On 3/9/22, H.Fujii <hisab...@gmail.com> wrote: > I'm currently developing a console program in Python 3.9. > I want to detect the shutdown of Windows and save the data to a file > safely. > I created a sample program by referring to the following URL. > https://docs.microsoft.com/en-us/windows/console/registering-a-control-handler-function > > However, the sample program does not detect shutdown > (CTRL_SHUTDOWN_EVENT) well.
Console control events are sent by the Windows session server, csrss.exe, by creating a thread in the target process that starts at CtrlRoutine() in kernelbase.dll. This includes the cancel (i.e. Ctrl+C), break, and close events that are requested by a console session host (i.e. conhost.exe or openconsole.exe), as well as the system-initiated logoff and shutdown events. The session server sends the logoff and shutdown events to any process that isn't a GUI process. It doesn't matter whether or not the process is attached to a console. For example, the service control manager in services.exe depends on the console shutdown event, even though it is not a console application and is not attached to a console. A GUI process is one that's connected to a window station (e.g. interactive "WinSta0"), with one or more threads connected to a desktop (e.g. "WinSta0\Default"). Loading user32.dll, directly or indirectly, connects the process and loading thread to a window station and desktop (e.g. as set by its STARTUPINFO). In order to avoid getting converted to a GUI process, a console or background application has to carefully restrict itself to the base API, avoiding anything that might end up loading user32.dll, or by spawning a child process to call anything that loads user32.dll as a remote procedure call. Python 3.9+ starts out okay in this regard. But some extension modules in the standard library -- e.g. _ssl.pyd, _hashlib.pyd, and _ctypes.pyd -- do not delay-load dependencies that end up loading user32.dll. Thus, for example, it is currently impossible to use ctypes to handle the console logoff and shutdown events. As to win32api, it directly depends on user32.dll as well as indirectly via other DLLs. I think partitioning out a win32base module would be a worthy goal, but that's up to the PyWin32 project developers. If you can't take the simple route of using console logoff and shutdown events, then all you can do is fully embrace being a GUI process. Create a hidden top-level window with a message loop that handles WM_QUERYENDSESSION [1] and WM_ENDSESSION [2]. --- [1] https://docs.microsoft.com/en-us/windows/win32/shutdown/wm-queryendsession [2] https://docs.microsoft.com/en-us/windows/win32/shutdown/wm-endsession _______________________________________________ python-win32 mailing list python-win32@python.org https://mail.python.org/mailman/listinfo/python-win32
