Re: Debugging NSNotificationCenter

[Fred Kiefer]

Hi Andreas,

no idea what is going wrong, but my first try would be to start gdb and
have a look at the notification directly. If this does not seem like a
good idea, I would recommend that you ask the notification for its class
and print that instead of the notification itself. If this works and it
is the class notification, you could ask the notification for its name
and have that printed.
My guess is that either the object or the user information of the
notification fail to print.

Cheers
Fred


Andreas Höschler schrieb:
> 
> my app crashes under GNUstep. It does not crash under MacOSX. I got the
> following stack trace and am stuck
> 
> #0  objc_msg_lookup (receiver=0x908da98, op=0xfe71aef8) at sarray.h:230
> #1  0xfe480ee6 in GSFormat (s=0x8046760, format=0x908da98, ap=0x80470d4
> "\230Ú\b\tØe\016\tpíKþðÝsþ", locale=0x0) at GSFormat.m:1856
> #2  0xfe4935f8 in -[GSPlaceholderString
> initWithFormat:locale:arguments:] (self=0x80e1a88, _cmd=0xfe741820,
> format=0x86e62e8, locale=0x0,
>    argList=0x80470d4 "\230Ú\b\tØe\016\tpíKþðÝsþ") at GSString.m:715
> #3  0xfe577f44 in -[NSString initWithFormat:arguments:] (self=0x80e1a88,
> _cmd=0xfe74d1d0, format=0x86e62e8,
>    argList=0x80470d4 "\230Ú\b\tØe\016\tpíKþðÝsþ") at NSString.m:1049
> #4  0xfe5bc617 in +[NSString(GSCategories) stringWithFormat:arguments:]
> (self=0xfe7416c0, _cmd=0xfe734bb8, format=0x86e62e8,
>    argList=0x80470d4 "\230Ú\b\tØe\016\tpíKþðÝsþ") at NSZone.h:281
> #5  0xfe52a20a in NSLogv (format=0x86e62e8, args=0x80470d4
> "\230Ú\b\tØe\016\tpíKþðÝsþ") at NSLog.m:345
> #6  0xfe529ea7 in NSLog (format=0xfe735918) at NSLog.m:252
> #7  0xfe532c47 in -[NSNotificationCenter postNotification:]
> (self=0x80b81a8, _cmd=0xfea79788, notification=0x908da98)
>    at NSNotificationCenter.m:1106
> #8  0xfe53cd0b in -[NSObject performSelector:withObject:]
> (self=0x80b81a8, _cmd=0xfe73ddd8, aSelector=0xfea79788, anObject=0x908da98)
>    at NSObject.m:1788
> #9  0xfe56262d in -[GSRunLoopPerformer fire] (self=0x81f3b70,
> _cmd=0xfe73de98) at NSRunLoop.m:104
> #10 0xfe56345b in -[NSRunLoop(Private) _checkPerformers:] (self=0x60,
> _cmd=0xfe73df48, context=0x82f1810) at NSRunLoop.m:464
> #11 0xfe564659 in -[NSRunLoop acceptInputForMode:beforeDate:]
> (self=0x82e1be0, _cmd=0xfe73df90, mode=0xfe73e020, limit_date=0x82f5e18)
>    at NSRunLoop.m:906
> #12 0xfe564c79 in -[NSRunLoop runMode:beforeDate:] (self=0x82e1be0,
> _cmd=0xfeee3f78, mode=0xfe73e020, date=0x82ebb38) at NSRunLoop.m:1045
> #13 0xfedbb91c in -[GSDisplayServer(EventOps)
> getEventMatchingMask:beforeDate:inMode:dequeue:] (self=0x82d7718,
> _cmd=0xfdb0d720,
>    mask=4294967295, limit=0x82ebb38, mode=0xfe73e020, flag=1 '\001') at
> GSDisplayServer.m:877
> #14 0xfdab8ae3 in -[XGServer(X11Ops)
> getEventMatchingMask:beforeDate:inMode:dequeue:] (self=0x82d7718,
> _cmd=0xfeea7af8, mask=4294967295,
>    limit=0x82ebb38, mode=0xfe73e020, flag=1 '\001') at XGServerEvent.m:1989
> #15 0xfec96c17 in -[NSApplication
> nextEventMatchingMask:untilDate:inMode:dequeue:] (self=0x81c5348,
> _cmd=0xfeea7d48, mask=4294967295,
> 
> I have inserted the following logs in NSNotificationCenter.m
> 
> - (void) postNotification: (NSNotification*)notification
> {
>   NSLog(@"postNotification...");
>   NSLog(@"postNotification %@", notification);
>   NSLog(@"postNotification %@ %@", notification, [notification name]);
>   if (notification == nil)
>    {
>      [NSException raise: NSInvalidArgumentException
> ...
> 
> The last log that is printed is "postNotification...". Then the app
> crashes with a segmentation fault. It seems someone is posting a bad
> notification. I have no idea how to track this down any further. Hints
> are greatly appreciated!
> 
> Regards,
> 
>  Andreas
>