Uninstall: Shutdown running application

[peters]

The uninstaller should send a window message to the program you are attempting to uinstall, telling it to shutdown. This would solve a couple of edge cases where you mark certain files as DELETE_ON_REBOOT. These are pretty niché scenarios, but you are bound to have some clients trying to uninstall / install an application (without rebooting).

This is mainly related to #181

Appearently this can be achieved rather easily with Shimmer sending a window message (hey no IPC) to the target application:

ds.dwData = WM_USER + 50; // the "message" you want to send
cds.cbData = sizeof(MyDataForMessage50); // the size of the chunk of data
cds.lpData = lpMessage50Data; // a pointer to the chunk of data
SendMessage(hwndTarget, WM_COPYDATA, reinterpret_cast<WPARAM>(hwndSender),
            reinterpret_cast<LPARAM>(&cds));

See sending-a-custom-windows-message-custom-data-marshalling

Then you could just override a virtual method in AppSetup that allows the application to perform a clean shutdown (not referring to OnUninstall).

[shiftkey]

And here I was thinking a Process.Kill would be "good enough" on uninstall :)

I'll leave this one open if someone wants to have a crack at it, but I'd love to get this in sooner rather than later.

[peters]

@shiftkey Sure, give me some pointers to where Process.Kill happens and i'll provide a PR ;)

[shiftkey]

@peters nah, let's Do It The Right Way.

As for where the code should live, I think here is a good place to start experimenting...

[shiftkey]

Sure, give me some pointers to where Process.Kill happens and i'll provide a PR ;)

I'm not doing that at the moment, it was just a (horrible) thought...

[anaisbetts]

Hm, I actually think this should be a more explicit API than just sending a window message. First of all, you have no idea that WM_USER + 50 is free, and you also have no idea how to find the (possibly multiple) window handles to target. What if the application runs in the background and doesn't have a window loop?

[anaisbetts]

Instead, I would have an API that is called on startup, and opens or creates a named pipe and parks itself on a read, then the installer can send down a "Shut it down" message that all of the open applications will receive and respond to

[peters]

@paulcbetts IPC is the most proven solution, no doubt about it. wyupdate has a simple implementation available, it does the job... but it's not as elegant as how EasyHook does it ;)

[shiftkey]

@paulcbetts @peters yep, an IPC-based solution would be the most-sane way to do it

[peters]

Closing this one because of Squirrel/Squirrel.Windows#229.