Re: UNIX signals
Re: UNIX signals
- Subject: Re: UNIX signals
- From: "Michael Ash" <email@hidden>
- Date: Wed, 17 Dec 2008 22:55:17 -0500
On Wed, Dec 17, 2008 at 2:32 PM, Greg Parker <email@hidden> wrote:
> On Dec 16, 2008, at 7:22 PM, Michael Ash wrote:
>>
>> On Tue, Dec 16, 2008 at 8:02 PM, Chris Idou <email@hidden> wrote:
>>>
>>> Is there any Cocoa and/or Carbon interface to UNIX signals?
>>
>> Nope. It's pretty easy to set up a signal handler that can call back
>> to a Cocoa/CoreFoundation runloop though, by having it write to a pipe
>> or mach port which the runloop monitors.
>
> Be warned that, to a close approximation, your code isn't allowed to do
> anything inside the signal handler itself. This includes sending any
> Objective-C messages to any object. (objc_msgSend may take locks. If the
> signal is interrupting a thread that already holds those locks, you're
> stuck.)
>
> The official list of functions you can call is in the sigaction man page.
> Some Mach functions are also safe, but I don't know of an official list of
> which ones.
Yep, that's a very good point. To use my suggestion, your signal
handler must do *nothing* but write to the pipe or mach port, and it
must ensure that the write is guaranteed non-blocking. This isn't too
hard, but it must be adhered to rigidly.
Mike
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