The main function of the code is to copy itself to the system directory and write it to the registry to achieve startup on boot. It also sets a timer to periodically perform some operations. The program also listens for device plug and unplug events and copies itself to the drive when a removable drive is inserted.
Specifically, the kill_process function in the code is used to terminate a process with a specified name. The wnd_proc function is a window procedure function that handles window messages and performs corresponding operations. The main function is the main logic of the program, it registers a window class and creates a window. Then, it enters a loop to handle window messages.
In the end of the main function, the program first copies itself to a file named "virus.exe" in the system directory. Then, it writes the path of the file to the registry to automatically run on system startup. Finally, it sets a timer to trigger a timer message every 1 second.
In summary, the purpose of this code is to automatically run on system startup, listen for device plug and unplug events, and copy itself to removable drives.