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2022-04-13Revert "Merge branch 'ps/avoid-unnecessary-hook-invocation-with-packed-refs'"Libravatar Junio C Hamano1-19/+7
This reverts commit 991b4d47f0accd3955d05927d5ce434e03ffbdb6, reversing changes made to bcd020f88e1e22f38422ac3f73ab06b34ec4bef1.
2022-03-29Merge branch 'ab/refs-various-fixes'Libravatar Junio C Hamano1-32/+32
Code clean-up. * ab/refs-various-fixes: refs debug: add a wrapper for "read_symbolic_ref" packed-backend: remove stub BUG(...) functions misc *.c: use designated initializers for struct assignments refs: use designated initializers for "struct ref_iterator_vtable" refs: use designated initializers for "struct ref_storage_be"
2022-03-25Merge branch 'ps/fsync-refs'Libravatar Junio C Hamano1-0/+1
Updates to refs traditionally weren't fsync'ed, but we can configure using core.fsync variable to do so. * ps/fsync-refs: core.fsync: new option to harden references
2022-03-17refs: use designated initializers for "struct ref_iterator_vtable"Libravatar Ævar Arnfjörð Bjarmason1-6/+6
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-03-17refs: use designated initializers for "struct ref_storage_be"Libravatar Ævar Arnfjörð Bjarmason1-26/+26
Change the definition of the three refs backends we currently carry to use designated initializers. The "= NULL" assignments being retained here are redundant, and could be removed, but let's keep them for clarity. All of these backends define almost all fields, so we're not saving much in terms of line count by omitting these, but e.g. for "refs_be_debug" it's immediately apparent that we're omitting "init" when comparing its assignment to the others. This is a follow-up to similar work merged in bd4232fac33 (Merge branch 'ab/struct-init', 2021-07-16), a4b9fb6a5cf (Merge branch 'ab/designated-initializers-more', 2021-10-18) and a30321b9eae (Merge branch 'ab/designated-initializers' into ab/designated-initializers-more, 2021-09-27). Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-03-15core.fsync: new option to harden referencesLibravatar Patrick Steinhardt1-0/+1
When writing both loose and packed references to disk we first create a lockfile, write the updated values into that lockfile, and on commit we rename the file into place. According to filesystem developers, this behaviour is broken because applications should always sync data to disk before doing the final rename to ensure data consistency [1][2][3]. If applications fail to do this correctly, a hard crash of the machine can easily result in corrupted on-disk data. This kind of corruption can in fact be easily observed with Git when the machine hard-resets shortly after writing references to disk. On machines with ext4, this will likely lead to the "empty files" problem: the file has been renamed, but its data has not been synced to disk. The result is that the reference is corrupt, and in the worst case this can lead to data loss. Implement a new option to harden references so that users and admins can avoid this scenario by syncing locked loose and packed references to disk before we rename them into place. [1]: https://thunk.org/tytso/blog/2009/03/15/dont-fear-the-fsync/ [2]: https://btrfs.wiki.kernel.org/index.php/FAQ (What are the crash guarantees of overwrite-by-rename) [3]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/admin-guide/ext4.rst (see auto_da_alloc) Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-03-01refs/files-backend: optimize reading of symbolic refsLibravatar Patrick Steinhardt1-6/+28
When reading references via `files_read_raw_ref()` we always consult both the loose reference, and if that wasn't found, we also consult the packed-refs file. While this makes sense to read a generic reference, it is wasteful in the case where we only care about symbolic references: the packed-refs backend does not support them, and thus it cannot ever return one for us. Special-case reading of symbolic references for the files backend such that we always skip asking the packed-refs backend. We use `refs_read_symbolic_ref()` extensively to determine whether we need to skip updating local symbolic references during a fetch, which is why the change results in a significant speedup when doing fetches in repositories with huge numbers of references. The following benchmark executes a mirror-fetch in a repository with about 2 million references via `git fetch --prune --no-write-fetch-head +refs/*:refs/*`: Benchmark 1: HEAD~ Time (mean ± σ): 68.372 s ± 2.344 s [User: 65.629 s, System: 8.786 s] Range (min … max): 65.745 s … 70.246 s 3 runs Benchmark 2: HEAD Time (mean ± σ): 60.259 s ± 0.343 s [User: 61.019 s, System: 7.245 s] Range (min … max): 60.003 s … 60.649 s 3 runs Summary 'HEAD' ran 1.13 ± 0.04 times faster than 'HEAD~' Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-03-01refs: add ability for backends to special-case reading of symbolic refsLibravatar Patrick Steinhardt1-0/+1
