delta/git.git, branch nd/worktree-kill-parse-ref

branch: fix branch renaming not updating HEADs correctly

2017-08-24T21:15:18+00:00

There are two bugs that sort of work together and cause
problems. Let's start with one in replace_each_worktree_head_symref.

Before fa099d2322 (worktree.c: kill parse_ref() in favor of
refs_resolve_ref_unsafe() - 2017-04-24), this code looks like this:

    if (strcmp(oldref, worktrees[i]->head_ref))
            continue;
    set_worktree_head_symref(...);

After fa099d2322, it is possible that head_ref can be NULL. However,
the updated code takes the wrong exit. In the error case (NULL
head_ref), we should "continue;" to the next worktree. The updated
code makes us _skip_ "continue;" and update HEAD anyway.

The NULL head_ref is triggered by the second bug in add_head_info (in
the same commit). With the flag RESOLVE_REF_READING, resolve_ref_unsafe()
will abort if it cannot resolve the target ref. For orphan checkouts,
HEAD always points to an unborned branch, resolving target ref will
always fail. Now we have NULL head_ref. Now we always update HEAD.

Correct the logic in replace_ function so that we don't accidentally
update HEAD on error. As it turns out, correcting the logic bug above
breaks branch renaming completely, thanks to the second bug.

"git branch -[Mm]" does two steps (on a normal checkout, no orphan!):

 - rename the branch on disk (e.g. refs/heads/abc to refs/heads/def)
 - update HEAD if it points to the branch being renamed.

At the second step, since the branch pointed to by HEAD (e.g. "abc") no
longer exists on disk, we run into a temporary orphan checkout situation
that has been just corrected to _not_ update HEAD. But we need to update
HEAD since it's not actually an orphan checkout. We need to update HEAD
to move out of that orphan state.

Correct add_head_info(), remove RESOLVE_REF_READING flag. With the flag
gone, we should always return good "head_ref" in orphan checkouts (either
temporary or permanent). With good head_ref, things start to work again.

Noticed-by: Nish Aravamudan 
Signed-off-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano

refs: kill set_worktree_head_symref()

2017-04-25T04:28:55+00:00

70999e9cec (branch -m: update all per-worktree HEADs - 2016-03-27)
added this function in order to update HEADs of all relevant
worktrees, when a branch is renamed.

It, as a public ref api, kind of breaks abstraction when it uses
internal functions of files backend. With the introduction of
refs_create_symref(), we can move back pretty close to the code before
70999e9cec, where create_symref() was used for updating HEAD.

Signed-off-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano

worktree.c: kill parse_ref() in favor of refs_resolve_ref_unsafe()

2017-04-25T04:28:55+00:00

The manual parsing code is replaced with a call to refs_resolve_ref_unsafe().
The manual parsing code must die because only refs/files-backend.c
should do that.

Signed-off-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano

refs: introduce get_worktree_ref_store()

2017-04-25T04:28:55+00:00

files-backend at this point is still aware of the per-repo/worktree
separation in refs, so it can handle a linked worktree.

Some refs operations are known not working when current files-backend is
used in a linked worktree (e.g. reflog). Tests will be written when
refs_* functions start to be called with worktree backend to verify that
they work as expected.

Note: accessing a worktree of a submodule remains unaddressed. Perhaps
after get_worktrees() can access submodule (or rather a new function
get_submodule_worktrees(), that lists worktrees of a submodule), we can
update this function to work with submodules as well.

Signed-off-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano

refs: add REFS_STORE_ALL_CAPS

2017-04-25T04:28:55+00:00

Signed-off-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano

refs.c: make submodule ref store hashmap generic

2017-04-17T01:24:29+00:00

This removes the "submodule" from submodule_hash_entry and other
function names. The goal is to reuse the same code and data structure
for other ref store types. The first one is worktree ref stores.

Signed-off-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano

environment.c: fix potential segfault by get_git_common_dir()

2017-04-17T01:24:29+00:00

setup_git_env() must be called before this function to initialize
git_common_dir so that it returns a non NULL string. And it must return
a non NULL string or segfault can happen because all callers expect so.

It does not do so explicitly though and depends on get_git_dir() being
called first (which will guarantee setup_git_env()). Avoid this
dependency and call setup_git_env() by itself.

test-ref-store.c will hit this problem because it's very lightweight,
just enough initialization to exercise refs code, and get_git_dir() will
never be called until get_worktrees() is, which uses get_git_common_dir
and hits a segfault.

Signed-off-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano

refs.h: add a note about sorting order of for_each_ref_*

2017-04-14T10:53:25+00:00

Signed-off-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano

t1406: new tests for submodule ref store

2017-04-14T10:53:25+00:00

Signed-off-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano

t1405: some basic tests on main ref store

2017-04-14T10:53:25+00:00

Signed-off-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano