Git 2.2.0-rc1

Signed-off-by: Junio C Hamano <gitster@pobox.com>
builtin/notes: Fix premature failure when trying to add the empty blob

This fixes a small buglet when trying to explicitly add the empty blob
as a note object using the -c or -C option to git notes add/append.
Instead of failing with a nonsensical error message indicating that the
empty blob does not exist, we should rather behave as if an empty notes
message was given (e.g. using -m "" or -F /dev/null).

The next patch contains a test that verifies the fixed behavior.

Found-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Johan Herland <johan@herland.net>
t3301: Verify that 'git notes' removes empty notes by default

Add test cases documenting the current behavior when trying to
add/append/edit empty notes. This is in preparation for adding
--allow-empty; to allow empty notes to be stored.

Improved-by: Eric Sunshine <sunshine@sunshineco.com>
Improved-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Johan Herland <johan@herland.net>
builtin/notes: Improve naming

In preparation for some needed refactoring, rename struct msg_arg to
struct note_data, and rename its instances from "msg" to "d" (also
removing some unnecessary parentheses). The 'msg_arg' name was
inherited from tag.c, but is not really a good name for the contents
of a note.

Also rename write_note_data() to copy_obj_to_fd(), which more aptly
describes what it actually does: Copying the contents of a git object
(given by its SHA1) into a given file descriptor.

Signed-off-by: Johan Herland <johan@herland.net>
builtin/notes: Refactor note file path into struct note_data

Move the 'path' variable from create_note() and into the
note_data struct. Unify cleanup of note_data objects with
a free_note_data() function.

This might not make too much sense on its own, but it makes the
future refactoring of create_note() considerably cleaner.

Signed-off-by: Johan Herland <johan@herland.net>
builtin/notes: Simplify early exit code in add()

Signed-off-by: Johan Herland <johan@herland.net>
builtin/notes: Split create_note() to clarify add vs. remove logic

create_note() has a non-trivial interface, and comprises three loosely
related parts:

 1. launching the editor with the note contents, if needed
 2. appending to an existing note, if append_only was given
 3. adding or removing the resulting note, based on whether it's non-empty

Split it along those lines to make the logic clearer: The first part
goes into a new function - prepare_note_data(), with a simpler interface.
The second part is moved into append_edit(), which is the only user of
this code. Finally, the add vs. remove decision is moved into the callers
(add() and append_edit()), keeping the logic for writing the actual note
object in a separate function: write_note_data().

Suggested-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Johan Herland <johan@herland.net>
builtin/notes: Add --allow-empty, to allow storing empty notes

Although the "git notes" man page advertises that we support binary-safe
notes addition (using the -C option), we currently do not support adding
the empty note (i.e. using the empty blob to annotate an object). Instead,
an empty note is always treated as an intent to remove the note
altogether.

Introduce the --allow-empty option to the add/append/edit subcommands,
to explicitly allow an empty note to be stored into the notes tree.

Also update the documentation, and add test cases for the new option.

Reported-by: James H. Fisher <jhf@trifork.com>
Improved-by: Kyle J. McKay <mackyle@gmail.com>
Improved-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Johan Herland <johan@herland.net>
notes: Empty notes should be shown by 'git log'

If the user has gone through the trouble of explicitly adding an empty
note, then "git log" should not silently skip it (as if it didn't exist).

Signed-off-by: Johan Herland <johan@herland.net>
t3301: Use write_script(), nitpick whitespace

Signed-off-by: Johan Herland <johan@herland.net>
WIP