Reading of symbolic and non-symbolic references is currently treated the same in reference backends: we always call `refs_read_raw_ref()` and then decide based on the returned flags what type it is. This has one downside though: symbolic references may be treated different from normal references in a backend from normal references. The packed-refs backend for example doesn't even know about symbolic references, and as a result it is pointless to even ask it for one. There are cases where we really only care about whether a reference is symbolic or not, but don't care about whether it exists at all or may be a non-symbolic reference. But it is not possible to optimize for this case right now, and as a consequence we will always first check for a loose reference to exist, and if it doesn't, we'll query the packed-refs backend for a known-to-not-be-symbolic reference. This is inefficient and requires us to search all packed references even though we know to not care for the result at all. Introduce a new function `refs_read_symbolic_ref()` which allows us to fix this case. This function will only ever return symbolic references and can thus optimize for the scenario layed out above. By default, if the backend doesn't provide an implementation for it, we just use the old code path and fall back to `read_raw_ref()`. But in case the backend provides its own, more efficient implementation, we will use that one instead. Note that this function is explicitly designed to not distinguish between missing references and non-symbolic references. If it did, we'd be forced to always search the packed-refs backend to see whether the symbolic reference the user asked for really doesn't exist, or if it exists as a non-symbolic reference. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-02-18Merge branch 'ps/avoid-unnecessary-hook-invocation-with-packed-refs'Libravatar Junio C Hamano1-7/+19
Because a deletion of ref would need to remove it from both the loose ref store and the packed ref store, a delete-ref operation that logically removes one ref may end up invoking ref-transaction hook twice, which has been corrected. * ps/avoid-unnecessary-hook-invocation-with-packed-refs: refs: skip hooks when deleting uncovered packed refs refs: do not execute reference-transaction hook on packing refs refs: demonstrate excessive execution of the reference-transaction hook refs: allow skipping the reference-transaction hook refs: allow passing flags when beginning transactions refs: extract packed_refs_delete_refs() to allow control of transaction
2022-01-26refs API: remove "failure_errno" from refs_resolve_ref_unsafe()Libravatar Ævar Arnfjörð Bjarmason1-22/+9
Remove the now-unused "failure_errno" parameter from the refs_resolve_ref_unsafe() signature. In my recent 96f6623ada0 (Merge branch 'ab/refs-errno-cleanup', 2021-11-29) series we made all of its callers explicitly request the errno via an output parameter. As that series shows all but one caller ended up passing in a boilerplate "ignore_errno", since they only cared about whether the return value was NULL or not, i.e. if the ref could be resolved. There was one small issue with that series fixed with a follow-up in 31e39123695 (Merge branch 'ab/refs-errno-cleanup', 2022-01-14) a small bug in that series was fixed. After those two there was one caller left in sequencer.c that used the "failure_errno', but as of the preceding commit it uses a boilerplate "ignore_errno" instead. This leaves the public refs API without any use of "failure_errno" at all. We could still do with a bit of cleanup and generalization between refs.c and refs/files-backend.c before the "reftable" integration lands, but that's all internal to the reference code itself. So let's remove this output parameter. Not only isn't it used now, but it's unlikely that we'll want it again in the future. We'd like to slowly move the refs API to a more file-backend independent way of communicating error codes, having it use a "failure_errno" was only the first step in that direction. If this or any other function needs to communicate what specifically is wrong with the requested "refname" it'll be better to have the function set some output enum of well-defined error states than piggy-backend on "errno". Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-17refs: skip hooks when deleting uncovered packed refsLibravatar Patrick Steinhardt1-3/+6
When deleting refs from the loose-files refs backend, then we need to be careful to also delete the same ref from the packed refs backend, if it exists. If we don't, then deleting the loose ref would "uncover" the packed ref. We thus always have to queue up deletions of refs for both the loose and the packed refs backend. This is done in two separate transactions, where the end result is that the reference-transaction hook is executed twice for the deleted refs. This behaviour is quite misleading: it's exposing implementation details of how the files backend works to the user, in contrast to the logical updates that we'd really want to expose via the hook. Worse yet, whether the hook gets executed once or twice depends on how well-packed the repository is: if the ref only exists as a loose ref, then we execute it once, otherwise if it is also packed then we execute it twice. Fix this behaviour and don't execute the reference-transaction hook at all when refs in the packed-refs backend if it's driven by the files backend. This works as expected even in case the refs to be deleted only exist in the packed-refs backend because the loose-backend always queues refs in its own transaction even if they don't exist such that they can be locked for concurrent creation. And it also does the right thing in case neither of the backends has the ref because that would cause the transaction to fail completely. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-17refs: do not execute reference-transaction hook on packing refsLibravatar Patrick Steinhardt1-2/+4
