Provide 'git notes get-ref' to easily retrieve current notes ref

Script may use 'git notes get-ref' to easily retrieve the current notes ref.

Suggested-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-notes.txt

@@ -19,6 +19,7 @@ SYNOPSIS
 'git notes' merge --abort [-v | -q]
 'git notes' remove [<object>]
 'git notes' prune [-n | -v]
+'git notes' get-ref
 
 
 DESCRIPTION
@@ -109,6 +110,10 @@ remove::
 prune::
 	Remove all notes for non-existing/unreachable objects.
 
+get-ref::
+	Print the current notes ref. This provides an easy way to
+	retrieve the current notes ref (e.g. from scripts).
+
 OPTIONS
 -------
 -f::

builtin/notes.c

@@ -31,6 +31,7 @@ static const char * const git_notes_usage[] = {
 	"git notes merge --abort [-v | -q]",
 	"git notes [--ref <notes_ref>] remove [<object>]",
 	"git notes [--ref <notes_ref>] prune [-n | -v]",
+	"git notes [--ref <notes_ref>] get-ref",
 	NULL
 };
 
@@ -82,6 +83,11 @@ static const char * const git_notes_prune_usage[] = {
 	NULL
 };
 
+static const char * const git_notes_get_ref_usage[] = {
+	"git notes get-ref",
+	NULL
+};
+
 static const char note_template[] =
 	"\n"
 	"#\n"
@@ -1002,6 +1008,21 @@ static int prune(int argc, const char **argv, const char *prefix)
 	return 0;
 }
 
+static int get_ref(int argc, const char **argv, const char *prefix)
+{
+	struct option options[] = { OPT_END() };
+	argc = parse_options(argc, argv, prefix, options,
+			     git_notes_get_ref_usage, 0);
+
+	if (argc) {
+		error("too many parameters");
+		usage_with_options(git_notes_get_ref_usage, options);
+	}
+
+	puts(default_notes_ref());
+	return 0;
+}
+
 int cmd_notes(int argc, const char **argv, const char *prefix)
 {
 	int result;
@@ -1040,6 +1061,8 @@ int cmd_notes(int argc, const char **argv, const char *prefix)
 		result = remove_cmd(argc, argv, prefix);
 	else if (!strcmp(argv[0], "prune"))
 		result = prune(argc, argv, prefix);
+	else if (!strcmp(argv[0], "get-ref"))
+		result = get_ref(argc, argv, prefix);
 	else {
 		result = error("Unknown subcommand: %s", argv[0]);
 		usage_with_options(git_notes_usage, options);

t/t3301-notes.sh

@@ -1058,4 +1058,23 @@ test_expect_success 'git notes copy diagnoses too many or too few parameters' '
 	test_must_fail git notes copy one two three
 '
 
+test_expect_success 'git notes get-ref (no overrides)' '
+	git config --unset core.notesRef &&
+	unset GIT_NOTES_REF &&
+	test "$(git notes get-ref)" = "refs/notes/commits"
+'
+
+test_expect_success 'git notes get-ref (core.notesRef)' '
+	git config core.notesRef refs/notes/foo &&
+	test "$(git notes get-ref)" = "refs/notes/foo"
+'
+
+test_expect_success 'git notes get-ref (GIT_NOTES_REF)' '
+	test "$(GIT_NOTES_REF=refs/notes/bar git notes get-ref)" = "refs/notes/bar"
+'
+
+test_expect_success 'git notes get-ref (--ref)' '
+	test "$(GIT_NOTES_REF=refs/notes/bar git notes --ref=baz get-ref)" = "refs/notes/baz"
+'
+
 test_done