lib/common/btree.c

/*
 * COPYRIGHT (c) International Business Machines Corp. 2005-2017
 *
 * This program is provided under the terms of the Common Public License,
 * version 1.0 (CPL-1.0). Any use, reproduction or distribution for this
 * software constitutes recipient's acceptance of CPL-1.0 terms which can be
 * found in the file LICENSE file or at
 * https://opensource.org/licenses/cpl1.0.php
 */

/*
 * btree.c
 * Author: Kent Yoder <yoder1@us.ibm.com>
 *
 * v1 Binary tree functions 4/5/2011
 *
 */


#include <stdio.h>
#include <stdlib.h>

#include "pkcs11types.h"
#include "local_types.h"
#include "trace.h"

#define GET_NODE_HANDLE(n) get_node_handle(n, 1)
#define TREE_DUMP(t)  tree_dump((t)->top, 0)

/*
 * bt_get_node
 *
 * Return a node of the tree @t with position @node_num. If the node has been
 * freed or doesn't exist, return NULL
 */
struct btnode *bt_get_node(struct btree *t, unsigned long node_num)
{
    __transaction_atomic {      /* start transaction */
        struct btnode *temp = t->top;
        unsigned long i;

        if (!node_num || node_num > t->size)
            return NULL;
        if (node_num == 1) {
            temp = t->top;
            goto done;
        }

        i = node_num;
        while (i != 1) {
            if (i & 1) {
                /* If the bit is 1, traverse right */
                temp = temp->right;
            } else {
                /* If the bit is 0, traverse left */
                temp = temp->left;
            }
            i >>= 1;
        }
done:
        return ((temp->flags & BT_FLAG_FREE) ? NULL : temp);
    }                           /* end transaction */
}

void *bt_get_node_value(struct btree *t, unsigned long node_num)
{
    struct btnode *n = bt_get_node(t, node_num);

    return ((n) ? n->value : NULL);
}

/* create a new node and set @parent_ptr to its location */
static struct btnode *node_create(struct btnode **child_ptr,
                                  struct btnode *parent_ptr, void *value)
{
    struct btnode *node = malloc(sizeof(struct btnode));

    if (!node)
        return NULL;

    node->left = node->right = NULL;
    node->flags = 0;
    node->value = value;
    *child_ptr = node;
    node->parent = parent_ptr;

    return node;
}

/*
 * get_node_handle
 *
 * Recursively construct a node's handle by tracing its path back to the root
 * node
 */
static unsigned long get_node_handle(struct btnode *node,
                                     unsigned long handle_so_far)
{
    if (!node->parent)
        return handle_so_far;
    else if (node->parent->left == node)
        return get_node_handle(node->parent, handle_so_far << 1);
    else
        return get_node_handle(node->parent, (handle_so_far << 1) + 1);
}

/* return node number (handle) of newly created node, or 0 for failure */
unsigned long bt_node_add(struct btree *t, void *value)
{
    __transaction_atomic {      /*start transaction */
        struct btnode *temp = t->top;
        unsigned long new_node_index;

        if (!temp) {            /* no root node yet exists, create it */
            t->size = 1;
            if (!node_create(&t->top, NULL, value)) {
                return 0;
            }

            return 1;
        } else if (t->free_list) {
            /* there's a node on the free list,
             * use it instead of mallocing new
             */
            temp = t->free_list;
            t->free_list = temp->value;
            temp->value = value;
            temp->flags &= (~BT_FLAG_FREE);
            t->free_nodes--;
            new_node_index = GET_NODE_HANDLE(temp);
            return new_node_index;
        }

        new_node_index = t->size + 1;

        while (new_node_index != 1) {
            if (new_node_index & 1) {
                if (!temp->right) {
                    if (!(node_create(&temp->right, temp, value))) {
                        return 0;
                    }
                    break;
                } else {
                    /* If the bit is 1, traverse right */
                    temp = temp->right;
                }
            } else {
                if (!temp->left) {
                    if (!(node_create(&temp->left, temp, value))) {
                        return 0;
                    }
                    break;
                } else {
                    /* If the bit is 0, traverse left */
                    temp = temp->left;
                }
            }

            new_node_index >>= 1;
        }

        t->size++;

        return t->size;
    }                           /* end transaction */
}

void tree_dump(struct btnode *n, int depth)
{
    int i;

    if (!n)
        return;

