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Bug 2431

Summary: SDL eats SIGINT by default
Product: SDL Reporter: Tiffany Bennett <tiffany>
Component: *don't know*Assignee: Ryan C. Gordon <icculus>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: API change    
Priority: P2 CC: tiffany
Version: 2.0.1Keywords: triage-2.0.4
Hardware: x86_64   
OS: Linux   

Description Tiffany Bennett 2014-03-06 21:09:09 UTC 
This is rather ugly behaviour which causes SDL to completely eat and ignore any ctrl+C sent to the application unless you explicitly look at the documentation and see that it generates SDL_QUIT, and handle SDL_QUIT.

In my case, I am leaving it to the caller to install signal handlers for ctrl+C, and it is not preferred behaviour to have SDL eating my ctrl+Cs for demos which I didn't bother to install cleanup code for.

At the very least, there should be a flag (perhaps reuse SDL_INIT_NOPARACHUTE?) to disable SDL attempting to install these signal handlers.

Steps to reproduce:

1. Create any application which does not include logic to handle SDL_QUIT.
2. Compile and run it.
3. Press ctrl+C

Expected result:

The application should terminate.

Actual result:

Nothing. SDL catches the signal, fires the SDL_QUIT event, which is ignored, and the application continues running as if nothing happened.
Comment 1 Ryan C. Gordon 2015-02-19 05:22:18 UTC 
Marking a large number of bugs with the "triage-2.0.4" keyword at once. Sorry if you got a lot of email from this. This is to help me sort through some bugs in regards to a 2.0.4 release. We may or may not fix this bug for 2.0.4, though!
Comment 2 Ryan C. Gordon 2015-03-24 18:41:02 UTC 
As of https://hg.libsdl.org/SDL/rev/0af69dab9bb6, you can use a hint to prevent SDL from touching the signal handlers.

From your program, before calling SDL_Init()...

    SDL_SetHint(SDL_HINT_NO_SIGNAL_HANDLERS, "1");

...it is safe to call this on any platform, but it only does something on Unix-like things.

You can also force this from the command line: set the "SDL_NO_SIGNAL_HANDLERS" environment variable to "1".

The default will continue to be to install the signal handler, but now you can explicitly prevent this if your app ignores SDL_QUIT or wants its own handler instead.

--ryan.