No way to disable SDL signal catching

[jonas-schievink]

Citing the SDL Wiki:

On POSIX systems, SDL_Init() installs signal handlers for SIGINT (keyboard interrupt) and SIGTERM (system termination request), if handlers do not already exist, that generate SDL_QUIT events as well. There is no way to determine the cause of an SDL_QUIT event, but setting a signal handler in your application will override the default generation of quit events for that signal.

IMO implicitly installing signal handlers is very bad practice, and there should at least be a convenient way of undoing this in rust-sdl2

[Kerollmops]

up ?

[AngryLawyer]

Okay; what's the sort of pattern where you wouldn't use SDL_init in a C application? I've never gone without signal handlers before so I'm not exactly sure what a solution would look like.

[jonas-schievink]

This becomes a problem when not using the SDL event loop, since the generated Quit events will go nowhere.

For me, this was the case when I tried to support multiple window backends in Breeze - The emulator could only be exited with ^C when the SDL backend was used since that's using the event loop (I'm still using SDL to drive input handling, even with other rendering backends).

My workaround is this, saving the signal handlers before initializing SDL and restoring them afterwards.

Apparently SDL can be told not to install handlers by setting SDL_HINT_NO_SIGNAL_HANDLERS. There is no need to stop using SDL_init, just set the hint before doing so (I think).

[AngryLawyer]

Okay, so it sounds like the solution would be to either provide arguments to the following function, or provide an alternative for this special case?

https://github.com/AngryLawyer/rust-sdl2/blob/master/src/sdl2/sdl.rs#L40-L61

[jonas-schievink]

Yes, looks like it. Or somehow expose a method to set hints manually.

[AngryLawyer]

Well, setting that hint while SDL2 has already been init doesn't make any sense, so I think I'll take a pop at doing it in our own initialization step.

I'll see if I can get time this week to take a peek.