    for (i = 0; i < depth; i++)
        printf("  ");

    if (n->flags & BT_FLAG_FREE)
        printf("`- (deleted node)\n");
    else
        printf("`- %p\n", n->value);

    tree_dump(n->left, depth + 1);
    tree_dump(n->right, depth + 1);
}

/*
 * bt_node_free
 *
 * Move @node_num in tree @t to the free list, calling @delete_func on its value
 * first.
 *
 * Note that bt_get_node will return NULL if the node is already on the free
 * list, so no double freeing can occur
 */
struct btnode *bt_node_free(struct btree *t, unsigned long node_num,
                            void (*delete_func) (void *))
{
    struct btnode *node = bt_get_node(t, node_num);

    if (node) {
        if (delete_func)
            (*delete_func) (node->value);

        __transaction_atomic {  /* start transaction */
            node->flags |= BT_FLAG_FREE;

            /* add node to the free list,
             * which is chained by using
             * the value pointer
             */
            node->value = t->free_list;
            t->free_list = node;
            t->free_nodes++;
        }                       /* end transaction */
    }

    return node;
}

struct btnode *bt_node_free_(STDLL_TokData_t *tokdata, struct btree *t,
                             unsigned long node_num,
                             void (*delete_func) (STDLL_TokData_t *tokdata,
                                                  void *))
{
    struct btnode *node = bt_get_node(t, node_num);

    if (node) {
        if (delete_func)
            (*delete_func) (tokdata, node->value);

        __transaction_atomic {  /* start transaction */
            node->flags |= BT_FLAG_FREE;

            /* add node to the free list,
             * which is chained by using
             * the value pointer
             */
            node->value = t->free_list;
            t->free_list = node;
            t->free_nodes++;
        }                       /* end transaction */
    }

    return node;
}

/* bt_is_empty
 *
 * return 0 if binary tree has at least 1 node in use, !0 otherwise
 */
int bt_is_empty(struct btree *t)
{
    __transaction_atomic {      /* start transaction */
        return (t->free_nodes == t->size);
    }                           /* end transaction */
}

/* bt_nodes_in_use
 *
 * return the number of nodes in the binary tree that are not free'd
 */
unsigned long bt_nodes_in_use(struct btree *t)
{
    __transaction_atomic {      /* start transaction */
        return (t->size - t->free_nodes);
    }                           /* end transaction */
}

/* bt_for_each_node
 *
 * For each non-free'd node in the tree, run @func on it
 *
 * @func:
 *  p1 is the node's value
 *  p2 is the node's handle
 *  p3 is passed through this function for the caller
 */
void bt_for_each_node(STDLL_TokData_t *tokdata, struct btree *t, void (*func)
                       (STDLL_TokData_t *tokdata, void *p1, unsigned long p2,
                        void *p3), void *p3)
{
    unsigned int i;
    struct btnode *node;

    for (i = 1; i < t->size + 1; i++) {
        node = bt_get_node(t, i);

        if (node) {
            (*func) (tokdata, node->value, i, p3);
        }
    }
}

/* bt_destroy
 *
 * Walk a binary tree backwards (largest index to smallest), deleting nodes
 * along the way.
 * Call @func on node->value before freeing the node.
 */
void bt_destroy(struct btree *t, void (*func) (void *))
{
    unsigned long i;
    struct btnode *temp;

    while (t->size) {
        __transaction_atomic {  /* start transaction */
            temp = t->top;
            i = t->size;
            while (i != 1) {
                if (i & 1) {
                    /* If the bit is 1, traverse right */
                    temp = temp->right;
                } else {
                    /* If the bit is 0, traverse left */
                    temp = temp->left;
                }
                i >>= 1;
            }
        }                       /* end transaction */

        /*
         * The value pointed by value in a node marked as freed points
         * to the next node element in free_list and it shouldn't be
         * freed here because the loop will iterate through each node,
         * freed or not.
         */
        if (func && !(temp->flags & BT_FLAG_FREE))
            (*func) (temp->value);

        __transaction_atomic {  /* start transaction */
            free(temp);
            t->size--;
        }                       /* end transaction */
    }

    __transaction_atomic {      /* start transaction */
        /* the tree is gone now, clear all the other variables */
        t->top = NULL;
        t->free_list = NULL;
        t->free_nodes = 0;
    }                           /* end transaction */
}