Merge branch 'jh/notes'

* jh/notes: (33 commits)
  Documentation: fix a few typos in git-notes.txt
  notes: fix malformed tree entry
  builtin-notes: Minor (mostly parse_options-related) fixes
  builtin-notes: Add "copy" subcommand for copying notes between objects
  builtin-notes: Misc. refactoring of argc and exit value handling
  builtin-notes: Add -c/-C options for reusing notes
  builtin-notes: Refactor handling of -F option to allow combining -m and -F
  builtin-notes: Deprecate the -m/-F options for "git notes edit"
  builtin-notes: Add "append" subcommand for appending to note objects
  builtin-notes: Add "add" subcommand for adding notes to objects
  builtin-notes: Add --message/--file aliases for -m/-F options
  builtin-notes: Add "list" subcommand for listing note objects
  Documentation: Generalize git-notes docs to 'objects' instead of 'commits'
  builtin-notes: Add "prune" subcommand for removing notes for missing objects
  Notes API: prune_notes(): Prune notes that belong to non-existing objects
  t3305: Verify that removing notes triggers automatic fanout consolidation
  builtin-notes: Add "remove" subcommand for removing existing notes
  Teach builtin-notes to remove empty notes
  Teach notes code to properly preserve non-notes in the notes tree
  t3305: Verify that adding many notes with git-notes triggers increased fanout
  ...

Conflicts:
	Makefile

14 files changed, 2167 insertions, 196 deletions

diff --git a/Documentation/git-notes.txt b/Documentation/git-notes.txt
index d4487cab52..bef2f3942e 100644
--- a/Documentation/git-notes.txt
+++ b/Documentation/git-notes.txt
@@ -3,57 +3,112 @@ git-notes(1)
 
 NAME
 ----
-git-notes - Add/inspect commit notes
+git-notes - Add/inspect object notes
 
 SYNOPSIS
 --------
 [verse]
-'git notes' (edit [-F <file> | -m <msg>] | show) [commit]
+'git notes' [list [<object>]]
+'git notes' add [-f] [-F <file> | -m <msg> | (-c | -C) <object>] [<object>]
+'git notes' copy [-f] <from-object> <to-object>
+'git notes' append [-F <file> | -m <msg> | (-c | -C) <object>] [<object>]
+'git notes' edit [<object>]
+'git notes' show [<object>]
+'git notes' remove [<object>]
+'git notes' prune
+
 
 DESCRIPTION
 -----------
-This command allows you to add notes to commit messages, without
-changing the commit.  To discern these notes from the message stored
-in the commit object, the notes are indented like the message, after
-an unindented line saying "Notes:".
+This command allows you to add/remove notes to/from objects, without
+changing the objects themselves.
+
+A typical use of notes is to extend a commit message without having
+to change the commit itself. Such commit notes can be shown by `git log`
+along with the original commit message. To discern these notes from the
+message stored in the commit object, the notes are indented like the
+message, after an unindented line saying "Notes:".
 
-To disable commit notes, you have to set the config variable
-core.notesRef to the empty string.  Alternatively, you can set it
-to a different ref, something like "refs/notes/bugzilla".  This setting
-can be overridden by the environment variable "GIT_NOTES_REF".
+To disable notes, you have to set the config variable core.notesRef to
+the empty string.  Alternatively, you can set it to a different ref,
+something like "refs/notes/bugzilla".  This setting can be overridden
+by the environment variable "GIT_NOTES_REF".
 
 
 SUBCOMMANDS
 -----------
 
+list::
+	List the notes object for a given object. If no object is
+	given, show a list of all note objects and the objects they
+	annotate (in the format "<note object> <annotated object>").
+	This is the default subcommand if no subcommand is given.
+
+add::
+	Add notes for a given object (defaults to HEAD). Abort if the
+	object already has notes (use `-f` to overwrite an
+	existing note).
+
+copy::
+	Copy the notes for the first object onto the second object.
+	Abort if the second object already has notes, or if the first
+	object has none (use -f to overwrite existing notes to the
+	second object). This subcommand is equivalent to:
+	`git notes add [-f] -C $(git notes list <from-object>) <to-object>`
+
+append::
+	Append to the notes of an existing object (defaults to HEAD).
+	Creates a new notes object if needed.
+
 edit::
-	Edit the notes for a given commit (defaults to HEAD).
+	Edit the notes for a given object (defaults to HEAD).
 
 show::
-	Show the notes for a given commit (defaults to HEAD).
+	Show the notes for a given object (defaults to HEAD).
+
+remove::
+	Remove the notes for a given object (defaults to HEAD).
+	This is equivalent to specifying an empty note message to
+	the `edit` subcommand.
 
+prune::
+	Remove all notes for non-existing/unreachable objects.
 
 OPTIONS
 -------
+-f::
+--force::
+	When adding notes to an object that already has notes,
+	overwrite the existing notes (instead of aborting).
+
 -m <msg>::
+--message=<msg>::
 	Use the given note message (instead of prompting).
-	If multiple `-m` (or `-F`) options are given, their
-	values are concatenated as separate paragraphs.
+	If multiple `-m` options are given, their values
+	are concatenated as separate paragraphs.
 
 -F <file>::
+--file=<file>::
 	Take the note message from the given file.  Use '-' to
 	read the note message from the standard input.
-	If multiple `-F` (or `-m`) options are given, their
-	values are concatenated as separate paragraphs.
 
+-C <object>::
+--reuse-message=<object>::
+	Reuse the note message from the given note object.
+
+-c <object>::
+--reedit-message=<object>::
+	Like '-C', but with '-c' the editor is invoked, so that
+	the user can further edit the note message.
 
 Author
 ------
-Written by Johannes Schindelin <johannes.schindelin@gmx.de>
+Written by Johannes Schindelin <johannes.schindelin@gmx.de> and
+Johan Herland <johan@herland.net>
 
 Documentation
 -------------
-Documentation by Johannes Schindelin
+Documentation by Johannes Schindelin and Johan Herland
 
 GIT
 ---
diff --git a/Makefile b/Makefile
index 8fdc421073..7c616f8b0a 100644
--- a/Makefile
+++ b/Makefile
@@ -335,7 +335,6 @@ SCRIPT_SH += git-merge-octopus.sh
 SCRIPT_SH += git-merge-one-file.sh
 SCRIPT_SH += git-merge-resolve.sh
 SCRIPT_SH += git-mergetool.sh
-SCRIPT_SH += git-notes.sh
 SCRIPT_SH += git-pull.sh
 SCRIPT_SH += git-quiltimport.sh
 SCRIPT_SH += git-rebase--interactive.sh
@@ -677,6 +676,7 @@ BUILTIN_OBJS += builtin/mktag.o
 BUILTIN_OBJS += builtin/mktree.o
 BUILTIN_OBJS += builtin/mv.o
 BUILTIN_OBJS += builtin/name-rev.o
+BUILTIN_OBJS += builtin/notes.o
 BUILTIN_OBJS += builtin/pack-objects.o
 BUILTIN_OBJS += builtin/pack-redundant.o
 BUILTIN_OBJS += builtin/pack-refs.o
diff --git a/builtin.h b/builtin.h
index e8202f3f5e..cdf98477a6 100644
--- a/builtin.h
+++ b/builtin.h
@@ -5,6 +5,7 @@
 #include "strbuf.h"
 #include "cache.h"
 #include "commit.h"
+#include "notes.h"
 
 extern const char git_version_string[];
 extern const char git_usage_string[];
@@ -18,6 +19,7 @@ extern int fmt_merge_msg(int merge_summary, struct strbuf *in,
 extern int commit_tree(const char *msg, unsigned char *tree,
 		struct commit_list *parents, unsigned char *ret,
 		const char *author);
+extern int commit_notes(struct notes_tree *t, const char *msg);
 extern int check_pager_config(const char *cmd);
 