The reference-transaction hook is supposed to track logical changes to references, but it currently also gets executed when packing refs in a repository. This is unexpected and ultimately not all that useful: packing refs is not supposed to result in any user-visible change to the refs' state, and it ultimately is an implementation detail of how refs stores work. Fix this excessive execution of the hook when packing refs. Reported-by: Waleed Khan <me@waleedkhan.name> Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-17refs: allow passing flags when beginning transactionsLibravatar Patrick Steinhardt1-5/+5
We do not currently have any flags when creating reference transactions, but we'll add one to disable execution of the reference transaction hook in some cases. Allow passing flags to `ref_store_transaction_begin()` to prepare for this change. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-17refs: extract packed_refs_delete_refs() to allow control of transactionLibravatar Patrick Steinhardt1-3/+10
When deleting loose refs, then we also have to delete the refs in the packed backend. This is done by calling `refs_delete_refs()`, which then uses the packed-backend's logic to delete refs. This doesn't allow us to exercise any control over the reference transaction which is being created in the packed backend, which is required in a subsequent commit. Extract a new function `packed_refs_delete_refs()`, which hosts most of the logic to delete refs except for creating the transaction itself. Like this, we can easily create the transaction in the files backend and thus exert more control over it. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-14Merge branch 'ab/refs-errno-cleanup'Libravatar Junio C Hamano1-2/+1
A brown-paper-bag fix on top of a topic that was merged during this cycle. * ab/refs-errno-cleanup: refs API: use "failure_errno", not "errno"
2022-01-13refs API: use "failure_errno", not "errno"Libravatar Ævar Arnfjörð Bjarmason1-2/+1
Fix a logic error in refs_resolve_ref_unsafe() introduced in a recent series of mine to abstract the refs API away from errno. See 96f6623ada0 (Merge branch 'ab/refs-errno-cleanup', 2021-11-29)for that series. In that series introduction of "failure_errno" to refs_resolve_ref_unsafe came in ef18119dec8 (refs API: add a version of refs_resolve_ref_unsafe() with "errno", 2021-10-16). There we'd set "errno = 0" immediately before refs_read_raw_ref(), and then set "failure_errno" to "errno" if errno was non-zero afterwards. Then in the next commit 8b72fea7e91 (refs API: make refs_read_raw_ref() not set errno, 2021-10-16) we started expecting "refs_read_raw_ref()" to set "failure_errno". It would do that if refs_read_raw_ref() failed, but it wouldn't be the same errno. So we might set the "errno" here to any arbitrary bad value, and end up e.g. returning NULL when we meant to return the refname from refs_resolve_ref_unsafe(), or the other way around. Instrumenting this code will reveal cases where refs_read_raw_ref() will fail, and "errno" and "failure_errno" will be set to different values. In practice I haven't found a case where this scary bug changed anything in practice. The reason for that is that we'll not care about the actual value of "errno" here per-se, but only whether: 1. We have an errno 2. If it's one of ENOENT, EISDIR or ENOTDIR. See the adjacent code added in a1c1d8170db (refs_resolve_ref_unsafe: handle d/f conflicts for writes, 2017-10-06) I.e. if we clobber "failure_errno" with "errno", but it happened to be one of those three, and we'll clobber it with another one of the three we were OK. Perhaps there are cases where the difference ended up mattering, but I haven't found them. Instrumenting the test suite to fail if "errno" and "failure_errno" are different shows a lot of failures, checking if they're different *and* one is but not the other is outside that list of three "errno" values yields no failures. But let's fix the obvious bug. We should just stop paying attention to "errno" in refs_resolve_ref_unsafe(). In addition let's change the partial resetting of "errno" in files_read_raw_ref() to happen just before the "return", to ensure that any such bug will be more easily spotted in the future. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-10Merge branch 'ab/reflog-prep'Libravatar Junio C Hamano1-24/+20
