
161			* Move right, looking for the page. At each move we have to move
162			* up the stack until we don't have to move to the next page. If
163			* we have to change pages at an internal level, we have to fix the
164			* stack back up.
165			*/
166			while (h->pgno != c->pg.pgno) {
167			if ((nextpg = h->nextpg) == P_INVALID)
168			break;
169			mpool_put(t->bt_mp, h, 0);
170
171			/* Move up the stack. */
172			for (level = 0; (parent = BT_POP(t)) != NULL; ++level) {
173			/* Get the parent page. */
174			if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
175			return (1);
176
177			/* Move to the next index. */
178			if (parent->index != NEXTINDEX(h) - 1) {
179			idx = parent->index + 1;
180			BT_PUSH(t, h->pgno, idx);
181			break;
182			}
183			mpool_put(t->bt_mp, h, 0);
184			}
185
186			/* Restore the stack. */
187			while (level--) {
188			/* Push the next level down onto the stack. */
189			bi = GETBINTERNAL(h, idx);
190			pgno = bi->pgno;
191			BT_PUSH(t, pgno, 0);
192
193			/* Lose the currently pinned page. */
194			mpool_put(t->bt_mp, h, 0);
195
196			/* Get the next level down. */
197			if ((h = mpool_get(t->bt_mp, pgno, 0)) == NULL)
198			return (1);
199			idx = 0;
200			}
201			mpool_put(t->bt_mp, h, 0);
202			if ((h = mpool_get(t->bt_mp, nextpg, 0)) == NULL)
203			return (1);
204			}
205
206			if (h->pgno == c->pg.pgno)
207			goto ret;
208
209			/* Reacquire the original stack. */
210			mpool_put(t->bt_mp, h, 0);
211			if ((e = __bt_search(t, &c->key, &exact)) == NULL)
212			return (1);
213			h = e->page;
214
215			/*
216			* Move left, looking for the page. At each move we have to move
217			* up the stack until we don't have to change pages to move to the
218			* next page. If we have to change pages at an internal level, we
219			* have to fix the stack back up.
220			*/
221			while (h->pgno != c->pg.pgno) {
222			if ((prevpg = h->prevpg) == P_INVALID)
223			break;
224			mpool_put(t->bt_mp, h, 0);
225
226			/* Move up the stack. */
227			for (level = 0; (parent = BT_POP(t)) != NULL; ++level) {
228			/* Get the parent page. */
229			if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
230			return (1);
231
232			/* Move to the next index. */
233			if (parent->index != 0) {
234			idx = parent->index - 1;
235			BT_PUSH(t, h->pgno, idx);
236			break;
237			}
238			mpool_put(t->bt_mp, h, 0);
239			}
240
241			/* Restore the stack. */
242			while (level--) {
243			/* Push the next level down onto the stack. */
244			bi = GETBINTERNAL(h, idx);
245			pgno = bi->pgno;
246
247			/* Lose the currently pinned page. */
248			mpool_put(t->bt_mp, h, 0);
249
250			/* Get the next level down. */
251			if ((h = mpool_get(t->bt_mp, pgno, 0)) == NULL)
252			return (1);
253
254			idx = NEXTINDEX(h) - 1;
255			BT_PUSH(t, pgno, idx);
256			}
257			mpool_put(t->bt_mp, h, 0);
258			if ((h = mpool_get(t->bt_mp, prevpg, 0)) == NULL)
259			return (1);
260			}
261
262
263			ret: mpool_put(t->bt_mp, h, 0);
264			return ((*hp = mpool_get(t->bt_mp, c->pg.pgno, 0)) == NULL);
265			}
266
267			/*
268			* __bt_bdelete --
269			* Delete all key/data pairs matching the specified key.
