Re: [PATCH] gdb output pipelining to shell

[Abhijit Halder <abhijit.k.halder@gmail.com>]

Hi,

I am pretty new in this community. Just curious to know whether I will
get any notification if my patch get accepted or rejected.

Thanks,
Abhijit Halder

>
> On Tue, Jul 19, 2011 at 2:20 PM, Abhijit Halder <abhijit.k.halder@gmail.com> wrote:
>>
>> I have made a correction to handle possibly all the cases. Hope this
>> is my last correction. Please bear with me.
>>
>> I have changed the syntax of using shell command. Here it is:
>> (gdb) gdb command | `{ shell command }`
>>
>> The shell command to be executed has to be encapsulated in `{}` and
>> not only {} as gdb command itself can have braces, no spaces between
>> backtick and braces are allowed. Hope this constraint will be
>> acceptable from usability point of view.
>>
>> Regards,
>> Abhijit Halder
>>
>> On Tue, Jul 19, 2011 at 11:03 AM, Abhijit Halder
>> <abhijit.k.halder@gmail.com> wrote:
>> > Further concern. The last submitted patch does not work in following scenario:
>> > (gdb) p argc | {int} &argc | {vim -}
>> >
>> > I think now I should take a pause and refrain myself of doing patch
>> > submission in this thread for some time!
>> >
>> > Regards,
>> > Abhijit Halder
>> >
>> > On Tue, Jul 19, 2011 at 12:31 AM, Abhijit Halder
>> > <abhijit.k.halder@gmail.com> wrote:
>> >> Since I was overwriting the braces by space character, this could
>> >> essentially change a valid gdb command having braces after pipe.
>> >> Here is the example:
>> >> (gdb) p argc | {int} &argc
>> >>
>> >> I have modified the patch to defer the any overwrite (and essentially
>> >> the modification) of actual input string for very last moment when the
>> >> a sub-string of a given input in gdb prompt is qualified to be in a
>> >> valid format of shell command.
>> >>
>> >> I am re-submitting the patch for review and comments with the
>> >> necessary corrections in place. Please do comment on the changes.
>> >>
>> >>  top.c     |   77 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
>> >>  ui-file.c |   15 ++++++++++++
>> >>  ui-file.h |    3 ++
>> >>  3 files changed, 94 insertions(+), 1 deletion(-)
>> >>
>> >> Regards,
>> >> Abhijit Halder
>> >>
>> >>
>> >> On Mon, Jul 18, 2011 at 11:31 PM, Abhijit Halder
>> >> <abhijit.k.halder@gmail.com> wrote:
>> >>> Please don't consider this patch. This has a conflict with following
>> >>> syntax of of
>> >>> (gdb) p var | {type} address
>> >>>
>> >>> On Sat, Jul 16, 2011 at 11:35 PM, Abhijit Halder
>> >>> <abhijit.k.halder@gmail.com> wrote:
>> >>>> A small correction. Re-submitting the patch. The earlier patch was not
>> >>>> able to handle below situation:
>> >>>> (gdb) p '|' | { less }
>> >>>>
>> >>>> On Sat, Jul 16, 2011 at 3:38 PM, Abhijit Halder
>> >>>> <abhijit.k.halder@gmail.com> wrote:
>> >>>>> On Sat, Jul 16, 2011 at 3:17 PM, Eli Zaretskii <eliz@gnu.org> wrote:
>> >>>>>>> Date: Sat, 16 Jul 2011 14:12:35 +0530
>> >>>>>>> From: Abhijit Halder <abhijit.k.halder@gmail.com>
>> >>>>>>>
>> >>>>>>> I have implemented a feature which will allow one to pass the output
>> >>>>>>> of any gdb command to the shell for further processing.
>> >>>>>>
>> >>>>>> Thanks.
>> >>>>>>
>> >>>>>> If this is accepted, we will need a corresponding addition to the
>> >>>>>> manual.
>> >>>>>>
>> >>>>>>> +      for (cpos = spos; (cpos = memchr (cpos, '"', (sh_cmd-cpos))) != NULL; cpos++)
>> >>>>>>> +        quote_cnt++;
>> >>>>>>> +      spos = (sh_cmd + 1);
>> >>>>>>> +      if ((quote_cnt % 2) == 0 || (sh_cmd = strchr (spos, '|')) == NULL)
>> >>>>>>> +        break;
>> >>>>>>
>> >>>>>> I'm not sure I understand this (comments would be helpful).  Are you
>> >>>>>> assuming that quote characters `"' in shell commands cannot be
>> >>>>>> escaped, e.g. with a backslash?  And what about quoting with a single
>> >>>>>> quote character ("'")?
>> >>>>>>
>> >>>>> Any pipe ('|' character), not within double quote will be considered
>> >>>>> as either a bitwise-OR operator or a pipe between gdb and shell.
>> >>>>> String after pipe (not within double quote) will be considered as
>> >>>>> shell command if (and only if) it is encapsulated within opening and
>> >>>>> closing braces ('{' and '}') . The shell command can surely contain
>> >>>>> double quote, even braces. There is no validation done for shell
>> >>>>> command.
>> >>>>>
>> >>>>>>> +    if (*cpos != '{')
>> >>>>>>> +      return NULL;
>> >>>>>>> +
>> >>>>>>> +    *cpos = ' ';
>> >>>>>>> +
>> >>>>>>> +    cpos = epos;
>> >>>>>>> +    while (isspace(*cpos))
>> >>>>>>> +      cpos--;
>> >>>>>>> +
>> >>>>>>> +    if (*cpos != '}')
>> >>>>>>> +      return NULL;
>> >>>>>>
>> >>>>>> What is this magic about {...} that you are removing?  Again, comments
>> >>>>>> could help.
>> >>>>>>
>> >>>>> Here I am removing the braces from the shell command. An example will
>> >>>>> help in understanding this:
>> >>>>> (gdb) thread apply all bt | { grep "foo" }
>> >>>>> This will be a valid command. { grep "foo" } will be considered as
>> >>>>> shell command and we need to erase the braces part of it to make it a
>> >>>>> valid shell command.
>> >>>>>>> +
>> >>>>>>> +    *cpos = ' ';
>> >>>>>>> +    }
>> >>>>>>> +
>> >>>>>>> +  if (sh_cmd)
>> >>>>>>> +    *sh_cmd++ = '\0';
>> >>>>>>> +
>> >>>>>>> +  return sh_cmd;
>> >>>>>>
>> >>>>>> This butchers the string passed to execute_command.  Are you sure all
>> >>>>>> the callers of execute_command can safely deal with that?  What if the
>> >>>>>> string is a constant string, for example?
>> >>>>>>
>> >>>>> The new code path will be executed only when one will enter a command
>> >>>>> containing pipeline between gdb and shell. In that case the string
>> >>>>> passed to execute_command must not be a constant string (since it is
>> >>>>> user input from gdb prompt). Hence we are safe.
>> >>>>>
>> >>>>
>> >>>
>> >>
>> >
>