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From: Patrick Steinhardt <ps@pks.im>
To: Junio C Hamano <gitster@pobox.com>
Cc: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>, git@vger.kernel.org
Subject: Re: [PATCH 2/2] config: allow specifying config entries via envvar pairs
Date: Tue, 17 Nov 2020 07:28:50 +0100
Message-ID: <X7NtovvfE7IjWzie@ncase> (raw)
In-Reply-To: <xmqqy2j1851k.fsf@gitster.c.googlers.com>

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On Mon, Nov 16, 2020 at 11:39:35AM -0800, Junio C Hamano wrote:
> Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:
> 
> > On Fri, Nov 13 2020, Patrick Steinhardt wrote:
> >
> >> While not document, it is currently possible to specify config entries
> >
> > "While not documented..."
> >
> >> +		strbuf_addf(&envvar, "GIT_CONFIG_KEY_%d", i);
> >> +		if ((key = getenv(envvar.buf)) == NULL)
> >> +			break;
> >
> > The convention in git.git is to avoid explicit NULL checks. So maybe
> > something like this, which also avoids the assignment inside an "if"
> >
> >     key = getenv(envvar.buf);
> >     if (!key)
> >         break;
> 
> All good suggestions, but...
> 
> "While not documented" yes, for sure, but we do not document it for
> a good reason---it is a pure implementation detail between Git
> process that runs another one as its internal implementation detail.

Agreed

> I especially do not think we want to read from unbounded number of
> GIT_CONFIG_KEY_<N> variables like this patch does.  How would a
> script cleanse its environment to protect itself from stray such
> environment variable pair?  Count up from 1 to forever?  Run "env"
> and grep for "GIT_CONFIG_KEY_[0-9]*=" (the answer is No.  What if
> some environment variables have newline in its values?)

You only have to unset `GIT_CONFIG_KEY_1` as the parser will stop
iterating on the first missing key. More generally, if you set `n` keys,
it's sufficient to unset key `n+1`.

Patrick

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  parent reply	other threads:[~2020-11-17  6:30 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-13 12:16 [PATCH 0/2] " Patrick Steinhardt
2020-11-13 12:16 ` [PATCH 1/2] config: extract function to parse config pairs Patrick Steinhardt
2020-11-13 12:16 ` [PATCH 2/2] config: allow specifying config entries via envvar pairs Patrick Steinhardt
2020-11-13 13:04   ` Ævar Arnfjörð Bjarmason
2020-11-16 19:39     ` Junio C Hamano
2020-11-17  2:34       ` Jeff King
2020-11-17  6:37         ` Patrick Steinhardt
2020-11-17  7:01           ` Jeff King
2020-11-17 14:22         ` Ævar Arnfjörð Bjarmason
2020-11-17 23:57           ` Jeff King
2020-11-18 13:44             ` Ævar Arnfjörð Bjarmason
2020-11-18  0:50         ` brian m. carlson
2020-11-18  1:59           ` Jeff King
2020-11-18  2:25             ` brian m. carlson
2020-11-18  7:04               ` Patrick Steinhardt
2020-11-19  2:11                 ` brian m. carlson
2020-11-19  6:37                   ` Patrick Steinhardt
2020-11-18  5:44           ` Junio C Hamano
2020-11-17  6:28       ` Patrick Steinhardt [this message]
2020-11-17  7:06         ` Junio C Hamano
2020-11-18 13:49           ` Ævar Arnfjörð Bjarmason
2020-11-18 13:56             ` Patrick Steinhardt
2020-11-18 16:01             ` Junio C Hamano
2020-11-17 14:03       ` Ævar Arnfjörð Bjarmason
2020-11-13 16:37   ` Philip Oakley
2020-11-17  6:40     ` Patrick Steinhardt
2020-11-13 13:11 ` [PATCH 0/2] " Ævar Arnfjörð Bjarmason

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