Merge branch 'cc/pretty-contents-size' into master

"git for-each-ref --format=<>" learned %(contents:size).

* cc/pretty-contents-size:
  ref-filter: add support for %(contents:size)
  t6300: test refs pointing to tree and blob
  Documentation: clarify %(contents:XXXX) doc

Documentation/git-for-each-ref.txt

@@ -232,12 +232,27 @@ Fields that have name-email-date tuple as its value (`author`,
 `committer`, and `tagger`) can be suffixed with `name`, `email`,
 and `date` to extract the named component.
 
-The complete message in a commit and tag object is `contents`.
+The message in a commit or a tag object is `contents`, from which
-Its first line is `contents:subject`, where subject is the concatenation
+`contents:<part>` can be used to extract various parts out of:
-of all lines of the commit message up to the first blank line.  The next
+
-line is `contents:body`, where body is all of the lines after the first
+contents:size::
-blank line.  The optional GPG signature is `contents:signature`.  The
+	The size in bytes of the commit or tag message.
-first `N` lines of the message is obtained using `contents:lines=N`.
+
+contents:subject::
+	The first paragraph of the message, which typically is a
+	single line, is taken as the "subject" of the commit or the
+	tag message.
+
+contents:body::
+	The remainder of the commit or the tag message that follows
+	the "subject".
+
+contents:signature::
+	The optional GPG signature of the tag.
+
+contents:lines=N::
+	The first `N` lines of the message.
+
 Additionally, the trailers as interpreted by linkgit:git-interpret-trailers[1]
 are obtained as `trailers` (or by using the historical alias
 `contents:trailers`).  Non-trailer lines from the trailer block can be omitted

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)

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)
@@ -650,6 +669,25 @@ test_atom refs/tags/signed-long contents "subject line
 body contents
 $sig"
 
+test_expect_success 'set up refs pointing to tree and blob' '
+	git update-ref refs/mytrees/first refs/heads/master^{tree} &&
+	git update-ref refs/myblobs/first refs/heads/master:one
+'
+
+test_atom refs/mytrees/first subject ""
+test_atom refs/mytrees/first contents:subject ""
+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/myblobs/first subject ""
+test_atom refs/myblobs/first contents:subject ""
+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_expect_success 'set up multiple-sort tags' '
 	for when in 100000 200000
 	do