Hey, I'm trying to write a program using binary search trees. Everything seems to work up to a certain point, which (as far as I know) shouldn't produce an error. It segmentation faults while it's executing the code below.

Code:

static BstreeNode* tree_insert_helper(Bstree *tree, BstreeNode *current_node, int key, void *value) {
if (current_node == NULL) { // create a new leaf node
current_node = (BstreeNode *)malloc(sizeof(BstreeNode));
current_node->left_child = NULL;
current_node->right_child = NULL;
current_node->key = key;
current_node->value = value;
printf("Beginning linking the root node\n");
printf("%d\n", current_node->key);
// If making the root node
if(tree->root->key == current_node->key) //!!! Has some problem with accessing tree's fields! This is where it seg faults.
{
printf("Linking the root node\n");
current_node->next = tree->sentinelNode;
current_node->prev = tree->sentinelNode;
tree->sentinelNode->next = current_node;
tree->sentinelNode->prev = current_node;
}
}
else {
int compare_result = key - current_node->key;
if (compare_result < 0)
{
current_node->left_child = tree_insert_helper(tree, current_node->left_child, key, value);
if(key == current_node->left_child->key)
{
current_node->left_child->next = current_node;
current_node->left_child->prev = current_node->prev;
current_node->prev = current_node->left_child;
current_node->left_child->prev->next = current_node->left_child;
}
}
else if (compare_result > 0)
{
current_node->right_child = tree_insert_helper(tree, current_node->right_child, key, value);
if(key == current_node->right_child->key)
{
current_node->right_child->prev = current_node;
current_node->right_child->next = current_node->next;
current_node->next = current_node->right_child;
current_node->right_child->next->prev = current_node->right_child;
}
}
// else set key to new value
else
current_node->value = value;
}
return current_node;
}
void bstree_insert(void *binary_tree, int key, void *value) {
Bstree *tree = (Bstree *)binary_tree;
tree->root = tree_insert_helper(tree, tree->root, key, value);
}

Not all of this code was written by me. I just had to modify it.

The definitions of Bstree and BstreeNode are as follows:

Code:

typedef struct bstreenode {
int key;
void *value;
struct bstreenode *left_child;
struct bstreenode *right_child;
struct bstreenode *next;
struct bstreenode *prev;
} BstreeNode;
typedef struct {
BstreeNode *root;
BstreeNode *sentinelNode;
} Bstree;

What could be causing a seg fault in this code?