Thanks for the accurate description.

The more interesting question here is why "blackboard.createEntry(it.key(), res->second);" is not doing what is expected to do.

Do you have perhaps a simple example to reproduce the issue?

I must have a reproducer lying around that I used when debugging this. I’ll try to attach one ASAP.

While I’m at it, I’ll try to deliver a minimal PoC for all the other ones as well!

Okay, after some debugging I came to the conclusion that unlike stated above in the original description suggested this was a simple null pointer dereference from createEntry/getEntry, this seems to be a more complex issue involving the any type system.

Minimal Reproducer

#include "behaviortree_cpp/blackboard.h"
#include <iostream>
#include <nlohmann/json.hpp>

int main() {
    try {
        auto bb = BT::Blackboard::create();
        
        // Set initial value 
        bb->set("mmmmmm5CnCaaG", -535822226);
        
        // Create JSON that will trigger the crash
        std::string json_str = R"({
            "@@@@@@@@@@@@@@@": -535822226,
            "mmmmmm5CnCaaG": null
        })";
        
        // Parse and import JSON - will crash
        auto json = nlohmann::json::parse(json_str);
        BT::ImportBlackboardFromJSON(json, *bb);
    }
    catch(const std::exception& e) {
        std::cerr << "Exception: " << e.what() << std::endl;
        return 1;
    }
    return 0;
}

Updated stack-trace

AddressSanitizer:DEADLYSIGNAL
=================================================================
==3669987==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000010
    #0 0x7dfae074647f in linb::any::swap(linb::any&) /home/user/BehaviorTree.CPP/include/behaviortree_cpp/contrib/any.hpp:183:32
    #1 0x7dfae074647f in linb::any::operator=(linb::any const&) /home/user/BehaviorTree.CPP/include/behaviortree_cpp/contrib/any.hpp:129:18
    #2 0x7dfae074647f in BT::Any::operator=(BT::Any const&) /home/user/BehaviorTree.CPP/include/behaviortree_cpp/utils/safe_any.hpp:306:14
    #3 0x7dfae074647f in BT::ImportBlackboardFromJSON(...) /home/user/BehaviorTree.CPP/src/blackboard.cpp:292:20

The issue appears to be related to type handling in the Any implementation when dealing with null values during JSON deserialization. This suggests the fix might need to handle:

• Proper null value handling in the JSON import
• Type safety checks in the Any implementation
• Validation of entry state before assignment

#include "behaviortree_cpp/blackboard.h"
#include <iostream>
#include <nlohmann/json.hpp>

int main() {
    try {
        auto bb = BT::Blackboard::create();
        
        // Set initial value 
        bb->set("mmmmmm5CnCaaG", -535822226);
        
        // Create JSON that will trigger the crash
        std::string json_str = R"({
            "@@@@@@@@@@@@@@@": -535822226,
            "mmmmmm5CnCaaG": null
        })";
        
        // Parse and import JSON - will crash
        auto json = nlohmann::json::parse(json_str);
        BT::ImportBlackboardFromJSON(json, *bb);
    }
    catch(const std::exception& e) {
        std::cerr << "Exception: " << e.what() << std::endl;
        return 1;
    }
    return 0;
}

Hi, @facontidavide

The reason why blackboard.createEntry(it.key(), res->second); did not perform as expected in this case is: When the current key was "@@@@@@@@@@@@@@@" (15 @ symbols), since the key starts with @, rootBlackboard()->createEntryImpl(key.substr(1, key.size() - 1), info); created an entry with key "@@@@@@@@@@@@@@" (14 @ symbols). The critical issue was that the implementation didn't recursively call createEntry during this process, while the getEntry method does employ recursive calls to getEntry. This inconsistency ultimately led to failing to find the entry when searching for an empty string key (after recursively stripping all @ prefixes).

I've submitted a PR to fix this behavior #929

fixed making that syntax illegal, as it should be

thanks