Teach notes code to properly preserve non-notes in the notes tree

The note tree structure allows for non-note entries to coexist with note
entries in a notes tree. Although we certainly expect there to be very
few non-notes in a notes tree, we should still support them to a certain
degree.

This patch teaches the notes code to preserve non-notes when updating the
notes tree with write_notes_tree(). Non-notes are not affected by fanout
restructuring.

For non-notes to be handled correctly, we can no longer allow subtree
entries that do not match the fanout structure produced by the notes code
itself. This means that fanouts like 4/36, 6/34, 8/32, 4/4/32, etc. are
no longer recognized as note subtrees; only 2-based fanouts are allowed
(2/38, 2/2/36, 2/2/2/34, etc.). Since the notes code has never at any point
_produced_ non-2-based fanouts, it is highly unlikely that this change will
cause problems for anyone.

The patch also adds some tests verifying the correct handling of non-notes
in a notes tree.

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

2 files changed, 52 insertions, 12 deletions

diff --git a/t/t3303-notes-subtrees.sh b/t/t3303-notes-subtrees.sh
index edc4bc884..75ec18778 100755
--- a/t/t3303-notes-subtrees.sh
+++ b/t/t3303-notes-subtrees.sh
@@ -95,12 +95,12 @@ INPUT_END
 test_expect_success 'test notes in 2/38-fanout' 'test_sha1_based "s|^..|&/|"'
 test_expect_success 'verify notes in 2/38-fanout' 'verify_notes'
 
-test_expect_success 'test notes in 4/36-fanout' 'test_sha1_based "s|^....|&/|"'
-test_expect_success 'verify notes in 4/36-fanout' 'verify_notes'
-
 test_expect_success 'test notes in 2/2/36-fanout' 'test_sha1_based "s|^\(..\)\(..\)|\1/\2/|"'
 test_expect_success 'verify notes in 2/2/36-fanout' 'verify_notes'
 
+test_expect_success 'test notes in 2/2/2/34-fanout' 'test_sha1_based "s|^\(..\)\(..\)\(..\)|\1/\2/\3/|"'
+test_expect_success 'verify notes in 2/2/2/34-fanout' 'verify_notes'
+
 test_same_notes () {
 	(
 		start_note_commit &&
@@ -128,14 +128,17 @@ INPUT_END
 	git fast-import --quiet
 }
 
-test_expect_success 'test same notes in 4/36-fanout and 2/38-fanout' 'test_same_notes "s|^..|&/|" "s|^....|&/|"'
-test_expect_success 'verify same notes in 4/36-fanout and 2/38-fanout' 'verify_notes'
+test_expect_success 'test same notes in no fanout and 2/38-fanout' 'test_same_notes "s|^..|&/|" ""'
+test_expect_success 'verify same notes in no fanout and 2/38-fanout' 'verify_notes'
+
+test_expect_success 'test same notes in no fanout and 2/2/36-fanout' 'test_same_notes "s|^\(..\)\(..\)|\1/\2/|" ""'
+test_expect_success 'verify same notes in no fanout and 2/2/36-fanout' 'verify_notes'
 
 test_expect_success 'test same notes in 2/38-fanout and 2/2/36-fanout' 'test_same_notes "s|^\(..\)\(..\)|\1/\2/|" "s|^..|&/|"'
 test_expect_success 'verify same notes in 2/38-fanout and 2/2/36-fanout' 'verify_notes'
 
-test_expect_success 'test same notes in 4/36-fanout and 2/2/36-fanout' 'test_same_notes "s|^\(..\)\(..\)|\1/\2/|" "s|^....|&/|"'
-test_expect_success 'verify same notes in 4/36-fanout and 2/2/36-fanout' 'verify_notes'
+test_expect_success 'test same notes in 2/2/2/34-fanout and 2/2/36-fanout' 'test_same_notes "s|^\(..\)\(..\)|\1/\2/|" "s|^\(..\)\(..\)\(..\)|\1/\2/\3/|"'
+test_expect_success 'verify same notes in 2/2/2/34-fanout and 2/2/36-fanout' 'verify_notes'
 
 test_concatenated_notes () {
 	(
@@ -176,13 +179,16 @@ verify_concatenated_notes () {
     test_cmp expect output
 }
 