 extern int cmd_add(int argc, const char **argv, const char *prefix);
@@ -78,6 +80,7 @@ extern int cmd_mktag(int argc, const char **argv, const char *prefix);
 extern int cmd_mktree(int argc, const char **argv, const char *prefix);
 extern int cmd_mv(int argc, const char **argv, const char *prefix);
 extern int cmd_name_rev(int argc, const char **argv, const char *prefix);
+extern int cmd_notes(int argc, const char **argv, const char *prefix);
 extern int cmd_pack_objects(int argc, const char **argv, const char *prefix);
 extern int cmd_pack_redundant(int argc, const char **argv, const char *prefix);
 extern int cmd_patch_id(int argc, const char **argv, const char *prefix);
diff --git a/builtin/notes.c b/builtin/notes.c
new file mode 100644
index 0000000000..feb710ac4a
--- /dev/null
+++ b/builtin/notes.c
@@ -0,0 +1,455 @@
+/*
+ * Builtin "git notes"
+ *
+ * Copyright (c) 2010 Johan Herland <johan@herland.net>
+ *
+ * Based on git-notes.sh by Johannes Schindelin,
+ * and builtin-tag.c by Kristian Høgsberg and Carlos Rica.
+ */
+
+#include "cache.h"
+#include "builtin.h"
+#include "notes.h"
+#include "blob.h"
+#include "commit.h"
+#include "refs.h"
+#include "exec_cmd.h"
+#include "run-command.h"
+#include "parse-options.h"
+
+static const char * const git_notes_usage[] = {
+	"git notes [list [<object>]]",
+	"git notes add [-f] [-m <msg> | -F <file> | (-c | -C) <object>] [<object>]",
+	"git notes copy [-f] <from-object> <to-object>",
+	"git notes append [-m <msg> | -F <file> | (-c | -C) <object>] [<object>]",
+	"git notes edit [<object>]",
+	"git notes show [<object>]",
+	"git notes remove [<object>]",
+	"git notes prune",
+	NULL
+};
+
+static const char note_template[] =
+	"\n"
+	"#\n"
+	"# Write/edit the notes for the following object:\n"
+	"#\n";
+
+struct msg_arg {
+	int given;
+	int use_editor;
+	struct strbuf buf;
+};
+
+static int list_each_note(const unsigned char *object_sha1,
+		const unsigned char *note_sha1, char *note_path,
+		void *cb_data)
+{
+	printf("%s %s\n", sha1_to_hex(note_sha1), sha1_to_hex(object_sha1));
+	return 0;
+}
+
+static void write_note_data(int fd, const unsigned char *sha1)
+{
+	unsigned long size;
+	enum object_type type;
+	char *buf = read_sha1_file(sha1, &type, &size);
+	if (buf) {
+		if (size)
+			write_or_die(fd, buf, size);
+		free(buf);
+	}
+}
+
+static void write_commented_object(int fd, const unsigned char *object)
+{
+	const char *show_args[5] =
+		{"show", "--stat", "--no-notes", sha1_to_hex(object), NULL};
+	struct child_process show;
+	struct strbuf buf = STRBUF_INIT;
+	FILE *show_out;
+
+	/* Invoke "git show --stat --no-notes $object" */
+	memset(&show, 0, sizeof(show));
+	show.argv = show_args;
+	show.no_stdin = 1;
+	show.out = -1;
+	show.err = 0;
+	show.git_cmd = 1;
+	if (start_command(&show))
+		die("unable to start 'show' for object '%s'",
+		    sha1_to_hex(object));
+
+	/* Open the output as FILE* so strbuf_getline() can be used. */
+	show_out = xfdopen(show.out, "r");
+	if (show_out == NULL)
+		die_errno("can't fdopen 'show' output fd");
+
+	/* Prepend "# " to each output line and write result to 'fd' */
+	while (strbuf_getline(&buf, show_out, '\n') != EOF) {
+		write_or_die(fd, "# ", 2);
+		write_or_die(fd, buf.buf, buf.len);
+		write_or_die(fd, "\n", 1);
+	}
+	strbuf_release(&buf);
+	if (fclose(show_out))
+		die_errno("failed to close pipe to 'show' for object '%s'",
+			  sha1_to_hex(object));
+	if (finish_command(&show))
+		die("failed to finish 'show' for object '%s'",
+		    sha1_to_hex(object));
+}
+
+static void create_note(const unsigned char *object, struct msg_arg *msg,
+			int append_only, const unsigned char *prev,
+			unsigned char *result)
+{
+	char *path = NULL;
+
+	if (msg->use_editor || !msg->given) {
+		int fd;
+
+		/* write the template message before editing: */
+		path = git_pathdup("NOTES_EDITMSG");
+		fd = open(path, O_CREAT | O_TRUNC | O_WRONLY, 0600);
+		if (fd < 0)
+			die_errno("could not create file '%s'", path);
+
+		if (msg->given)
+			write_or_die(fd, msg->buf.buf, msg->buf.len);
+		else if (prev && !append_only)
+			write_note_data(fd, prev);
+		write_or_die(fd, note_template, strlen(note_template));
+
+		write_commented_object(fd, object);
+
+		close(fd);
+		strbuf_reset(&(msg->buf));
+
+		if (launch_editor(path, &(msg->buf), NULL)) {
+			die("Please supply the note contents using either -m" \
+			    " or -F option");
+		}
+		stripspace(&(msg->buf), 1);
+	}
+
+	if (prev && append_only) {
+		/* Append buf to previous note contents */
+		unsigned long size;
+		enum object_type type;
+		char *prev_buf = read_sha1_file(prev, &type, &size);
+
+		strbuf_grow(&(msg->buf), size + 1);
+		if (msg->buf.len && prev_buf && size)
+			strbuf_insert(&(msg->buf), 0, "\n", 1);
+		if (prev_buf && size)
+			strbuf_insert(&(msg->buf), 0, prev_buf, size);
+		free(prev_buf);
+	}
+
+	if (!msg->buf.len) {
+		fprintf(stderr, "Removing note for object %s\n",
+			sha1_to_hex(object));
+		hashclr(result);
+	} else {
+		if (write_sha1_file(msg->buf.buf, msg->buf.len, blob_type, result)) {
+			error("unable to write note object");
+			if (path)
+				error("The note contents has been left in %s",
+				      path);
+			exit(128);
+		}
+	}
+
+	if (path) {
+		unlink_or_warn(path);
+		free(path);
+	}
+}
+
+static int parse_msg_arg(const struct option *opt, const char *arg, int unset)
+{
+	struct msg_arg *msg = opt->value;
+
+	strbuf_grow(&(msg->buf), strlen(arg) + 2);
+	if (msg->buf.len)
+		strbuf_addch(&(msg->buf), '\n');
+	strbuf_addstr(&(msg->buf), arg);
+	stripspace(&(msg->buf), 0);
+
+	msg->given = 1;
+	return 0;
+}
+
+static int parse_file_arg(const struct option *opt, const char *arg, int unset)
+{
+	struct msg_arg *msg = opt->value;
+
+	if (msg->buf.len)
+		strbuf_addch(&(msg->buf), '\n');
+	if (!strcmp(arg, "-")) {
+		if (strbuf_read(&(msg->buf), 0, 1024) < 0)
+			die_errno("cannot read '%s'", arg);
+	} else if (strbuf_read_file(&(msg->buf), arg, 1024) < 0)
+		die_errno("could not open or read '%s'", arg);
+	stripspace(&(msg->buf), 0);
+
+	msg->given = 1;
+	return 0;
+}
+
+static int parse_reuse_arg(const struct option *opt, const char *arg, int unset)
+{
+	struct msg_arg *msg = opt->value;
+	char *buf;
+	unsigned char object[20];
+	enum object_type type;
+	unsigned long len;
+
+	if (msg->buf.len)
+		strbuf_addch(&(msg->buf), '\n');
+
+	if (get_sha1(arg, object))
+		die("Failed to resolve '%s' as a valid ref.", arg);
+	if (!(buf = read_sha1_file(object, &type, &len)) || !len) {
+		free(buf);
+		die("Failed to read object '%s'.", arg);;
+	}
+	strbuf_add(&(msg->buf), buf, len);
+	free(buf);
+
+	msg->given = 1;
+	return 0;
+}
+
+static int parse_reedit_arg(const struct option *opt, const char *arg, int unset)
+{
+	struct msg_arg *msg = opt->value;
+	msg->use_editor = 1;
+	return parse_reuse_arg(opt, arg, unset);
+}
+
+int commit_notes(struct notes_tree *t, const char *msg)
+{
+	struct commit_list *parent;
+	unsigned char tree_sha1[20], prev_commit[20], new_commit[20];
+	struct strbuf buf = STRBUF_INIT;
+
+	if (!t)
+		t = &default_notes_tree;
+	if (!t->initialized || !t->ref || !*t->ref)
+		die("Cannot commit uninitialized/unreferenced notes tree");
+
+	/* Prepare commit message and reflog message */
+	strbuf_addstr(&buf, "notes: "); /* commit message starts at index 7 */
+	strbuf_addstr(&buf, msg);
+	if (buf.buf[buf.len - 1] != '\n')
+		strbuf_addch(&buf, '\n'); /* Make sure msg ends with newline */
+
+	/* Convert notes tree to tree object */
+	if (write_notes_tree(t, tree_sha1))
+		die("Failed to write current notes tree to database");
+
+	/* Create new commit for the tree object */
+	if (!read_ref(t->ref, prev_commit)) { /* retrieve parent commit */
+		parent = xmalloc(sizeof(*parent));
+		parent->item = lookup_commit(prev_commit);
+		parent->next = NULL;
+	} else {
+		hashclr(prev_commit);
+		parent = NULL;
+	}
+	if (commit_tree(buf.buf + 7, tree_sha1, parent, new_commit, NULL))
+		die("Failed to commit notes tree to database");
+
+	/* Update notes ref with new commit */
+	update_ref(buf.buf, t->ref, new_commit, prev_commit, 0, DIE_ON_ERR);
+
+	strbuf_release(&buf);
+	return 0;
+}
+
+int cmd_notes(int argc, const char **argv, const char *prefix)
+{
+	struct notes_tree *t;
+	unsigned char object[20], from_obj[20], new_note[20];
+	const unsigned char *note;
+	const char *object_ref;
+	char logmsg[100];
+
+	int list = 0, add = 0, copy = 0, append = 0, edit = 0, show = 0,
+	    remove = 0, prune = 0, force = 0;
+	int given_object = 0, i = 1, retval = 0;
+	struct msg_arg msg = { 0, 0, STRBUF_INIT };
+	struct option options[] = {
+		OPT_GROUP("Notes contents options"),
+		{ OPTION_CALLBACK, 'm', "message", &msg, "MSG",
+			"note contents as a string", PARSE_OPT_NONEG,
+			parse_msg_arg},
+		{ OPTION_CALLBACK, 'F', "file", &msg, "FILE",
+			"note contents in a file", PARSE_OPT_NONEG,
+			parse_file_arg},
+		{ OPTION_CALLBACK, 'c', "reedit-message", &msg, "OBJECT",
+			"reuse and edit specified note object", PARSE_OPT_NONEG,
+			parse_reedit_arg},
+		{ OPTION_CALLBACK, 'C', "reuse-message", &msg, "OBJECT",
+			"reuse specified note object", PARSE_OPT_NONEG,
+			parse_reuse_arg},
+		OPT_GROUP("Other options"),
+		OPT_BOOLEAN('f', "force", &force, "replace existing notes"),
+		OPT_END()
+	};
+
+	git_config(git_default_config, NULL);
+
+	argc = parse_options(argc, argv, prefix, options, git_notes_usage, 0);
+
+	if (argc && !strcmp(argv[0], "list"))
+		list = 1;
+	else if (argc && !strcmp(argv[0], "add"))
+		add = 1;
+	else if (argc && !strcmp(argv[0], "copy"))
+		copy = 1;
+	else if (argc && !strcmp(argv[0], "append"))
+		append = 1;
+	else if (argc && !strcmp(argv[0], "edit"))
+		edit = 1;
+	else if (argc && !strcmp(argv[0], "show"))
+		show = 1;
+	else if (argc && !strcmp(argv[0], "remove"))
+		remove = 1;
+	else if (argc && !strcmp(argv[0], "prune"))
+		prune = 1;
+	else if (!argc) {
+		list = 1; /* Default to 'list' if no other subcommand given */
+		i = 0;
+	}
+
+	if (list + add + copy + append + edit + show + remove + prune != 1)
+		usage_with_options(git_notes_usage, options);
+
+	if (msg.given && !(add || append || edit)) {
+		error("cannot use -m/-F/-c/-C options with %s subcommand.",
+		      argv[0]);
+		usage_with_options(git_notes_usage, options);
+	}
+
+	if (msg.given && edit) {
+		fprintf(stderr, "The -m/-F/-c/-C options have been deprecated "
+			"for the 'edit' subcommand.\n"
+			"Please use 'git notes add -f -m/-F/-c/-C' instead.\n");
+	}
+
+	if (force && !(add || copy)) {
+		error("cannot use -f option with %s subcommand.", argv[0]);
+		usage_with_options(git_notes_usage, options);
+	}
+
+	if (copy) {
+		const char *from_ref;
+		if (argc < 3) {
+			error("too few parameters");
+			usage_with_options(git_notes_usage, options);
+		}
+		from_ref = argv[i++];
+		if (get_sha1(from_ref, from_obj))
+			die("Failed to resolve '%s' as a valid ref.", from_ref);
+	}
+
+	given_object = argc > i;
+	object_ref = given_object ? argv[i++] : "HEAD";
+
+	if (argc > i || (prune && given_object)) {
+		error("too many parameters");
+		usage_with_options(git_notes_usage, options);
+	}
+
+	if (get_sha1(object_ref, object))
+		die("Failed to resolve '%s' as a valid ref.", object_ref);
+
+	init_notes(NULL, NULL, NULL, 0);
+	t = &default_notes_tree;
+
+	if (prefixcmp(t->ref, "refs/notes/"))
+		die("Refusing to %s notes in %s (outside of refs/notes/)",
+		    argv[0], t->ref);
+
+	note = get_note(t, object);
+
+	/* list command */
+
+	if (list) {
+		if (given_object) {
+			if (note) {
+				puts(sha1_to_hex(note));
+				goto end;
+			}
+		} else {
+			retval = for_each_note(t, 0, list_each_note, NULL);
+			goto end;
+		}
+	}
+
+	/* show command */
+
+	if ((list || show) && !note) {
+		error("No note found for object %s.", sha1_to_hex(object));
+		retval = 1;
+		goto end;
+	} else if (show) {
+		const char *show_args[3] = {"show", sha1_to_hex(note), NULL};
+		retval = execv_git_cmd(show_args);
+		goto end;
+	}
+
+	/* add/append/edit/remove/prune command */
+
+	if ((add || copy) && note) {
+		if (!force) {
+			error("Cannot %s notes. Found existing notes for object"
+			      " %s. Use '-f' to overwrite existing notes",
+			      argv[0], sha1_to_hex(object));
+			retval = 1;
+			goto end;
+		}
+		fprintf(stderr, "Overwriting existing notes for object %s\n",
+			sha1_to_hex(object));
+	}
+
+	if (remove) {
+		msg.given = 1;
+		msg.use_editor = 0;
+		strbuf_reset(&(msg.buf));
+	}
+
+	if (prune) {
+		hashclr(new_note);
+		prune_notes(t);
+		goto commit;
+	} else if (copy) {
+		const unsigned char *from_note = get_note(t, from_obj);
+		if (!from_note) {
+			error("Missing notes on source object %s. Cannot copy.",
+			      sha1_to_hex(from_obj));
+			retval = 1;
+			goto end;
+		}
+		hashcpy(new_note, from_note);
+	} else
+		create_note(object, &msg, append, note, new_note);
+
+	if (is_null_sha1(new_note))
+		remove_note(t, object);
+	else
+		add_note(t, object, new_note, combine_notes_overwrite);
+
+commit:
+	snprintf(logmsg, sizeof(logmsg), "Notes %s by 'git notes %s'",
+		 is_null_sha1(new_note) ? "removed" : "added", argv[0]);
+	commit_notes(t, logmsg);
+
+end:
+	free_notes(t);
+	strbuf_release(&(msg.buf));
+	return retval;
+}
diff --git a/git-notes.sh b/contrib/examples/git-notes.sh
index e642e47d9f..e642e47d9f 100755
--- a/git-notes.sh
+++ b/contrib/examples/git-notes.sh
diff --git a/git.c b/git.c
index f09948eed9..6bae30545b 100644
--- a/git.c
+++ b/git.c
@@ -346,6 +346,7 @@ static void handle_internal_command(int argc, const char **argv)
 		{ "mktree", cmd_mktree, RUN_SETUP },
 		{ "mv", cmd_mv, RUN_SETUP | NEED_WORK_TREE },
 		{ "name-rev", cmd_name_rev, RUN_SETUP },
+		{ "notes", cmd_notes, RUN_SETUP },
 		{ "pack-objects", cmd_pack_objects, RUN_SETUP },
 		{ "pack-redundant", cmd_pack_redundant, RUN_SETUP },
 		{ "patch-id", cmd_patch_id },
diff --git a/notes.c b/notes.c
index 023adce982..a4f9926d4d 100644
--- a/notes.c
+++ b/notes.c
@@ -1,7 +1,7 @@
 #include "cache.h"
-#include "commit.h"
 #include "notes.h"
-#include "refs.h"
+#include "blob.h"
+#include "tree.h"
 #include "utf8.h"
 #include "strbuf.h"
 #include "tree-walk.h"
@@ -25,10 +25,10 @@ struct int_node {
 /*
  * Leaf nodes come in two variants, note entries and subtree entries,
  * distinguished by the LSb of the leaf node pointer (see above).
- * As a note entry, the key is the SHA1 of the referenced commit, and the
+ * As a note entry, the key is the SHA1 of the referenced object, and the
  * value is the SHA1 of the note object.
  * As a subtree entry, the key is the prefix SHA1 (w/trailing NULs) of the
- * referenced commit, using the last byte of the key to store the length of
+ * referenced object, using the last byte of the key to store the length of
  * the prefix. The value is the SHA1 of the tree object containing the notes
  * subtree.
  */
@@ -37,6 +37,21 @@ struct leaf_node {
 	unsigned char val_sha1[20];
 };
 
