Fixed a bug involving self-referential insertion

main.c

@@ -77,7 +77,6 @@ void new_region(struct AllocationRecord *dummy, struct Arena *arena) {
     return;
   }
   for (int ii = 0; ii < size; ii++) {
-    printf("writing %p\n", ((void*) region) + ii);
     ((char*) region)[ii] = (char) rand();
   }
   insert_record(dummy, region, size);

tree_alloc.c

@@ -302,8 +302,8 @@ void insert_singleton(TreeAlloc **root_ptr, TreeAlloc *to_insert) {
 
 void insert_right(TreeAlloc** root_ptr, TreeAlloc* to_insert, TreeAlloc* after) {
   if (after->right != NULL) {
-    after->right = to_insert;
-    to_insert->parent = after;
+    after->right->parent = to_insert;
+    to_insert->right = after->right;
   }
   after->right = to_insert;
   to_insert->parent = after;
@@ -312,8 +312,8 @@ void insert_right(TreeAlloc** root_ptr, TreeAlloc* to_insert, TreeAlloc* after)
 
 void insert_left(TreeAlloc** root_ptr, TreeAlloc* to_insert, TreeAlloc* before) {
   if (before->left != NULL) {
-    before->left = to_insert;
-    to_insert->parent = before;
+    before->left->parent = to_insert;
+    to_insert->left = before->left;
   }
   before->left = to_insert;
   to_insert->parent = before;
@@ -343,7 +343,7 @@ int add_new_region(Arena *arena, uintptr_t size, uintptr_t padding, uintptr_t al
       while (head->right != NULL) {
         head = head->right;
       }
-      insert_right((TreeAlloc**) arena->root_freespace, (TreeAlloc*) newreg, (TreeAlloc*) newreg);
+      insert_right((TreeAlloc**) arena->root_freespace, (TreeAlloc*) newreg, (TreeAlloc*) head);
 #ifdef DEBUG
       printf("= POST-REGION-CREATION =\n");
       printf("==== FREESPACE TREE ====\n");