Re: [Valgrind-developers] Issue gdb commands for each valgrind hit?

[Dan S. <dan...@gm...>]

On 11 March 2013 22:38, Philippe Waroquiers
<phi...@sk...> wrote:
> On Mon, 2013-03-11 at 17:52 +0100, Dan Shelton wrote:
>> Has anyone found a way that for each valgrind hit a gdb command is issued?
>> I need a way to print a certain amount of commands per valgrind hit on
>> a live application (i.e. variables of interest).
> I guess that by valgrind hit, you mean an error reported by valgrind.
>
> One way with which you can do that is to have a gdb connected
> to Valgrind (use --vgdb-error=0 and follow the on-screen instructions).
>
> You can then put commands in the GDB "stop hook", using
>
> define hook-stop
>  print this_var
>  print other_var
>  ... any command accepted by gdb
>  ... including the Valgrind gdbserver monitor commands
> end
>
> (the commands of a hook-stop are run each time your program stops).
> There is one weakness with the GDB hook-stop: you cannot use
> a continue command in the list of commands.
> So, the bypass is to have a file containing a *lot* of
> continue command.
> You then source this file in GDB.
>
> So, in summary, at GDB side, you do:
>
> gdb your_program
> define hook-stop
>  ...
>  all your needed commands
>  ...
> end
> target remote | ... (as told by valgrind)
> set height 0        (this is needed to avoid having gdb pausing for each page of output
> source a_file_containing_a_lot_of_continue_command
>
> I guess it will be possible to do the above also with --db-attach=yes
> and giving GDB arguments to source a file of commands. This will however be very slow
> as this will imply two forks and one GDB execution for each error.

Ouch.

Do you have a simple beginner-class example which just issues the
command 'where' (I know, redundant!) for each valgrind hit? I spend
the last half hour with your suggestion and think that this is well
beyond my current abilities without a small example usage.

Dan