+/*
+ * A notes tree may contain entries that are not notes, and that do not follow
+ * the naming conventions of notes. There are typically none/few of these, but
+ * we still need to keep track of them. Keep a simple linked list sorted alpha-
+ * betically on the non-note path. The list is populated when parsing tree
+ * objects in load_subtree(), and the non-notes are correctly written back into
+ * the tree objects produced by write_notes_tree().
+ */
+struct non_note {
+	struct non_note *next; /* grounded (last->next == NULL) */
+	char *path;
+	unsigned int mode;
+	unsigned char sha1[20];
+};
+
 #define PTR_TYPE_NULL     0
 #define PTR_TYPE_INTERNAL 1
 #define PTR_TYPE_NOTE     2
@@ -46,17 +61,15 @@ struct leaf_node {
 #define CLR_PTR_TYPE(ptr)       ((void *) ((uintptr_t) (ptr) & ~3))
 #define SET_PTR_TYPE(ptr, type) ((void *) ((uintptr_t) (ptr) | (type)))
 
-#define GET_NIBBLE(n, sha1) (((sha1[n >> 1]) >> ((~n & 0x01) << 2)) & 0x0f)
+#define GET_NIBBLE(n, sha1) (((sha1[(n) >> 1]) >> ((~(n) & 0x01) << 2)) & 0x0f)
 
 #define SUBTREE_SHA1_PREFIXCMP(key_sha1, subtree_sha1) \
 	(memcmp(key_sha1, subtree_sha1, subtree_sha1[19]))
 
-static struct int_node root_node;
+struct notes_tree default_notes_tree;
 
-static int initialized;
-
-static void load_subtree(struct leaf_node *subtree, struct int_node *node,
-		unsigned int n);
+static void load_subtree(struct notes_tree *t, struct leaf_node *subtree,
+		struct int_node *node, unsigned int n);
 
 /*
  * Search the tree until the appropriate location for the given key is found:
@@ -73,7 +86,7 @@ static void load_subtree(struct leaf_node *subtree, struct int_node *node,
  *      - an unused leaf node (NULL)
  *      In any case, set *tree and *n, and return pointer to the tree location.
  */
-static void **note_tree_search(struct int_node **tree,
+static void **note_tree_search(struct notes_tree *t, struct int_node **tree,
 		unsigned char *n, const unsigned char *key_sha1)
 {
 	struct leaf_node *l;
@@ -85,27 +98,27 @@ static void **note_tree_search(struct int_node **tree,
 		if (!SUBTREE_SHA1_PREFIXCMP(key_sha1, l->key_sha1)) {
 			/* unpack tree and resume search */
 			(*tree)->a[0] = NULL;
-			load_subtree(l, *tree, *n);
+			load_subtree(t, l, *tree, *n);
 			free(l);
-			return note_tree_search(tree, n, key_sha1);
+			return note_tree_search(t, tree, n, key_sha1);
 		}
 	}
 
 	i = GET_NIBBLE(*n, key_sha1);
 	p = (*tree)->a[i];
-	switch(GET_PTR_TYPE(p)) {
+	switch (GET_PTR_TYPE(p)) {
 	case PTR_TYPE_INTERNAL:
 		*tree = CLR_PTR_TYPE(p);
 		(*n)++;
-		return note_tree_search(tree, n, key_sha1);
+		return note_tree_search(t, tree, n, key_sha1);
 	case PTR_TYPE_SUBTREE:
 		l = (struct leaf_node *) CLR_PTR_TYPE(p);
 		if (!SUBTREE_SHA1_PREFIXCMP(key_sha1, l->key_sha1)) {
 			/* unpack tree and resume search */
 			(*tree)->a[i] = NULL;
-			load_subtree(l, *tree, *n);
+			load_subtree(t, l, *tree, *n);
 			free(l);
-			return note_tree_search(tree, n, key_sha1);
+			return note_tree_search(t, tree, n, key_sha1);
 		}
 		/* fall through */
 	default:
@@ -118,10 +131,11 @@ static void **note_tree_search(struct int_node **tree,
  * Search to the tree location appropriate for the given key:
  * If a note entry with matching key, return the note entry, else return NULL.
  */
-static struct leaf_node *note_tree_find(struct int_node *tree, unsigned char n,
+static struct leaf_node *note_tree_find(struct notes_tree *t,
+		struct int_node *tree, unsigned char n,
 		const unsigned char *key_sha1)
 {
-	void **p = note_tree_search(&tree, &n, key_sha1);
+	void **p = note_tree_search(t, &tree, &n, key_sha1);
 	if (GET_PTR_TYPE(*p) == PTR_TYPE_NOTE) {
 		struct leaf_node *l = (struct leaf_node *) CLR_PTR_TYPE(*p);
 		if (!hashcmp(key_sha1, l->key_sha1))
@@ -130,55 +144,12 @@ static struct leaf_node *note_tree_find(struct int_node *tree, unsigned char n,
 	return NULL;
 }
 
-/* Create a new blob object by concatenating the two given blob objects */
-static int concatenate_notes(unsigned char *cur_sha1,
-		const unsigned char *new_sha1)
-{
-	char *cur_msg, *new_msg, *buf;
-	unsigned long cur_len, new_len, buf_len;
-	enum object_type cur_type, new_type;
-	int ret;
-
-	/* read in both note blob objects */
-	new_msg = read_sha1_file(new_sha1, &new_type, &new_len);
-	if (!new_msg || !new_len || new_type != OBJ_BLOB) {
-		free(new_msg);
-		return 0;
-	}
-	cur_msg = read_sha1_file(cur_sha1, &cur_type, &cur_len);
-	if (!cur_msg || !cur_len || cur_type != OBJ_BLOB) {
-		free(cur_msg);
-		free(new_msg);
-		hashcpy(cur_sha1, new_sha1);
-		return 0;
-	}
-
-	/* we will separate the notes by a newline anyway */
-	if (cur_msg[cur_len - 1] == '\n')
-		cur_len--;
-
-	/* concatenate cur_msg and new_msg into buf */
-	buf_len = cur_len + 1 + new_len;
-	buf = (char *) xmalloc(buf_len);
-	memcpy(buf, cur_msg, cur_len);
-	buf[cur_len] = '\n';
-	memcpy(buf + cur_len + 1, new_msg, new_len);
-
-	free(cur_msg);
-	free(new_msg);
-
-	/* create a new blob object from buf */
-	ret = write_sha1_file(buf, buf_len, "blob", cur_sha1);
-	free(buf);
-	return ret;
-}
-
 /*
  * To insert a leaf_node:
  * Search to the tree location appropriate for the given leaf_node's key:
  * - If location is unused (NULL), store the tweaked pointer directly there
  * - If location holds a note entry that matches the note-to-be-inserted, then
- *   concatenate the two notes.
+ *   combine the two notes (by calling the given combine_notes function).
  * - If location holds a note entry that matches the subtree-to-be-inserted,
  *   then unpack the subtree-to-be-inserted into the location.
  * - If location holds a matching subtree entry, unpack the subtree at that
@@ -186,16 +157,17 @@ static int concatenate_notes(unsigned char *cur_sha1,
  * - Else, create a new int_node, holding both the node-at-location and the
  *   node-to-be-inserted, and store the new int_node into the location.
  */
-static void note_tree_insert(struct int_node *tree, unsigned char n,
-		struct leaf_node *entry, unsigned char type)
+static void note_tree_insert(struct notes_tree *t, struct int_node *tree,
+		unsigned char n, struct leaf_node *entry, unsigned char type,
+		combine_notes_fn combine_notes)
 {
 	struct int_node *new_node;
 	struct leaf_node *l;
-	void **p = note_tree_search(&tree, &n, entry->key_sha1);
+	void **p = note_tree_search(t, &tree, &n, entry->key_sha1);
 
 	assert(GET_PTR_TYPE(entry) == 0); /* no type bits set */
 	l = (struct leaf_node *) CLR_PTR_TYPE(*p);
-	switch(GET_PTR_TYPE(*p)) {
+	switch (GET_PTR_TYPE(*p)) {
 	case PTR_TYPE_NULL:
 		assert(!*p);
 		*p = SET_PTR_TYPE(entry, type);
@@ -208,12 +180,11 @@ static void note_tree_insert(struct int_node *tree, unsigned char n,
 				if (!hashcmp(l->val_sha1, entry->val_sha1))
 					return;
 
-				if (concatenate_notes(l->val_sha1,
-						entry->val_sha1))
-					die("failed to concatenate note %s "
-					    "into note %s for commit %s",
-					    sha1_to_hex(entry->val_sha1),
+				if (combine_notes(l->val_sha1, entry->val_sha1))
+					die("failed to combine notes %s and %s"
+					    " for object %s",
 					    sha1_to_hex(l->val_sha1),
+					    sha1_to_hex(entry->val_sha1),
 					    sha1_to_hex(l->key_sha1));
 				free(entry);
 				return;
@@ -223,7 +194,7 @@ static void note_tree_insert(struct int_node *tree, unsigned char n,
 			if (!SUBTREE_SHA1_PREFIXCMP(l->key_sha1,
 						    entry->key_sha1)) {
 				/* unpack 'entry' */
-				load_subtree(entry, tree, n);
+				load_subtree(t, entry, tree, n);
 				free(entry);
 				return;
 			}
@@ -234,9 +205,10 @@ static void note_tree_insert(struct int_node *tree, unsigned char n,
 		if (!SUBTREE_SHA1_PREFIXCMP(entry->key_sha1, l->key_sha1)) {
 			/* unpack 'l' and restart insert */
 			*p = NULL;
-			load_subtree(l, tree, n);
+			load_subtree(t, l, tree, n);
 			free(l);
-			note_tree_insert(tree, n, entry, type);
+			note_tree_insert(t, tree, n, entry, type,
+					 combine_notes);
 			return;
 		}
 		break;
@@ -246,9 +218,83 @@ static void note_tree_insert(struct int_node *tree, unsigned char n,
 	assert(GET_PTR_TYPE(*p) == PTR_TYPE_NOTE ||
 	       GET_PTR_TYPE(*p) == PTR_TYPE_SUBTREE);
 	new_node = (struct int_node *) xcalloc(sizeof(struct int_node), 1);
-	note_tree_insert(new_node, n + 1, l, GET_PTR_TYPE(*p));
+	note_tree_insert(t, new_node, n + 1, l, GET_PTR_TYPE(*p),
+			 combine_notes);
 	*p = SET_PTR_TYPE(new_node, PTR_TYPE_INTERNAL);
-	note_tree_insert(new_node, n + 1, entry, type);
+	note_tree_insert(t, new_node, n + 1, entry, type, combine_notes);
+}
+
+/*
+ * How to consolidate an int_node:
+ * If there are > 1 non-NULL entries, give up and return non-zero.
+ * Otherwise replace the int_node at the given index in the given parent node
+ * with the only entry (or a NULL entry if no entries) from the given tree,
+ * and return 0.
+ */
+static int note_tree_consolidate(struct int_node *tree,
+	struct int_node *parent, unsigned char index)
+{
+	unsigned int i;
+	void *p = NULL;
+
+	assert(tree && parent);
+	assert(CLR_PTR_TYPE(parent->a[index]) == tree);
+
+	for (i = 0; i < 16; i++) {
+		if (GET_PTR_TYPE(tree->a[i]) != PTR_TYPE_NULL) {
+			if (p) /* more than one entry */
+				return -2;
+			p = tree->a[i];
+		}
+	}
+
+	/* replace tree with p in parent[index] */
+	parent->a[index] = p;
+	free(tree);
+	return 0;
+}
+
+/*
+ * To remove a leaf_node:
+ * Search to the tree location appropriate for the given leaf_node's key:
+ * - If location does not hold a matching entry, abort and do nothing.
+ * - Replace the matching leaf_node with a NULL entry (and free the leaf_node).
+ * - Consolidate int_nodes repeatedly, while walking up the tree towards root.
+ */
+static void note_tree_remove(struct notes_tree *t, struct int_node *tree,
+		unsigned char n, struct leaf_node *entry)
+{
+	struct leaf_node *l;
+	struct int_node *parent_stack[20];
+	unsigned char i, j;
+	void **p = note_tree_search(t, &tree, &n, entry->key_sha1);
+
+	assert(GET_PTR_TYPE(entry) == 0); /* no type bits set */
+	if (GET_PTR_TYPE(*p) != PTR_TYPE_NOTE)
+		return; /* type mismatch, nothing to remove */
+	l = (struct leaf_node *) CLR_PTR_TYPE(*p);
+	if (hashcmp(l->key_sha1, entry->key_sha1))
+		return; /* key mismatch, nothing to remove */
+
+	/* we have found a matching entry */
+	free(l);
+	*p = SET_PTR_TYPE(NULL, PTR_TYPE_NULL);
+
+	/* consolidate this tree level, and parent levels, if possible */
+	if (!n)
+		return; /* cannot consolidate top level */
+	/* first, build stack of ancestors between root and current node */
+	parent_stack[0] = t->root;
+	for (i = 0; i < n; i++) {
+		j = GET_NIBBLE(i, entry->key_sha1);
+		parent_stack[i + 1] = CLR_PTR_TYPE(parent_stack[i]->a[j]);
+	}
+	assert(i == n && parent_stack[i] == tree);
+	/* next, unwind stack until note_tree_consolidate() is done */
+	while (i > 0 &&
+	       !note_tree_consolidate(parent_stack[i], parent_stack[i - 1],
+				      GET_NIBBLE(i - 1, entry->key_sha1)))
+		i--;
 }
 
 /* Free the entire notes data contained in the given tree */
@@ -257,7 +303,7 @@ static void note_tree_free(struct int_node *tree)
 	unsigned int i;
 	for (i = 0; i < 16; i++) {
 		void *p = tree->a[i];
-		switch(GET_PTR_TYPE(p)) {
+		switch (GET_PTR_TYPE(p)) {
 		case PTR_TYPE_INTERNAL:
 			note_tree_free(CLR_PTR_TYPE(p));
 			/* fall through */
@@ -274,7 +320,7 @@ static void note_tree_free(struct int_node *tree)
  * - hex_len  - Length of above segment. Must be multiple of 2 between 0 and 40
  * - sha1     - Partial SHA1 value is written here
  * - sha1_len - Max #bytes to store in sha1, Must be >= hex_len / 2, and < 20
- * Returns -1 on error (invalid arguments or invalid SHA1 (not in hex format).
+ * Returns -1 on error (invalid arguments or invalid SHA1 (not in hex format)).
  * Otherwise, returns number of bytes written to sha1 (i.e. hex_len / 2).
  * Pads sha1 with NULs up to sha1_len (not included in returned length).
  */
@@ -296,14 +342,67 @@ static int get_sha1_hex_segment(const char *hex, unsigned int hex_len,
 	return len;
 }
 
-static void load_subtree(struct leaf_node *subtree, struct int_node *node,
-		unsigned int n)
+static int non_note_cmp(const struct non_note *a, const struct non_note *b)
+{
+	return strcmp(a->path, b->path);
+}
+
+static void add_non_note(struct notes_tree *t, const char *path,
+		unsigned int mode, const unsigned char *sha1)
+{
+	struct non_note *p = t->prev_non_note, *n;
+	n = (struct non_note *) xmalloc(sizeof(struct non_note));
+	n->next = NULL;
+	n->path = xstrdup(path);
+	n->mode = mode;
+	hashcpy(n->sha1, sha1);
+	t->prev_non_note = n;
+
+	if (!t->first_non_note) {
+		t->first_non_note = n;
+		return;
+	}
+
+	if (non_note_cmp(p, n) < 0)
+		; /* do nothing  */
+	else if (non_note_cmp(t->first_non_note, n) <= 0)
+		p = t->first_non_note;
+	else {
+		/* n sorts before t->first_non_note */
+		n->next = t->first_non_note;
+		t->first_non_note = n;
+		return;
+	}
+
+	/* n sorts equal or after p */
+	while (p->next && non_note_cmp(p->next, n) <= 0)
+		p = p->next;
+
+	if (non_note_cmp(p, n) == 0) { /* n ~= p; overwrite p with n */
+		assert(strcmp(p->path, n->path) == 0);
+		p->mode = n->mode;
+		hashcpy(p->sha1, n->sha1);
+		free(n);
+		t->prev_non_note = p;
+		return;
+	}
+
+	/* n sorts between p and p->next */
+	n->next = p->next;
+	p->next = n;
+}
+
+static void load_subtree(struct notes_tree *t, struct leaf_node *subtree,
+		struct int_node *node, unsigned int n)
 {
-	unsigned char commit_sha1[20];
+	unsigned char object_sha1[20];
 	unsigned int prefix_len;
 	void *buf;
 	struct tree_desc desc;
 	struct name_entry entry;
+	int len, path_len;
+	unsigned char type;
+	struct leaf_node *l;
 
 	buf = fill_tree_descriptor(&desc, subtree->val_sha1);
 	if (!buf)
@@ -312,86 +411,588 @@ static void load_subtree(struct leaf_node *subtree, struct int_node *node,
 
 	prefix_len = subtree->key_sha1[19];
 	assert(prefix_len * 2 >= n);
-	memcpy(commit_sha1, subtree->key_sha1, prefix_len);
+	memcpy(object_sha1, subtree->key_sha1, prefix_len);
 	while (tree_entry(&desc, &entry)) {
-		int len = get_sha1_hex_segment(entry.path, strlen(entry.path),
-				commit_sha1 + prefix_len, 20 - prefix_len);
+		path_len = strlen(entry.path);
+		len = get_sha1_hex_segment(entry.path, path_len,
+				object_sha1 + prefix_len, 20 - prefix_len);
 		if (len < 0)
-			continue; /* entry.path is not a SHA1 sum. Skip */
+			goto handle_non_note; /* entry.path is not a SHA1 */
 		len += prefix_len;
 
 		/*
-		 * If commit SHA1 is complete (len == 20), assume note object
-		 * If commit SHA1 is incomplete (len < 20), assume note subtree
+		 * If object SHA1 is complete (len == 20), assume note object
+		 * If object SHA1 is incomplete (len < 20), and current
+		 * component consists of 2 hex chars, assume note subtree
 		 */
 		if (len <= 20) {
-			unsigned char type = PTR_TYPE_NOTE;
-			struct leaf_node *l = (struct leaf_node *)
+			type = PTR_TYPE_NOTE;
+			l = (struct leaf_node *)
 				xcalloc(sizeof(struct leaf_node), 1);
-			hashcpy(l->key_sha1, commit_sha1);
+			hashcpy(l->key_sha1, object_sha1);
 			hashcpy(l->val_sha1, entry.sha1);
 			if (len < 20) {
-				if (!S_ISDIR(entry.mode))
-					continue; /* entry cannot be subtree */
+				if (!S_ISDIR(entry.mode) || path_len != 2)
+					goto handle_non_note; /* not subtree */
 				l->key_sha1[19] = (unsigned char) len;
 				type = PTR_TYPE_SUBTREE;
 			}
-			note_tree_insert(node, n, l, type);
+			note_tree_insert(t, node, n, l, type,
+					 combine_notes_concatenate);
+		}
+		continue;
+
+handle_non_note:
+		/*
+		 * Determine full path for this non-note entry:
+		 * The filename is already found in entry.path, but the
+		 * directory part of the path must be deduced from the subtree
+		 * containing this entry. We assume here that the overall notes
+		 * tree follows a strict byte-based progressive fanout
+		 * structure (i.e. using 2/38, 2/2/36, etc. fanouts, and not
+		 * e.g. 4/36 fanout). This means that if a non-note is found at
+		 * path "dead/beef", the following code will register it as
+		 * being found on "de/ad/beef".
+		 * On the other hand, if you use such non-obvious non-note
+		 * paths in the middle of a notes tree, you deserve what's
+		 * coming to you ;). Note that for non-notes that are not
+		 * SHA1-like at the top level, there will be no problems.
+		 *
+		 * To conclude, it is strongly advised to make sure non-notes
+		 * have at least one non-hex character in the top-level path
+		 * component.
+		 */
+		{
+			char non_note_path[PATH_MAX];
+			char *p = non_note_path;
+			const char *q = sha1_to_hex(subtree->key_sha1);
+			int i;
+			for (i = 0; i < prefix_len; i++) {
+				*p++ = *q++;
+				*p++ = *q++;
+				*p++ = '/';
+			}
+			strcpy(p, entry.path);
+			add_non_note(t, non_note_path, entry.mode, entry.sha1);
 		}
 	}
 	free(buf);
 }
 
