[PATCH 1/2] notes: don't expand qualified refs in expand_notes_ref

[Jacob Keller <jacob.e.keller@intel.com>]

From: Jacob Keller <jacob.keller@gmail.com>

The documentation for --refs says that it will treat unqualified refs as
under refs/notes. Current behavior is to prefix refs/notes to all
strings that do not start with refs/notes or notes/, resulting in
performing actions on refs such as "refs/notes/refs/foo/bar" instead of
attempting to perform actions on "refs/foo/bar". A future patch will
introduce the idea of performing non-writable actions to refs outside of
refs/notes. Change the behavior of expand_notes_ref to leave qualified
refs under refs/* alone.

In addition, fix git notes merge <ref> to prevent merges from refs which
are not under refs/notes, in a similar way to how we already check note
refs in init_notes_check. This is required in order to keep current
tests passing without change. A future patch will change the behavior of
git notes merge so that it can merge from a ref outside of refs/notes.

Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
---
 builtin/notes.c | 4 ++++
 notes.c         | 4 ++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/builtin/notes.c b/builtin/notes.c
index 6371d536d164..0f55d38983f0 100644
--- a/builtin/notes.c
+++ b/builtin/notes.c
@@ -810,6 +810,10 @@ static int merge(int argc, const char **argv, const char *prefix)
 	o.local_ref = default_notes_ref();
 	strbuf_addstr(&remote_ref, argv[0]);
 	expand_notes_ref(&remote_ref);
+	if (!starts_with(remote_ref.buf, "refs/notes"))
+		die("Refusing to merge notes from %s (outside of refs/notes/)",
+		    remote_ref.buf);
+
 	o.remote_ref = remote_ref.buf;
 
 	t = init_notes_check("merge", NOTES_INIT_WRITABLE);
diff --git a/notes.c b/notes.c
index 6ef347ca3ac4..d49168fb3f01 100644
--- a/notes.c
+++ b/notes.c
@@ -1296,8 +1296,8 @@ int copy_note(struct notes_tree *t,
 
 void expand_notes_ref(struct strbuf *sb)
 {
-	if (starts_with(sb->buf, "refs/notes/"))
-		return; /* we're happy */
+	if (starts_with(sb->buf, "refs/"))
+		return; /* fully qualified, so we're happy */
 	else if (starts_with(sb->buf, "notes/"))
 		strbuf_insert(sb, 0, "refs/", 5);
 	else
-- 
2.6.0.rc2.248.g5b5be23