From: Daniel Colascione <dan.colascione@gmail.com>
To: Jason Rumney <jasonr@gnu.org>
Cc: emacs-devel@gnu.org
Subject: Re: Fixing Windows and DOS command line argument quoting
Date: Mon, 25 Apr 2011 02:22:31 -0700 [thread overview]
Message-ID: <4DB53D57.9030606@gmail.com> (raw)
In-Reply-To: <4DB537BB.1090205@gnu.org>
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On 4/25/11 1:58 AM, Jason Rumney wrote:
> On 25/04/2011 16:49, Daniel Colascione wrote:
>
>> 1. we can have cmdproxy level-two-dequote the supplied command line
>> before giving it to CreateProcess, or
>>
>> 2. we can remove optimization described above and have cmdproxy always
>> run the command interpreter.
>>
>> I favor the second option: cmd starts very quickly, and we don't save
>> much time by bypassing it.
>
> IIRC, this "optimisation" isn't about saving time, but about avoiding
> limitations in cmd.exe where possible.
>
> Another possibility is to make the decision whether to use cmd.exe or
> not based on the presence of "level 2" metacharacters rather than "level
> 1".
I see. Is it just the length limit?
CreateProcess supports 32kb of command line; cmd supports 8kb. If the
extra 24kb is important, then we can do what you suggest:
shell-quote-argument would also to be further modified to only use level
2 metacharacters when strictly necessary. Bear in mind that the new
limit would apply only to *shell* commands explicitly, not to subprocess
invocations in general, which would continue to be handled directly by
the code in w32proc. Besides, I think it's counter-intuitive for a
shell pipeline to stop working merely because it contains more than one
command.
Also, my objection regarding false positives arising from shell
metacharacters embedded in quoted arguments stands: if users do rely on
the successful execution of long, simple shell command lines, these
commands should not break merely because they contain *quoted* shell
metacharacters. We could have cmdproxy distinguish between quoted and
unquoted metacharacters, but at that point, we could just add
level-2-dequoting as well and solve the problem that way.
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next prev parent reply other threads:[~2011-04-25 9:22 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-25 2:09 Fixing Windows and DOS command line argument quoting Daniel Colascione
2011-04-25 6:41 ` Eli Zaretskii
2011-04-25 8:49 ` Daniel Colascione
2011-04-25 8:58 ` Jason Rumney
2011-04-25 9:15 ` Eli Zaretskii
2011-04-25 9:22 ` Daniel Colascione [this message]
2011-04-25 17:56 ` Daniel Colascione
2011-04-25 18:47 ` Eli Zaretskii
2011-04-26 10:44 ` Daniel Colascione
2011-04-26 17:50 ` Eli Zaretskii
2011-04-25 9:35 ` Eli Zaretskii
2011-04-25 18:24 ` Daniel Colascione
2011-04-25 18:48 ` Eli Zaretskii
-- strict thread matches above, loose matches on Subject: below --
2011-04-27 0:58 Ben Key
2011-04-27 1:25 ` Daniel Colascione
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