-static void initialize_notes(const char *notes_ref_name)
+/*
+ * Determine optimal on-disk fanout for this part of the notes tree
+ *
+ * Given a (sub)tree and the level in the internal tree structure, determine
+ * whether or not the given existing fanout should be expanded for this
+ * (sub)tree.
+ *
+ * Values of the 'fanout' variable:
+ * - 0: No fanout (all notes are stored directly in the root notes tree)
+ * - 1: 2/38 fanout
+ * - 2: 2/2/36 fanout
+ * - 3: 2/2/2/34 fanout
+ * etc.
+ */
+static unsigned char determine_fanout(struct int_node *tree, unsigned char n,
+		unsigned char fanout)
 {
-	unsigned char sha1[20], commit_sha1[20];
+	/*
+	 * The following is a simple heuristic that works well in practice:
+	 * For each even-numbered 16-tree level (remember that each on-disk
+	 * fanout level corresponds to _two_ 16-tree levels), peek at all 16
+	 * entries at that tree level. If all of them are either int_nodes or
+	 * subtree entries, then there are likely plenty of notes below this
+	 * level, so we return an incremented fanout.
+	 */
+	unsigned int i;
+	if ((n % 2) || (n > 2 * fanout))
+		return fanout;
+	for (i = 0; i < 16; i++) {
+		switch (GET_PTR_TYPE(tree->a[i])) {
+		case PTR_TYPE_SUBTREE:
+		case PTR_TYPE_INTERNAL:
+			continue;
+		default:
+			return fanout;
+		}
+	}
+	return fanout + 1;
+}
+
+static void construct_path_with_fanout(const unsigned char *sha1,
+		unsigned char fanout, char *path)
+{
+	unsigned int i = 0, j = 0;
+	const char *hex_sha1 = sha1_to_hex(sha1);
+	assert(fanout < 20);
+	while (fanout) {
+		path[i++] = hex_sha1[j++];
+		path[i++] = hex_sha1[j++];
+		path[i++] = '/';
+		fanout--;
+	}
+	strcpy(path + i, hex_sha1 + j);
+}
+
+static int for_each_note_helper(struct notes_tree *t, struct int_node *tree,
+		unsigned char n, unsigned char fanout, int flags,
+		each_note_fn fn, void *cb_data)
+{
+	unsigned int i;
+	void *p;
+	int ret = 0;
+	struct leaf_node *l;
+	static char path[40 + 19 + 1];  /* hex SHA1 + 19 * '/' + NUL */
+
+	fanout = determine_fanout(tree, n, fanout);
+	for (i = 0; i < 16; i++) {
+redo:
+		p = tree->a[i];
+		switch (GET_PTR_TYPE(p)) {
+		case PTR_TYPE_INTERNAL:
+			/* recurse into int_node */
+			ret = for_each_note_helper(t, CLR_PTR_TYPE(p), n + 1,
+				fanout, flags, fn, cb_data);
+			break;
+		case PTR_TYPE_SUBTREE:
+			l = (struct leaf_node *) CLR_PTR_TYPE(p);
+			/*
+			 * Subtree entries in the note tree represent parts of
+			 * the note tree that have not yet been explored. There
+			 * is a direct relationship between subtree entries at
+			 * level 'n' in the tree, and the 'fanout' variable:
+			 * Subtree entries at level 'n <= 2 * fanout' should be
+			 * preserved, since they correspond exactly to a fanout
+			 * directory in the on-disk structure. However, subtree
+			 * entries at level 'n > 2 * fanout' should NOT be
+			 * preserved, but rather consolidated into the above
+			 * notes tree level. We achieve this by unconditionally
+			 * unpacking subtree entries that exist below the
+			 * threshold level at 'n = 2 * fanout'.
+			 */
+			if (n <= 2 * fanout &&
+			    flags & FOR_EACH_NOTE_YIELD_SUBTREES) {
+				/* invoke callback with subtree */
+				unsigned int path_len =
+					l->key_sha1[19] * 2 + fanout;
+				assert(path_len < 40 + 19);
+				construct_path_with_fanout(l->key_sha1, fanout,
+							   path);
+				/* Create trailing slash, if needed */
+				if (path[path_len - 1] != '/')
+					path[path_len++] = '/';
+				path[path_len] = '\0';
+				ret = fn(l->key_sha1, l->val_sha1, path,
+					 cb_data);
+			}
+			if (n > fanout * 2 ||
+			    !(flags & FOR_EACH_NOTE_DONT_UNPACK_SUBTREES)) {
+				/* unpack subtree and resume traversal */
+				tree->a[i] = NULL;
+				load_subtree(t, l, tree, n);
+				free(l);
+				goto redo;
+			}
+			break;
+		case PTR_TYPE_NOTE:
+			l = (struct leaf_node *) CLR_PTR_TYPE(p);
+			construct_path_with_fanout(l->key_sha1, fanout, path);
+			ret = fn(l->key_sha1, l->val_sha1, path, cb_data);
+			break;
+		}
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
+struct tree_write_stack {
+	struct tree_write_stack *next;
+	struct strbuf buf;
+	char path[2]; /* path to subtree in next, if any */
+};
+
+static inline int matches_tree_write_stack(struct tree_write_stack *tws,
+		const char *full_path)
+{
+	return  full_path[0] == tws->path[0] &&
+		full_path[1] == tws->path[1] &&
+		full_path[2] == '/';
+}
+
+static void write_tree_entry(struct strbuf *buf, unsigned int mode,
+		const char *path, unsigned int path_len, const
+		unsigned char *sha1)
+{
+	strbuf_addf(buf, "%o %.*s%c", mode, path_len, path, '\0');
+	strbuf_add(buf, sha1, 20);
+}
+
+static void tree_write_stack_init_subtree(struct tree_write_stack *tws,
+		const char *path)
+{
+	struct tree_write_stack *n;
+	assert(!tws->next);
+	assert(tws->path[0] == '\0' && tws->path[1] == '\0');
+	n = (struct tree_write_stack *)
+		xmalloc(sizeof(struct tree_write_stack));
+	n->next = NULL;
+	strbuf_init(&n->buf, 256 * (32 + 40)); /* assume 256 entries per tree */
+	n->path[0] = n->path[1] = '\0';
+	tws->next = n;
+	tws->path[0] = path[0];
+	tws->path[1] = path[1];
+}
+
+static int tree_write_stack_finish_subtree(struct tree_write_stack *tws)
+{
+	int ret;
+	struct tree_write_stack *n = tws->next;
+	unsigned char s[20];
+	if (n) {
+		ret = tree_write_stack_finish_subtree(n);
+		if (ret)
+			return ret;
+		ret = write_sha1_file(n->buf.buf, n->buf.len, tree_type, s);
+		if (ret)
+			return ret;
+		strbuf_release(&n->buf);
+		free(n);
+		tws->next = NULL;
+		write_tree_entry(&tws->buf, 040000, tws->path, 2, s);
+		tws->path[0] = tws->path[1] = '\0';
+	}
+	return 0;
+}
+
+static int write_each_note_helper(struct tree_write_stack *tws,
+		const char *path, unsigned int mode,
+		const unsigned char *sha1)
+{
+	size_t path_len = strlen(path);
+	unsigned int n = 0;
+	int ret;
+
+	/* Determine common part of tree write stack */
+	while (tws && 3 * n < path_len &&
+	       matches_tree_write_stack(tws, path + 3 * n)) {
+		n++;
+		tws = tws->next;
+	}
+
+	/* tws point to last matching tree_write_stack entry */
+	ret = tree_write_stack_finish_subtree(tws);
+	if (ret)
+		return ret;
+
+	/* Start subtrees needed to satisfy path */
+	while (3 * n + 2 < path_len && path[3 * n + 2] == '/') {
+		tree_write_stack_init_subtree(tws, path + 3 * n);
+		n++;
+		tws = tws->next;
+	}
+
+	/* There should be no more directory components in the given path */
+	assert(memchr(path + 3 * n, '/', path_len - (3 * n)) == NULL);
+
+	/* Finally add given entry to the current tree object */
+	write_tree_entry(&tws->buf, mode, path + 3 * n, path_len - (3 * n),
+			 sha1);
+
+	return 0;
+}
+
+struct write_each_note_data {
+	struct tree_write_stack *root;
+	struct non_note *next_non_note;
+};
+
+static int write_each_non_note_until(const char *note_path,
+		struct write_each_note_data *d)
+{
+	struct non_note *n = d->next_non_note;
+	int cmp, ret;
+	while (n && (!note_path || (cmp = strcmp(n->path, note_path)) <= 0)) {
+		if (note_path && cmp == 0)
+			; /* do nothing, prefer note to non-note */
+		else {
+			ret = write_each_note_helper(d->root, n->path, n->mode,
+						     n->sha1);
+			if (ret)
+				return ret;
+		}
+		n = n->next;
+	}
+	d->next_non_note = n;
+	return 0;
+}
+
+static int write_each_note(const unsigned char *object_sha1,
+		const unsigned char *note_sha1, char *note_path,
+		void *cb_data)
+{
+	struct write_each_note_data *d =
+		(struct write_each_note_data *) cb_data;
+	size_t note_path_len = strlen(note_path);
+	unsigned int mode = 0100644;
+
+	if (note_path[note_path_len - 1] == '/') {
+		/* subtree entry */
+		note_path_len--;
+		note_path[note_path_len] = '\0';
+		mode = 040000;
+	}
+	assert(note_path_len <= 40 + 19);
+
+	/* Weave non-note entries into note entries */
+	return  write_each_non_note_until(note_path, d) ||
+		write_each_note_helper(d->root, note_path, mode, note_sha1);
+}
+
+struct note_delete_list {
+	struct note_delete_list *next;
+	const unsigned char *sha1;
+};
+
+static int prune_notes_helper(const unsigned char *object_sha1,
+		const unsigned char *note_sha1, char *note_path,
+		void *cb_data)
+{
+	struct note_delete_list **l = (struct note_delete_list **) cb_data;
+	struct note_delete_list *n;
+
+	if (has_sha1_file(object_sha1))
+		return 0; /* nothing to do for this note */
+
+	/* failed to find object => prune this note */
+	n = (struct note_delete_list *) xmalloc(sizeof(*n));
+	n->next = *l;
+	n->sha1 = object_sha1;
+	*l = n;
+	return 0;
+}
+
+int combine_notes_concatenate(unsigned char *cur_sha1,
+		const unsigned char *new_sha1)
+{
+	char *cur_msg = NULL, *new_msg = NULL, *buf;
+	unsigned long cur_len, new_len, buf_len;
+	enum object_type cur_type, new_type;
+	int ret;
+
+	/* read in both note blob objects */
+	if (!is_null_sha1(new_sha1))
+		new_msg = read_sha1_file(new_sha1, &new_type, &new_len);
+	if (!new_msg || !new_len || new_type != OBJ_BLOB) {
+		free(new_msg);
+		return 0;
+	}
+	if (!is_null_sha1(cur_sha1))
+		cur_msg = read_sha1_file(cur_sha1, &cur_type, &cur_len);
+	if (!cur_msg || !cur_len || cur_type != OBJ_BLOB) {
+		free(cur_msg);
+		free(new_msg);
+		hashcpy(cur_sha1, new_sha1);
+		return 0;
+	}
+
+	/* we will separate the notes by a newline anyway */
+	if (cur_msg[cur_len - 1] == '\n')
+		cur_len--;
+
+	/* concatenate cur_msg and new_msg into buf */
+	buf_len = cur_len + 1 + new_len;
+	buf = (char *) xmalloc(buf_len);
+	memcpy(buf, cur_msg, cur_len);
+	buf[cur_len] = '\n';
+	memcpy(buf + cur_len + 1, new_msg, new_len);
+	free(cur_msg);
+	free(new_msg);
+
+	/* create a new blob object from buf */
+	ret = write_sha1_file(buf, buf_len, blob_type, cur_sha1);
+	free(buf);
+	return ret;
+}
+
+int combine_notes_overwrite(unsigned char *cur_sha1,
+		const unsigned char *new_sha1)
+{
+	hashcpy(cur_sha1, new_sha1);
+	return 0;
+}
+
+int combine_notes_ignore(unsigned char *cur_sha1,
+		const unsigned char *new_sha1)
+{
+	return 0;
+}
+
+void init_notes(struct notes_tree *t, const char *notes_ref,
+		combine_notes_fn combine_notes, int flags)
+{
+	unsigned char sha1[20], object_sha1[20];
 	unsigned mode;
 	struct leaf_node root_tree;
 
-	if (!notes_ref_name || read_ref(notes_ref_name, commit_sha1) ||
-	    get_tree_entry(commit_sha1, "", sha1, &mode))
+	if (!t)
+		t = &default_notes_tree;
+	assert(!t->initialized);
+
+	if (!notes_ref)
+		notes_ref = getenv(GIT_NOTES_REF_ENVIRONMENT);
+	if (!notes_ref)
+		notes_ref = notes_ref_name; /* value of core.notesRef config */
+	if (!notes_ref)
+		notes_ref = GIT_NOTES_DEFAULT_REF;
+
+	if (!combine_notes)
+		combine_notes = combine_notes_concatenate;
+
+	t->root = (struct int_node *) xcalloc(sizeof(struct int_node), 1);
+	t->first_non_note = NULL;
+	t->prev_non_note = NULL;
+	t->ref = notes_ref ? xstrdup(notes_ref) : NULL;
+	t->combine_notes = combine_notes;
+	t->initialized = 1;
+
+	if (flags & NOTES_INIT_EMPTY || !notes_ref ||
+	    read_ref(notes_ref, object_sha1))
 		return;
+	if (get_tree_entry(object_sha1, "", sha1, &mode))
+		die("Failed to read notes tree referenced by %s (%s)",
+		    notes_ref, object_sha1);
 
 	hashclr(root_tree.key_sha1);
 	hashcpy(root_tree.val_sha1, sha1);
-	load_subtree(&root_tree, &root_node, 0);
+	load_subtree(t, &root_tree, t->root, 0);
 }
 
-static unsigned char *lookup_notes(const unsigned char *commit_sha1)
+void add_note(struct notes_tree *t, const unsigned char *object_sha1,
+		const unsigned char *note_sha1, combine_notes_fn combine_notes)
 {
-	struct leaf_node *found = note_tree_find(&root_node, 0, commit_sha1);
-	if (found)
-		return found->val_sha1;
-	return NULL;
+	struct leaf_node *l;
+
+	if (!t)
+		t = &default_notes_tree;
+	assert(t->initialized);
+	if (!combine_notes)
+		combine_notes = t->combine_notes;
+	l = (struct leaf_node *) xmalloc(sizeof(struct leaf_node));
+	hashcpy(l->key_sha1, object_sha1);
+	hashcpy(l->val_sha1, note_sha1);
+	note_tree_insert(t, t->root, 0, l, PTR_TYPE_NOTE, combine_notes);
+}
+
+void remove_note(struct notes_tree *t, const unsigned char *object_sha1)
+{
+	struct leaf_node l;
+
+	if (!t)
+		t = &default_notes_tree;
+	assert(t->initialized);
+	hashcpy(l.key_sha1, object_sha1);
+	hashclr(l.val_sha1);
+	return note_tree_remove(t, t->root, 0, &l);
+}
+
+const unsigned char *get_note(struct notes_tree *t,
+		const unsigned char *object_sha1)
+{
+	struct leaf_node *found;
+
+	if (!t)
+		t = &default_notes_tree;
+	assert(t->initialized);
+	found = note_tree_find(t, t->root, 0, object_sha1);
+	return found ? found->val_sha1 : NULL;
 }
 
-void free_notes(void)
+int for_each_note(struct notes_tree *t, int flags, each_note_fn fn,
+		void *cb_data)
 {
-	note_tree_free(&root_node);
-	memset(&root_node, 0, sizeof(struct int_node));
-	initialized = 0;
+	if (!t)
+		t = &default_notes_tree;
+	assert(t->initialized);
+	return for_each_note_helper(t, t->root, 0, 0, flags, fn, cb_data);
 }
 
