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

[Philippe W. <phi...@sk...>]

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.

Philippe