[PATCH v2 00/25] Lockfile correctness and refactoring

This is a second attempt at renovating the lock file code. Thanks to Peff, Junio, Torsten, and Eric for their helpful reviews of v1.

v1 of this patch series [1] did some refactoring and then added a new feature to the lock_file API: the ability to activate a new version of a locked file while retaining the lock.

But the review of v1 turned up even more correctness issues in the existing implementation of lock files. So this v2 dials back the scope of the changes (it omits the new feature) but does more work to fix problems with the current lock file implementation.

The main theme of this patch series is to better define the state diagram for lock_file objects and to fix code that left them in incorrect, indeterminate, or unexpected states. There are also a few patches that convert several functions to use strbufs instead of limiting pathnames to a maximum length.

I hope that submitting these patches separately will make it easier for them to be accepted without first having to decide wither the activate-file-while-retaining-lock feature is a good one.

[1] http://thread.gmane.org/gmane.comp.version-control.git/245609

Michael Haggerty (25):
  api-lockfile: expand the documentation
  unable_to_lock_die(): rename function from unable_to_lock_index_die()
  rollback_lock_file(): do not clear filename redundantly
  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 add lock_file object to lock_file_list
  struct lock_file: replace on_list field with flags field
  lockfile.c: document the various states of lock_file objects
  lockfile: define a constant 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(): make committing an unlocked lockfile a NOP
  lockfile: avoid transitory invalid states
  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_elm(): replace last_path_elm()

 Documentation/technical/api-lockfile.txt |  40 ++++-
 builtin/commit.c                         |  16 +-
 builtin/merge.c                          |  15 +-
 builtin/reflog.c                         |   2 +-
 builtin/update-index.c                   |   2 +-
 cache.h                                  |   6 +-
 config.c                                 |   6 +-
 lockfile.c                               | 282 +++++++++++++++++++------------
 refs.c                                   |  20 ++-
 shallow.c                                |   6 +-
 10 files changed, 243 insertions(+), 152 deletions(-)