[RFC] print stack trace after each syscall

[Luca Clementi]

On Thu, Jun 27, 2013 at 10:41 PM, Mike Frysinger <vapier at gentoo.org> wrote:
> On Tuesday 25 June 2013 02:41:21 Luca Clementi wrote:
>> On Mon, Jun 24, 2013 at 8:42 AM, Mike Frysinger <vapier at gentoo.org> wrote:
>> > On Monday 24 June 2013 03:18:58 Luca Clementi wrote:
>> >> +     AC_CHECK_LIB([unwind], [backtrace],[],[
>> >> +             AC_MSG_FAILURE([Unable to find libunwind])
>> >> +             ])
>> >> +        AC_CHECK_LIB([unwind-$arch], [_U${arch}_create_addr_space],[],
>> >> [ +                           AC_MSG_FAILURE([Unable to find
>> >> libunwind-$arch]) +     ])
>> >
>> > is the $arch stuff really necessary ?  isn't linking to -lunwind
>> > sufficient ?
>>
>> Actually what I do need is the libunwind-ptrace, but the problem is
>> that -lunwind-ptrace depends on -lunwind-$arch (basically they put all
>> the arch dependent code in there) so if you test libunwind-ptrace you
>> need to have the -lunwind-$arch in your linker flags if not the test
>> fails.
>
> i think what you want is to use PKG_CHECK_MODULES and look up libunwind-
> generic instead.  libunwind takes care of linking that to the right arch.
> lrwxrwxrwx 1 root root    19 Nov  2  2012 /usr/lib64/libunwind-generic.so ->
>         libunwind-x86_64.so

Hey Mike,
Thanks for pointing it out, using libunwind-generic is a cleaner test.

Regarding PKG_CHECKS_MODULE I am not too convinced (although I must
say that I am not an expert of autoconf).
For example Ubuntu 12.04 the system libunwind7 and libunwind7-dev do
not include the .pc files needed by PKG_CHECKS_MODULE.

I have been looking around and I found that ltrace uses libunwind for
the same purpose and it uses AC_CHECK_LIB to do its checks:
http://anonscm.debian.org/gitweb/?p=collab-maint/ltrace.git;a=blob;f=configure.ac;h=16c7a615962d23c7fd733e7d2b67145d75e0a9de;hb=HEAD#l132

I will post shortly a solution based on ltrace autoconf script.

Please let me know if you have issue with that.

Luca