patch, 4 partsworktree: cleanups & simplification

The primary change of this series is a response to Junio's observation[1] that it would be nice if get_main_worktree() didn't employ special cases for path normalization. I was planning on investigating the topic eventually anyway but ended up having to tackle the same sort of manual special case normalization in another worktree-related topic I'm working on, thus this series fell out naturally from that other work. Along the way, while re-studying the worktree code, I came across a few other issues which deserved attention, but which are not directly related to the other topic I'm working on, so I bundled all these small changes together here.

Eric Sunshine (4):
  worktree: drop pointless strbuf_release()
  worktree: drop unused code from get_linked_worktree()
  worktree: drop bogus and unnecessary path munging
  worktree: retire special-case normalization of main worktree path

 worktree.c | 18 +++---------------
 1 file changed, 3 insertions(+), 15 deletions(-)

The content of .git/worktrees/<id>/gitdir must be a path of the form "/path/to/worktree/.git". Any other content would be indicative of a corrupt "gitdir" file. To determine the path of the worktree itself one merely strips the "/.git" suffix, and this is indeed how the worktree path was determined from inception.

However, 5193490442 (worktree: add a function to get worktree details, 2015-10-08) extended the path manipulation in a mysterious way. If it is unable to strip "/.git" from the path, then it instead reports the current working directory as the linked worktree's path:

    if (!strbuf_strip_suffix(&worktree_path, "/.git")) {
        strbuf_reset(&worktree_path);
        strbuf_add_absolute_path(&worktree_path, ".");
        strbuf_strip_suffix(&worktree_path, "/.");
    }

This logic is clearly bogus; it can never be generally correct behavior. It materialized out of thin air in 5193490442 with neither explanation nor tests to illustrate a case in which it would be desirable.

It's possible that this logic was introduced to somehow deal with a corrupt "gitdir" file, so that it returns _some_ sort of meaningful value, but returning the current working directory is not helpful. In fact, it is quite misleading (except in the one specific case when the current directory is the worktree whose "gitdir" entry is corrupt). Moreover, reporting the corrupt value to the user, rather than fibbing about it and hiding it outright, is more helpful since it may aid in diagnosing the problem.

Therefore, drop this bogus path munging and restore the logic to the original behavior of merely stripping "/.git".

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
---
 worktree.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

This code has been unused since fa099d2322 (worktree.c: kill parse_ref() in favor of refs_resolve_ref_unsafe(), 2017-04-24), so drop it.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
---

Notes:
    This is a companion to 02bbbe9df9 (worktree: drop unused code from
    get_main_worktree(), 2020-02-23), which also cleaned up fallout from
    fa099d2322 (worktree.c: kill parse_ref() in favor of
    refs_resolve_ref_unsafe(), 2017-04-24).

 worktree.c | 3 ---
 1 file changed, 3 deletions(-)

In order for "git-worktree list" to present consistent results, get_main_worktree() performs manual normalization on the repository path (returned by get_common_dir()) after passing it through strbuf_add_absolute_path(). In particular, it cleans up the path for three distinct cases when the current working directory is (1) the main worktree, (2) the .git/ subdirectory, or (3) a bare repository.

The need for such special-cases is a direct consequence of employing strbuf_add_absolute_path() which, for the sake of efficiency, doesn't bother normalizing the path (such as folding out redundant path components) after making it absolute. Lack of normalization is not typically a problem since redundant path elements make no difference when working with paths at the filesystem level. However, when preparing paths for presentation, possible redundant path components make it difficult to ensure consistency.

Eliminate the need for these special cases by instead making the path absolute via strbuf_add_real_path() which normalizes the path for us. Once normalized, the only case we need to handle manually is converting it to the path of the main worktree by stripping the "/.git" suffix. This stripping of the "/.git" suffix is a regular idiom in worktree-related code; for instance, it is employed by get_linked_worktree(), as well.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
---

Notes:
    This is a followup to 5f4ee57ad9 (worktree: avoid dead-code in
    conditional, 2020-06-24) which dropped dead code from the manual
    normalization done by get_main_worktree() but which did not
    eliminate the special cases.
    
    It's also a direct response to Junio's observation[1] that it would
    be better if we didn't have to handle these special cases in the
    first place.
    
    [1]: https://lore.kernel.org/git/xmqqbll8569x.fsf@gitster.c.googlers.com/

 worktree.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

The content of this strbuf is unconditionally detached several lines before the strbuf_release() and the strbuf is never touched again after that point.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
---

Notes:
    I'm on the fence about this change. On the one hand, I spent extra
    cycles studying the code to determine if the strbuf was used again
    after being detached. On the other hand, the strbuf_release() at the
    end of the function protects against a leak if someone ever inserts
    code which re-uses the strbuf. So, I wouldn't be bothered if this
    patch is dropped from the series.

 worktree.c | 2 --
 1 file changed, 2 deletions(-)