-void get_commit_notes(const struct commit *commit, struct strbuf *sb,
-		const char *output_encoding, int flags)
+int write_notes_tree(struct notes_tree *t, unsigned char *result)
+{
+	struct tree_write_stack root;
+	struct write_each_note_data cb_data;
+	int ret;
+
+	if (!t)
+		t = &default_notes_tree;
+	assert(t->initialized);
+
+	/* Prepare for traversal of current notes tree */
+	root.next = NULL; /* last forward entry in list is grounded */
+	strbuf_init(&root.buf, 256 * (32 + 40)); /* assume 256 entries */
+	root.path[0] = root.path[1] = '\0';
+	cb_data.root = &root;
+	cb_data.next_non_note = t->first_non_note;
+
+	/* Write tree objects representing current notes tree */
+	ret = for_each_note(t, FOR_EACH_NOTE_DONT_UNPACK_SUBTREES |
+				FOR_EACH_NOTE_YIELD_SUBTREES,
+			write_each_note, &cb_data) ||
+		write_each_non_note_until(NULL, &cb_data) ||
+		tree_write_stack_finish_subtree(&root) ||
+		write_sha1_file(root.buf.buf, root.buf.len, tree_type, result);
+	strbuf_release(&root.buf);
+	return ret;
+}
+
+void prune_notes(struct notes_tree *t)
+{
+	struct note_delete_list *l = NULL;
+
+	if (!t)
+		t = &default_notes_tree;
+	assert(t->initialized);
+
+	for_each_note(t, 0, prune_notes_helper, &l);
+
+	while (l) {
+		remove_note(t, l->sha1);
+		l = l->next;
+	}
+}
+
+void free_notes(struct notes_tree *t)
+{
+	if (!t)
+		t = &default_notes_tree;
+	if (t->root)
+		note_tree_free(t->root);
+	free(t->root);
+	while (t->first_non_note) {
+		t->prev_non_note = t->first_non_note->next;
+		free(t->first_non_note->path);
+		free(t->first_non_note);
+		t->first_non_note = t->prev_non_note;
+	}
+	free(t->ref);
+	memset(t, 0, sizeof(struct notes_tree));
+}
+
+void format_note(struct notes_tree *t, const unsigned char *object_sha1,
+		struct strbuf *sb, const char *output_encoding, int flags)
 {
 	static const char utf8[] = "utf-8";
-	unsigned char *sha1;
+	const unsigned char *sha1;
 	char *msg, *msg_p;
 	unsigned long linelen, msglen;
 	enum object_type type;
 
-	if (!initialized) {
-		const char *env = getenv(GIT_NOTES_REF_ENVIRONMENT);
-		if (env)
-			notes_ref_name = getenv(GIT_NOTES_REF_ENVIRONMENT);
-		else if (!notes_ref_name)
-			notes_ref_name = GIT_NOTES_DEFAULT_REF;
-		initialize_notes(notes_ref_name);
-		initialized = 1;
-	}
+	if (!t)
+		t = &default_notes_tree;
+	if (!t->initialized)
+		init_notes(t, NULL, NULL, 0);
 
-	sha1 = lookup_notes(commit->object.sha1);
+	sha1 = get_note(t, object_sha1);
 	if (!sha1)
 		return;
 
diff --git a/notes.h b/notes.h
index a1421e351a..bad03ccab7 100644
--- a/notes.h
+++ b/notes.h
@@ -1,13 +1,201 @@
 #ifndef NOTES_H
 #define NOTES_H
 
-/* Free (and de-initialize) the internal notes tree structure */
-void free_notes(void);
+/*
+ * Function type for combining two notes annotating the same object.
+ *
+ * When adding a new note annotating the same object as an existing note, it is
+ * up to the caller to decide how to combine the two notes. The decision is
+ * made by passing in a function of the following form. The function accepts
+ * two SHA1s -- of the existing note and the new note, respectively. The
+ * function then combines the notes in whatever way it sees fit, and writes the
+ * resulting SHA1 into the first SHA1 argument (cur_sha1). A non-zero return
+ * value indicates failure.
+ *
+ * The two given SHA1s must both be non-NULL and different from each other.
+ *
+ * The default combine_notes function (you get this when passing NULL) is
+ * combine_notes_concatenate(), which appends the contents of the new note to
+ * the contents of the existing note.
+ */
+typedef int combine_notes_fn(unsigned char *cur_sha1, const unsigned char *new_sha1);
 
+/* Common notes combinators */
+int combine_notes_concatenate(unsigned char *cur_sha1, const unsigned char *new_sha1);
+int combine_notes_overwrite(unsigned char *cur_sha1, const unsigned char *new_sha1);
+int combine_notes_ignore(unsigned char *cur_sha1, const unsigned char *new_sha1);
+
+/*
+ * Notes tree object
+ *
+ * Encapsulates the internal notes tree structure associated with a notes ref.
+ * Whenever a struct notes_tree pointer is required below, you may pass NULL in
+ * order to use the default/internal notes tree. E.g. you only need to pass a
+ * non-NULL value if you need to refer to several different notes trees
+ * simultaneously.
+ */
+extern struct notes_tree {
+	struct int_node *root;
+	struct non_note *first_non_note, *prev_non_note;
+	char *ref;
+	combine_notes_fn *combine_notes;
+	int initialized;
+} default_notes_tree;
+
+/*
+ * Flags controlling behaviour of notes tree initialization
+ *
+ * Default behaviour is to initialize the notes tree from the tree object
+ * specified by the given (or default) notes ref.
+ */
+#define NOTES_INIT_EMPTY 1
+
+/*
+ * Initialize the given notes_tree with the notes tree structure at the given
+ * ref. If given ref is NULL, the value of the $GIT_NOTES_REF environment
+ * variable is used, and if that is missing, the default notes ref is used
+ * ("refs/notes/commits").
+ *
+ * If you need to re-intialize a notes_tree structure (e.g. when switching from
+ * one notes ref to another), you must first de-initialize the notes_tree
+ * structure by calling free_notes(struct notes_tree *).
+ *
+ * If you pass t == NULL, the default internal notes_tree will be initialized.
+ *
+ * The combine_notes function that is passed becomes the default combine_notes
+ * function for the given notes_tree. If NULL is passed, the default
+ * combine_notes function is combine_notes_concatenate().
+ *
+ * Precondition: The notes_tree structure is zeroed (this can be achieved with
+ * memset(t, 0, sizeof(struct notes_tree)))
+ */
+void init_notes(struct notes_tree *t, const char *notes_ref,
+		combine_notes_fn combine_notes, int flags);
+
+/*
+ * Add the given note object to the given notes_tree structure
+ *
+ * IMPORTANT: The changes made by add_note() to the given notes_tree structure
+ * are not persistent until a subsequent call to write_notes_tree() returns
+ * zero.
+ */
+void add_note(struct notes_tree *t, const unsigned char *object_sha1,
+		const unsigned char *note_sha1, combine_notes_fn combine_notes);
+
+/*
+ * Remove the given note object from the given notes_tree structure
+ *
+ * IMPORTANT: The changes made by remove_note() to the given notes_tree
+ * structure are not persistent until a subsequent call to write_notes_tree()
+ * returns zero.
+ */
+void remove_note(struct notes_tree *t, const unsigned char *object_sha1);
+
+/*
+ * Get the note object SHA1 containing the note data for the given object
+ *
+ * Return NULL if the given object has no notes.
+ */
+const unsigned char *get_note(struct notes_tree *t,
+		const unsigned char *object_sha1);
+
+/*
+ * Flags controlling behaviour of for_each_note()
+ *
+ * Default behaviour of for_each_note() is to traverse every single note object
+ * in the given notes tree, unpacking subtree entries along the way.
+ * The following flags can be used to alter the default behaviour:
+ *
+ * - DONT_UNPACK_SUBTREES causes for_each_note() NOT to unpack and recurse into
+ *   subtree entries while traversing the notes tree. This causes notes within
+ *   those subtrees NOT to be passed to the callback. Use this flag if you
+ *   don't want to traverse _all_ notes, but only want to traverse the parts
+ *   of the notes tree that have already been unpacked (this includes at least
+ *   all notes that have been added/changed).
+ *
+ * - YIELD_SUBTREES causes any subtree entries that are encountered to be
+ *   passed to the callback, before recursing into them. Subtree entries are
+ *   not note objects, but represent intermediate directories in the notes
+ *   tree. When passed to the callback, subtree entries will have a trailing
+ *   slash in their path, which the callback may use to differentiate between
+ *   note entries and subtree entries. Note that already-unpacked subtree
+ *   entries are not part of the notes tree, and will therefore not be yielded.
+ *   If this flag is used together with DONT_UNPACK_SUBTREES, for_each_note()
+ *   will yield the subtree entry, but not recurse into it.
+ */
+#define FOR_EACH_NOTE_DONT_UNPACK_SUBTREES 1
+#define FOR_EACH_NOTE_YIELD_SUBTREES 2
+
+/*
+ * Invoke the specified callback function for each note in the given notes_tree
+ *
+ * If the callback returns nonzero, the note walk is aborted, and the return
+ * value from the callback is returned from for_each_note(). Hence, a zero
+ * return value from for_each_note() indicates that all notes were walked
+ * successfully.
+ *
+ * IMPORTANT: The callback function is NOT allowed to change the notes tree.
+ * In other words, the following functions can NOT be invoked (on the current
+ * notes tree) from within the callback:
+ * - add_note()
+ * - remove_note()
+ * - free_notes()
+ */
+typedef int each_note_fn(const unsigned char *object_sha1,
+		const unsigned char *note_sha1, char *note_path,
+		void *cb_data);
+int for_each_note(struct notes_tree *t, int flags, each_note_fn fn,
+		void *cb_data);
+
+/*
+ * Write the given notes_tree structure to the object database
+ *
+ * Creates a new tree object encapsulating the current state of the given
+ * notes_tree, and stores its SHA1 into the 'result' argument.
+ *
+ * Returns zero on success, non-zero on failure.
+ *
+ * IMPORTANT: Changes made to the given notes_tree are not persistent until
+ * this function has returned zero. Please also remember to create a
+ * corresponding commit object, and update the appropriate notes ref.
+ */
+int write_notes_tree(struct notes_tree *t, unsigned char *result);
+
+/*
+ * Remove all notes annotating non-existing objects from the given notes tree
+ *
+ * All notes in the given notes_tree that are associated with objects that no
+ * longer exist in the database, are removed from the notes tree.
+ *
+ * IMPORTANT: The changes made by prune_notes() to the given notes_tree
+ * structure are not persistent until a subsequent call to write_notes_tree()
+ * returns zero.
+ */
+void prune_notes(struct notes_tree *t);
+
+/*
+ * Free (and de-initialize) the given notes_tree structure
+ *
+ * IMPORTANT: Changes made to the given notes_tree since the last, successful
+ * call to write_notes_tree() will be lost.
+ */
+void free_notes(struct notes_tree *t);
+
+/* Flags controlling how notes are formatted */
 #define NOTES_SHOW_HEADER 1
 #define NOTES_INDENT 2
 
-void get_commit_notes(const struct commit *commit, struct strbuf *sb,
-		const char *output_encoding, int flags);
+/*
+ * Fill the given strbuf with the notes associated with the given object.
+ *
+ * If the given notes_tree structure is not initialized, it will be auto-
+ * initialized to the default value (see documentation for init_notes() above).
+ * If the given notes_tree is NULL, the internal/default notes_tree will be
+ * used instead.
+ *
+ * 'flags' is a bitwise combination of the above formatting flags.
+ */
+void format_note(struct notes_tree *t, const unsigned char *object_sha1,
+		struct strbuf *sb, const char *output_encoding, int flags);
 
 #endif
diff --git a/pretty.c b/pretty.c
index d493cade26..f999485a54 100644
--- a/pretty.c
+++ b/pretty.c
@@ -775,8 +775,9 @@ static size_t format_commit_one(struct strbuf *sb, const char *placeholder,
 		}
 		return 0;	/* unknown %g placeholder */
 	case 'N':
-		get_commit_notes(commit, sb, git_log_output_encoding ?
-			     git_log_output_encoding : git_commit_encoding, 0);
+		format_note(NULL, commit->object.sha1, sb,
+			    git_log_output_encoding ? git_log_output_encoding
+						    : git_commit_encoding, 0);
 		return 1;
 	}
 
