[PATCH v3 4/4] ref-filter: add support for %(contents:size)

[Christian Couder <christian.couder@gmail.com>]

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 788258c3ad..049bc93e6a 100644
--- a/Documentation/git-for-each-ref.txt
+++ b/Documentation/git-for-each-ref.txt
@@ -236,6 +236,9 @@ The complete message (subject, body, trailers and signature) of a
 commit or tag object is `contents`. This field can also be used in the
 following ways:
 
+contents:size::
+	The size in bytes of the complete message.
+
 contents:subject::
 	The "subject" of the commit or tag message.  It's actually the
 	concatenation of all lines of the commit message up to the
diff --git a/ref-filter.c b/ref-filter.c
index 8447cb09be..8ec28f0535 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("%ld", 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 371e45e5ad..b580e27a32 100755
--- a/t/t6300-for-each-ref.sh
+++ b/t/t6300-for-each-ref.sh
@@ -125,6 +125,7 @@ test_atom head contents:body ''
 test_atom head contents:signature ''
 test_atom head contents 'Initial
 '
+test_atom head contents:size '8'
 test_atom head HEAD '*'
 
 test_atom tag refname refs/tags/testtag
@@ -170,6 +171,7 @@ test_atom tag contents:body ''
 test_atom tag contents:signature ''
 test_atom tag contents 'Tagging at 1151968727
 '
+test_atom tag contents:size '22'
 test_atom tag HEAD ' '
 
 test_expect_success 'Check invalid atoms names are errors' '
@@ -580,6 +582,7 @@ test_atom refs/tags/subject-body contents 'the subject line
 first body line
 second body line
 '
+test_atom refs/tags/subject-body contents:size '51'
 
 test_expect_success 'create tag with multiline subject' '
 	cat >msg <<-\EOF &&
@@ -606,6 +609,7 @@ second subject line
 first body line
 second body line
 '
+test_atom refs/tags/multiline contents:size '73'
 
 test_expect_success GPG 'create signed tags' '
 	git tag -s -m "" signed-empty &&
@@ -622,6 +626,16 @@ sig='-----BEGIN PGP SIGNATURE-----
 -----END PGP SIGNATURE-----
 '
 
+# We cannot use test_atom to check contents:size of signed tags due to sanitize_pgp
+test_tag_contents_size_pgp () {
+	ref="$1"
+	test_expect_success $PREREQ "basic atom: $ref contents:size" "
+		git cat-file tag $ref | tail -n +6 | wc -c >expected &&
+		git for-each-ref --format='%(contents:size)' $ref >actual &&
+		test_cmp expected actual
+	"
+}
+
 PREREQ=GPG
 test_atom refs/tags/signed-empty subject ''
 test_atom refs/tags/signed-empty contents:subject ''
@@ -629,6 +643,7 @@ test_atom refs/tags/signed-empty body "$sig"
 test_atom refs/tags/signed-empty contents:body ''
 test_atom refs/tags/signed-empty contents:signature "$sig"
 test_atom refs/tags/signed-empty contents "$sig"
+test_tag_contents_size_pgp refs/tags/signed-empty
 
 test_atom refs/tags/signed-short subject 'subject line'
 test_atom refs/tags/signed-short contents:subject 'subject line'
@@ -637,6 +652,7 @@ test_atom refs/tags/signed-short contents:body ''
 test_atom refs/tags/signed-short contents:signature "$sig"
 test_atom refs/tags/signed-short contents "subject line
 $sig"
+test_tag_contents_size_pgp refs/tags/signed-short
 
 test_atom refs/tags/signed-long subject 'subject line'
 test_atom refs/tags/signed-long contents:subject 'subject line'
@@ -649,6 +665,7 @@ test_atom refs/tags/signed-long contents "subject line
 
 body contents
 $sig"
+test_tag_contents_size_pgp refs/tags/signed-long
 
 test_expect_success 'set up refs pointing to tree and blob' '
 	git update-ref refs/mytrees/first refs/heads/master^{tree} &&
@@ -664,6 +681,7 @@ test_atom refs/mytrees/first body ""
 test_atom refs/mytrees/first contents:body ""
 test_atom refs/mytrees/first contents:signature ""
 test_atom refs/mytrees/first contents ""
+test_atom refs/mytrees/first contents:size ""
 
 test_atom refs/myblobs/first subject ""
 test_atom refs/myblobs/first contents:subject ""
@@ -671,6 +689,7 @@ test_atom refs/myblobs/first body ""
 test_atom refs/myblobs/first contents:body ""
 test_atom refs/myblobs/first contents:signature ""
 test_atom refs/myblobs/first contents ""
+test_atom refs/myblobs/first contents:size ""
 
 test_expect_success 'set up multiple-sort tags' '
 	for when in 100000 200000
-- 
2.27.0.460.g66f3a24dd5