Re: [PATCH] gdb output pipelining to shell

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

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.
>>
>