git/refs.h, branch v2.51.2

Merge branch 'kn/refs-files-case-insensitive' into maint-2.51

2025-10-15T17:29:31Z

Deal more gracefully with directory / file conflicts when the files backend is used for ref storage, by failing only the ones that are involved in the conflict while allowing others. * kn/refs-files-case-insensitive: refs/files: handle D/F conflicts during locking refs/files: handle F/D conflicts in case-insensitive FS refs/files: use correct error type when lock exists refs/files: catch conflicts on case-insensitive file-systems

Merge branch 'ps/reflog-migrate-fixes' into maint-2.51

2025-10-15T17:29:28Z

"git refs migrate" to migrate the reflog entries from a refs backend to another had a handful of bugs squashed. * ps/reflog-migrate-fixes: refs: fix invalid old object IDs when migrating reflogs refs: stop unsetting REF_HAVE_OLD for log-only updates refs/files: detect race when generating reflog entry for HEAD refs: fix identity for migrated reflogs ident: fix type of string length parameter builtin/reflog: implement subcommand to write new entries refs: export `ref_transaction_update_reflog()` builtin/reflog: improve grouping of subcommands Documentation/git-reflog: convert to use synopsis type

refs/files: catch conflicts on case-insensitive file-systems

2025-09-17T16:19:07Z

During the 'prepare' phase of a reference transaction in the files backend, we create the lock files for references to be created. When using batched updates on case-insensitive filesystems, the entire batched updates would be aborted if there are conflicting names such as: refs/heads/Foo refs/heads/foo This affects all commands which were migrated to use batched updates in Git 2.51, including 'git-fetch(1)' and 'git-receive-pack(1)'. Before that, reference updates would be applied serially with one transaction used per update. When users fetched multiple references on case-insensitive systems, subsequent references would simply overwrite any earlier references. So when fetching: refs/heads/foo: 5f34ec0bfeac225b1c854340257a65b106f70ea6 refs/heads/Foo: ec3053b0977e83d9b67fc32c4527a117953994f3 refs/heads/sample: 2eefd1150e06d8fca1ddfa684dec016f36bf4e56 The user would simply end up with: refs/heads/foo: ec3053b0977e83d9b67fc32c4527a117953994f3 refs/heads/sample: 2eefd1150e06d8fca1ddfa684dec016f36bf4e56 This is buggy behavior since the user is never informed about the overrides performed and missing references. Nevertheless, the user is left with a working repository with a subset of the references. Since Git 2.51, in such situations fetches would simply fail without updating any references. Which is also buggy behavior and worse off since the user is left without any references. The error is triggered in `lock_raw_ref()` where the files backend attempts to create a lock file. When a lock file already exists the function returns a 'REF_TRANSACTION_ERROR_GENERIC'. When this happens, the entire batched updates, not individual operation, is aborted as if it were in a transaction. Change this to return 'REF_TRANSACTION_ERROR_CASE_CONFLICT' instead to aid the batched update mechanism to simply reject such errors. The change only affects batched updates since batched updates will reject individual updates with non-generic errors. So specifically this would only affect: 1. git fetch 2. git receive-pack 3. git update-ref --batch-updates This bubbles the error type up to `files_transaction_prepare()` which tries to lock each reference update. So if the locking fails, we check if the rejection type can be ignored, which is done by calling `ref_transaction_maybe_set_rejected()`. As the error type is now 'REF_TRANSACTION_ERROR_CASE_CONFLICT', the specific reference update would simply be rejected, while other updates in the transaction would continue to be applied. This allows partial application of references in case-insensitive filesystems when fetching colliding references. While the earlier implementation allowed the last reference to be applied overriding the initial references, this change would allow the first reference to be applied while rejecting consequent collisions. This should be an okay compromise since with the files backend, there is no scenario possible where we would retain all colliding references. Let's also be more proactive and notify users on case-insensitive filesystems about such problems by providing a brief about the issue while also recommending using the reftable backend, which doesn't have the same issue. Reported-by: Joe Drew Helped-by: Patrick Steinhardt Signed-off-by: Karthik Nayak Signed-off-by: Junio C Hamano

