Re: Segmentation fault while loading Cocoa NIB

[Andy Balholm]

Thank you for looking into this bug. Here is the source for the  
project as it was just before I removed the user defaults controller  
from CompanyInfo.nib.

R2O.zip
Description: Zip archive

To show the Company Info window, select Edit Company Info... from the  
file menu (with a document open). To get the crash, close that window  
and then open it again.

As far as I know, no other objects in the NIB reference the user  
defaults controller.

I have also discovered another bug relating to this NIB. The bindings  
that it contains seem to be read-only; if there is data in the model  
objects, it is displayed, but any changes I make in the text fields  
are not reflected in the model.

Here's a sample data file too:

Test.r2o
Description: Binary data

Andy Balholm
(509) 276-9718
andy@balholm.com



On Jun 18, 2009, at 12:37 PM, Fred Kiefer wrote:

> Hi Andy,
>
> thank you for the bug report and the analysis you did yourself. In
> general it really helps to have the source code and of course the NIB
> files to dig into such a problem.
>
> The decoding code for NSUserDefaultsController is rather simple:
>
> - (id) initWithCoder: (NSCoder *)aDecoder
> {
>  if ([aDecoder allowsKeyedCoding])
>    if ([aDecoder decodeBoolForKey: @"NSSharedInstance"])
>      {
>        RELEASE(self);
>        return [NSUserDefaultsController sharedUserDefaultsController];
>      }
>
>  return [super initWithCoder: aDecoder];
> }
>
> I don't expect that this itself is causing the problem. Maybe another
> object is having a reference to this object and the code there doesn't
> properly handle the case the the decoded object gets replaced by  
> another
> one. I would need to look at the NIB file (best in XML format) to
> further analyse this.
>
> Fred
>
>
>
> Andy Balholm wrote:
> > I sent this message a while ago. Since then I investigated further  
> > with
> > GDB and discovered that the segmentation fault happens while the  
> > shared
> > user defaults controller is being unarchived from the NIB. For this
> > particular program, the NIB didn't need to have a user defaults
> > controller in it. (IB put it in without asking.) But someone may  
> > want to
> > look into the problem in general.
> >
> > There is also another crash that occurs only under FreeBSD, but not
> > under Windows, in the same circumstances. It says that virtual  
> > memory is
> > exhausted.
> >
> > Andy Balholm
> > (509) 276-9718
> > andy@balholm.com
> >
> >
> >
> > Begin forwarded message:
> >
> > > From: Andy Balholm <andy@balholm.com>
> > > Date: June 16, 2009 4:29:48 PM PDT
> > > To: bug-gnustep@gnu.org
> > > Subject: Segmentation fault while loading Cocoa NIB
> > >
> > > I am developing an application to run under MacOS and GNUstep. The
> > > windows are stored as Cocoa NIBs. One of the windows causes a crash
> > > the second or third time it loads when I'm running the program under
> > > GNUstep for either Windows or FreeBSD. (The main document window is
> > > fine, though.) It does not crash under MacOS, so I suppose it  
> > > would be
> > > considered a bug in GNUstep rather than in my program.
> > >
> > > It doesn't seem to matter whether I save the NIB as format version 2
> > > or format version 3 in Interface Builder. The crash still happens.
> > >
> > > Under Windows, I'm using gnustep-core version 0.23.0. Under FreeBSD,
> > > I'm using sources from Subversion downloaded on Saturday (Jun 13).
> > >
> > > Here is the stack trace I got with gdb under FreeBSD:
> > >
> > > #0  0x28865a64 in objc_msg_lookup () from /usr/lib/libobjc.so.3
> > > #1  0x285c919d in GSIArraySetItemAtIndex (array=0x2933a900,  
> > > item={addr
> > > = 692693272, obj = 0x2949a918, nso = 0x2949a918}, index=115) at
> > > GSIArray.h:502
> > > #2  0x285c8d0e in -[NSKeyedUnarchiver(Private) _decodeObject:]
> > > (self=0x28ece248, _cmd=0x28801ac8, index=115) at  
> > > NSKeyedUnarchiver.m:226
> > > #3  0x285c86c5 in -[NSKeyedUnarchiver(Internal)
> > > _decodeArrayOfObjectsForKey:] (self=0x28ece248, _cmd=0x287ce5f8,
> > > aKey=0x287cdad8) at NSKeyedUnarchiver.m:114
> > > #4  0x284e5d4e in -[GSPlaceholderArray initWithCoder:]
> > > (self=0x28d3b8d8, _cmd=0x28801b08, aCoder=0x28ece248) at GSArray.m: 
