Bug #7668: set_trace_func and TracePoint don't handle exception in finish frame

• Status: Closed
• Assignee: ko1 (Koichi Sasada)
• Target version: 2.0.0
• ruby -v: ruby 2.0.0dev (2013-01-07 trunk 38719) [i686-linux]

[ko1 (Koichi Sasada)]

The following code should trap exception correctly (should output ":ok"):

def m
a = 1
b = 2
c = 3
raise
end

trace = TracePoint.new{|tp|
p tp
raise # if tp.event == :c_return # if tp.event == :b_return
}

begin
trace.enable{
m
}
rescue => e
p :ok
end

But it outputs same event hook infinite:

#TracePoint:b_call@/home/ko1/src/ruby/trunk/test.rb:15
#TracePoint:b_return@/home/ko1/src/ruby/trunk/test.rb:15
#<TracePoint:c_return enable'@/home/ko1/src/ruby/trunk/test.rb:15> #<TracePoint:c_return enable'@/home/ko1/src/ruby/trunk/test.rb:15>
#<TracePoint:c_return `enable'@/home/ko1/src/ruby/trunk/test.rb:15>
...

It is a bug.

This patch solve this issue:

Index: vm_trace.c

--- vm_trace.c (revision 38718)
+++ vm_trace.c (working copy)
@@ -316,7 +316,12 @@ rb_threadptr_exec_event_hooks_orig(rb_tr
th->vm->trace_running--;

if (state) {

•   if (pop_p) th->cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(th->cfp);
  

•   if (pop_p) {
  

•   if (VM_FRAME_TYPE_FINISH_P(th->cfp)) {
  

•       th->tag = th->tag->prev;
  

•   }
  

•   th->cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(th->cfp);
  

•   }
    TH_JUMP_TAG(th, state);
  

  }
  th->state = outer_state;

Output:
#TracePoint:b_call@../trunk/test.rb:15
#TracePoint:b_return@../trunk/test.rb:15
:ok

[ko1 (Koichi Sasada)]

• Status changed from Assigned to Closed
• % Done changed from 0 to 100

This issue was solved with changeset r38721.
Koichi, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

---

• vm_trace.c (rb_threadptr_exec_event_hooks_orig): pop tag before
  JUMP_TAG() if frame is `finish' frame.
  Without this patch, there is an inconsistency between control
  frame stack and tags stack.
  [Bug #7668]
• test/ruby/test_settracefunc.rb: add a test for above.