From: Derrick Stolee <stolee@gmail.com> To: Junio C Hamano <gitster@pobox.com> Cc: Emily Shaffer <emilyshaffer@google.com>, git@vger.kernel.org Subject: Re: ds/maintenance-part-3 (was Re: What's cooking in git.git (Nov 2020, #02; Mon, 9)) Date: Tue, 17 Nov 2020 16:12:08 -0500 Message-ID: <f8b1a1cc-dcda-0e53-4c46-bb5bfff3fdd4@gmail.com> (raw) In-Reply-To: <xmqqlfez6alb.fsf@gitster.c.googlers.com> On 11/17/2020 2:34 PM, Junio C Hamano wrote: > Derrick Stolee <stolee@gmail.com> writes: >> Thank you for finding and reporting this bug. >> >> Can I at least have a short moment of griping about anyone putting >> regex characters into their directory names? ;) > > Sure, but the blame mostly lies in the one who thought using ERE was > a good idea ('+' is very often used). Yes, the example provided is not nearly as problematic as it could be. I also appreciate finding this in 'next' instead of in a release! >>>> 0. Quote the value_regex properly, instead of blindly using a value >>>> that comes from the environment. ... >> The only place I see where we do that currently is in >> builtin/sparse-checkout.c:escaped_pattern(). Please let me know if >> you know of a more suitable way to escape regex characters. > > If we wanted to go that route, yes, we need to prevent random input > taken from the end user or the environment to be regexes, when they > are literal strings. But I think we should just bite the bullet and > say "git config --unset --literal-value-pattern vari.able va+l+ue", etc. > > This is not a suggestion for the option name, but a suggestion to do > this with a new option and not with a special value-pattern syntax. > > Side note. It is tempting to declare that something like > > git config --unset vari.able "!!$end_user_value" > > is the syntax to use literal/fixed pattern, and that way we > do not have to touch the callchain from builtin/config.c > leading down to git_config_set_multivar_in_file_gently(). > It is backward incompatible change that is unlikely hurt > real people. If a script is feeding "$end_user_value" > without cleansing as the value_regex already, it is already > broken (e.g. if $end_user_value happens to being with '!', > this will unset everything that does not match the regexp) > anyway. And users already know to say '[!]some-pattern' > when they mean the pattern begins with a literal '!' and not > "does not match some-pattern", so reserving '!!' prefix does > not sound too bad. This is very clever. However, I fear it is _too_ clever. >>>>> 1. Teach 'git config' to learn either which regex parser to use >>>>> (including fixed), or at least to learn "value isn't a regex", or >>>>> >>>>> 2. Don't spin a child process in 'git maintenance [un]register' and >>>>> instead just call the config API. >>>> ... >>>> My short-to-mid-term preference is to do #1 to allow a value to be >>>> spelled literally (i.e. remove entry with _this_ value, and add this >>>> one instead), and optionally do #2 as an optimization that is not >>>> essential. I do not offhand know how you can make #2 alone fly >>>> without doing some form of #1, as I think the same value_regex that >>>> ought to be ERE to specify entries to be replaced needs to be used >>>> under the cover even if you use "config API" anyway. >>> >>> Ah, right you are - I had figured the regex parsing was done earlier, >>> but it indeed looks to happen in >>> config.c:git_config_set_multivar_in_file_gently. Thanks. >> >> So the "real fix" is to allow a command-line option to 'git config' >> that makes the "value_regex" parameter a literal string? Of course, >> this would either require wiring an option down into >> git_config_set_multivar_in_file_gently() to treat the string as a >> literal _or_ to escape the input string in builtin/config.c. >> >> Am I understanding the intended plan here? > > Yup, if people cannot poke holes with the wishful thinking that the > breaking of backward compatibility by using the "!!" prefix would > not cause practical issues, then I am also fine with that, but > inventing a flags word with a VALUE_PATTERN_FIXED bit in it and > updating the callchain to pass it down from the command line option > parser would be much less risky, I would think. I will get started on this fix as a series on top of part-3. Thanks, -Stolee
next prev parent reply other threads:[~2020-11-17 21:13 UTC|newest] Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-11-09 23:42 What's cooking in git.git (Nov 2020, #02; Mon, 9) Junio C Hamano 2020-11-10 0:44 ` Elijah Newren 2020-11-10 1:03 ` Jeff King 2020-11-10 13:31 ` ds/maintenance-part-3 (was Re: What's cooking in git.git (Nov 2020, #02; Mon, 9)) Derrick Stolee 2020-11-16 23:56 ` Emily Shaffer 2020-11-17 0:40 ` Junio C Hamano 2020-11-17 1:07 ` Emily Shaffer 2020-11-17 13:56 ` Derrick Stolee 2020-11-17 19:18 ` Emily Shaffer 2020-11-17 19:34 ` Junio C Hamano 2020-11-17 21:12 ` Derrick Stolee [this message] 2020-11-19 2:16 ` Junio C Hamano 2020-11-19 13:25 ` Derrick Stolee 2020-11-19 15:53 ` Derrick Stolee 2020-11-19 18:06 ` Junio C Hamano
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