Re: [PATCH v5 3/3] ref-filter: add support for %(contents:size)

> It's useful and efficient to be able to get the size of the
> contents directly without having to pipe through `wc -c`.
> 
> Also the result of the following:
> 
> `git for-each-ref --format='%(contents)' refs/heads/my-branch | wc -c`
> 
> is off by one as `git for-each-ref` appends a newline character
> after the contents, which can be seen by comparing its output
> with the output from `git cat-file`.
> 
> As with %(contents), %(contents:size) is silently ignored, if a
> ref points to something other than a commit or a tag:
> 
> ```
> $ git update-ref refs/mytrees/first HEAD^{tree}
> $ git for-each-ref --format='%(contents)' refs/mytrees/first
> 
> $ git for-each-ref --format='%(contents:size)' refs/mytrees/first
> 
> ```
> 
> Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
> ---
>  Documentation/git-for-each-ref.txt |  3 +++
>  ref-filter.c                       |  7 ++++++-
>  t/t6300-for-each-ref.sh            | 19 +++++++++++++++++++
>  3 files changed, 28 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/git-for-each-ref.txt b/Documentation/git-for-each-ref.txt
> index b739412c30..2ea71c5f6c 100644
> --- a/Documentation/git-for-each-ref.txt
> +++ b/Documentation/git-for-each-ref.txt
> @@ -235,6 +235,9 @@ and `date` to extract the named component.
>  The message in a commit or a tag object is `contents`, from which
>  `contents:<part>` can be used to extract various parts out of:
>  
> +contents:size::
> +	The size in bytes of the commit or tag message.
> +
>  contents:subject::
>  	The first paragraph of the message, which typically is a
>  	single line, is taken as the "subject" of the commit or the
> diff --git a/ref-filter.c b/ref-filter.c
> index 8447cb09be..73d8bfa86d 100644
> --- a/ref-filter.c
> +++ b/ref-filter.c
> @@ -127,7 +127,8 @@ static struct used_atom {
>  			unsigned int nobracket : 1, push : 1, push_remote : 1;
>  		} remote_ref;
>  		struct {
> -			enum { C_BARE, C_BODY, C_BODY_DEP, C_LINES, C_SIG, C_SUB, C_TRAILERS } option;
> +			enum { C_BARE, C_BODY, C_BODY_DEP, C_LENGTH,
> +			       C_LINES, C_SIG, C_SUB, C_TRAILERS } option;
>  			struct process_trailer_options trailer_opts;
>  			unsigned int nlines;
>  		} contents;
> @@ -338,6 +339,8 @@ static int contents_atom_parser(const struct ref_format *format, struct used_ato
>  		atom->u.contents.option = C_BARE;
>  	else if (!strcmp(arg, "body"))
>  		atom->u.contents.option = C_BODY;
> +	else if (!strcmp(arg, "size"))
> +		atom->u.contents.option = C_LENGTH;
>  	else if (!strcmp(arg, "signature"))
>  		atom->u.contents.option = C_SIG;
>  	else if (!strcmp(arg, "subject"))
> @@ -1253,6 +1256,8 @@ static void grab_sub_body_contents(struct atom_value *val, int deref, void *buf)
>  			v->s = copy_subject(subpos, sublen);
>  		else if (atom->u.contents.option == C_BODY_DEP)
>  			v->s = xmemdupz(bodypos, bodylen);
> +		else if (atom->u.contents.option == C_LENGTH)
> +			v->s = xstrfmt("%"PRIuMAX, (uintmax_t)strlen(subpos));
>  		else if (atom->u.contents.option == C_BODY)
>  			v->s = xmemdupz(bodypos, nonsiglen);
>  		else if (atom->u.contents.option == C_SIG)
> diff --git a/t/t6300-for-each-ref.sh b/t/t6300-for-each-ref.sh
> index e9f468d360..ea9bb6dade 100755
> --- a/t/t6300-for-each-ref.sh
> +++ b/t/t6300-for-each-ref.sh
> @@ -52,6 +52,25 @@ test_atom() {
>  		sanitize_pgp <actual >actual.clean &&
>  		test_cmp expected actual.clean
>  	"
> +	# Automatically test "contents:size" atom after testing "contents"
> +	if test "$2" = "contents"
> +	then
> +		case $(git cat-file -t "$ref") in
> +		tag)
> +			# We cannot use $3 as it expects sanitize_pgp to run
> +			expect=$(git cat-file tag $ref | tail -n +6 | wc -c) ;;
> +		tree | blob)
> +			expect='' ;;
> +		commit)
> +			expect=$(printf '%s' "$3" | wc -c) ;;
> +		esac
> +		# Leave $expect unquoted to lose possible leading whitespaces
> +		echo $expect >expected
> +		test_expect_${4:-sucess} $PREREQ "basic atom: $1 contents:size" '

> +			git for-each-ref --format="%(contents:size)" "$ref" >actual &&
> +			test_cmp expect actual
> +		'
> +	fi
>  }
>  
>  hexlen=$(test_oid hexsz)
>