How to build a plog in a dynamic link library

[EricYoung121]

I used a dynamic link library to create a console to record the data generated by the dll, but it could not output the data after I initialized it, or the program crashed after I called PLOG_INFO. Is there any way to create a console using a dynamic link library and call it?

[SergiusTheBest]

Could you post the code you've used?

[EricYoung121]

class logger
{
public:
	explicit logger(std::string_view console_title, file file) : 
		m_file_path(file)
	{
		if ((m_did_console_exist = AttachConsole(GetCurrentProcessId())) == false)
			AllocConsole();
		 
		if((m_console_handle = GetStdHandle(STD_OUTPUT_HANDLE)) != nullptr)
		{
			SetConsoleTitleA(console_title.data());
			SetConsoleOutputCP(CP_UTF8);

			m_console_out.open("CONOUT$", std::ios_base::out | std::ios_base::app);

			plog::init(plog::debug, m_file_path.c_str());
			plog::ColorConsoleAppender<plog::TxtFormatter> consoleAppender;
			plog::get()->addAppender(&consoleAppender);
		}
		g_logger = this;
	}
   }；

BOOL APIENTRY DllMain(HMODULE hModule, DWORD ul_reason_for_call, LPVOID lpReserved)
{
    if (ul_reason_for_call == DLL_PROCESS_ATTACH)
    {
        DisableThreadLibraryCalls(hModule);
        g_main_thread = CreateThread(nullptr, 0,
            [](PVOID)->DWORD
            {      
                  std::make_unique<logger>("TEST", g_file_manager.get_project_file("./cout.log"));
                  PLOG_VERBOSE << "TEST VERBOSE MESSAGE";

                  CloseHandle(g_main_thread);
                  FreeLibraryAndExitThread(g_hmodule, 0);
            }, nullptr, 0, &g_main_thread_id);

Since I wouldn't use it in a dynamic link library, I tried to create a console program and use it just like I would in the main function, but it crashed my program directly

[SergiusTheBest]

@EricYoung121 Thanks for the code. I'll try it tomorrow when I have access to a Windows machine. Meanwhile it would be helpful if you post a crash stack trace.

[SergiusTheBest]

@EricYoung121 I can see a couple of variable life-time issues:

• std::make_unique<logger>("TEST", g_file_manager.get_project_file("./cout.log")); - the result should be stored in a variable that lives long enough or else it will be immediately destroyed
• plog::ColorConsoleAppender<plog::TxtFormatter> consoleAppender; - should be stored in a variable that lives long enough, in your case in as a member of logger

Also be careful with DisableThreadLibraryCalls:

Do not call this function from a DLL that is linked to the static C run-time library (CRT): https://learn.microsoft.com/en-us/windows/win32/api/libloaderapi/nf-libloaderapi-disablethreadlibrarycalls