> > > 1133
> > > #5  0x285c8ca1 in -[NSKeyedUnarchiver(Private) _decodeObject:]
> > > (self=0x28ece248, _cmd=0x28801ac8, index=121) at  
> > > NSKeyedUnarchiver.m:219
> > > #6  0x285cb8db in -[NSKeyedUnarchiver decodeObjectForKey:]
> > > (self=0x28ece248, _cmd=0x2845e0b8, aKey=0x2845c450) at
> > > NSKeyedUnarchiver.m:600
> > > #7  0x283575ff in -[NSIBObjectData initWithCoder:] (self=0x28ecf928,
> > > _cmd=0x28801b08, coder=0x28ece248) at GSNibLoading.m:1680
> > > #8  0x285c8ca1 in -[NSKeyedUnarchiver(Private) _decodeObject:]
> > > (self=0x28ece248, _cmd=0x28801ac8, index=1) at NSKeyedUnarchiver.m: 
> > > 219
> > > #9  0x285cb8db in -[NSKeyedUnarchiver decodeObjectForKey:]
> > > (self=0x28ece248, _cmd=0x28469988, aKey=0x28469484) at
> > > NSKeyedUnarchiver.m:600
> > > #10 0x2836bbd4 in -[GSNibLoader
> > > loadModelData:externalNameTable:withZone:] (self=0x28d75f28,
> > > _cmd=0x284699d8, data=0x28eba668, context=0x28ecab88,  
> > > zone=0x2883a320)
> > > at GSNibLoader.m:73
> > > #11 0x2836bf43 in -[GSNibLoader
> > > loadModelFile:externalNameTable:withZone:] (self=0x28d75f28,
> > > _cmd=0x283a49a0, fileName=0x28e1c828, context=0x28ecab88,
> > > zone=0x2883a320) at GSNibLoader.m:133
> > > #12 0x2816dd6f in +[NSBundle(NSBundleAdditions)
> > > loadNibFile:externalNameTable:withZone:] (self=0x287e1da0,
> > > _cmd=0x28434570, fileName=0x28e1c828, context=0x28ecab88,
> > > zone=0x2883a320) at NSBundleAdditions.m:205
> > > #13 0x282e8049 in -[NSWindowController loadWindow] (self=0x28e3b6a8,
> > > _cmd=0x28434490) at NSWindowController.m:467
> > > #14 0x282e75ea in -[NSWindowController window] (self=0x28e3b6a8,
> > > _cmd=0x28434408) at NSWindowController.m:301
> > > #15 0x282e70af in -[NSWindowController setDocumentEdited:]
> > > (self=0x28e3b6a8, _cmd=0x283c02b0, flag=0 '\000') at
> > > NSWindowController.m:210
> > > #16 0x281aee29 in -[NSDocument addWindowController:]  
> > > (self=0x28e1c588,
> > > _cmd=0x804be00, windowController=0x28e3b6a8) at NSDocument.m:319
> > > #17 0x08048e15 in -[MyDocument showCompanyInfoWindow:]
> > > (self=0x28e1c588, _cmd=0x28d1ac08, sender=0x2939a1f8) at  
> > > MyDocument.m:43
> > > #18 0x286efa8f in L10 () from
> > > /usr/GNUstep/System/Library/Libraries/libgnustep-base.so.1.19
> > > #19 0x28e1c588 in ?? ()
> > > #20 0x28d1ac08 in ?? ()
> > > #21 0x2939a1f8 in ?? ()
> > > #22 0x288710f0 in ?? () from /usr/lib/libobjc.so.3
> > > #23 0x28e00000 in ?? ()
> > > #24 0x0804f438 in ?? ()
> > > #25 0x0804f540 in ?? ()
> > > #26 0x2886aea0 in objc_free () from /usr/lib/libobjc.so.3
> > > #27 0x286ae70d in GSFFCallInvokeWithTargetAndImp (_inv=0x28e48fd8,
> > > anObject=0x28e1c588, imp=0x8048c60 <-[MyDocument
> > > showCompanyInfoWindow:]>) at GSFFCallInvocation.m:709
> > > #28 0x286aeaec in -[GSFFCallInvocation invokeWithTarget:]
> > > (self=0x28e48fd8, _cmd=0x283977e8, anObject=0x28e1c588) at
> > > GSFFCallInvocation.m:779
> > > #29 0x2813dc3f in -[NSApplication sendAction:to:from:]
> > > (self=0x28e1c4c8, _cmd=0x283e2dd0, aSelector=0x28d1ac08,  
> > > aTarget=0x0,
> > > sender=0x2939a1f8) at NSApplication.m:2087
> > > #30 0x2820d871 in -[NSMenu performActionForItemAtIndex:]
> > > (self=0x293d39c8, _cmd=0x283e5798, index=9) at NSMenu.m:1242
> > > #31 0x282171d5 in -[NSMenuView trackWithEvent:] (self=0x293af6c8,
> > > _cmd=0x283e5818, event=0x28e3b3d8) at NSMenuView.m:1633
> > > #32 0x28217354 in -[NSMenuView mouseDown:] (self=0x293af6c8,
> > > _cmd=0x28433190, theEvent=0x28e3b568) at NSMenuView.m:1678
> > > #33 0x282df26e in -[NSWindow sendEvent:] (self=0x28d03a08,
> > > _cmd=0x283977a0, theEvent=0x28e3b568) at NSWindow.m:3588
> > > #34 0x2813d5dd in -[NSApplication sendEvent:] (self=0x28e1c4c8,
> > > _cmd=0x283976e0, theEvent=0x28e3b568) at NSApplication.m:1963
> > > #35 0x2813c019 in -[NSApplication run] (self=0x28e1c4c8,
> > > _cmd=0x2838cc60) at NSApplication.m:1465
> > > #36 0x2811b4c1 in NSApplicationMain (argc=1, argv=0xbfbfe824) at
> > > Functions.m:74
> > > #37 0x0804ac9e in main (argc=Error accessing memory address  
> > > 0x160001:
> > > Bad address.
> > >
> > > I would be glad to send you the application source if it would help
> > > you find the problem.
> > >
> > > Andy Balholm
> > > (509) 276-9718
> > > andy@balholm.com