@@ -1095,8 +1096,8 @@ void pretty_print_commit(enum cmit_fmt fmt, const struct commit *commit,
 		strbuf_addch(sb, '\n');
 
 	if (context->show_notes)
-		get_commit_notes(commit, sb, encoding,
-				 NOTES_SHOW_HEADER | NOTES_INDENT);
+		format_note(NULL, commit->object.sha1, sb, encoding,
+			    NOTES_SHOW_HEADER | NOTES_INDENT);
 
 	free(reencoded);
 }
diff --git a/t/t3301-notes.sh b/t/t3301-notes.sh
index 714626d2d6..37b96871c5 100755
--- a/t/t3301-notes.sh
+++ b/t/t3301-notes.sh
@@ -13,11 +13,11 @@ echo "$MSG" > "$1"
 echo "$MSG" >& 2
 EOF
 chmod a+x fake_editor.sh
-VISUAL=./fake_editor.sh
-export VISUAL
+GIT_EDITOR=./fake_editor.sh
+export GIT_EDITOR
 
 test_expect_success 'cannot annotate non-existing HEAD' '
-	(MSG=3 && export MSG && test_must_fail git notes edit)
+	(MSG=3 && export MSG && test_must_fail git notes add)
 '
 
 test_expect_success setup '
@@ -33,18 +33,18 @@ test_expect_success setup '
 
 test_expect_success 'need valid notes ref' '
 	(MSG=1 GIT_NOTES_REF=/ && export MSG GIT_NOTES_REF &&
-	 test_must_fail git notes edit) &&
+	 test_must_fail git notes add) &&
 	(MSG=2 GIT_NOTES_REF=/ && export MSG GIT_NOTES_REF &&
 	 test_must_fail git notes show)
 '
 
-test_expect_success 'refusing to edit in refs/heads/' '
+test_expect_success 'refusing to add notes in refs/heads/' '
 	(MSG=1 GIT_NOTES_REF=refs/heads/bogus &&
 	 export MSG GIT_NOTES_REF &&
-	 test_must_fail git notes edit)
+	 test_must_fail git notes add)
 '
 
-test_expect_success 'refusing to edit in refs/remotes/' '
+test_expect_success 'refusing to edit notes in refs/remotes/' '
 	(MSG=1 GIT_NOTES_REF=refs/remotes/bogus &&
 	 export MSG GIT_NOTES_REF &&
 	 test_must_fail git notes edit)
@@ -57,8 +57,35 @@ test_expect_success 'handle empty notes gracefully' '
 
 test_expect_success 'create notes' '
 	git config core.notesRef refs/notes/commits &&
-	MSG=b1 git notes edit &&
-	test ! -f .git/new-notes &&
+	MSG=b4 git notes add &&
+	test ! -f .git/NOTES_EDITMSG &&
+	test 1 = $(git ls-tree refs/notes/commits | wc -l) &&
+	test b4 = $(git notes show) &&
+	git show HEAD^ &&
+	test_must_fail git notes show HEAD^
+'
+
+test_expect_success 'edit existing notes' '
+	MSG=b3 git notes edit &&
+	test ! -f .git/NOTES_EDITMSG &&
+	test 1 = $(git ls-tree refs/notes/commits | wc -l) &&
+	test b3 = $(git notes show) &&
+	git show HEAD^ &&
+	test_must_fail git notes show HEAD^
+'
+
+test_expect_success 'cannot add note where one exists' '
+	! MSG=b2 git notes add &&
+	test ! -f .git/NOTES_EDITMSG &&
+	test 1 = $(git ls-tree refs/notes/commits | wc -l) &&
+	test b3 = $(git notes show) &&
+	git show HEAD^ &&
+	test_must_fail git notes show HEAD^
+'
+
+test_expect_success 'can overwrite existing note with "git notes add -f"' '
+	MSG=b1 git notes add -f &&
+	test ! -f .git/NOTES_EDITMSG &&
 	test 1 = $(git ls-tree refs/notes/commits | wc -l) &&
 	test b1 = $(git notes show) &&
 	git show HEAD^ &&
@@ -81,6 +108,7 @@ test_expect_success 'show notes' '
 	git log -1 > output &&
 	test_cmp expect output
 '
+
 test_expect_success 'create multi-line notes (setup)' '
 	: > a3 &&
 	git add a3 &&
@@ -88,7 +116,7 @@ test_expect_success 'create multi-line notes (setup)' '
 	git commit -m 3rd &&
 	MSG="b3
 c3c3c3c3
-d3d3d3" git notes edit
+d3d3d3" git notes add
 '
 
 cat > expect-multiline << EOF
@@ -111,19 +139,16 @@ test_expect_success 'show multi-line notes' '
 	git log -2 > output &&
 	test_cmp expect-multiline output
 '
-test_expect_success 'create -m and -F notes (setup)' '
+test_expect_success 'create -F notes (setup)' '
 	: > a4 &&
 	git add a4 &&
 	test_tick &&
 	git commit -m 4th &&
 	echo "xyzzy" > note5 &&
-	git notes edit -m spam -F note5 -m "foo
-bar
-baz"
+	git notes add -F note5
 '
 
-whitespace="    "
-cat > expect-m-and-F << EOF
+cat > expect-F << EOF
 commit 15023535574ded8b1a89052b32673f84cf9582b8
 Author: A U Thor <author@example.com>
 Date:   Thu Apr 7 15:16:13 2005 -0700
@@ -131,21 +156,15 @@ Date:   Thu Apr 7 15:16:13 2005 -0700
     4th
 
 Notes:
-    spam
-$whitespace
     xyzzy
-$whitespace
-    foo
-    bar
-    baz
 EOF
 
-printf "\n" >> expect-m-and-F
-cat expect-multiline >> expect-m-and-F
+printf "\n" >> expect-F
+cat expect-multiline >> expect-F
 
-test_expect_success 'show -m and -F notes' '
+test_expect_success 'show -F notes' '
 	git log -3 > output &&
-	test_cmp expect-m-and-F output
+	test_cmp expect-F output
 '
 
 cat >expect << EOF
@@ -165,13 +184,7 @@ test_expect_success 'git log --pretty=raw does not show notes' '
 cat >>expect <<EOF
 
 Notes:
-    spam
-$whitespace
     xyzzy
-$whitespace
-    foo
-    bar
-    baz
 EOF
 test_expect_success 'git log --show-notes' '
 	git log -1 --pretty=raw --show-notes >output &&
@@ -180,17 +193,17 @@ test_expect_success 'git log --show-notes' '
 
 test_expect_success 'git log --no-notes' '
 	git log -1 --no-notes >output &&
-	! grep spam output
+	! grep xyzzy output
 '
 
 test_expect_success 'git format-patch does not show notes' '
 	git format-patch -1 --stdout >output &&
-	! grep spam output
+	! grep xyzzy output
 '
 
 test_expect_success 'git format-patch --show-notes does show notes' '
 	git format-patch --show-notes -1 --stdout >output &&
-	grep spam output
+	grep xyzzy output
 '
 
 for pretty in \
@@ -203,8 +216,433 @@ do
 	esac
 	test_expect_success "git show $pretty does$not show notes" '
 		git show $p >output &&
-		eval "$negate grep spam output"
+		eval "$negate grep xyzzy output"
 	'
 done
 
