[bug #26766] Segfault when falling back to Ximage....

[Petr Hluzin]

URL:
  <http://savannah.gnu.org/bugs/?26766>

                 Summary: Segfault when falling back to Ximage....
                 Project: GNUstep
            Submitted by: gcasa
            Submitted on: Tue 09 Jun 2009 04:13:23 PM EDT
                Category: None
                Severity: 3 - Normal
              Item Group: None
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any

    _______________________________________________________

Details:

/usr/GNUstep/System/Applications/SystemPreferences.app/SystemPreferences
2009-06-08 16:25:59.718 SystemPreferences[1689] Unknown time zone name
`PST'.
2009-06-08 16:25:59.718 SystemPreferences[1689] Using time zone with absolute
offset 0.
2009-06-08 16:25:59.713 SystemPreferences[1689] XShm pixmaps not supported by
X server.
2009-06-08 16:25:59.718 SystemPreferences[1689] Falling back to normal
XImage: s (will be slower).
Segmentation fault

This was recently reported to me... I'm not sure why it's happening and I
can't reproduce it myself.  

GC




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[Petr Hluzin]

Update of bug #26766 (project gnustep):

                Category:                    None => Gui/AppKit            
              Item Group:                    None => Bug                    


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[Petr Hluzin]

Update of bug #26766 (project gnustep):

                  Status:                    None => Need Info              

    _______________________________________________________

Follow-up Comment #1:

We will need a bit more information than this to resolve the issue. There is
no sign that the fall back, that happens on all newer X11 systems, and the
segmentation fault are in any way related. Could you please run the
application in a debugger and report thefull backtrace?

A simalar error has been reported on the mailing list last week and in that
case the reason was that two versions of SystemPreferences where installed on
the computer, one in Local and one in System. Removing these and reinstalling
resolved the problem.

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[Petr Hluzin]

Follow-up Comment #2, bug #26766 (project gnustep):

(gdb) run
Starting program:
/usr/GNUstep/System/Applications/SystemPreferences.app/SystemPreferences
[Thread debugging using libthread_db enabled]
Warning: guessed host libthread_db library "/lib64/libthread_db.so.1".
Using host libthread_db library "/lib64/libthread_db.so.1".
[New Thread 0xf74166b0 (LWP 18060)]
2009-06-09 20:52:49.401 SystemPreferences[18060] Unknown time zone name
`PST'.
2009-06-09 20:52:49.401 SystemPreferences[18060] Using time zone with
absolute offset 0.
2009-06-09 20:52:49.400 SystemPreferences[18060] XShm pixmaps not supported
by X server.
2009-06-09 20:52:49.401 SystemPreferences[18060] Falling back to normal
XImage: s (will be slower).

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0xf74166b0 (LWP 18060)]
0x0807c330 in ?? ()
(gdb) bt
#0  0x0807c330 in ?? ()
#1  0xf79422da in -[NSDistributedNotificationCenter(Private) _connect]
(self=0x8316c00, _cmd=0xf7b8e308) at NSDistributedNotificationCenter.m:782
#2  0xf7940b0b in -[NSDistributedNotificationCenter
addObserver:selector:name:object:suspensionBehavior:] (self=0x8316c00,
_cmd=0xf7b8e2f0, anObserver=0x8315228, aSelector=0xf7fa19d8,
notificationName=0x0, anObject=0xf7fa0ee0,
    suspensionBehavior=2) at NSDistributedNotificationCenter.m:341
#3  0xf7940809 in -[NSDistributedNotificationCenter
addObserver:selector:name:object:] (self=0x8316c00, _cmd=0xf7fa19e0,
anObserver=0x8315228, aSelector=0xf7fa19d8, notificationName=0x0,
anObject=0xf7fa0ee0)
    at NSDistributedNotificationCenter.m:266
#4  0xf7e54812 in -[_GSWorkspaceCenter init] (self=0x8315228,
_cmd=0xf7ba48c8) at NSWorkspace.m:283
#5  0xf798c609 in +[NSObject new] (self=0xf7fa1860, _cmd=0xf7fa1960) at
NSObject.m:1101
#6  0xf7e5569f in -[NSWorkspace init] (self=0x83143b0, _cmd=0xf7fa19c8) at
NSWorkspace.m:642
#7  0xf7e554d4 in +[NSWorkspace sharedWorkspace] (self=0xf7fa1760,
_cmd=0xf7f02840) at NSWorkspace.m:611
#8  0xf7cad657 in -[NSApplication finishLaunching] (self=0x8155f08,
_cmd=0xf7f02940) at NSApplication.m:1064
#9  0xf7caeebd in -[NSApplication run] (self=0x8155f08, _cmd=0x804f4f0) at
NSApplication.m:1438
#10 0x0804916f in main () at main.m:13



