[PATCH] gdb output pipelining to shell

[Abhijit Halder]

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.
>>>>>
>>>>
>>>
>>
>
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