Re: gui apps segfault on Linux/x86/clang/libobjc2

[Riccardo Mottola]

Hi Fred,

I would rather not point the bug into xcb or X11, other non-gnustep apps 
do work fine, including sensitive apps like Firefox and emacs.

Fred Kiefer wrote:
> Both the reported issues should be rather harmless. For the one in back I 
> already committed a fix to prevent it. Please try with the current version on 
> git.

INdeed, updating back makes the error go away in valgrind (but... not 
the segfault)

> I will look into the base issue as well, but expect that this is also not the 
> cause of your problem. It is far more interesting that you get the segmentation 
> fault only when not running with valgrind. Is the stack trace of the 
> segmentation fault still the same?

"interesting" but what does it tell us? Valgrind is preventing some 
memory damage: It is a matter of Heiseberg, trying to measure modifies 
the object of measure! It may happen with gdb too, but not in this case.

==9086== Source and destination overlap in memcpy(0x9e68c18, 0x9e68c18, 24)
==9086==    at 0x4035409: __GI_memcpy (in 
/usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==9086==    by 0x4C1224C: 
_i_GSFFIInvocation__initWithCallback_values_frame_signature_ (in 
/System/Library/Libraries/libgnustep-base.so.1.25.1)
==9086==    by 0x4C1359A: GSFFIInvocationCallback (in 
/System/Library/Libraries/libgnustep-base.so.1.25.1)
==9086==    by 0x7566A74: ??? (in /usr/lib/libffi.so.6.0.4)
==9086==    by 0x7566E25: ??? (in /usr/lib/libffi.so.6.0.4)
==9086==    by 0x4A776EA: 
_i_NSDistributedNotificationCenter_Private__connect (in 
/System/Library/Libraries/libgnustep-base.so.1.25.1)
==9086==    by 0x4A75C22: 
_i_NSDistributedNotificationCenter__addObserver_selector_name_object_suspensionBehavior_ 
(in /System/Library/Libraries/libgnustep-base.so.1.25.1)
==9086==    by 0x4A7592D: 
_i_NSDistributedNotificationCenter__addObserver_selector_name_object_ 
(in /System/Library/Libraries/libgnustep-base.so.1.25.1)
==9086==    by 0x4558336: _i__GSWorkspaceCenter__init (in 
/System/Library/Libraries/libgnustep-gui.so.0.26.2)
==9086==    by 0x4AFACCA: _c_NSObject__new (in 
/System/Library/Libraries/libgnustep-base.so.1.25.1)
==9086==    by 0x455A2C4: _i_NSWorkspace__init (in 
/System/Library/Libraries/libgnustep-gui.so.0.26.2)
==9086==    by 0x455A06B: _c_NSWorkspace__sharedWorkspace (in 
/System/Library/Libraries/libgnustep-gui.so.0.26.2)
==9086==
2018-12-02 15:06:56.370 Ink[9086:9086] Unable to contact pasteboard 
server - please ensure that gpbs is running for local host.
2018-12-02 15:07:09.316 Ink[9086:9086] Unable to contact pasteboard 
server - please ensure that gpbs is running for local host.
==9086==
==9086== HEAP SUMMARY:
==9086==     in use at exit: 7,056,137 bytes in 65,574 blocks
==9086==   total heap usage: 224,958 allocs, 159,384 frees, 24,190,943 
bytes allocated
==9086==
==9086== LEAK SUMMARY:
==9086==    definitely lost: 429,675 bytes in 9,125 blocks
==9086==    indirectly lost: 21,386 bytes in 1,258 blocks
==9086==      possibly lost: 1,589,835 bytes in 14,925 blocks
==9086==    still reachable: 5,015,241 bytes in 40,266 blocks
==9086==                       of which reachable via heuristic:
==9086==                         newarray           : 46,317 bytes in 
1,466 blocks
==9086==         suppressed: 0 bytes in 0 blocks
==9086== Rerun with --leak-check=full to see details of leaked memory
==9086==
==9086== For counts of detected and suppressed errors, rerun with: -v
==9086== ERROR SUMMARY: 10 errors from 1 contexts (suppressed: 1 from 1)


Program received signal SIGSEGV, Segmentation fault.
0xb3ead101 in xcb_writev () from /usr/lib/libxcb.so.1
(gdb) bt
#0  0xb3ead101 in xcb_writev () from /usr/lib/libxcb.so.1
#1  0xb40473ce in _XSend () from /usr/lib/libX11.so.6
#2  0xb40479c1 in _XReply () from /usr/lib/libX11.so.6
#3  0xb402d45e in XGetWindowProperty () from /usr/lib/libX11.so.6
#4  0xb402c253 in XGetIconSizes () from /usr/lib/libX11.so.6
#5  0xb4438452 in -[XGServer(WindowOps) iconSize] () from 
/System/Library/Bundles/libgnustep-back-026.bundle/libgnustep-back-026
#6  0xb7d418fe in GSGetIconSize () from 
/System/Library/Libraries/libgnustep-gui.so.0.26
#7  0xb7a56380 in +[NSAppIconView initialize] () from 
/System/Library/Libraries/libgnustep-gui.so.0.26
#8  0xb714015c in objc_send_initialize () from 
/System/Library/Libraries/libobjc.so.4.6
#9  0xb714c4d8 in slowMsgLookup () from 
/System/Library/Libraries/libobjc.so.4.6
#10 0xb71525e1 in objc_msgSend () from 
/System/Library/Libraries/libobjc.so.4.6
#11 0xb7a626cd in -[NSApplication(Private) _appIconInit] () from 
/System/Library/Libraries/libgnustep-gui.so.0.26
#12 0xb7a58041 in -[NSApplication _init] () from 
/System/Library/Libraries/libgnustep-gui.so.0.26
#13 0xb7455232 in -[NSObject performSelector:withObject:] () from 
/System/Library/Libraries/libgnustep-base.so.1.25
#14 0xb74eb675 in -[NSObject(NSThreadPerformAdditions) 
performSelector:onThread:withObject:waitUntilDone:modes:] ()
   from /System/Library/Libraries/libgnustep-base.so.1.25
#15 0xb74eb2ec in -[NSObject(NSThreadPerformAdditions) 
performSelectorOnMainThread:withObject:waitUntilDone:modes:] ()
   from /System/Library/Libraries/libgnustep-base.so.1.25
#16 0xb74eb391 in -[NSObject(NSThreadPerformAdditions) 
performSelectorOnMainThread:withObject:waitUntilDone:] ()
   from /System/Library/Libraries/libgnustep-base.so.1.25
#17 0xb7a58420 in -[NSApplication init] () from 
/System/Library/Libraries/libgnustep-gui.so.0.26
#18 0xb7a57bbf in +[NSApplication sharedApplication] () from 
/System/Library/Libraries/libgnustep-gui.so.0.26
#19 0xb7a2c6f2 in NSApplicationMain () from 
/System/Library/Libraries/libgnustep-gui.so.0.26
#20 0x0804ab52 in main ()