270			*
271			* Parameters:
272			* t: tree
273			* key: key to delete
274			*
275			* Returns:
276			* RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
277			*/
278			static int
279			__bt_bdelete(BTREE t, const DBT key)
280			{
281			EPG *e;
282			PAGE *h;
283			int deleted, exact, redo;
284
285			deleted = 0;
286
287			/* Find any matching record; __bt_search pins the page. */
288			loop: if ((e = __bt_search(t, key, &exact)) == NULL)
289			return (deleted ? RET_SUCCESS : RET_ERROR);
290			if (!exact) {
291			mpool_put(t->bt_mp, e->page, 0);
292			return (deleted ? RET_SUCCESS : RET_SPECIAL);
293			}
294
295			/*
296			* Delete forward, then delete backward, from the found key. If
297			* there are duplicates and we reach either side of the page, do
298			* the key search again, so that we get them all.
299			*/
300			redo = 0;
301			h = e->page;
302			do {
303			if (__bt_dleaf(t, key, h, e->index)) {
304			mpool_put(t->bt_mp, h, 0);
305			return (RET_ERROR);
306			}
307			if (F_ISSET(t, B_NODUPS)) {
308			if (NEXTINDEX(h) == 0) {
309			if (__bt_pdelete(t, h))
310			return (RET_ERROR);
311			} else
312			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
313			return (RET_SUCCESS);
314			}
315			deleted = 1;
316			} while (e->index < NEXTINDEX(h) && __bt_cmp(t, key, e) == 0);
317
318			/* Check for right-hand edge of the page. */
319			if (e->index == NEXTINDEX(h))
320			redo = 1;
321
322			/* Delete from the key to the beginning of the page. */
323			while (e->index-- > 0) {
324			if (__bt_cmp(t, key, e) != 0)
325			break;
326			if (__bt_dleaf(t, key, h, e->index) == RET_ERROR) {
327			mpool_put(t->bt_mp, h, 0);
328			return (RET_ERROR);
329			}
330			if (e->index == 0)
331			redo = 1;
332			}
333
334			/* Check for an empty page. */
335			if (NEXTINDEX(h) == 0) {
336			if (__bt_pdelete(t, h))
337			return (RET_ERROR);
338			goto loop;
339			}
340
341			/* Put the page. */
342			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
343
344			if (redo)
345			goto loop;
346			return (RET_SUCCESS);
347			}
348
349			/*
350			* __bt_pdelete --
351			* Delete a single page from the tree.
352			*
353			* Parameters:
354			* t: tree
355			* h: leaf page
356			*
357			* Returns:
358			* RET_SUCCESS, RET_ERROR.
359			*
360			* Side-effects:
361			* mpool_put's the page
362			*/
363			static int
364			__bt_pdelete(BTREE t, PAGE h)
365			{
366			BINTERNAL *bi;
367			PAGE *pg;
368			EPGNO *parent;
369			indx_t cnt, idx, *ip, offset;
370			u_int32_t nksize;
371			char *from;
372
373			/*
374			* Walk the parent page stack -- a LIFO stack of the pages that were
375			* traversed when we searched for the page where the delete occurred.
376			* Each stack entry is a page number and a page index offset. The
377			* offset is for the page traversed on the search. We've just deleted
378			* a page, so we have to delete the key from the parent page.
379			*
380			* If the delete from the parent page makes it empty, this process may
381			* continue all the way up the tree. We stop if we reach the root page
382			* (which is never deleted, it's just not worth the effort) or if the
383			* delete does not empty the page.
384			*/
385			while ((parent = BT_POP(t)) != NULL) {
386			/* Get the parent page. */
387			if ((pg = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
388			return (RET_ERROR);
389
390			idx = parent->index;
391			bi = GETBINTERNAL(pg, idx);
392
393			/* Free any overflow pages. */
394			if (bi->flags & P_BIGKEY &&
395			__ovfl_delete(t, bi->bytes) == RET_ERROR) {
396			mpool_put(t->bt_mp, pg, 0);
397			return (RET_ERROR);
398			}
399
400			/*
401			* Free the parent if it has only the one key and it's not the
402			* root page. If it's the rootpage, turn it back into an empty
403			* leaf page.