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[Petr Hluzin]

Update of bug #26766 (project gnustep):

                Category:              Gui/AppKit => Base/Foundation        
                  Status:               Need Info => None                  
                 Summary: Segfault when falling back to Ximage.... =>
Segfault when connecting to distributed notification centre

    _______________________________________________________

Follow-up Comment #3:

Thank you for the additional information. I changed the bug to the base
category and adjusted the summary.

From what I understand this looks like there is a communication problem
between the gdnc process and SystemPreferences. Could you make sure that there
is only one current version of gdnc installed on your machine and that this
one is up and running.



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[Petr Hluzin]

Follow-up Comment #4, bug #26766 (project gnustep):

please check the following:

1. only one version of gdnc installed and linked against current core
libaries
2. gdnc is installed is installed as root (on smoe system it works without,
but it shoudl really, you should  perform make install as root when being in
the Tools directory containint gdnc, or you install your whole gnustep stuff
as root)
3. if you have GWorkspace, uninstall, clean, recompile and install that one
too (just to be on the safe side)
4. make sure you have gdomap and gdnc entries in /etc/services

then you can to the following:

1. kill all gnustep processes, including gdomap and gdnc.
2. open a shell, run in it "gdnc -f"
You should see no errors and gdnc should not return to the prompt (it means
that it did not fork and remains waiting for connection)
3. in another shell start your application

hope that it works. If not, two thing used to happen to me in the past:
- gdnc in the other shell dies - thus it is a gdnc problem
- the application attempts to start another gdnc instance but the one you
started non-forking remains running



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[Petr Hluzin]

Follow-up Comment #5, bug #26766 (project gnustep):

While advice about killing all existing processes and then making sure only
one copy of gdnc is running is good, the problem is a segmentation fault
rather than an exception, so there is an issue in the local process (even if
it's triggered by something else going on in a remote one), so I don't think
looking at gdnc will help.

The segfault is at 'NSDistributedNotificationCenter.m:782' which (assuming
the code is running a recent version of the base library) is in the call to
-registerClient: in the gdnc process ... ie it's at the point when handling
sending of a DO method or receiving its response.

That pretty  much isolates the issue to the ffcall or ffi library and/or its
interaction with  gnustep-base.  I don't know what system this is running on,
but the gdb warning 'Using host libthread_db library
"/lib64/libthread_db.so.1".' suggests it's a 64bit cpu, and we know that
support for 64bit systems in libffi and ffcall has historically been rather
weak, so the thing to do would be to check that the base library is linked
with the latest available libffi (which might mean something more recent than
whatever comes with the operating system).

If that doesn't work then the thing to do is set a breakpoint at
NSDistributedNotificationCenter.m:782 and then step through instruction by
instruction to find where things are going wrong ... if the crash is inside
libffi itsself, this would also need you to get the source for libffi and
build/use it so that gdb could show you the code as you step through.


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[Petr Hluzin]

Follow-up Comment #6, bug #26766 (project gnustep):

I had sth. similar on OpenBSD sparc64 a while ago, and I guess it is still
there, take a look at bug #23040. There the crasher is in line 780, I guess
the offset of just two lines is from a code change meanwhile. Haven't tested
latest versions since then, but I guess it is still the same.


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[Petr Hluzin]

Follow-up Comment #7, bug #26766 (project gnustep):

Ok -- this seemed to be cleared up by switching from ffcall library to
libffi.


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[Petr Hluzin]

Update of bug #26766 (project gnustep):

             Open/Closed:                    Open => Closed                

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Follow-up Comment #8:

closed on request of the user.

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