Re: [PATCH] sequencer.c: terminate the last line of author-script properly

From: Junio C Hamano <gitster@pobox.com>
Date: Jul 12, 2018, 20:13 UTC
Message-ID: <xmqqa7qww6uk.fsf@gitster-ct.c.googlers.com>
In-Reply-To: <86a7qwpt9g.knu@iDaemons.org>

"Akinori MUSHA" <knu@iDaemons.org> writes:

Show 15 quoted lines

> diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
> index 352a52e59..345b103eb 100755
> --- a/t/t3404-rebase-interactive.sh
> +++ b/t/t3404-rebase-interactive.sh
> @@ -75,6 +75,19 @@ test_expect_success 'rebase --keep-empty' '
>  	test_line_count = 6 actual
>  '
>  
> +test_expect_success 'rebase -i writes out .git/rebase-merge/author-script in "edit" that sh(1) can parse' '
> +	test_when_finished "git rebase --abort ||:" &&
> +	git checkout master &&
> +	set_fake_editor &&
> +	FAKE_LINES="edit 1" git rebase -i HEAD^ &&
> +	test -f .git/rebase-merge/author-script &&
> +	unset GIT_AUTHOR_NAME GIT_AUTHOR_EMAIL GIT_AUTHOR_DATE &&

Is this "unset" safe? Some POSIX compliant shells barf if you unset a variable that is not set, so the answer to my question is yes only if we know these three variables are always set.

> +	eval "$(cat .git/rebase-merge/author-script)" &&
> +	test "$(git show --quiet --pretty=format:%an)" = "$GIT_AUTHOR_NAME" &&
> +	test "$(git show --quiet --pretty=format:%ae)" = "$GIT_AUTHOR_EMAIL" &&
> +	test "$(git show --quiet --date=raw --pretty=format:@%ad)" = "$GIT_AUTHOR_DATE"

Oh, actually it is even worse than that. What if author-script is bogus, like in the version before your patch fixes the code? We do not restore the AUTHOR_NAME/EMAIL/DATE after this test_expect_success fails. How does that, i.e. missing some variable, affect execution of later steps in this same test script?

I _think_ the right and safe way to fix taht is to do something like this:

	test -f .git/rebase-merge/author-script &&
	(
		safe_unset GIT_AUTHOR_NAME GIT_AUTHOR_EMAIL ... &&
		eval "$(cat .git/rebase-merge/author-script)" &&
		test ... &&
		test ... &&
		test ...
	)

That way, we won't have to worry about GIT_AUTHOR_* variables getting modified and affecting the tests that come later in the script.

Show 7 quoted lines

> +'
> +
>  test_expect_success 'rebase -i with the exec command' '
>  	git checkout master &&
>  	(
> -- 
> 2.18.0