Code refactoring in the reflog part of refs API. * ab/reflog-prep: reflog + refs-backend: move "verbose" out of the backend refs files-backend: assume cb->newlog if !EXPIRE_REFLOGS_DRY_RUN reflog: reduce scope of "struct rev_info" reflog expire: don't use lookup_commit_reference_gently() reflog expire: refactor & use "tip_commit" only for UE_NORMAL reflog expire: use "switch" over enum values reflog: change one->many worktree->refnames to use a string_list reflog expire: narrow scope of "cb" in cmd_reflog_expire() reflog delete: narrow scope of "cmd" passed to count_reflog_ent()
2021-12-22reflog + refs-backend: move "verbose" out of the backendLibravatar Ævar Arnfjörð Bjarmason1-24/+20
Move the handling of the "verbose" flag entirely out of "refs/files-backend.c" and into "builtin/reflog.c". This allows the backend to stop knowing about the EXPIRE_REFLOGS_VERBOSE flag. The expire_reflog_ent() function shouldn't need to deal with the implementation detail of whether or not we're emitting verbose output, by doing this the --verbose output becomes backend-agnostic, so reftable will get the same output. I think the output is rather bad currently, and should e.g. be implemented with some better future mode of progress.[ch], but that's a topic for another improvement. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-22refs files-backend: assume cb->newlog if !EXPIRE_REFLOGS_DRY_RUNLibravatar Ævar Arnfjörð Bjarmason1-2/+2
It's not possible for "cb->newlog" to be NULL if !EXPIRE_REFLOGS_DRY_RUN, since files_reflog_expire() would have error()'d and taken the "goto failure" branch if it couldn't open the file. By not using the "newlog" field private to "file-backend.c"'s "struct expire_reflog_cb", we can move this verbosity logging to "builtin/reflog.c" in a subsequent commit. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-22refs: centralize initialization of the base ref_store.Libravatar Han-Wen Nienhuys1-4/+1
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-22refs: pass gitdir to packed_ref_store_createLibravatar Han-Wen Nienhuys1-3/+2
This is consistent with the calling convention for ref backend creation, and avoids storing ".git/packed-refs" (the name of a regular file) in a variable called ref_store::gitdir. Signed-off-by: Han-Wen Nienhuys <hanwen@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-15Merge branch 'hn/allow-bogus-oid-in-ref-tests'Libravatar Junio C Hamano1-23/+30
The test helper for refs subsystem learned to write bogus and/or nonexistent object name to refs to simulate error situations we want to test Git in. * hn/allow-bogus-oid-in-ref-tests: t1430: create valid symrefs using test-helper t1430: remove refs using test-tool refs: introduce REF_SKIP_REFNAME_VERIFICATION flag refs: introduce REF_SKIP_OID_VERIFICATION flag refs: update comment. test-ref-store: plug memory leak in cmd_delete_refs test-ref-store: parse symbolic flag constants test-ref-store: remove force-create argument for create-reflog
2021-12-10Merge branch 'hn/create-reflog-simplify'Libravatar Junio C Hamano1-3/+2
A small simplification of API. * hn/create-reflog-simplify: refs: drop force_create argument of create_reflog API
2021-12-07refs: introduce REF_SKIP_OID_VERIFICATION flagLibravatar Han-Wen Nienhuys1-21/+29
This lets the ref-store test helper write non-existent or unparsable objects into the ref storage. Use this to make t1006 and t3800 independent of the files storage backend. Signed-off-by: Han-Wen Nienhuys <hanwen@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-07refs: update comment.Libravatar Han-Wen Nienhuys1-2/+1
REF_IS_PRUNING is right below this comment, so it clearly does not belong in this comment. This was apparently introduced in commit 5ac95fee (Nov 5, 2017 "refs: tidy up and adjust visibility of the `ref_update` flags"). Signed-off-by: Han-Wen Nienhuys <hanwen@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-11-29Merge branch 'ab/refs-errno-cleanup'Libravatar Junio C Hamano1-51/+102
The "remainder" of hn/refs-errno-cleanup topic. * ab/refs-errno-cleanup: (21 commits) refs API: post-migration API renaming [2/2] refs API: post-migration API renaming [1/2] refs API: don't expose "errno" in run_transaction_hook() refs API: make expand_ref() & repo_dwim_log() not set errno refs API: make resolve_ref_unsafe() not set errno refs API: make refs_ref_exists() not set errno refs API: make refs_resolve_refdup() not set errno refs tests: ignore ignore errno in test-ref-store helper refs API: ignore errno in worktree.c's find_shared_symref() refs API: ignore errno in worktree.c's add_head_info() refs API: make files_copy_or_rename_ref() et al not set errno refs API: make loose_fill_ref_dir() not set errno refs API: make resolve_gitlink_ref() not set errno refs API: remove refs_read_ref_full() wrapper refs/files: remove "name exist?" check in lock_ref_oid_basic() reflog tests: add --updateref tests refs API: make refs_rename_ref_available() static refs API: make parse_loose_ref_contents() not set errno refs API: make refs_read_raw_ref() not set errno refs API: add a version of refs_resolve_ref_unsafe() with "errno" ...
