Thread-topic: IONotificationPortGetRunLoopSource, CFRunLoopAddSource, and CFRunLoopRemoveSource
Done. Radar 3822301. Thank you for checking.
> ----------
> From: Chris Sarcone
> Sent: Thursday, September 30, 2004 10:57 AM
> To: Joe van Tunen
> Cc: email@hidden
> Subject: Re: IONotificationPortGetRunLoopSource, CFRunLoopAddSource, and CFRunLoopRemoveSource
>
> Joe --
>
> > I am following the steps in the "Passing Untyped Data Asynchronously"
> > "Application Procedure Using CFRunLoop" section of the "Writing a
> > Custom User Client" documentation at
> > http://developer.apple.com/documentation/DeviceDrivers/Conceptual/
> > WritingDeviceDriver/MakingHWAccessible/chapter_5_section_3.html
> >
> > but I have run into a minor problem. I have setup code based on the
> > documentation that looks like this:
> >
> > kernResult = IOMasterPort(MACH_PORT_NULL, &masterPort);
> > appRunLoop = CFRunLoopGetCurrent();
> > CFRetain( appRunLoop );
> > notificationPortRef = IONotificationPortCreate( masterPort );
> > notificationRunLoopSource = IONotificationPortGetRunLoopSource(
> > notificationPortRef );
> > CFRunLoopAddSource( appRunLoop, notificationRunLoopSource,
> > kCFRunLoopDefaultMode );
> > notificationMachPort = IONotificationPortGetMachPort(
> > notificationPortRef );
> > kernResult = IOConnectSetNotificationPort( userClient, 0,
> > notificationMachPort, 0 );
> > and cleanup code that looks like this (the real code checks function
> > results):
> >
> > CFRunLoopRemoveSource( appRunLoop, notificationRunLoopSource,
> > kCFRunLoopDefaultMode );
> > CFRelease( notificationRunLoopSource );
> > IONotificationPortDestroy( notificationPortRef );
> > CFRelease( appRunLoop );
> >
> > The application crashes when IONotificationPortDestroy is called
> > (using OS X 10.3.5):
> >
> > 0 libobjc.A.dylib 0x908311f4 objc_msgSend + 0x14
> > 1 com.apple.CoreFoundation 0x901d8714 __CFMachPortDeallocate
> > + 0x2c
> > 2 com.apple.CoreFoundation 0x90190cf8 CFRelease + 0x1e8
> > 3 com.apple.CoreFoundation 0x90190cf8 CFRelease + 0x1e8
> > 4 com.apple.framework.IOKit 0x9058d70c
> > IONotificationPortDestroy + 0x2c
> > If I remove the "CFRelease( notificationRunLoopSource )" line, the
> > crash does not occur. The documentation says "Obtain a run-loop source
> > object from the notification-port object. Call the
> > IONotificationPortGetRunLoopSource function, passing in the
> > IONotificationPortRef object. This call returns a CFRunLoopSourceRef
> > object." and "Release the CFRunLoopSourceRef object by calling
> > CFRelease on it." Is the documentation wrong and the CFRelease should
> > not be there, or is there something else wrong with my code? Maybe a
> > CFRetain should be added but I don't think that would be necessary
> > because CFRunLoopAddSource should do that, shouldn't it?
>
> If you look at the source for the IOKitUser project in Darwin, you'll
> see that IONotificationPortDestroy() checks to see if the runloop
> source is NULL or not and will call CFRelease() on it. Since you called
> IONotificationPortGetRunLoopSource(), not
> IONotificationPortCreateRunLoopSource() or
> IONotificationPortCopyRunLoopSource(), I don't think you're supposed to
> release it (and the documentation is incorrect). Please file a bug
> against the documentation.
>
> Thanks,
>
> -- Chris
>
> ------------------
> 6 Infinite Loop
> M/S 306-2MS
> Cupertino CA 95014
> phone: (408) 974-4033
> fax: (408) 862-7577
> email: email@hidden
>
>
>
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