[patch] Don't crash on stepping "bad frame"

[Mark Wielaard <mark@klomp.org>]

Hi,

While working on #5259 I noticed that the stepping engine crashes and
burns on x86_64 when a bad frame without unwind info is being stepped
into. This patch handles that case gracefully. And you can now safely
next through simple examples programs like funit-hello as we did in the
last demo - you can still drop into the wrong frame till #5259 is fixed
though.

frysk-core/frysk/stepping/ChangeLog
2008-02-29  Mark Wielaard  <mwielaard@redhat.com>

    * StepOverTestState.java (handleUpdate): Don't crash when there is
    a bad outer frame.

Committed,

Mark

--- a/frysk-core/frysk/stepping/StepOverTestState.java
+++ b/frysk-core/frysk/stepping/StepOverTestState.java
@@ -86,6 +86,16 @@ public class StepOverTestState extends State {
                 * it exits - success!
                 */
                Frame frame = newFrame.getOuter();
+               if (frame == null)
+                 {
+                   // But urgh... Where did our outer frame go...
+                   // We need to just try to keep stepping till we are
+                   // able to get a solid frame again.
+                   tse.getSteppingEngine().continueForStepping(this.task,
+                                                               true);
+                   return this;
+                 }
+
                tse.getSteppingEngine().setBreakpoint(this.task,
                        frame.getAddress());
                return new StepOverState(this.task);