2021-11-22refs: drop force_create argument of create_reflog APILibravatar Han-Wen Nienhuys1-3/+2
There is only one caller, builtin/checkout.c, and it hardcodes force_create=1. This argument was introduced in abd0cd3a301 (refs: new public ref function: safe_create_reflog, 2015-07-21), which promised to immediately use it in a follow-on commit, but that never happened. Signed-off-by: Han-Wen Nienhuys <hanwen@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-25Merge branch 'jt/no-abuse-alternate-odb-for-submodules'Libravatar Junio C Hamano1-5/+11
Follow through the work to use the repo interface to access submodule objects in-process, instead of abusing the alternate object database interface. * jt/no-abuse-alternate-odb-for-submodules: submodule: trace adding submodule ODB as alternate submodule: pass repo to check_has_commit() object-file: only register submodule ODB if needed merge-{ort,recursive}: remove add_submodule_odb() refs: peeling non-the_repository iterators is BUG refs: teach arbitrary repo support to iterators refs: plumb repo into ref stores
2021-10-16refs API: post-migration API renaming [2/2]Libravatar Ævar Arnfjörð Bjarmason1-9/+9
Rename the transitory refs_werrres_ref_unsafe() function to refs_resolve_ref_unsafe(), now that all callers of the old function have learned to pass in a "failure_errno" parameter. The coccinelle semantic patch added in the preceding commit works, but I couldn't figure out how to get spatch(1) to re-flow these argument lists (and sometimes make lines way too long), so this rename was done with: perl -pi -e 's/refs_werrres_ref_unsafe/refs_resolve_ref_unsafe/g' \ $(git grep -l refs_werrres_ref_unsafe -- '*.c') But after that "make contrib/coccinelle/refs.cocci.patch" comes up empty, so the result would have been the same. Let's remove that transitory semantic patch file, we won't need to retain it for any other in-flight changes, refs_werrres_ref_unsafe() only existed within this patch series. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-16refs API: make files_copy_or_rename_ref() et al not set errnoLibravatar Ævar Arnfjörð Bjarmason1-4/+6
None of the callers of rename_ref() and copy_ref() care about errno, and as seen in the context here we already emit our own non-errno using error() in the case where we'd use it. So let's have it explicitly ignore errno, and do the same in commit_ref_update(), which is only used within other code in files_copy_or_rename_ref() itself which doesn't care about errno either. It might actually be sensible to have the callers use errno if the failure was filesystem-specific, and with the upcoming reftable backend we don't want to rely on that sort of thing, so let's keep ignoring that for now. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-16refs API: make loose_fill_ref_dir() not set errnoLibravatar Ævar Arnfjörð Bjarmason1-2/+3
Change the refs_resolve_ref_unsafe() invoked in loose_fill_ref_dir() to a form that ignores errno. The only eventual caller of this function is create_ref_cache(), whose callers in turn don't have their failure depend on any errno set here. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-16refs API: remove refs_read_ref_full() wrapperLibravatar Ævar Arnfjörð Bjarmason1-14/+22
Remove the refs_read_ref_full() wrapper in favor of migrating various refs.c API users to the underlying refs_werrres_ref_unsafe() function. A careful reading of these callers shows that the callers of this function did not care about "errno", by moving away from the refs_resolve_ref_unsafe() wrapper we can be sure that nothing relies on it anymore. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-16refs/files: remove "name exist?" check in lock_ref_oid_basic()Libravatar Ævar Arnfjörð Bjarmason1-24/+24
In lock_ref_oid_basic() we'll happily lock a reference that doesn't exist yet. That's normal, and is how references are initially born, but we don't need to retain checks here in lock_ref_oid_basic() about the state of the ref, when what we're checking is either checked already, or something we're about to discover by trying to lock the ref with raceproof_create_file(). The one exception is the caller in files_reflog_expire(), who passes us a "type" to find out if the reference is a symref or not. We can move the that logic over to that caller, which can now defer its discovery of whether or not the ref is a symref until it's needed. In the preceding commit an exhaustive regression test was added for that case in a new test in "t1417-reflog-updateref.sh". The improved diagnostics here were added in 5b2d8d6f218 (lock_ref_sha1_basic(): improve diagnostics for ref D/F conflicts, 2015-05-11), and then much of the surrounding code went away recently in my 245fbba46d6 (refs/files: remove unused "errno == EISDIR" code, 2021-08-23). The refs_resolve_ref_unsafe() code being removed here looks like it should be tasked with doing that, but it's actually redundant to other code. The reason for that is as noted in 245fbba46d6 this once widely used function now only