[PATCH v6 00/39] Lockfile correctness and refactoring

Next iteration of my lockfile fixes and refactoring. Thanks to Jonathan Nieder and Torsten Bögershausen for their comments about v5.

I believe that this series addresses all of the comments from v1 [1], v2 [2], v3 [3], v4 [4], and v5 [5].

Changes since v4:

* Revise API documentation.

* Split out a separate header file for the lockfile API: lockfile.h.

* Change close_lock_file() to rollback on errors and make it into a
  NOOP if the file is already closed.

* Don't set lk->on_list until the lock_file object is completely on
  the lock_file_list.

* Delete some information from the docstring in lockfile.c (now
  lockfile.h) that is redundant with the API docs in api-lockfile.txt.

* Remove the accidental extra call of git_config_clear() in
  git_config_set_multivar_in_file() when commit_lock_file() fails.

* Adjust some comments, error messages, and commit messages.

* Rebase to current master.

[1] http://thread.gmane.org/gmane.comp.version-control.git/245609 [2] http://thread.gmane.org/gmane.comp.version-control.git/245801 [3] http://thread.gmane.org/gmane.comp.version-control.git/246222 [4] http://thread.gmane.org/gmane.comp.version-control.git/256564 [5] http://thread.gmane.org/gmane.comp.version-control.git/257159

Michael Haggerty (39):
  unable_to_lock_die(): rename function from unable_to_lock_index_die()
  api-lockfile: revise and expand the documentation
  close_lock_file(): exit (successfully) if file is already closed
  rollback_lock_file(): do not clear filename redundantly
  rollback_lock_file(): exit early if lock is not active
  rollback_lock_file(): set fd to -1
  lockfile: unlock file if lockfile permissions cannot be adjusted
  hold_lock_file_for_append(): release lock on errors
  lock_file(): always initialize and register lock_file object
  lockfile.c: document the various states of lock_file objects
  cache.h: define constants LOCK_SUFFIX and LOCK_SUFFIX_LEN
  delete_ref_loose(): don't muck around in the lock_file's filename
  prepare_index(): declare return value to be (const char *)
  write_packed_entry_fn(): convert cb_data into a (const int *)
  lock_file(): exit early if lockfile cannot be opened
  remove_lock_file(): call rollback_lock_file()
  commit_lock_file(): inline temporary variable
  commit_lock_file(): die() if called for unlocked lockfile object
  close_lock_file(): if close fails, roll back
  commit_lock_file(): rollback lock file on failure to rename
  api-lockfile: document edge cases
  dump_marks(): remove a redundant call to rollback_lock_file()
  git_config_set_multivar_in_file(): avoid call to rollback_lock_file()
  lockfile: avoid transitory invalid states
  struct lock_file: declare some fields volatile
  try_merge_strategy(): remove redundant lock_file allocation
  try_merge_strategy(): use a statically-allocated lock_file object
  commit_lock_file(): use a strbuf to manage temporary space
  Change lock_file::filename into a strbuf
  resolve_symlink(): use a strbuf for internal scratch space
  resolve_symlink(): take a strbuf parameter
  trim_last_path_component(): replace last_path_elm()
  Extract a function commit_lock_file_to()
  Rename LOCK_NODEREF to LOCK_NO_DEREF
  lockfile.c: rename static functions
  get_locked_file_path(): new function
  hold_lock_file_for_append(): restore errno before returning
  Move read_index() definition to read-cache.c
  lockfile.h: extract new header file for the functions in lockfile.c

 Documentation/technical/api-lockfile.txt | 220 ++++++++++++++++++------
 builtin/add.c                            |   1 +
 builtin/apply.c                          |   1 +
 builtin/checkout-index.c                 |   2 +-
 builtin/checkout.c                       |   2 +-
 builtin/clone.c                          |   1 +
 builtin/commit.c                         |  17 +-
 builtin/describe.c                       |   1 +
 builtin/diff.c                           |   1 +
 builtin/gc.c                             |   2 +-
 builtin/merge.c                          |  16 +-
 builtin/mv.c                             |   2 +-
 builtin/read-tree.c                      |   1 +
 builtin/receive-pack.c                   |   1 +
 builtin/reflog.c                         |   4 +-
 builtin/reset.c                          |   1 +
 builtin/rm.c                             |   2 +-
 builtin/update-index.c                   |   3 +-
 bundle.c                                 |   1 +
 cache-tree.c                             |   1 +
 cache.h                                  |  20 +--
 config.c                                 |  16 +-
 credential-store.c                       |   1 +
 fast-import.c                            |   5 +-
 fetch-pack.c                             |   1 +
 lockfile.c                               | 284 +++++++++++++++++--------------
 lockfile.h                               |  84 +++++++++
 merge-recursive.c                        |   1 +
 merge.c                                  |   1 +
 read-cache.c                             |  21 ++-
 refs.c                                   |  30 ++--
 rerere.c                                 |   1 +
 sequencer.c                              |   1 +
 sha1_file.c                              |   1 +
 shallow.c                                |   7 +-
 test-scrap-cache-tree.c                  |   1 +
 36 files changed, 492 insertions(+), 263 deletions(-)
 create mode 100644 lockfile.h