[0/2] safe.directory clean-up

Message

Junio C Hamano July 20, 2024, 10:09 p.m. UTC

Recently we discussed what we should do when either the path
configured in the safe.directory configuration or coming from
the caller of ensure_valid_ownership() function as a result of
repository discovery is not normalized and textual equality check is
not sufficient.  See the thread the contains

  https://lore.kernel.org/git/[e-mail]/

Here are two patches (yes, two) that implements the comparison
between normalized path and configuration value.

Imagine that you have a repository at /mnt/disk4/repos/frotz
directory but in order to make it simpler to manage and use, you
have your users use /projects/frotz to access the repository.  A
symlink /projects/frotz pointing at /mnt/disk4/repos/frotz directory
allows you to do so.

 - The first patch normalizes the path to the directory that we
   suspect is a usable repository, before comparing it with the
   safe.directory configuration variable.  The safe.directory may
   say /mnt/disk4/repos/frotz or /mnt/disk4/repos/*, but the path to
   the repository for the users may be /mnt/disk4/repos/frotz or
   /projects/frotz, depending on where they come from and what their
   $PWD makes getcwd() to say.

 - The second patch normalizes the value of the safe.directory
   variable.  This allows safe.directory to say /projects/frotz
   or /projects/* and have them match /mnt/disk4/repos/frotz (which
   is how the first patch normalizes the repository path to).

 - The third patch is a preliminary clean-up that would be needed if
   we wanted to use the fourth patch.

 - The fourth patch would become relevant if we were to call
   ensure_valid_ownership() on many directories in a single process.
   We grab safe.directory values and normalize them just once before
   using in ensure_valid_ownership() to optimize away repeated
   normalization.

It turns out that nobody calls ensure_valid_ownership() on many
different directories even in the repository discovery loop, which
means the fourth patch is not needed, which in turn means the third
patch that is a preliminary clean-up is also not necessary.

Junio C Hamano (4):
  safe.directory: normalize the checked path
  safe.directory: normalize the configured path
  setup: allow centralized clean-up when leaving setup_git_directory_gently_1()
  setup: cache normalized safe.directory configuration

 setup.c                   | 141 +++++++++++++++++++++++++++++++-------
 t/t0033-safe-directory.sh |  90 ++++++++++++++++++++++++
 2 files changed, 205 insertions(+), 26 deletions(-)