has a handful of callers left, which all handle this case themselves. To the extent that we're racy between their check and ours removing this check actually improves the situation, as we'll be doing fewer things between the not-under-lock initial check and acquiring the lock. Why this is OK for all the remaining callers of lock_ref_oid_basic() is noted below. There are only two of those callers: * "git branch -[cm] <oldbranch> <newbranch>": In files_copy_or_rename_ref() we'll call this when we copy or rename refs via rename_ref() and copy_ref(). but only after we've checked if the refname exists already via its own call to refs_resolve_ref_unsafe() and refs_rename_ref_available(). As the updated comment to the latter here notes neither of those are actually needed. If we delete not only this code but also refs_rename_ref_available() we'll do just fine, we'll just emit a less friendly error message if e.g. "git branch -m A B/C" would have a D/F conflict with a "B" file. Actually we'd probably die before that in case reflogs for the branch existed, i.e. when the try to rename() or copy_file() the relevant reflog, since if we've got a D/F conflict with a branch name we'll probably also have the same with its reflogs (but not necessarily, we might have reflogs, but it might not). As some #leftoverbits that code seems buggy to me, i.e. the reflog "protocol" should be to get a lock on the main ref, and then perform ref and/or reflog operations. That code dates back to c976d415e53 (git-branch: add options and tests for branch renaming, 2006-11-28) and probably pre-dated the solidifying of that convention. But in any case, that edge case is not our bug or problem right now. * "git reflog expire <ref>": In files_reflog_expire() we'll call this without previous ref existence checking in files-backend.c, but that code is in turn called by code that's just finished checking if the refname whose reflog we're expiring exists. See ae35e16cd43 (reflog expire: don't lock reflogs using previously seen OID, 2021-08-23) for the current state of that code, and 5e6f003ca8a (reflog_expire(): ignore --updateref for symbolic references, 2015-03-03) for the code we'd break if we only did a "update = !!ref" here, which is covered by the aforementioned regression test in "t1417-reflog-updateref.sh". Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-16refs API: make refs_rename_ref_available() staticLibravatar Ævar Arnfjörð Bjarmason1-0/+29
Move the refs_rename_ref_available() function into "refs/files-backend.c". It is file-backend specific. This function was added in 5fe7d825da8 (refs.c: pass a list of names to skip to is_refname_available, 2014-05-01) as rename_ref_available() and was only ever used in this one file-backend specific codepath. So let's move it there. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-16refs API: make parse_loose_ref_contents() not set errnoLibravatar Han-Wen Nienhuys1-11/+20
Change the parse_loose_ref_contents() function to stop setting "errno" and failure, and to instead pass up a "failure_errno" via a parameter. This requires changing its callers to do the same. The EINVAL error from parse_loose_ref_contents is used in files-backend to create a custom error message. In untangling this we discovered a tricky edge case. The refs_read_special_head() function was relying on parse_loose_ref_contents() setting EINVAL. By converting it to use "saved_errno" we can migrate away from "errno" in this part of the code entirely, and do away with an existing "save_errno" pattern, its only purpose was to not clobber the "errno" we previously needed at the end of files_read_raw_ref(). Let's assert that we can do that by not having files_read_raw_ref() itself operate on *failure_errno in addition to passing it on. Instead we'll assert that if we return non-zero we actually do set errno, thus assuring ourselves and callers that they can trust the resulting "failure_errno". Signed-off-by: Han-Wen Nienhuys <hanwen@google.com> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-16refs API: make refs_read_raw_ref() not set errnoLibravatar Han-Wen Nienhuys1-4/+6
Add a "failure_errno" to refs_read_raw_ref(), his allows refs_werrres_ref_unsafe() to pass along its "failure_errno", as a first step before its own callers are migrated to pass it further up the chain. We are leaving out out the refs_read_special_head() in refs_read_raw_ref() for now, as noted in a subsequent commit moving it to "failure_errno" will require some special consideration. Signed-off-by: Han-Wen Nienhuys <hanwen@google.com> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-11Merge branch 'jk/ref-paranoia'Libravatar Junio C Hamano1-0/+5
