Struggling with using gdb to debug C++ code w/ Ada library - c++

Question

I can't get into the specifics, for a variety of reasons, but here's the essential architecture of what I'm working with
I have a C++ framework, which uses C++ object files built by me to execute a dynamic simulation.
The C++ libraries call, among other things, a shared (.so) library, written in Ada.
As best as I can tell, the Ada library (which is a large collection of nontrivial code) is generating exceptions on fringe cases, but I'm having trouble isolating the function that is generating the exception.
Here's what I'm using:
CentOS 4.8 (Final)
gcc 3.4.6 (w/ gnat)
gdb 6.3.0.0-1.162.el4rh
This is the error I get under normal execution:
terminate called without an active exception
raised PROGRAM_ERROR : unhandled signal
I can get gdb to catch the exception as soon as it returns to the C++, but I can't get it to catch inside the Ada code. I've made sure to compile everything with -g, but that doesn't seem to help the problem.
When I try to catch/break on the signal/exception in gdb (which politely tells me Catch of signal not yet implemented), I get this:
[Thread debugging using libthread_db enabled]
[New thread -1208371520 (LWP 14568)]
terminate called without an active exception
Program received signal SIGABRT, Aborted.
[Switching to thread -1208371520 (LWP 14568)]
0x001327a2 in _dl_sysinfo_int80 () from /lib/ld-linux.so.2
I believe the terminate called [...] line is from the framework. When I try to capture that break, then run a backtrace (bt), I get something like this:
#0 0x001327a2 in gdb makes me want to flip tables.
#1 0x00661825 in raise () from /lib/tls/libc.so.6
#2 0x00663289 in abort () from /lib/tls/libc.so.6
#3 0x0061123e in __gnu_cxx: __verbose_terminate_handler () from /usr/lib/libstdc++.so.6
#4 0x0060eed1 in __xac_call_unexpected () from /usr/lib/libstdc++.so.6
#5 0x0060ef06 in std::terminate () from /usr/lib/libstdc++.so.6
#6 0x0060f0a3 in __xax_rethrow () from /usr/lib/libstdc++.so.6
#7 0x001fe526 in cpputil::ExceptionBase::Rethrow (scope=#0xbfe67470) at ExceptionBase.cpp:140
At that point, it's into the framework code.
I've read several guides and tutorials and man pages online, but I'm at a bit of a loss. I'm hoping that someone here can help get me pointed in the right direction.

Answer 1

It sounds like you're able to compile the Ada source code. Assuming that's the case, in the subprogram(s) that are being called through whose execution the exceptions are being raised, add an exception handler at the end that dumps the exception information:
when E : others =>
Ada.Text_IO.Put_Line(Ada.Exceptions.Exception_Information(E));
raise;
You'll also need to add a 'with' of Ada.Exceptions to the package. And Ada.Text_IO if that isn't already present.
I'm not sure exactly what you'll get out from that version of GNAT, but it's probably the invocation addresses which you can then decode using addr2line.

Answer 2

Could you start the C++ framework from an Ada main? If so, and you can propagate the exceptions through the C++ framework to the Ada main, its last chance handler ought to give you a pretty good report with exception, source file and line where it occurred, and a stack dump for addr2line. My experience with these is that the debugger usually isn't needed after that.
I could be off beam here because I haven't used a Gnat anywhere near as old as yours...