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/* SPDX-License-Identifier: LGPL-3.0-or-later */
/*
* rbtree.c
*
* Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
*/
#include "config.h"
#include "sqfs/error.h"
#include "rbtree.h"
#include <stdlib.h>
#include <string.h>
#define IS_RED(n) ((n) && (n)->is_red)
static void destroy_nodes_dfs(rbtree_node_t *n)
{
rbtree_node_t *l, *r;
if (n != NULL) {
l = n->left;
r = n->right;
free(n);
destroy_nodes_dfs(l);
destroy_nodes_dfs(r);
}
}
static void flip_colors(rbtree_node_t *n)
{
n->is_red = !n->is_red;
n->left->is_red = !n->left->is_red;
n->right->is_red = !n->right->is_red;
}
static rbtree_node_t *rotate_right(rbtree_node_t *n)
{
rbtree_node_t *x;
x = n->left;
n->left = x->right;
x->right = n;
x->is_red = x->right->is_red;
x->right->is_red = 1;
return x;
}
static rbtree_node_t *rotate_left(rbtree_node_t *n)
{
rbtree_node_t *x;
x = n->right;
n->right = x->left;
x->left = n;
x->is_red = x->left->is_red;
x->left->is_red = 1;
return x;
}
static rbtree_node_t *subtree_balance(rbtree_node_t *n)
{
if (IS_RED(n->right) && !IS_RED(n->left))
n = rotate_left(n);
if (IS_RED(n->left) && IS_RED(n->left->left))
n = rotate_right(n);
if (IS_RED(n->left) && IS_RED(n->right))
flip_colors(n);
return n;
}
static rbtree_node_t *subtree_insert(rbtree_t *tree, rbtree_node_t *root,
rbtree_node_t *new)
{
if (root == NULL)
return new;
if (tree->key_compare(new->data, root->data) < 0) {
root->left = subtree_insert(tree, root->left, new);
} else {
root->right = subtree_insert(tree, root->right, new);
}
return subtree_balance(root);
}
static rbtree_node_t *mknode(const rbtree_t *t, const void *key, const void *value)
{
rbtree_node_t *node;
node = calloc(1, sizeof(*node) + t->key_size_padded + t->value_size);
if (node == NULL)
return NULL;
node->value_offset = t->key_size_padded;
node->is_red = 1;
memcpy(node->data, key, t->key_size);
memcpy(node->data + t->key_size_padded, value, t->value_size);
return node;
}
int rbtree_init(rbtree_t *tree, size_t keysize, size_t valuesize,
int(*key_compare)(const void *, const void *))
{
size_t diff, size;
memset(tree, 0, sizeof(*tree));
tree->key_compare = key_compare;
tree->key_size = keysize;
tree->key_size_padded = keysize;
tree->value_size = valuesize;
/* make sure the value always has pointer alignment */
diff = keysize % sizeof(void *);
if (diff != 0) {
diff = sizeof(void *) - diff;
if (SZ_ADD_OV(tree->key_size_padded, diff,
&tree->key_size_padded)) {
return SQFS_ERROR_OVERFLOW;
}
}
/* make sure the node can store the offset */
if (sizeof(size_t) > sizeof(sqfs_u32)) {
if (tree->key_size_padded > 0x0FFFFFFFFUL)
return SQFS_ERROR_OVERFLOW;
}
/* make sure the nodes fit in memory */
size = sizeof(rbtree_node_t);
if (SZ_ADD_OV(size, tree->key_size_padded, &size))
return SQFS_ERROR_OVERFLOW;
if (SZ_ADD_OV(size, tree->value_size, &size))
return SQFS_ERROR_OVERFLOW;
return 0;
}
void rbtree_cleanup(rbtree_t *tree)
{
destroy_nodes_dfs(tree->root);
memset(tree, 0, sizeof(*tree));
}
int rbtree_insert(rbtree_t *tree, const void *key, const void *value)
{
rbtree_node_t *node = mknode(tree, key, value);
if (node == NULL)
return SQFS_ERROR_ALLOC;
tree->root = subtree_insert(tree, tree->root, node);
tree->root->is_red = 0;
return 0;
}
rbtree_node_t *rbtree_lookup(const rbtree_t *tree, const void *key)
{
rbtree_node_t *node = tree->root;
int ret;
while (node != NULL) {
ret = tree->key_compare(key, node->data);
if (ret == 0)
break;
node = ret < 0 ? node->left : node->right;
}
return node;
}
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