winapi - How to gracefully terminate a process?

Question

I want to terminate a number of processes, but I want to give each process the chance to save its data, ask the user about saving a file and even ignore the close request.

So TerminateProcess is out of the question, because it kills the process instantly. Another way would be to use SendMessage/PostMessage to send a WM_CLOSE to the main window, unfortunately I don't know anything about the windows of the processes, I only have the process id, so FindWindow doesn't help either. Is there any other way to find the main windows of a process?

In other words: Is there any way to terminate any process gracefully just like the Windows 7 task manager did when you clicked on "End Task"? (and not "End Process")

Answer 1

EnumWindows enumerates all the top level windows in a process. GetWindowThreadProcessId gets the process and Id of each thread.

You now have enough information to gracefully close any GUI application.

You can send WM_CLOSE messages to any window you wish to close. Many windows handle WM_CLOSE to prompt the user to save documents.You can send a WM_QUIT message using PostThreadMessage to the discovered threads to cause the message loop to terminate.

User code is not allowed to call DestroyWindow from a different app or thread to the windows... if the app does not respond to WM_CLOSE or WM_QUIT requests you're back in TerminateProcess land.

This will not close console applications as the application process, and process that owns the window, are different.

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Refer to T.s. Arun's answer below for the correct method for dealing with console applications.