The ref iteration code used to optionally allow dangling refs to be shown, which has been tightened up. * jk/ref-paranoia: refs: drop "broken" flag from for_each_fullref_in() ref-filter: drop broken-ref code entirely ref-filter: stop setting FILTER_REFS_INCLUDE_BROKEN repack, prune: drop GIT_REF_PARANOIA settings refs: turn on GIT_REF_PARANOIA by default refs: omit dangling symrefs when using GIT_REF_PARANOIA refs: add DO_FOR_EACH_OMIT_DANGLING_SYMREFS flag refs-internal.h: reorganize DO_FOR_EACH_* flag documentation refs-internal.h: move DO_FOR_EACH_* flags next to each other t5312: be more assertive about command failure t5312: test non-destructive repack t5312: create bogus ref as necessary t5312: drop "verbose" helper t5600: provide detached HEAD for corruption failures t5516: don't use HEAD ref for invalid ref-deletion tests t7900: clean up some more broken refs
2021-10-08refs: peeling non-the_repository iterators is BUGLibravatar Jonathan Tan1-2/+3
There is currently no support for peeling the current ref of an iterator iterating over a non-the_repository ref store, and none is needed. Thus, for now, BUG() if that happens. Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-08refs: teach arbitrary repo support to iteratorsLibravatar Jonathan Tan1-1/+4
Note that should_pack_ref() is called when writing refs, which is only supported for the_repository, hence the_repository is hardcoded there. Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-08refs: plumb repo into ref storesLibravatar Jonathan Tan1-2/+4
In preparation for the next 2 patches that adds (partial) support for arbitrary repositories to ref iterators, plumb a repository into all ref stores. There are no changes to program logic. Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-06Merge branch 'ab/retire-refs-unused-funcs'Libravatar Junio C Hamano1-3/+3
Code cleanup. * ab/retire-refs-unused-funcs: refs/ref-cache.[ch]: remove "incomplete" from create_dir_entry() refs/ref-cache.c: remove "mkdir" parameter from find_containing_dir() refs/ref-cache.[ch]: remove unused add_ref_entry() refs/ref-cache.[ch]: remove unused remove_entry_from_dir() refs.[ch]: remove unused ref_storage_backend_exists()
2021-10-03Merge branch 'hn/refs-errno-cleanup'Libravatar Junio C Hamano1-23/+126
Futz with the way 'errno' is relied on in the refs API to carry the failure modes up the call chain. * hn/refs-errno-cleanup: refs: make errno output explicit for read_raw_ref_fn refs/files-backend: stop setting errno from lock_ref_oid_basic refs: remove EINVAL errno output from specification of read_raw_ref_fn refs file backend: move raceproof_create_file() here
2021-10-03Merge branch 'ab/refs-files-cleanup'Libravatar Junio C Hamano1-97/+35
Continued work on top of the hn/refs-errno-cleanup topic. * ab/refs-files-cleanup: refs/files: remove unused "errno != ENOTDIR" condition refs/files: remove unused "errno == EISDIR" code refs/files: remove unused "oid" in lock_ref_oid_basic() refs API: remove OID argument to reflog_expire() reflog expire: don't lock reflogs using previously seen OID refs/files: add a comment about refs_reflog_exists() call refs: make repo_dwim_log() accept a NULL oid refs/debug: re-indent argument list for "prepare" refs/files: remove unused "skip" in lock_raw_ref() too refs/files: remove unused "extras/skip" in lock_ref_oid_basic() refs: drop unused "flags" parameter to lock_ref_oid_basic() refs/files: remove unused REF_DELETING in lock_ref_oid_basic() refs/packet: add missing BUG() invocations to reflog callbacks
2021-09-28refs/ref-cache.[ch]: remove "incomplete" from create_dir_entry()Libravatar Ævar Arnfjörð Bjarmason1-3/+3
Remove the now-unused "incomplete" parameter from create_dir_entry(), all its callers specify it as "1", so let's drop the "incomplete=0" case. The last caller to use it was search_for_subdir(), but that code was removed in the preceding commit. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-27refs: add DO_FOR_EACH_OMIT_DANGLING_SYMREFS flagLibravatar Jeff King1-0/+5
When the DO_FOR_EACH_INCLUDE_BROKEN flag is used, we include both actual corrupt refs (illegal names, missing objects), but also symrefs that point to nothing. This latter is not really a corruption, but just something that may happen normally. For example, the symref at refs/remotes/origin/HEAD may point to a tracking branch which is later deleted. (The local HEAD may also be unborn, of course, but we do not access it through ref iteration). Most callers of for_each_ref() etc, do not care. They don't pass INCLUDE_BROKEN, so don't see it at all. But for those which do pass it, this somewhat-normal state causes extra warnings (e.g., from for-each-ref) or even aborts operations (destructive repacks with GIT_REF_PARANOIA set). This patch just introduces the flag and the mechanism; there are no callers yet (and hence no tests). Two things to note on the implementation: - we actually skip any symref that does not resolve to a ref. This includes ones which point to an invalidly-named ref. You could argue this is a more serious breakage than simple dangling. But the overall effect is the same (we could not follow the symref), as well as the impact on things like REF_PARANOIA (either way, a symref we can't follow won't impact reachability, because we'll see the ref itself during iteration). The underlying resolution function doesn't