+test_expect_success 'create -m notes (setup)' '
+	: > a5 &&
+	git add a5 &&
+	test_tick &&
+	git commit -m 5th &&
+	git notes add -m spam -m "foo
+bar
+baz"
+'
+
+whitespace="    "
+cat > expect-m << EOF
+commit bd1753200303d0a0344be813e504253b3d98e74d
+Author: A U Thor <author@example.com>
+Date:   Thu Apr 7 15:17:13 2005 -0700
+
+    5th
+
+Notes:
+    spam
+$whitespace
+    foo
+    bar
+    baz
+EOF
+
+printf "\n" >> expect-m
+cat expect-F >> expect-m
+
+test_expect_success 'show -m notes' '
+	git log -4 > output &&
+	test_cmp expect-m output
+'
+
+test_expect_success 'remove note with add -f -F /dev/null (setup)' '
+	git notes add -f -F /dev/null
+'
+
+cat > expect-rm-F << EOF
+commit bd1753200303d0a0344be813e504253b3d98e74d
+Author: A U Thor <author@example.com>
+Date:   Thu Apr 7 15:17:13 2005 -0700
+
+    5th
+EOF
+
+printf "\n" >> expect-rm-F
+cat expect-F >> expect-rm-F
+
+test_expect_success 'verify note removal with -F /dev/null' '
+	git log -4 > output &&
+	test_cmp expect-rm-F output &&
+	! git notes show
+'
+
+test_expect_success 'do not create empty note with -m "" (setup)' '
+	git notes add -m ""
+'
+
+test_expect_success 'verify non-creation of note with -m ""' '
+	git log -4 > output &&
+	test_cmp expect-rm-F output &&
+	! git notes show
+'
+
+cat > expect-combine_m_and_F << EOF
+foo
+
+xyzzy
+
+bar
+
+zyxxy
+
+baz
+EOF
+
+test_expect_success 'create note with combination of -m and -F' '
+	echo "xyzzy" > note_a &&
+	echo "zyxxy" > note_b &&
+	git notes add -m "foo" -F note_a -m "bar" -F note_b -m "baz" &&
+	git notes show > output &&
+	test_cmp expect-combine_m_and_F output
+'
+
+test_expect_success 'remove note with "git notes remove" (setup)' '
+	git notes remove HEAD^ &&
+	git notes remove
+'
+
+cat > expect-rm-remove << EOF
+commit bd1753200303d0a0344be813e504253b3d98e74d
+Author: A U Thor <author@example.com>
+Date:   Thu Apr 7 15:17:13 2005 -0700
+
+    5th
+
+commit 15023535574ded8b1a89052b32673f84cf9582b8
+Author: A U Thor <author@example.com>
+Date:   Thu Apr 7 15:16:13 2005 -0700
+
+    4th
+EOF
+
+printf "\n" >> expect-rm-remove
+cat expect-multiline >> expect-rm-remove
+
+test_expect_success 'verify note removal with "git notes remove"' '
+	git log -4 > output &&
+	test_cmp expect-rm-remove output &&
+	! git notes show HEAD^
+'
+
+cat > expect << EOF
+c18dc024e14f08d18d14eea0d747ff692d66d6a3 1584215f1d29c65e99c6c6848626553fdd07fd75
+c9c6af7f78bc47490dbf3e822cf2f3c24d4b9061 268048bfb8a1fb38e703baceb8ab235421bf80c5
+EOF
+
+test_expect_success 'list notes with "git notes list"' '
+	git notes list > output &&
+	test_cmp expect output
+'
+
+test_expect_success 'list notes with "git notes"' '
+	git notes > output &&
+	test_cmp expect output
+'
+
+cat > expect << EOF
+c18dc024e14f08d18d14eea0d747ff692d66d6a3
+EOF
+
+test_expect_success 'list specific note with "git notes list <object>"' '
+	git notes list HEAD^^ > output &&
+	test_cmp expect output
+'
+
+cat > expect << EOF
+EOF
+
+test_expect_success 'listing non-existing notes fails' '
+	test_must_fail git notes list HEAD > output &&
+	test_cmp expect output
+'
+
+cat > expect << EOF
+Initial set of notes
+
+More notes appended with git notes append
+EOF
+
+test_expect_success 'append to existing note with "git notes append"' '
+	git notes add -m "Initial set of notes" &&
+	git notes append -m "More notes appended with git notes append" &&
+	git notes show > output &&
+	test_cmp expect output
+'
+
+test_expect_success 'appending empty string does not change existing note' '
+	git notes append -m "" &&
+	git notes show > output &&
+	test_cmp expect output
+'
+
+test_expect_success 'git notes append == add when there is no existing note' '
+	git notes remove HEAD &&
+	test_must_fail git notes list HEAD &&
+	git notes append -m "Initial set of notes
+
+More notes appended with git notes append" &&
+	git notes show > output &&
+	test_cmp expect output
+'
+
+test_expect_success 'appending empty string to non-existing note does not create note' '
+	git notes remove HEAD &&
+	test_must_fail git notes list HEAD &&
+	git notes append -m "" &&
+	test_must_fail git notes list HEAD
+'
+
+test_expect_success 'create other note on a different notes ref (setup)' '
+	: > a6 &&
+	git add a6 &&
+	test_tick &&
+	git commit -m 6th &&
+	GIT_NOTES_REF="refs/notes/other" git notes add -m "other note"
+'
+
+cat > expect-other << EOF
+commit 387a89921c73d7ed72cd94d179c1c7048ca47756
+Author: A U Thor <author@example.com>
+Date:   Thu Apr 7 15:18:13 2005 -0700
+
+    6th
+
+Notes:
+    other note
+EOF
+
+cat > expect-not-other << EOF
+commit 387a89921c73d7ed72cd94d179c1c7048ca47756
+Author: A U Thor <author@example.com>
+Date:   Thu Apr 7 15:18:13 2005 -0700
+
+    6th
+EOF
+
+test_expect_success 'Do not show note on other ref by default' '
+	git log -1 > output &&
+	test_cmp expect-not-other output
+'
+
+test_expect_success 'Do show note when ref is given in GIT_NOTES_REF' '
+	GIT_NOTES_REF="refs/notes/other" git log -1 > output &&
+	test_cmp expect-other output
+'
+
+test_expect_success 'Do show note when ref is given in core.notesRef config' '
+	git config core.notesRef "refs/notes/other" &&
+	git log -1 > output &&
+	test_cmp expect-other output
+'
+
+test_expect_success 'Do not show note when core.notesRef is overridden' '
+	GIT_NOTES_REF="refs/notes/wrong" git log -1 > output &&
+	test_cmp expect-not-other output
+'
+
+test_expect_success 'Allow notes on non-commits (trees, blobs, tags)' '
+	echo "Note on a tree" > expect
+	git notes add -m "Note on a tree" HEAD: &&
+	git notes show HEAD: > actual &&
+	test_cmp expect actual &&
+	echo "Note on a blob" > expect
+	filename=$(git ls-tree --name-only HEAD | head -n1) &&
+	git notes add -m "Note on a blob" HEAD:$filename &&
+	git notes show HEAD:$filename > actual &&
+	test_cmp expect actual &&
+	echo "Note on a tag" > expect
+	git tag -a -m "This is an annotated tag" foobar HEAD^ &&
+	git notes add -m "Note on a tag" foobar &&
+	git notes show foobar > actual &&
+	test_cmp expect actual
+'
+
+cat > expect << EOF
+commit 2ede89468182a62d0bde2583c736089bcf7d7e92
+Author: A U Thor <author@example.com>
+Date:   Thu Apr 7 15:19:13 2005 -0700
+
+    7th
+
+Notes:
+    other note
+EOF
+
+test_expect_success 'create note from other note with "git notes add -C"' '
+	: > a7 &&
+	git add a7 &&
+	test_tick &&
+	git commit -m 7th &&
+	git notes add -C $(git notes list HEAD^) &&
+	git log -1 > actual &&
+	test_cmp expect actual &&
+	test "$(git notes list HEAD)" = "$(git notes list HEAD^)"
+'
+
+test_expect_success 'create note from non-existing note with "git notes add -C" fails' '
+	: > a8 &&
+	git add a8 &&
+	test_tick &&
+	git commit -m 8th &&
+	test_must_fail git notes add -C deadbeef &&
+	test_must_fail git notes list HEAD
+'
+
+cat > expect << EOF
+commit 016e982bad97eacdbda0fcbd7ce5b0ba87c81f1b
+Author: A U Thor <author@example.com>
+Date:   Thu Apr 7 15:21:13 2005 -0700
+
+    9th
+
+Notes:
+    yet another note
+EOF
+
+test_expect_success 'create note from other note with "git notes add -c"' '
+	: > a9 &&
+	git add a9 &&
+	test_tick &&
+	git commit -m 9th &&
+	MSG="yet another note" git notes add -c $(git notes list HEAD^^) &&
+	git log -1 > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'create note from non-existing note with "git notes add -c" fails' '
+	: > a10 &&
+	git add a10 &&
+	test_tick &&
+	git commit -m 10th &&
+	test_must_fail MSG="yet another note" git notes add -c deadbeef &&
+	test_must_fail git notes list HEAD
+'
+
+cat > expect << EOF
+commit 016e982bad97eacdbda0fcbd7ce5b0ba87c81f1b
+Author: A U Thor <author@example.com>
+Date:   Thu Apr 7 15:21:13 2005 -0700
+
+    9th
+
+Notes:
+    yet another note
+$whitespace
+    yet another note
+EOF
+
+test_expect_success 'append to note from other note with "git notes append -C"' '
+	git notes append -C $(git notes list HEAD^) HEAD^ &&
+	git log -1 HEAD^ > actual &&
+	test_cmp expect actual
+'
+
+cat > expect << EOF
+commit ffed603236bfa3891c49644257a83598afe8ae5a
+Author: A U Thor <author@example.com>
+Date:   Thu Apr 7 15:22:13 2005 -0700
+
+    10th
+
+Notes:
+    other note
+EOF
+
+test_expect_success 'create note from other note with "git notes append -c"' '
+	MSG="other note" git notes append -c $(git notes list HEAD^) &&
+	git log -1 > actual &&
+	test_cmp expect actual
+'
+
+cat > expect << EOF
+commit ffed603236bfa3891c49644257a83598afe8ae5a
+Author: A U Thor <author@example.com>
+Date:   Thu Apr 7 15:22:13 2005 -0700
+
+    10th
+
+Notes:
+    other note
+$whitespace
+    yet another note
+EOF
+
+test_expect_success 'append to note from other note with "git notes append -c"' '
+	MSG="yet another note" git notes append -c $(git notes list HEAD) &&
+	git log -1 > actual &&
+	test_cmp expect actual
+'
+
+cat > expect << EOF
+commit 6352c5e33dbcab725fe0579be16aa2ba8eb369be
+Author: A U Thor <author@example.com>
+Date:   Thu Apr 7 15:23:13 2005 -0700
+
+    11th
+
+Notes:
+    other note
+$whitespace
+    yet another note
+EOF
+
+test_expect_success 'copy note with "git notes copy"' '
+	: > a11 &&
+	git add a11 &&
+	test_tick &&
+	git commit -m 11th &&
+	git notes copy HEAD^ HEAD &&
+	git log -1 > actual &&
+	test_cmp expect actual &&
+	test "$(git notes list HEAD)" = "$(git notes list HEAD^)"
+'
+
+test_expect_success 'prevent overwrite with "git notes copy"' '
+	test_must_fail git notes copy HEAD~2 HEAD &&
+	git log -1 > actual &&
+	test_cmp expect actual &&
+	test "$(git notes list HEAD)" = "$(git notes list HEAD^)"
+'
+
+cat > expect << EOF
+commit 6352c5e33dbcab725fe0579be16aa2ba8eb369be
+Author: A U Thor <author@example.com>
+Date:   Thu Apr 7 15:23:13 2005 -0700
+
+    11th
+
+Notes:
+    yet another note
+$whitespace
+    yet another note
+EOF
+
+test_expect_success 'allow overwrite with "git notes copy -f"' '
+	git notes copy -f HEAD~2 HEAD &&
+	git log -1 > actual &&
+	test_cmp expect actual &&
+	test "$(git notes list HEAD)" = "$(git notes list HEAD~2)"
+'
+
+test_expect_success 'cannot copy note from object without notes' '
+	: > a12 &&
+	git add a12 &&
+	test_tick &&
+	git commit -m 12th &&
+	: > a13 &&
+	git add a13 &&
+	test_tick &&
+	git commit -m 13th &&
+	test_must_fail git notes copy HEAD^ HEAD
+'
+
 test_done
diff --git a/t/t3303-notes-subtrees.sh b/t/t3303-notes-subtrees.sh
index edc4bc8841..75ec18778e 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 256687ffb5..1709e8c00b 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 add -f -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
diff --git a/t/t3305-notes-fanout.sh b/t/t3305-notes-fanout.sh
new file mode 100755
index 0000000000..b1ea64b213
--- /dev/null
+++ b/t/t3305-notes-fanout.sh
@@ -0,0 +1,95 @@
+#!/bin/sh
+
+test_description='Test that adding/removing many notes triggers automatic fanout restructuring'
+
+. ./test-lib.sh
+
+test_expect_success 'creating many notes with git-notes' '
+	num_notes=300 &&
+	i=0 &&
+	while test $i -lt $num_notes
+	do
+		i=$(($i + 1)) &&
+		test_tick &&
+		echo "file for commit #$i" > file &&
+		git add file &&
+		git commit -q -m "commit #$i" &&
+		git notes add -m "note #$i" || return 1
+	done
+'
+
+test_expect_success 'many notes created correctly with git-notes' '
+	git log | grep "^    " > output &&
+	i=300 &&
+	while test $i -gt 0
+	do
+		echo "    commit #$i" &&
+		echo "    note #$i" &&
+		i=$(($i - 1));
+	done > expect &&
+	test_cmp expect output
+'
+
+test_expect_success 'many notes created with git-notes triggers fanout' '
+	# Expect entire notes tree to have a fanout == 1
+	git ls-tree -r --name-only refs/notes/commits |
+	while read path
+	do
+		case "$path" in
+		??/??????????????????????????????????????)
+			: true
+			;;
+		*)
+			echo "Invalid path \"$path\"" &&
+			return 1
+			;;
+		esac
+	done
+'
+
+test_expect_success 'deleting most notes with git-notes' '
+	num_notes=250 &&
+	i=0 &&
+	git rev-list HEAD |
+	while read sha1
+	do
+		i=$(($i + 1)) &&
+		if test $i -gt $num_notes
+		then
+			break
+		fi &&
+		test_tick &&
+		git notes remove "$sha1"
+	done
+'
+
+test_expect_success 'most notes deleted correctly with git-notes' '
+	git log HEAD~250 | grep "^    " > output &&
+	i=50 &&
+	while test $i -gt 0
+	do
+		echo "    commit #$i" &&
+		echo "    note #$i" &&
+		i=$(($i - 1));
+	done > expect &&
+	test_cmp expect output
+'
+
+test_expect_success 'deleting most notes triggers fanout consolidation' '
+	# Expect entire notes tree to have a fanout == 0
+	git ls-tree -r --name-only refs/notes/commits |
+	while read path
+	do
+		case "$path" in
+		????????????????????????????????????????)
+			: true
+			;;
+		*)
+			echo "Invalid path \"$path\"" &&
+			return 1
+			;;
+		esac
+	done
+'
+
+test_done
diff --git a/t/t3306-notes-prune.sh b/t/t3306-notes-prune.sh
new file mode 100755
index 0000000000..a0ed0353e6
--- /dev/null
+++ b/t/t3306-notes-prune.sh
@@ -0,0 +1,94 @@
+#!/bin/sh
+
+test_description='Test git notes prune'
+
+. ./test-lib.sh
+
+test_expect_success 'setup: create a few commits with notes' '
+
+	: > file1 &&
+	git add file1 &&
+	test_tick &&
+	git commit -m 1st &&
+	git notes add -m "Note #1" &&
+	: > file2 &&
+	git add file2 &&
+	test_tick &&
+	git commit -m 2nd &&
+	git notes add -m "Note #2" &&
+	: > file3 &&
+	git add file3 &&
+	test_tick &&
+	git commit -m 3rd &&
+	git notes add -m "Note #3"
+'
+
+cat > expect <<END_OF_LOG
+commit 5ee1c35e83ea47cd3cc4f8cbee0568915fbbbd29
+Author: A U Thor <author@example.com>
+Date:   Thu Apr 7 15:15:13 2005 -0700
+
+    3rd
+
+Notes:
+    Note #3
+
+commit 08341ad9e94faa089d60fd3f523affb25c6da189
+Author: A U Thor <author@example.com>
+Date:   Thu Apr 7 15:14:13 2005 -0700
+
+    2nd
+
+Notes:
+    Note #2
+
+commit ab5f302035f2e7aaf04265f08b42034c23256e1f
+Author: A U Thor <author@example.com>
+Date:   Thu Apr 7 15:13:13 2005 -0700
+
+    1st
+
+Notes:
+    Note #1
+END_OF_LOG
+
+test_expect_success 'verify commits and notes' '
+
+	git log > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'remove some commits' '
+
+	git reset --hard HEAD~2 &&
+	git reflog expire --expire=now HEAD &&
+	git gc --prune=now
+'
+
+test_expect_success 'verify that commits are gone' '
+
+	! git cat-file -p 5ee1c35e83ea47cd3cc4f8cbee0568915fbbbd29 &&
+	! git cat-file -p 08341ad9e94faa089d60fd3f523affb25c6da189 &&
+	git cat-file -p ab5f302035f2e7aaf04265f08b42034c23256e1f
+'
+
+test_expect_success 'verify that notes are still present' '
+
+	git notes show 5ee1c35e83ea47cd3cc4f8cbee0568915fbbbd29 &&
+	git notes show 08341ad9e94faa089d60fd3f523affb25c6da189 &&
+	git notes show ab5f302035f2e7aaf04265f08b42034c23256e1f
+'
+
+test_expect_success 'prune notes' '
+
+	git notes prune
+'
+
+test_expect_success 'verify that notes are gone' '
+
+	! git notes show 5ee1c35e83ea47cd3cc4f8cbee0568915fbbbd29 &&
+	! git notes show 08341ad9e94faa089d60fd3f523affb25c6da189 &&
+	git notes show ab5f302035f2e7aaf04265f08b42034c23256e1f
+'
+
+test_done