notes: allow treeish expressions as notes ref

init_notes() is the main point of entry to the notes API. It ensures
that the input can be used as ref, because it needs a ref to update to
store notes tree after modifying it.

There however are many use cases where notes tree is only read, e.g.
"git log --notes=...".  Any notes-shaped treeish could be used for such
purpose, but it is not allowed due to existing restriction.

Allow treeish expressions to be used in the case the notes tree is going
to be used without write "permissions".  Add a flag to distinguish
whether the notes tree is intended to be used read-only, or will be
updated.

With this change, operations that use notes read-only can be fed any
notes-shaped tree-ish can be used, e.g. git log --notes=notes@{1}.

Signed-off-by: Mike Hommey <mh@glandium.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 16 insertions, 13 deletions

diff --git a/builtin/notes.c b/builtin/notes.c
index 52aa9af74b..e1556896f9 100644
--- a/builtin/notes.c
+++ b/builtin/notes.c
@@ -286,7 +286,7 @@ static int notes_copy_from_stdin(int force, const char *rewrite_cmd)
 		if (!c)
 			return 0;
 	} else {
-		init_notes(NULL, NULL, NULL, 0);
+		init_notes(NULL, NULL, NULL, NOTES_INIT_WRITABLE);
 		t = &default_notes_tree;
 	}
 
@@ -329,15 +329,18 @@ static int notes_copy_from_stdin(int force, const char *rewrite_cmd)
 	return ret;
 }
 
-static struct notes_tree *init_notes_check(const char *subcommand)
+static struct notes_tree *init_notes_check(const char *subcommand,
+					   int flags)
 {
 	struct notes_tree *t;
-	init_notes(NULL, NULL, NULL, 0);
+	const char *ref;
+	init_notes(NULL, NULL, NULL, flags);
 	t = &default_notes_tree;
 
-	if (!starts_with(t->ref, "refs/notes/"))
+	ref = (flags & NOTES_INIT_WRITABLE) ? t->update_ref : t->ref;
+	if (!starts_with(ref, "refs/notes/"))
 		die("Refusing to %s notes in %s (outside of refs/notes/)",
-		    subcommand, t->ref);
+		    subcommand, ref);
 	return t;
 }
 
@@ -360,7 +363,7 @@ static int list(int argc, const char **argv, const char *prefix)
 		usage_with_options(git_notes_list_usage, options);
 	}
 
-	t = init_notes_check("list");
+	t = init_notes_check("list", 0);
 	if (argc) {
 		if (get_sha1(argv[0], object))
 			die(_("Failed to resolve '%s' as a valid ref."), argv[0]);
@@ -420,7 +423,7 @@ static int add(int argc, const char **argv, const char *prefix)
 	if (get_sha1(object_ref, object))
 		die(_("Failed to resolve '%s' as a valid ref."), object_ref);
 
-	t = init_notes_check("add");
+	t = init_notes_check("add", NOTES_INIT_WRITABLE);
 	note = get_note(t, object);
 
 	if (note) {
@@ -511,7 +514,7 @@ static int copy(int argc, const char **argv, const char *prefix)
 	if (get_sha1(object_ref, object))
 		die(_("Failed to resolve '%s' as a valid ref."), object_ref);
 
-	t = init_notes_check("copy");
+	t = init_notes_check("copy", NOTES_INIT_WRITABLE);
 	note = get_note(t, object);
 
 	if (note) {
@@ -589,7 +592,7 @@ static int append_edit(int argc, const char **argv, const char *prefix)
 	if (get_sha1(object_ref, object))
 		die(_("Failed to resolve '%s' as a valid ref."), object_ref);
 
-	t = init_notes_check(argv[0]);
+	t = init_notes_check(argv[0], NOTES_INIT_WRITABLE);
 	note = get_note(t, object);
 
 	prepare_note_data(object, &d, edit ? note : NULL);
@@ -652,7 +655,7 @@ static int show(int argc, const char **argv, const char *prefix)
 	if (get_sha1(object_ref, object))
 		die(_("Failed to resolve '%s' as a valid ref."), object_ref);
 
-	t = init_notes_check("show");
+	t = init_notes_check("show", 0);
 	note = get_note(t, object);
 
 	if (!note)
@@ -809,7 +812,7 @@ static int merge(int argc, const char **argv, const char *prefix)
 	expand_notes_ref(&remote_ref);
 	o.remote_ref = remote_ref.buf;
 
-	t = init_notes_check("merge");
+	t = init_notes_check("merge", NOTES_INIT_WRITABLE);
 
 	if (strategy) {
 		if (parse_notes_merge_strategy(strategy, &o.strategy)) {
@@ -901,7 +904,7 @@ static int remove_cmd(int argc, const char **argv, const char *prefix)
 	argc = parse_options(argc, argv, prefix, options,
 			     git_notes_remove_usage, 0);
 
-	t = init_notes_check("remove");
+	t = init_notes_check("remove", NOTES_INIT_WRITABLE);
 
 	if (!argc && !from_stdin) {
 		retval = remove_one_note(t, "HEAD", flag);
@@ -943,7 +946,7 @@ static int prune(int argc, const char **argv, const char *prefix)
 		usage_with_options(git_notes_prune_usage, options);
 	}
 
-	t = init_notes_check("prune");
+	t = init_notes_check("prune", NOTES_INIT_WRITABLE);
 
 	prune_notes(t, (verbose ? NOTES_PRUNE_VERBOSE : 0) |
 		(show_only ? NOTES_PRUNE_VERBOSE|NOTES_PRUNE_DRYRUN : 0) );