-test_expect_success 'test notes in 4/36-fanout concatenated with 2/38-fanout' 'test_concatenated_notes "s|^..|&/|" "s|^....|&/|"'
-test_expect_success 'verify notes in 4/36-fanout concatenated with 2/38-fanout' 'verify_concatenated_notes'
+test_expect_success 'test notes in no fanout concatenated with 2/38-fanout' 'test_concatenated_notes "s|^..|&/|" ""'
+test_expect_success 'verify notes in no fanout concatenated with 2/38-fanout' 'verify_concatenated_notes'
+
+test_expect_success 'test notes in no fanout concatenated with 2/2/36-fanout' 'test_concatenated_notes "s|^\(..\)\(..\)|\1/\2/|" ""'
+test_expect_success 'verify notes in no fanout concatenated with 2/2/36-fanout' 'verify_concatenated_notes'
 
 test_expect_success 'test notes in 2/38-fanout concatenated with 2/2/36-fanout' 'test_concatenated_notes "s|^\(..\)\(..\)|\1/\2/|" "s|^..|&/|"'
 test_expect_success 'verify notes in 2/38-fanout concatenated with 2/2/36-fanout' 'verify_concatenated_notes'
 
-test_expect_success 'test notes in 4/36-fanout concatenated with 2/2/36-fanout' 'test_concatenated_notes "s|^\(..\)\(..\)|\1/\2/|" "s|^....|&/|"'
-test_expect_success 'verify notes in 4/36-fanout concatenated with 2/2/36-fanout' 'verify_concatenated_notes'
+test_expect_success 'test notes in 2/2/36-fanout concatenated with 2/2/2/34-fanout' 'test_concatenated_notes "s|^\(..\)\(..\)\(..\)|\1/\2/\3/|" "s|^\(..\)\(..\)|\1/\2/|"'
+test_expect_success 'verify notes in 2/2/36-fanout concatenated with 2/2/2/34-fanout' 'verify_concatenated_notes'
 
 test_done
diff --git a/t/t3304-notes-mixed.sh b/t/t3304-notes-mixed.sh
index 256687ffb..c975a6d3f 100755
--- a/t/t3304-notes-mixed.sh
+++ b/t/t3304-notes-mixed.sh
@@ -131,6 +131,17 @@ data <<EOF
 another non-note with SHA1-like name
 EOF
 
+M 644 inline de/adbeefdeadbeefdeadbeefdeadbeefdeadbeef
+data <<EOF
+This is actually a valid note, albeit to a non-existing object.
+It is needed in order to trigger the "mishandling" of the dead/beef non-note.
+EOF
+
+M 644 inline dead/beef
+data <<EOF
+yet another non-note with SHA1-like name
+EOF
+
 INPUT_END
 	git fast-import --quiet <input &&
 	git config core.notesRef refs/notes/commits
@@ -158,6 +169,9 @@ EXPECT_END
 cat >expect_nn3 <<EXPECT_END
 another non-note with SHA1-like name
 EXPECT_END
+cat >expect_nn4 <<EXPECT_END
+yet another non-note with SHA1-like name
+EXPECT_END
 
 test_expect_success "verify contents of non-notes" '
 
@@ -166,7 +180,27 @@ test_expect_success "verify contents of non-notes" '
 	git cat-file -p refs/notes/commits:deadbeef > actual_nn2 &&
 	test_cmp expect_nn2 actual_nn2 &&
 	git cat-file -p refs/notes/commits:de/adbeef > actual_nn3 &&
-	test_cmp expect_nn3 actual_nn3
+	test_cmp expect_nn3 actual_nn3 &&
+	git cat-file -p refs/notes/commits:dead/beef > actual_nn4 &&
+	test_cmp expect_nn4 actual_nn4
+'
+
+test_expect_success "git-notes preserves non-notes" '
+
+	test_tick &&
+	git notes edit -m "foo bar"
+'
+
+test_expect_success "verify contents of non-notes after git-notes" '
+
+	git cat-file -p refs/notes/commits:foobar/non-note.txt > actual_nn1 &&
+	test_cmp expect_nn1 actual_nn1 &&
+	git cat-file -p refs/notes/commits:deadbeef > actual_nn2 &&
+	test_cmp expect_nn2 actual_nn2 &&
+	git cat-file -p refs/notes/commits:de/adbeef > actual_nn3 &&
+	test_cmp expect_nn3 actual_nn3 &&
+	git cat-file -p refs/notes/commits:dead/beef > actual_nn4 &&
+	test_cmp expect_nn4 actual_nn4
 '
 
 test_done