404			*/
405			if (NEXTINDEX(pg) == 1) {
406			if (pg->pgno == P_ROOT) {
407			pg->lower = BTDATAOFF;
408			pg->upper = t->bt_psize;
409			pg->flags = P_BLEAF;
410			} else {
411			if (__bt_relink(t, pg) \|\| __bt_free(t, pg))
412			return (RET_ERROR);
413			continue;
414			}
415			} else {
416			/* Pack remaining key items at the end of the page. */
417			nksize = NBINTERNAL(bi->ksize);
418			from = (char *)pg + pg->upper;
419			memmove(from + nksize, from, (char *)bi - from);
420			pg->upper += nksize;
421
422			/* Adjust indices' offsets, shift the indices down. */
423			offset = pg->linp[idx];
424			for (cnt = idx, ip = &pg->linp[0]; cnt--; ++ip)
425			if (ip[0] < offset)
426			ip[0] += nksize;
427			for (cnt = NEXTINDEX(pg) - idx; --cnt; ++ip)
428			ip[0] = ip[1] < offset ? ip[1] + nksize : ip[1];
429			pg->lower -= sizeof(indx_t);
430			}
431
432			mpool_put(t->bt_mp, pg, MPOOL_DIRTY);
433			break;
434			}
435
436			/* Free the leaf page, as long as it wasn't the root. */
437			if (h->pgno == P_ROOT) {
438			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
439			return (RET_SUCCESS);
440			}
441			return (__bt_relink(t, h) \|\| __bt_free(t, h));
442			}
443
444			/*
445			* __bt_dleaf --
446			* Delete a single record from a leaf page.
447			*
448			* Parameters:
449			* t: tree
450			* key: referenced key
451			* h: page
452			* idx: index on page to delete
453			*
454			* Returns:
455			* RET_SUCCESS, RET_ERROR.
456			*/
457			int
458			__bt_dleaf(BTREE t, const DBT key, PAGE *h, u_int idx)
459			{
460			BLEAF *bl;
461			indx_t cnt, *ip, offset;
462			u_int32_t nbytes;
463			void *to;
464			char *from;
465
466			/* If this record is referenced by the cursor, delete the cursor. */
467			if (F_ISSET(&t->bt_cursor, CURS_INIT) &&
468			!F_ISSET(&t->bt_cursor, CURS_ACQUIRE) &&
469			t->bt_cursor.pg.pgno == h->pgno && t->bt_cursor.pg.index == idx &&
470			__bt_curdel(t, key, h, idx))
471			return (RET_ERROR);
472
473			/* If the entry uses overflow pages, make them available for reuse. */
474			to = bl = GETBLEAF(h, idx);
475			if (bl->flags & P_BIGKEY && __ovfl_delete(t, bl->bytes) == RET_ERROR)
476			return (RET_ERROR);
477			if (bl->flags & P_BIGDATA &&
478			__ovfl_delete(t, bl->bytes + bl->ksize) == RET_ERROR)
479			return (RET_ERROR);
480
481			/* Pack the remaining key/data items at the end of the page. */
482			nbytes = NBLEAF(bl);
483			from = (char *)h + h->upper;
484			memmove(from + nbytes, from, (char *)to - from);
485			h->upper += nbytes;
486
487			/* Adjust the indices' offsets, shift the indices down. */
488			offset = h->linp[idx];
489			for (cnt = idx, ip = &h->linp[0]; cnt--; ++ip)
490			if (ip[0] < offset)
491			ip[0] += nbytes;
492			for (cnt = NEXTINDEX(h) - idx; --cnt; ++ip)
493			ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1];
494			h->lower -= sizeof(indx_t);
495
496			/* If the cursor is on this page, adjust it as necessary. */
497			if (F_ISSET(&t->bt_cursor, CURS_INIT) &&
498			!F_ISSET(&t->bt_cursor, CURS_ACQUIRE) &&
499			t->bt_cursor.pg.pgno == h->pgno && t->bt_cursor.pg.index > idx)
500			--t->bt_cursor.pg.index;
501
502			return (RET_SUCCESS);
503			}
504
505			/*
506			* __bt_curdel --
507			* Delete the cursor.
508			*
509			* Parameters:
510			* t: tree
511			* key: referenced key (or NULL)
512			* h: page
513			* idx: index on page to delete
514			*
515			* Returns:
516			* RET_SUCCESS, RET_ERROR.
