Re: [patch] python prompt additions at first prompt.

Matt Rice
2011-08-01T14:08:43Z

On Mon, Aug 1, 2011 at 2:50 AM, Phil Muldoon <pmuldoon@redhat.com> wrote:
> Matt Rice <ratmice@gmail.com> writes:
>
>> little bug with the new python prompt stuff, the prompt_hook doesn't
>> take effect until the second prompt.
>
> Thanks for doing this.  This looks fine to me, apart from one question.
>
> For tests, there are prompt tests in the python.exp file for prompt
> substitutions.  For passing arguments to GDB at start-up, see usage of
> $GDBFLAGS in the testsuite.

I'd tried that, but didn't have much luck,
i'll give it another shot.

>> -     prompt, otherwise just print the prompt.  */
>> -  if (async_command_editing_p)
>> -    {
>> -      int length;
>> -      char *a_prompt;
>> -      char *gdb_prompt = get_prompt (0);
>> -
>> -      /* Tell readline what the prompt to display is and what function
>> -         it will need to call after a whole line is read.  This also
>> -         displays the first prompt.  */
>> -      length = strlen (get_prefix (0))
>> -     + strlen (gdb_prompt) + strlen (get_suffix(0)) + 1;
>> -      a_prompt = (char *) alloca (length);
>> -      strcpy (a_prompt, get_prefix (0));
>> -      strcat (a_prompt, gdb_prompt);
>> -      strcat (a_prompt, get_suffix (0));
>> -      rl_callback_handler_install (a_prompt, input_handler);
>> -    }
>> -  else
>> -    display_gdb_prompt (0);
>> +  display_gdb_prompt (0);
>
>
> display_gdb_prompt removes any handler that is present, and then
> installs a handler.  As this is the first prompt, the above code does
> not (because there could not have been a handler installed).  I think
> attempting to remove a handler that does not exist just results in a
> NOOP, but it is worth checking.  I know very little about readline,
> however.  So my question is: with GDB's copy of readline, is this okay?

Yes, the effect of it seems to turn zero's into zero's.
by my reading and valgrind, it seems fine,

the documentation doesn't specify one way or the other though.

If it is deemed not OK, it needs to be handled in display_gdb_prompt regardless,
because gdb -ex 'set editing off' ' followed by a 'set editing on', at
the gdb prompt, results in 2 calls to _remove before the callback is
installed
from display_gdb_prompt, and change_line_handler.