Re: [PATCH v4 2/2] apply: reload .gitattributes after patching it

From: Phillip Wood <phillip.wood123@gmail.com>
To: "brian m. carlson" <sandals@crustytoothpaste.net>, git@vger.kernel.org
Cc: "SZEDER Gábor" <szeder.dev@gmail.com>,
	"Taylor Blau" <me@ttaylorr.com>, "Jeff King" <peff@peff.net>,
	"Junio C Hamano" <gitster@pobox.com>
Subject: Re: [PATCH v4 2/2] apply: reload .gitattributes after patching it
Date: Mon, 19 Aug 2019 10:41:42 +0100	[thread overview]
Message-ID: <9b940950-666a-0c4c-58c0-1e61ac9e654c@gmail.com> (raw)
In-Reply-To: <20190818184403.861907-3-sandals@crustytoothpaste.net>

Hi Brian

On 18/08/2019 19:44, brian m. carlson wrote:
> When applying multiple patches with git am, or when rebasing using the
> am backend, it's possible that one of our patches has updated a
> gitattributes file. Currently, we cache this information, so if a
> file in a subsequent patch has attributes applied, the file will be
> written out with the attributes in place as of the time we started the
> rebase or am operation, not with the attributes applied by the previous
> patch. This problem does not occur when using the -m or -i flags to
> rebase.

Do you know why -m and -i aren't affected?

> To ensure we write the correct data into the working tree, expire the
> cache after each patch that touches a path ending in ".gitattributes".
> 
> Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
> ---
>   apply.c           |  7 +++++++
>   convert.c         |  9 ++++++++-
>   convert.h         |  6 ++++++
>   t/t3400-rebase.sh | 36 ++++++++++++++++++++++++++++++++++++
>   4 files changed, 57 insertions(+), 1 deletion(-)
> 
> diff --git a/apply.c b/apply.c
> index cde95369bb..d57bc635e4 100644
> --- a/apply.c
> +++ b/apply.c
> @@ -4643,6 +4643,7 @@ static int apply_patch(struct apply_state *state,
>   	struct patch *list = NULL, **listp = &list;
>   	int skipped_patch = 0;
>   	int res = 0;
> +	int flush_attributes = 0;
>   
>   	state->patch_input_file = filename;
>   	if (read_patch_file(&buf, fd) < 0)
> @@ -4670,6 +4671,10 @@ static int apply_patch(struct apply_state *state,
>   			patch_stats(state, patch);
>   			*listp = patch;
>   			listp = &patch->next;
> +
> +			if ((patch->new_name && ends_with_path_components(patch->new_name, GITATTRIBUTES_FILE)) ||
> +			    (patch->old_name && ends_with_path_components(patch->old_name, GITATTRIBUTES_FILE)))
> +				flush_attributes = 1;

style nit - these lines are very long compared to 80 characters

>   		}
>   		else {
>   			if (state->apply_verbosity > verbosity_normal)
> @@ -4746,6 +4751,8 @@ static int apply_patch(struct apply_state *state,
>   	if (state->summary && state->apply_verbosity > verbosity_silent)
>   		summary_patch_list(list);
>   
> +	if (flush_attributes)
> +		reset_parsed_attributes();
>   end:
>   	free_patch_list(list);
>   	strbuf_release(&buf);
> diff --git a/convert.c b/convert.c
> index 94ff837649..030e9b81b9 100644
> --- a/convert.c
> +++ b/convert.c
> @@ -1293,10 +1293,11 @@ struct conv_attrs {
>   	const char *working_tree_encoding; /* Supported encoding or default encoding if NULL */
>   };
>   
> +static struct attr_check *check;

I was concerned about the impact adding a file global if we ever want to 
multi-thread this for submodules, but looking through the file there are 
a couple of others already so this isn't creating a new problem.

Best Wishes

Phillip

> +
>   static void convert_attrs(const struct index_state *istate,
>   			  struct conv_attrs *ca, const char *path)
>   {
> -	static struct attr_check *check;
>   	struct attr_check_item *ccheck = NULL;
>   
>   	if (!check) {
> @@ -1339,6 +1340,12 @@ static void convert_attrs(const struct index_state *istate,
>   		ca->crlf_action = CRLF_AUTO_INPUT;
>   }
>   
> +void reset_parsed_attributes(void)
> +{
> +	attr_check_free(check);
> +	check = NULL;
> +}
> +
>   int would_convert_to_git_filter_fd(const struct index_state *istate, const char *path)
>   {
>   	struct conv_attrs ca;
> diff --git a/convert.h b/convert.h
> index 831559f10d..3710969d43 100644
> --- a/convert.h
> +++ b/convert.h
> @@ -94,6 +94,12 @@ void convert_to_git_filter_fd(const struct index_state *istate,
>   int would_convert_to_git_filter_fd(const struct index_state *istate,
>   				   const char *path);
>   
> +/*
> + * Reset the internal list of attributes used by convert_to_git and
> + * convert_to_working_tree.
> + */
> +void reset_parsed_attributes(void);
> +
>   /*****************************************************************
>    *
>    * Streaming conversion support
> diff --git a/t/t3400-rebase.sh b/t/t3400-rebase.sh
> index 80b23fd326..23469cc789 100755
> --- a/t/t3400-rebase.sh
> +++ b/t/t3400-rebase.sh
> @@ -301,6 +301,42 @@ test_expect_success 'rebase --am and --show-current-patch' '
>   	)
>   '
>   
> +test_expect_success 'rebase --am and .gitattributes' '
> +	test_create_repo attributes &&
> +	(
> +		cd attributes &&
> +		test_commit init &&
> +		git config filter.test.clean "sed -e '\''s/smudged/clean/g'\''" &&
> +		git config filter.test.smudge "sed -e '\''s/clean/smudged/g'\''" &&
> +
> +		test_commit second &&
> +		git checkout -b test HEAD^ &&
> +
> +		echo "*.txt filter=test" >.gitattributes &&
> +		git add .gitattributes &&
> +		test_commit third &&
> +
> +		echo "This text is smudged." >a.txt &&
> +		git add a.txt &&
> +		test_commit fourth &&
> +
> +		git checkout -b removal HEAD^ &&
> +		git rm .gitattributes &&
> +		git add -u &&
> +		test_commit fifth &&
> +		git cherry-pick test &&
> +
> +		git checkout test &&
> +		git rebase master &&
> +		grep "smudged" a.txt &&
> +
> +		git checkout removal &&
> +		git reset --hard &&
> +		git rebase master &&
> +		grep "clean" a.txt
> +	)
> +'
> +
>   test_expect_success 'rebase--merge.sh and --show-current-patch' '
>   	test_create_repo conflict-merge &&
>   	(
> 