Re: GDB Python API: stop/continue after breakpoint

Kevin Pouget
2011-03-11T17:52:50Z

thanks for your answer, the patch seems to feature what I was looking for.

I'm a bit surprised that the stop/continue decision can't be done in
this breakpoint_stop handler, but I guess that was too complicated ?

> On Fri, Mar 11, 2011 at 5:25 PM, Phil Muldoon <pmuldoon@redhat.com> wrote:
>>
>> Kevin Pouget <kevin.pouget@gmail.com> writes:
>>
>> > Hello,
>> >
>> > I've tried the GDB python interface today, which seems quite
>> > efficient, but there is one important thing I couldn't figure out by
>> > myself:
>> >
>> > how to restart GDB when a[n internal] breakpoint is hit ?
>> > from the testsuite I've got this code:
>>
>>
>> You almost can. One part is pending:
>>
>> http://sourceware.org/ml/gdb-patches/2011-03/msg00656.html
>>
>> The implementation of the "stop" API.  The idea behind this is that if a
>> breakpoint is hit, that is tracked from Python and has an implemented
>> stop method, that method would be called.  You can do what you like in
>> that method.  If you want the inferior process to continue, return True
>> otherwise return False (and print out/do whatever else you need to do in
>> Python).
>>
>> Because internal breakpoints are not tracked by default in the Python
>> Breakpoint API, you would have to create your breakpoint by
>> instantiating a gdb.Breakpoint class, and pass the keyword
>> internal=True.
>>
>> So, long story short soon.  OTOH I'm not sure if there is a unhacky way
>> of doing it now.  You could use a convenience function, but that patch
>> is replacing that hacky way.
>>
>> Cheers
>>
>> Phil
>> >
>> > def breakpoint_stop_handler (event):
>> >     if (isinstance (event, gdb.StopEvent)):
>> >         print "event type: stop"
>> >     if (isinstance (event, gdb.BreakpointEvent)):
>> >         print "stop reason: breakpoint"
>> >         print "breakpoint number: %s" % (event.breakpoint.number)
>> >         if ( event.inferior_thread is not None) :
>> >             print "thread num: %s" % (event.inferior_thread.num);
>> >         else:
>> >             print "all threads stopped"
>> >
>> > gdb.events.stop.connect (breakpoint_stop_handler)
>> >
>> >
>> > which where I get the notification of the stop, but I'd to be able to
>> > tell GDB something like
>> >
>> > enum bpstat_what_main_action {
>> >     /* Remove breakpoints, single step once, then put them back in and
>> >        go back to what we were doing.  It's possible that this should
>> >        be removed from the main_action and put into a separate field,
>> >        to more cleanly handle  BPSTAT_WHAT_CLEAR_LONGJMP_RESUME_SINGLE.  */
>> >     BPSTAT_WHAT_SINGLE,
>> >     /* Stop silently.  */
>> >     BPSTAT_WHAT_STOP_SILENT,
>> >
>> >     /* Stop and print.  */
>> >     BPSTAT_WHAT_STOP_NOISY,
>> > ...
>> > }
>> >
>> > to continue silently, stop silently or print the breakpoint hit.
>> >
>> > is it possible at this stage ?
>> >
>> > Thanks,
>> >
>> > Kevin
>