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

[Richard Frith-Macdonald]

> On 29 Nov 2018, at 23:45, Riccardo Mottola <riccardo.mottola@libero.it> wrote:
> 
> Hi,
> 
> on plain Linux/x86, using clang, a simple gui app like Ink fails to start:
> 
> Program received signal SIGSEGV, Segmentation fault.
> 0xb3ecb101 in xcb_writev () from /usr/lib/libxcb.so.1
> (gdb) bt
> #0  0xb3ecb101 in xcb_writev () from /usr/lib/libxcb.so.1
> #1  0xb40653ce in _XSend () from /usr/lib/libX11.so.6
> #2  0xb40659c1 in _XReply () from /usr/lib/libX11.so.6
> #3  0xb404b45e in XGetWindowProperty () from /usr/lib/libX11.so.6
> #4  0xb404a253 in XGetIconSizes () from /usr/lib/libX11.so.6
> #5  0xb443ba49 in -[XGServer(WindowOps) iconSize] (self=0x8434cd4, 
> _cmd=0xb7f74b18 <.objc_selector_list+64>)
>    at XGServerWindow.m:4565
> #6  0xb7d418ce in GSGetIconSize () from 
> /System/Library/Libraries/libgnustep-gui.so.0.26
> #7  0xb7a56180 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 0xb7a6243d in -[NSApplication(Private) _appIconInit] () from 
> /System/Library/Libraries/libgnustep-gui.so.0.26
> #12 0xb7a57e3b in -[NSApplication _init] () from 
> /System/Library/Libraries/libgnustep-gui.so.0.26
> #13 0xb74551a2 in -[NSObject performSelector:withObject:] () from 
> /System/Library/Libraries/libgnustep-base.so.1.25
> #14 0xb74eb575 in -[NSObject(NSThreadPerformAdditions) 
> performSelector:onThread:withObject:waitUntilDone:modes:] ()
>   from /System/Library/Libraries/libgnustep-base.so.1.25
> #15 0xb74eb1ef in -[NSObject(NSThreadPerformAdditions) 
> performSelectorOnMainThread:withObject:waitUntilDone:modes:] ()
>   from /System/Library/Libraries/libgnustep-base.so.1.25
> #16 0xb74eb294 in -[NSObject(NSThreadPerformAdditions) 
> performSelectorOnMainThread:withObject:waitUntilDone:] ()
>   from /System/Library/Libraries/libgnustep-base.so.1.25
> #17 0xb7a58220 in -[NSApplication init] () from 
> /System/Library/Libraries/libgnustep-gui.so.0.26
> #18 0xb7a579bf in +[NSApplication sharedApplication] () from 
> /System/Library/Libraries/libgnustep-gui.so.0.26
> #19 0xb7a2c6f5 in NSApplicationMain () from 
> /System/Library/Libraries/libgnustep-gui.so.0.26
> #20 0x0804aae0 in main (argc=<optimized out>, argv=<optimized out>, 
> env=<optimized out>) at main.m:33
> 
> I somehow have a de-ja-vu about iconsize, but it was fixed by Wolfgang Months 
> ago!
> 
> What's wrong??

Segmentation fault inside the X code. not in the GNUstep code.

That (assuming it's not an X bug), suggests corrupt memory or something like 
that.  Possibly a memory error in GNUstep code, possibly incorrect/multiple 
library versions linked in to the binary (eg the main executable and a bundle 
having different versions of the same library linked).

I'd suggest valgrind to look form emory corruption and looking at all the 
libraries linked to the executables/bindles in use (though rebuilding 
*everything* from scratrch will usually fix library version issues).