Re: [patchv2] Fix corruption of non-C++ symbols by the demangler

[Mark Wielaard <mjw at redhat dot com>]

On Wed, 2014-01-15 at 14:09 +0100, Jan Kratochvil wrote:
> On Tue, 14 Jan 2014 11:22:41 +0100, Mark Wielaard wrote:
> > On Tue, 2014-01-14 at 10:07 +0100, Jan Kratochvil wrote:
> > > On Tue, 14 Jan 2014 10:00:59 +0100, Mark Wielaard wrote:
> > > > The __GLOBAL__.[ID]_xxx functions are wrappers generated when a module
> > > > xxx contains constructors and destructors of static objects, which will
> > > > call the actual static initialization and destruction functions for all
> > > > globals in the module. Since they are "normal" functions they could
> > > > potentially end up in a backtrace, but I am not sure "demangling" them
> > > > provides any real benefit.
> > > 
> > > In such case I will add it, it should be there.
> > 
> > It probably doesn't hurt, but it also isn't a real/proper mangling
> > scheme. Just an g++ convention. It "demangles" to 'global constructors
> > keyed to xxx'. According to the documentation the only prefix you should
> > check for is _Z:
> > http://mentorembedded.github.io/cxx-abi/abi.html#demangler
> 
> elfutils already implements various non-upstream-standard extensions, like
> .gnu_debugdata for all so I do not find it a relevant argument here.
> So probably another disagreement if you did not agree with it by "doesn't
> hurt", not sure.  It is not in the patch below.

I just meant I wouldn't bother since it seems it is a somewhat fringe
corner case with an internal gcc detail that gets translated/demangled
into something that IMHO isn't that interesting to begin with. I am not
opposed to do more than just simple demangling. But maybe we should add
a helper function for it somewhere in that case since there are various
places where we would use it.

> src/
> 2014-01-13  Jan Kratochvil  <jan.kratochvil@redhat.com>
> 
> 	Fix corruption of non-C++ symbols by the demangler.
> 	* nm.c (show_symbols_sysv, show_symbols_bsd, show_symbols_posix)
> 	(show_symbols): Check for _Z.
> 	* stack.c (print_frames) <USE_DEMANGLE>: Check for _Z.
> 
> tests/
> 2014-01-13  Jan Kratochvil  <jan.kratochvil@redhat.com>
> 
> 	Fix corruption of non-C++ symbols by the demangler.
> 	* Makefile.am (TESTS): Add run-backtrace-demangle.sh.
> 	<!DEMANGLE>: Add ELFUTILS_DISABLE_DEMANGLE export.
> 	(EXTRA_DIST): Add run-backtrace-demangle.sh,
> 	testfile-backtrace-demangle.bz2, testfile-backtrace-demangle.cc,
> 	testfile-backtrace-demangle.core.bz2.
> 	* backtrace-demangle.cc: New file.
> 	* run-backtrace-demangle.sh: New file.
> 	* testfile-backtrace-demangle.bz2: New file.
> 	* testfile-backtrace-demangle.cc: New file.
> 	* testfile-backtrace-demangle.core.bz2: New file.

Looks good.

Thanks,

Mark