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Re: question on gdb


On Sun, Jan 24, 2010 at 07:42:32AM +0000, Marco Atzeri wrote:
>Hi,
>recently, after some change in the source, the octave 
>development branch started to SIGSEV on exit. 
>The strange issue is that this happen only
>for cygwin and not on the other platforms.
>I have not yet found a solution, only a possible workaround
>removing some specific C++ "free" actions, so to fallback to
>libstdc++ cleaning activity.
>
>My question however is about the gdb backtrace, is the 
>"Cannot access memory at address 0x1a" at # 9 normal ?
>Unfortunately I am not really an expert on gdb:

It happens sometimes but it does seem like something is screwed up
somewhere sinc eyou have _sigfe in the stack trace with functions from
other DLLs below it.  That doesn't seem right.  It looks like the
stack is damaged.

Can you set a breakpoint at cygwin_exit and (eventually) step into
atexit to see where the problem is occurring?  It sounds like a
destructor is having problems.

cgf

>Here the gdb session
>----------------------------------------------
>octave:1> exit
>
>
>Program received signal SIGSEGV, Segmentation fault.
>0x20f414d0 in ?? ()
>(gdb) backtrace
>#0  0x20f414d0 in ?? ()
>#1  0x6112e117 in __call_exitprocs () from /usr/bin/cygwin1.dll
>#2  0x6110b6da in exit () from /usr/bin/cygwin1.dll
>#3  0x61004e5a in cygwin_exit () from /usr/bin/cygwin1.dll
>#4  0x610b6838 in _sigfe () from /usr/bin/cygwin1.dll
>#5  0x0022bba8 in ?? ()
>#6  0x6c4e401e in cygstdc++-6!_ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc ()
>   from /usr/bin/cygstdc++-6.dll
>#7  0x6e5c8c65 in _fu4930___ZSt4cerr () at ../../octave_clone/src/toplev.cc:625
>#8  0x6e58fd9c in _fu4441___ZN8file_ops14static_members8instanceE ()
>    at ../../octave_clone/src/octave.cc:876
>#9  0x00401167 in main (argc=Cannot access memory at address 0x1a
>) at ../../octave_clone/src/main.c:35
>(gdb)
>-------------------------------------------

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