xref: /onnv-gate/usr/src/cmd/mdb/common/modules/genunix/avl.c (revision 789)

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident	"%Z%%M%	%I%	%E% SMI"

#include <sys/avl.h>

#include <mdb/mdb_modapi.h>

struct aw_info {
	void *aw_buff;		/* buffer to hold the tree's data structure */
	avl_tree_t aw_tree;	/* copy of avl_tree_t being walked */
};

/*
 * common code used to find the addr of the the leftmost child below
 * an AVL node
 */
static uintptr_t
avl_leftmostchild(uintptr_t addr, void * buff, size_t offset, size_t size)
{
	avl_node_t *node = (avl_node_t *)((uintptr_t)buff + offset);

	for (;;) {
		addr -= offset;
		if (mdb_vread(buff, size, addr) == -1) {
			mdb_warn("read of avl_node_t failed: %p", addr);
			return ((uintptr_t)-1L);
		}
		if (node->avl_child[0] == NULL)
			break;
		addr = (uintptr_t)node->avl_child[0];
	}
	return (addr);
}

/*
 * initialize a forward walk thru an avl tree.
 */
int
avl_walk_init(mdb_walk_state_t *wsp)
{
	struct aw_info *aw;
	avl_tree_t *tree;
	uintptr_t addr;

	/*
	 * allocate the AVL walk data
	 */
	wsp->walk_data = aw = mdb_zalloc(sizeof (struct aw_info), UM_SLEEP);

	/*
	 * get an mdb copy of the avl_tree_t being walked
	 */
	tree = &aw->aw_tree;
	if (mdb_vread(tree, sizeof (avl_tree_t), wsp->walk_addr) == -1) {
		mdb_warn("read of avl_tree_t failed: %p", wsp->walk_addr);
		goto error;
	}
	if (tree->avl_size < tree->avl_offset + sizeof (avl_node_t)) {
		mdb_warn("invalid avl_tree_t at %p, avl_size:%d, avl_offset:%d",
		    wsp->walk_addr, tree->avl_size, tree->avl_offset);
		goto error;
	}

	/*
	 * allocate a buffer to hold the mdb copy of tree's structs
	 * "node" always points at the avl_node_t field inside the struct
	 */
	aw->aw_buff = mdb_zalloc(tree->avl_size, UM_SLEEP);

	/*
	 * get the first avl_node_t address, use same algorithm
	 * as avl_start() -- leftmost child in tree from root
	 */
	addr = (uintptr_t)tree->avl_root;
	if (addr == NULL) {
		wsp->walk_addr = NULL;
		return (WALK_NEXT);
	}
	addr = avl_leftmostchild(addr, aw->aw_buff, tree->avl_offset,
	    tree->avl_size);
	if (addr == (uintptr_t)-1L)
		goto error;

	wsp->walk_addr = addr;
	return (WALK_NEXT);

error:
	if (aw->aw_buff != NULL)
		mdb_free(aw->aw_buff, sizeof (tree->avl_size));
	mdb_free(aw, sizeof (struct aw_info));
	return (WALK_ERR);
}

/*
 * At each step, visit (callback) the current node, then move to the next
 * in the AVL tree.  Uses the same algorithm as avl_walk().
 */
int
avl_walk_step(mdb_walk_state_t *wsp)
{
	struct aw_info *aw;
	size_t offset;
	size_t size;
	uintptr_t addr;
	avl_node_t *node;
	int status;
	int was_child;

	/*
	 * don't walk past the end of the tree!
	 */
	addr = wsp->walk_addr;
	if (addr == NULL)
		return (WALK_DONE);

	aw = (struct aw_info *)wsp->walk_data;
	size = aw->aw_tree.avl_size;
	offset = aw->aw_tree.avl_offset;
	node = (avl_node_t *)((uintptr_t)aw->aw_buff + offset);

	/*
	 * must read the current node for the call back to use
	 */
	if (mdb_vread(aw->aw_buff, size, addr) == -1) {
		mdb_warn("read of avl_node_t failed: %p", addr);
		return (WALK_ERR);
	}

	/*
	 * do the call back
	 */
	status = wsp->walk_callback(addr, aw->aw_buff, wsp->walk_cbdata);
	if (status != WALK_NEXT)
		return (status);

	/*
	 * move to the next node....
	 * note we read in new nodes, so the pointer to the buffer is fixed
	 */

	/*
	 * if the node has a right child then go to it and then all the way
	 * thru as many left children as possible
	 */
	addr = (uintptr_t)node->avl_child[1];
	if (addr != NULL) {
		addr = avl_leftmostchild(addr, aw->aw_buff, offset, size);
		if (addr == (uintptr_t)-1L)
			return (WALK_ERR);

	/*
	 * othewise return to parent nodes, stopping if we ever return from
	 * a left child
	 */
	} else {
		for (;;) {
			was_child = AVL_XCHILD(node);
			addr = (uintptr_t)AVL_XPARENT(node);
			if (addr == NULL)
				break;
			addr -= offset;
			if (was_child == 0) /* stop on return from left child */
				break;
			if (mdb_vread(aw->aw_buff, size, addr) == -1) {
				mdb_warn("read of avl_node_t failed: %p", addr);
				return (WALK_ERR);
			}
		}
	}

	wsp->walk_addr = addr;
	return (WALK_NEXT);
}

/*
 * Release the memory allocated for the walk
 */
void
avl_walk_fini(mdb_walk_state_t *wsp)
{
	struct aw_info *aw;

	aw = (struct aw_info *)wsp->walk_data;

	if (aw == NULL)
		return;

	if (aw->aw_buff != NULL)
		mdb_free(aw->aw_buff, aw->aw_tree.avl_size);

	mdb_free(aw, sizeof (struct aw_info));
}