Re: Using systemtap to validate manual code inspection.

[Siddhesh Poyarekar <siddhesh at redhat dot com>]

On Mon, May 06, 2013 at 03:41:10AM -0400, Carlos O'Donell wrote:
> I recently had to do some manual code inspection
> for a bug which has no reproducer (patch forthcoming).
> 
> The manual inspection found real bugs, but I wanted
> to get more coverage for the failure scenarios.
> 
> I wrote up my experience using systemtap to inject
> failures into glibc:
> http://sourceware.org/glibc/wiki/Testing/WhiteBox
> 
> Looking forward to white box and unit tests ;-)

This is really neat, but the problem here is not limited to systemtap
needing root privileges.  The more subtle problem is the dependency of
these tests on line numbers within code.  The tests will have to be
continually updated as the code gets updated and that may blow out of
proportion as the number of such tests per source file grows.

It would be nicer if it were possible to add annotations within source
that systemtap picks up and set probes at those points.  I'm not
talking about probe points, since they're additional code within the
library and not just source level annotations.  Something like this:

some_func (int *in)
{
  /** SYSPROBE:probe=simulate_crash;file=simulate_crash.stp */
  glob = *in;
}

The problem with doing this is that it could quickly clutter up code
with white box testing annotations.

Siddhesh