Re: [PATCH v2 00/15][GSoC] iterate dirs before or after their contents

> This is the second version of a patch series which implements pre-order and
> post-order iteration over directories. In this version I use the new iteration
> scheme to convert entry.c remove_subtree() function from using opendir/readdir/
> closedir API to dir-iterator API.
> 
> v1: https://lore.kernel.org/git/20220410111852.2097418-1-kioplato@gmail.com/
> 
> Fork: https://github.com/kioplato/git/tree/dir-iterator-v2
> CI: https://github.com/kioplato/git/actions/runs/2295239114
> I've ran the full test suite for each commit.
> 
> In comparison to v1 I changed/fixed/improved:
> 
> * In this version I followed Phillip's suggestion[1] to explain why I'm making
> the changes in each commit's description and create smaller, targeted commits.
> In v1 I did a lot of renaming to directory paths, test descriptions and files.
> In this version these renames have their own commits.
> 
> * Explained why I converted dir_iterator_advance() from iterative implementation
> to recursive in the related commit. Ævar[2] and Phillip[3] asked about why I did
> this conversion, so I thought it was appropriate to include an explanation in
> the commit's description.
> 
> * I talked about a subtle unexpected behavior of dir_iterator_begin() [4]. I was
> wrong about the two new states for the deepest directory. I introduced those
> states in order to implement recursive dir_iterator_advance() and not to deal
> with the unexpected behavior of dir_iterator_begin(). Therefore I splitted the
> conversion of dir_iteartor_advance() and the changes to deal with the unexpected
> behavior of dir_iteartor_begin() into two different commits. They need their own
> commits since they are two unrelated changes.
> 
> * Split the commit that introduces pre-order and post-order iteration into two.
> Like Phillip suggested here[5] the first changes dir-iterator default behavior
> and the second implements post-order iterator over directories. This helps split
> the tests introduced, which helps generate smaller diffs.
> 
> * Like Phillip suggested [6], I'll work with the existing code and change one
> aspect at a time in stages. In this series I converted entry.c remove_subtree()
> to use dir-iterator API instead of opendir/readdir/closedir API.
> 
> * The redundant tests [7] in this version were not removed. Instead I kept them
> for more detailed testing which helps in case a test fails.
> 
> * Ævar's idea[8] to change the default swich case in test-dir-iterator made me
> realize that test-dir-iterator does not print errno codes set by failed calls to
> dir_iterator_advance(). Therefore I made test-dir-iterator print them which
> makes all tests test_cmp for the errno code set by either dir_iteartor_begin()
> or dir_iterator_advance(). This presumably has the same effect as changing the
> default switch case to use BUG() macro. This change also led to two others, one
> that makes test-dir-iterator explicitly print ELOOP errno and the second that
> improves readability by consistently returning, C standard constants, either
> EXIT_SUCCESS or EXIT_FAILURE, instead of mixed integers and exit() calls.
> 
> * fixed coding style and introduces an enum for returning constants instead of
> more integers which worsens readability, as suggested by Ævar [9].
> 
> I also didn't CC Michael and Matheus in this version, since they weren't
> interested in v1 where I did CC them.

> [1]: https://lore.kernel.org/git/ed6656e0-a865-319e-0f56-23ab1da3eef3@gmail.com/
> [2]: https://lore.kernel.org/git/220411.86o817j2dt.gmgdl@evledraar.gmail.com/
> [3]: https://lore.kernel.org/git/35160d46-d337-2110-f968-238abb7e9f0e@gmail.com/
> [4]: https://lore.kernel.org/git/20220427154526.uuhpkoee322l7kmz@compass/
> [5]: https://lore.kernel.org/git/b75aaee8-c037-e8e0-6ee0-729922059352@gmail.com/
> [6]: https://lore.kernel.org/git/df287d4f-e9da-4ce0-d7e9-1b1fe7671aab@gmail.com/
> [7]: https://lore.kernel.org/git/220411.86sfqjj2o0.gmgdl@evledraar.gmail.com/
> [8]: https://lore.kernel.org/git/220411.86wnfvj2q6.gmgdl@evledraar.gmail.com/
> [9]: https://lore.kernel.org/git/220411.86o817j2dt.gmgdl@evledraar.gmail.com/
> 
> Plato Kiorpelidis (15):
>    t0066: refactor dir-iterator tests
>    t0066: remove dependency between unrelated tests
>    t0066: shorter expected and actual output file names
>    test-dir-iterator: consistently return EXIT_FAILURE or EXIT_SUCCESS
>    test-dir-iterator: print EACCES and ELOOP errno set by dir_iterator
>    test-dir-iterator: print errno name set by dir_iterator_advance
>    t0066: better test coverage for dir-iterator
>    t0066: reorder tests from simple to more complex
>    t0066: rename test directories
>    dir-iterator: refactor dir_iterator_advance()
>    dir-iterator: open root dir in dir_iterator_begin()
>    t0066: rename subtest descriptions
>    dir-iterator: option to iterate dirs in pre-order
>    dir-iterator: option to iterate dirs in post-order
>    entry.c: use dir-iterator to avoid explicit dir traversal
> 
>   builtin/clone.c              |    4 +-
>   dir-iterator.c               |  334 ++++++--
>   dir-iterator.h               |   36 +-
>   entry.c                      |   38 +-
>   refs/files-backend.c         |    2 +-
>   t/helper/test-dir-iterator.c |   24 +-
>   t/t0066-dir-iterator.sh      | 1478 +++++++++++++++++++++++++++++++---
>   7 files changed, 1704 insertions(+), 212 deletions(-)
>