refs: fix invalid old object IDs when migrating reflogs

2025-08-06T14:36:31Z

When migrating reflog entries between different storage formats we end up with invalid old object IDs for the migrated entries: instead of writing the old object ID of the to-be-migrated entry, we end up with the all-zeroes object ID. The root cause of this issue is that we don't know to use the old object ID provided by the caller. Instead, we manually resolve the old object ID by resolving the current value of its matching reference. But as that reference does not yet exist in the target ref storage we always end up resolving it to all-zeroes. This issue got unnoticed as there is no user-facing command that would even show the old object ID. While `git log -g` knows to show the new object ID, we don't have any formatting directive to show the old object ID. Fix the bug by introducing a new flag `REF_LOG_USE_PROVIDED_OIDS`. If set, backends are instructed to use the old and new object IDs provided by the caller, without doing any manual resolving. Set this flag in `ref_transaction_update_reflog()`. Amend our tests in t1460-refs-migrate to use our test tool to read reflog entries. This test tool prints out both old and new object ID of each reflog entry, which fixes the test gap. Furthermore it also prints the full identity used to write the reflog, which provides test coverage for the previous commit in this patch series that fixed the identity for migrated reflogs. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano

refs: export `ref_transaction_update_reflog()`

2025-08-06T14:36:29Z

In a subsequent commit we'll add another user that wants to write reflog entries. This requires them to call `ref_transaction_update_reflog()`, but that function is local to "refs.c". Export the function to prepare for the change. While at it, drop the `flags` field, as all callers are for now expected to use the same flags anyway. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano

Merge branch 'kn/for-each-ref-skip'

2025-08-04T01:44:26Z

"git for-each-ref" learns "--start-after" option to help applications that want to page its output. * kn/for-each-ref-skip: ref-cache: set prefix_state when seeking for-each-ref: introduce a '--start-after' option ref-filter: remove unnecessary else clause refs: selectively set prefix in the seek functions ref-cache: remove unused function 'find_ref_entry()' refs: expose `ref_iterator` via 'refs.h'

Merge branch 'ph/fetch-prune-optim'

2025-07-16T16:42:27Z

"git fetch --prune" used to be O(n^2) expensive when there are many refs, which has been corrected. * ph/fetch-prune-optim: clean up interface for refs_warn_dangling_symrefs refs: remove old refs_warn_dangling_symref fetch-prune: optimize dangling-ref reporting

refs: selectively set prefix in the seek functions

2025-07-15T18:54:20Z

The ref iterator exposes a `ref_iterator_seek()` function. The name suggests that this would seek the iterator to a specific reference in some ways similar to how `fseek()` works for the filesystem. However, the function actually sets the prefix for refs iteration. So further iteration would only yield references which match the particular prefix. This is a bit confusing. Let's add a 'flags' field to the function, which when set with the 'REF_ITERATOR_SEEK_SET_PREFIX' flag, will set the prefix for the iteration in-line with the existing behavior. Otherwise, the reference backends will simply seek to the specified reference and clears any previously set prefix. This allows users to start iteration from a specific reference. In the packed and reftable backend, since references are available in a sorted list, the changes are simply setting the prefix if needed. The changes on the files-backend are a little more involved, since the files backend uses the 'ref-cache' mechanism. We move out the existing logic within `cache_ref_iterator_seek()` to `cache_ref_iterator_set_prefix()` which is called when the 'REF_ITERATOR_SEEK_SET_PREFIX' flag is set. We then parse the provided seek string and set the required levels and their indexes to ensure that seeking is possible. Helped-by: Patrick Steinhardt Signed-off-by: Karthik Nayak Signed-off-by: Junio C Hamano

refs: expose `ref_iterator` via 'refs.h'

2025-07-15T18:54:19Z

The `ref_iterator` is an internal structure to the 'refs/' sub-directory, which allows iteration over refs. All reference iteration is built on top of these iterators. External clients of the 'refs' subsystem use the various 'refs_for_each...()' functions to iterate over refs. However since these are wrapper functions, each combination of functionality requires a new wrapper function. This is not feasible as the functions pile up with the increase in requirements. Expose the internal reference iterator, so advanced users can mix and match options as needed. Signed-off-by: Karthik Nayak Signed-off-by: Junio C Hamano

clean up interface for refs_warn_dangling_symrefs

2025-07-02T01:42:25Z

The refs_warn_dangling_symrefs interface is a bit fragile as it passes in printf-formatting strings with expectations about the number of arguments. This patch series made it worse by adding a 2nd positional argument. But there are only two call sites, and they both use almost identical display options. Make this safer by moving the format strings into the function that uses them to make it easier to see when the arguments don't match. Pass a prefix string and a dry_run flag so the decision logic can be handled where needed. Signed-off-by: Phil Hord Signed-off-by: Junio C Hamano