distinguish these two cases (they both get REF_ISBROKEN). - we change the iterator in refs/files-backend.c where we check INCLUDE_BROKEN. There's a matching spot in refs/packed-backend.c, but we don't know need to do anything there. The packed backend does not support symrefs at all. The resulting set of flags might be a bit easier to follow if we broke this down into "INCLUDE_CORRUPT_REFS" and "INCLUDE_DANGLING_SYMREFS". But there are a few reasons not do so: - adding a new OMIT_DANGLING_SYMREFS flag lets us leave existing callers intact, without changing their behavior (and some of them really do want to see the dangling symrefs; e.g., t5505 has a test which expects us to report when a symref becomes dangling) - they're not actually independent. You cannot say "include dangling symrefs" without also including refs whose objects are not reachable, because dangling symrefs by definition do not have an object. We could tweak the implementation to distinguish this, but in practice nobody wants to ask for that. Adding the OMIT flag keeps the implementation simple and makes sure we don't regress the current behavior. Signed-off-by: Jeff King <peff@peff.net> Reviewed-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-09refs/files-backend: remove unused open mode parameterLibravatar René Scharfe1-1/+1
We only need to provide a mode if we are willing to let open(2) create the file, which is not the case here, so drop the unnecessary parameter. Signed-off-by: René Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-08-25refs: make errno output explicit for read_raw_ref_fnLibravatar Han-Wen Nienhuys1-14/+15
This makes it explicit how alternative ref backends should report errors in read_raw_ref_fn. read_raw_ref_fn needs to supply a credible errno for a number of cases. These are primarily: 1) The files backend calls read_raw_ref from lock_raw_ref, and uses the resulting error codes to create/remove directories as needed. 2) ENOENT should be translated in a zero OID, optionally with REF_ISBROKEN set, returning the last successfully resolved symref. This is necessary so read_raw_ref("HEAD") on an empty repo returns refs/heads/main (or the default branch du-jour), and we know on which branch to create the first commit. Make this information flow explicit by adding a failure_errno to the signature of read_raw_ref. All errnos from the files backend are still propagated unchanged, even though inspection suggests only ENOTDIR, EISDIR and ENOENT are relevant. Signed-off-by: Han-Wen Nienhuys <hanwen@google.com> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-08-25refs/files-backend: stop setting errno from lock_ref_oid_basicLibravatar Han-Wen Nienhuys1-9/+2
refs/files-backend.c::lock_ref_oid_basic() tries to signal how it failed to its callers using errno. It is safe to stop setting errno here, because the callers of this file-scope static function are * files_copy_or_rename_ref() * files_create_symref() * files_reflog_expire() None of them looks at errno after seeing a negative return from lock_ref_oid_basic() to make any decision, and no caller of these three functions looks at errno after they signal a failure by returning a negative value. In particular, * files_copy_or_rename_ref() - here, calls are followed by error() (which performs I/O) or write_ref_to_lockfile() (which calls parse_object() which may perform I/O) * files_create_symref() - here, calls are followed by error() or create_symref_locked() (which performs I/O and does not inspect errno) * files_reflog_expire() - here, calls are followed by error() or refs_reflog_exists() (which calls a function in a vtable that is not documented to use and/or preserve errno) Signed-off-by: Han-Wen Nienhuys <hanwen@google.com> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-08-25refs file backend: move raceproof_create_file() hereLibravatar Ævar Arnfjörð Bjarmason1-0/+109
Move the raceproof_create_file() API added to cache.h and object-file.c in 177978f56ad (raceproof_create_file(): new function, 2017-01-06) to its only user, refs/files-backend.c. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-08-25refs/files: remove unused "errno != ENOTDIR" conditionLibravatar Ævar Arnfjörð Bjarmason1-2/+1
As a follow-up to the preceding commit where we removed the adjacent "errno == EISDIR" condition in the same function, remove the "last_errno != ENOTDIR" condition here. It's not possible for us to hit this condition added in 5b2d8d6f218 (lock_ref_sha1_basic(): improve diagnostics for ref D/F conflicts, 2015-05-11). Since a1c1d8170db (refs_resolve_ref_unsafe: handle d/f conflicts for writes, 2017-10-06) we've explicitly caught these in refs_resolve_ref_unsafe() before returning NULL: if (errno != ENOENT && errno != EISDIR && errno != ENOTDIR) return NULL; We'd then always return the refname from refs_resolve_ref_unsafe() even if we were in a broken state as explained in the preceding commit. The elided context here is a call to refs_resolve_ref_unsafe(). Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>