517			*/
518			static int
519			__bt_curdel(BTREE t, const DBT key, PAGE *h, u_int idx)
520			{
521			CURSOR *c;
522			EPG e;
523			PAGE *pg;
524			int curcopy, status;
525
526			/*
527			* If there are duplicates, move forward or backward to one.
528			* Otherwise, copy the key into the cursor area.
529			*/
530			c = &t->bt_cursor;
531			F_CLR(c, CURS_AFTER \| CURS_BEFORE \| CURS_ACQUIRE);
532
533			curcopy = 0;
534			if (!F_ISSET(t, B_NODUPS)) {
535			/*
536			* We're going to have to do comparisons. If we weren't
537			* provided a copy of the key, i.e. the user is deleting
538			* the current cursor position, get one.
539			*/
540			if (key == NULL) {
541			e.page = h;
542			e.index = idx;
543			if ((status = __bt_ret(t, &e,
544			&c->key, &c->key, NULL, NULL, 1)) != RET_SUCCESS)
545			return (status);
546			curcopy = 1;
547			key = &c->key;
548			}
549			/* Check previous key, if not at the beginning of the page. */
550			if (idx > 0) {
551			e.page = h;
552			e.index = idx - 1;
553			if (__bt_cmp(t, key, &e) == 0) {
554			F_SET(c, CURS_BEFORE);
555			goto dup2;
556			}
557			}
558			/* Check next key, if not at the end of the page. */
559			if (idx < NEXTINDEX(h) - 1) {
560			e.page = h;
561			e.index = idx + 1;
562			if (__bt_cmp(t, key, &e) == 0) {
563			F_SET(c, CURS_AFTER);
564			goto dup2;
565			}
566			}
567			/* Check previous key if at the beginning of the page. */
568			if (idx == 0 && h->prevpg != P_INVALID) {
569			if ((pg = mpool_get(t->bt_mp, h->prevpg, 0)) == NULL)
570			return (RET_ERROR);
571			e.page = pg;
572			e.index = NEXTINDEX(pg) - 1;
573			if (__bt_cmp(t, key, &e) == 0) {
574			F_SET(c, CURS_BEFORE);
575			goto dup1;
576			}
577			mpool_put(t->bt_mp, pg, 0);
578			}
579			/* Check next key if at the end of the page. */
580			if (idx == NEXTINDEX(h) - 1 && h->nextpg != P_INVALID) {
581			if ((pg = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL)
582			return (RET_ERROR);
583			e.page = pg;
584			e.index = 0;
585			if (__bt_cmp(t, key, &e) == 0) {
586			F_SET(c, CURS_AFTER);
587			dup1: mpool_put(t->bt_mp, pg, 0);
588			dup2: c->pg.pgno = e.page->pgno;
589			c->pg.index = e.index;
590			return (RET_SUCCESS);
591			}
592			mpool_put(t->bt_mp, pg, 0);
593			}
594			}
595			e.page = h;
596			e.index = idx;
597			if (curcopy \|\| (status =
598			__bt_ret(t, &e, &c->key, &c->key, NULL, NULL, 1)) == RET_SUCCESS) {
599			F_SET(c, CURS_ACQUIRE);
600			return (RET_SUCCESS);
601			}
602			return (status);
603			}
604
605			/*
606			* __bt_relink --
607			* Link around a deleted page.
608			*
609			* Parameters:
610			* t: tree
611			* h: page to be deleted
612			*/
613			static int
614			__bt_relink(BTREE t, PAGE h)
615			{
616			PAGE *pg;
617
618			if (h->nextpg != P_INVALID) {
619			if ((pg = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL)
620			return (RET_ERROR);
621			pg->prevpg = h->prevpg;
622			mpool_put(t->bt_mp, pg, MPOOL_DIRTY);
623			}
624			if (h->prevpg != P_INVALID) {
625			if ((pg = mpool_get(t->bt_mp, h->prevpg, 0)) == NULL)
626			return (RET_ERROR);
627			pg->nextpg = h->nextpg;
628			mpool_put(t->bt_mp, pg, MPOOL_DIRTY);
629			}
630			return (0);
631			}