[Bug translator/13516] New: more robust handling of ^C

["fche at redhat dot com" <sourceware-bugzilla at sourceware dot org>]

http://sourceware.org/bugzilla/show_bug.cgi?id=13516

             Bug #: 13516
           Summary: more robust handling of ^C
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: translator
        AssignedTo: systemtap@sourceware.org
        ReportedBy: fche@redhat.com
    Classification: Unclassified


In many places in the translator, we check for pending_interrupts,
and simply return or quit nested loops early, being assured that
eventually we'll bubble back up to the top level and get a proper
rc=EXIT_FAILURE.

This is not quite good enough.  In some cases, an unfortunately
timed interrupt can result in an exit from a routine, with
expected post-conditions not met.  For example, elaborate.cxx
includes:

1665    
1666          // Add created probe
1667          p->body = b;
1668          derive_probes (s, p, dps);
1669          for (unsigned i = 0; i < dps.size(); i++)
1670        {
1671          derived_probe* dp = dps[i];
1672          s.probes.push_back (dp);
1673          dp->join_group (s);
1674        }
1675          // Repopulate symbol and type info
1676          symresolution_info sym (s);
1677          sym.current_function = 0;
1678          sym.current_probe = dps[0];
1679          dps[0]->body->visit (& sym);

If the interrupt was taken during the derive_probes() call, it
will have left the dps[] array empty, but will simply return.
On line 1678, dps[0] will be dereferenced, bang, segv.

The code could, I suppose, protect itself with more explicit
checks, but this seems to be more labour than necessary.  Let's
instead explore replacing all
       if (pending_interrupts) break;
or     if (pending_interrupts) return;
with   if (pending_interrupts) throw runtime_error("interrupt received");
and catch that in main() someplace.  This should make it unnecessary
to check & test in quite so many places.

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