[LCP] Terminating signals to handle

[Jean-Daniel Pauget]

On Tue, Jan 13, 2009 at 09:32:06PM -0900, Christopher Howard wrote:
> I'm writing an ncurses app in C (my first C app, actually). The terminal 
> mode is set to raw, so the app shouldn't reason the SIGINT signal (well, I 
> guess not anyway...) But a friend of mine looked at the code and told me I 
> should have a function that handles terminating signals, to make sure that 
> the terminal is returned to a normal state if someone kills the program 
> externally.
> 
> Here are my questions: Which signals should I bother handling? I see in 
> the signal(7) man page here that there are something like twenty signals 
> that can be received. SIGHUP, SIGKILL, SIGTERM, and SIGSTOP seem relevant 
> for the aforementioned purpose...
> 
> Secondly: Can the signal function in signal.h be used to direct more than 
> one kind of signal to the same function? (Rather than a separate function 
> for each signal?)

    sur you can. the main idea (my humble opinion) is to process the
    less you can in the function signal handler. most things are
    "dangerous" in that function because it can be called anywhen during
    your code. so evreything that is started from the handler must be
    thread safe, re-entrant etc.
    personally I simply turn on or off some flags, protected with a
    semaphore or something alike, and leave the main job to the regular
    code for when it check those flags, say, at the next select
    loop ...

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    Jean-Daniel Pauget
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