Re: UNIX signals
Re: UNIX signals
- Subject: Re: UNIX signals
- From: Jean-Daniel Dupas <email@hidden>
- Date: Thu, 18 Dec 2008 09:30:26 +0100
Le 18 déc. 08 à 04:55, Michael Ash a écrit :
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
Although, as mention by Greg Parker, I didn't find doc that guarantee
that using mach_msg() is safe in a signal. (but Apple is using it in
securityd, so I'm not worry about it).
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