[SDK] Memory allocation error using the Python bindings of MasterBoardInterface

[sduminy]

Hello all, I am using the Python bindings of the MasterBoardInterface in a Python script to test some P_controller on the robot. The experimentation runs well but when arriving at the line MasterBoardInterface(name_interface).Stop(), I get errors such as Error in 'python3' : double free or corruption (out) or Error in 'python3' : free() : invalid pointer as well as Segmentation fault, which make me think that there is an issue with the allocation memory in the C++ file. Could someone solve this problem ? Thanks,

[nim65s]

I could investigate, if no one with more experience with the code has enough time.

[paLeziart]

When I did my tests of example.py with Python 2.7 I had no such issue.

When you say that the error happens at the line MasterBoardInterface(name_interface).Stop(), is MasterBoardInterface(name_interface).Stop() exactly your line?

If yes then the issue is likely because you are creating a masterboard interface (MasterBoardInterface(name_interface) is the constructor) then immediately stopping it with .Stop() without it being initialized with .Init().

Here is an example of creation, initialization and stop:

robot_if = mbs.MasterBoardInterface(name_interface)
robot_if.Init()  # Initialization of the interface between the computer and the master board
[... CODE ... ]
robot_if.Stop()  # Shut down the interface between the computer and the master board

When you call Init() that happens:

link_handler_ = new ETHERNET_manager(if_name_, my_mac_, dest_mac_);
link_handler_->set_recv_callback(this);
link_handler_->start();

And when you call Stop():

((ESPNOW_manager *)link_handler_)->unset_filter();
link_handler_->stop();
return 0;

So if you call Stop() without calling Init() then link_handler_->stop(); wants to free the link_handler_ pointer which has not been initialized. There is just LINK_manager *link_handler_; in the master_board_interface.h and it is assigned something with link_handler_ = new ETHERNET_manager(if_name_, my_mac_, dest_mac_); in Init(). It would explain these error messages (trying to free a non-assigned pointer).

[sduminy]

When you say that the error happens at the line MasterBoardInterface(name_interface).Stop(), is MasterBoardInterface(name_interface).Stop() exactly your line?

Yes, I used some print() to locate the error to this line.

If yes then the issue is likely because you are creating a masterboard interface (MasterBoardInterface(name_interface) is the constructor) then immediately stopping it with .Stop() without it being initialized with .Init().

I think the line .Stop() was at the same indentation as .Init() so the problem should not come from that...

I think, the better way to solve this would be to run the example.py programm with Python3 on the RT computer in salle Bauzil.

[thomasfla]

I tested the current master branch on adaRT with python3 and did not get any error. I will close this issue for now, fell free to reopen it if the bug persist.

[thomasfla]

After more testing, this issue still persist !