[Swarm-Support] crash from [controlPanel setStateStopped]

[Paul Johnson]

I'm working on Fedora Core 3 with Swarm-2.2 rc1.

I wanted a boids program and found Newboids in swarm FTP.  I found, to 
my surprise, that it DOES still run if you tell it to use the canvas 
display, but not with the Raster display.  I've gone through the code 
over and over, looking for the usual sorts of mistakes that cause 
unpredictable crashes (createBegin without createEnd, nil objects). 
Every time I found one of them, my heart would soar thinking I had found 
the problem. But no.

I've hacked it to a point now that makes me think it hits some 
vulnerability in tclObjc. The seg fault now follows the observer's use 
of [controlPanel setStateStopped]. The backtrace is below. If you have 
seen anything like it, please give me a heads up!

I will gladly give this code to anybody who wants to see.


Program received signal SIGSEGV, Segmentation fault.
0xb7ed0de2 in tclObjc_objectToName (obj=0x1)
    at /usr/src/debug/swarm-2.2/src/tclobjc/tclObjc.m:54
54            sprintf(name, "%s%c" PTRHEXFMT, obj->class_pointer->name, 
ATDELIMCHAR, obj);
(gdb) bt
#0  0xb7ed0de2 in tclObjc_objectToName (obj=0x1)
    at /usr/src/debug/swarm-2.2/src/tclobjc/tclObjc.m:54
#1  0xb7ed18e5 in tclObjc_msgSendToClientData (clientData=0x8198b40, 
interp=0x80c4320,
    argc=2, argv=0xbfffe4c4) at 
/usr/src/debug/swarm-2.2/src/tclobjc/tclObjc.m:356
#2  0xb7ed1a5b in tclObjc_msgSendToArgv1 (clientData=0x0, 
interp=0x80c4320, argc=3,
    argv=0xbfffe4c0) at /usr/src/debug/swarm-2.2/src/tclobjc/tclObjc.m:466
#3  0x4f54ce3c in TclInvokeStringCommand () from /usr/lib/libtcl8.4.so
#4  0x4f54e708 in TclEvalObjvInternal () from /usr/lib/libtcl8.4.so
#5  0x4f54fd50 in Tcl_EvalEx () from /usr/lib/libtcl8.4.so
#6  0x4f550870 in Tcl_EvalObjEx () from /usr/lib/libtcl8.4.so
#7  0x4f5a65c6 in Tcl_UplevelObjCmd () from /usr/lib/libtcl8.4.so
#8  0x4f54e708 in TclEvalObjvInternal () from /usr/lib/libtcl8.4.so
#9  0x4f5792ff in TclExprFloatError () from /usr/lib/libtcl8.4.so
#10 0x4f57cbb5 in TclCompEvalObj () from /usr/lib/libtcl8.4.so
#11 0x4f5a6da7 in TclObjInterpProc () from /usr/lib/libtcl8.4.so
#12 0x4f54e708 in TclEvalObjvInternal () from /usr/lib/libtcl8.4.so
#13 0x4f54e564 in TclEvalObjvInternal () from /usr/lib/libtcl8.4.so
#14 0x4f54fd50 in Tcl_EvalEx () from /usr/lib/libtcl8.4.so
#15 0x4f5501c0 in Tcl_Eval () from /usr/lib/libtcl8.4.so
#16 0x4f550b07 in Tcl_GlobalEval () from /usr/lib/libtcl8.4.so
#17 0x4f5f4627 in Tk_BindEvent () from /usr/lib/libtk8.4.so
#18 0x4f5f6b48 in TkBindEventProc () from /usr/lib/libtk8.4.so
#19 0x4f5fe1d8 in Tk_HandleEvent () from /usr/lib/libtk8.4.so
#20 0x4f5fea28 in TkQueueEventForAllChildren () from /usr/lib/libtk8.4.so
#21 0x4f59c923 in Tcl_ServiceEvent () from /usr/lib/libtcl8.4.so
#22 0x4f59cb5f in Tcl_DoOneEvent () from /usr/lib/libtcl8.4.so
#23 0xb7ecb24c in tkobjc_doOneEventSync ()
    at /usr/src/debug/swarm-2.2/src/tkobjc/common.m:157
#24 0xb7e846b5 in -[ControlPanel setStateStopped] (self=0x8113a18, 
_cmd=0x804e4f8)
    at /usr/src/debug/swarm-2.2/src/simtoolsgui/ControlPanel.m:151
#25 0x08049217 in -[ObserverSwarm buildObjects] (self=0x8112a18, 
_cmd=0x804e218)
    at ObserverSwarm.m:71
#26 0x08048eef in main (argc=1, argv=0x1) at main.m:19



--
Paul E. Johnson                       email: address@hidden
Dept. of Political Science            http://lark.cc.ku.edu/~pauljohn
1541 Lilac Lane, Rm 504
University of Kansas                  Office: (785) 864-9086
Lawrence, Kansas 66044-3177           FAX: (785) 864-5700