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2024-06-14hash: require hash algorithm in `oidread()` and `oidclr()`Patrick Steinhardt
Both `oidread()` and `oidclr()` use `the_repository` to derive the hash function that shall be used. Require callers to pass in the hash algorithm to get rid of this implicit dependency. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-06-07global: improve const correctness when assigning string constantsPatrick Steinhardt
We're about to enable `-Wwrite-strings`, which changes the type of string constants to `const char[]`. Fix various sites where we assign such constants to non-const variables. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-06-07update-ref: add support for 'symref-create' commandKarthik Nayak
Add 'symref-create' command to the '--stdin' mode 'git-update-ref' to allow creation of symbolic refs in a transaction. The 'symref-create' command takes in a <new-target>, which the created <ref> will point to. Also, support the 'core.prefersymlinkrefs' config, wherein if the config is set and the filesystem supports symlinks, we create the symbolic ref as a symlink. We fallback to creating a regular symref if creating the symlink is unsuccessful. Helped-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-06-07update-ref: add support for 'symref-delete' commandKarthik Nayak
Add a new command 'symref-delete' to allow deletions of symbolic refs in a transaction via the '--stdin' mode of the 'git-update-ref' command. The 'symref-delete' command can, when given an <old-target>, delete the provided <ref> only when it points to <old-target>. This command is only compatible with the 'no-deref' mode because we optionally want to check the 'old_target' of the ref being deleted. De-referencing a symbolic ref would provide a regular ref and we already have the 'delete' command for regular refs. While users can also use 'git symbolic-ref -d' to delete symbolic refs, the 'symref-delete' command in 'git-update-ref' allows users to do so within a transaction, which promises atomicity of the operation and can be batched with other commands. When no 'old_target' is provided it can also delete regular refs, similar to how the 'delete' command can delete symrefs when no 'old_oid' is provided. Helped-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-06-07update-ref: add support for 'symref-verify' commandKarthik Nayak
The 'symref-verify' command allows users to verify if a provided <ref> contains the provided <old-target> without changing the <ref>. If <old-target> is not provided, the command will verify that the <ref> doesn't exist. The command allows users to verify symbolic refs within a transaction, and this means users can perform a set of changes in a transaction only when the verification holds good. Since we're checking for symbolic refs, this command will only work with the 'no-deref' mode. This is because any dereferenced symbolic ref will point to an object and not a ref and the regular 'verify' command can be used in such situations. Add required tests for symref support in 'verify'. Since we're here, also add reflog checks for the pre-existing 'verify' tests, there is no divergence from behavior, but we never tested to ensure that reflog wasn't affected by the 'verify' command. Helped-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-06-07refs: create and use `ref_update_expects_existing_old_ref()`Karthik Nayak
The files and reftable backend, need to check if a ref must exist, so that the required validation can be done. A ref must exist only when the `old_oid` value of the update has been explicitly set and it is not the `null_oid` value. Since we also support symrefs now, we need to ensure that even when `old_target` is set a ref must exist. While this was missed when we added symref support in transactions, there are no active users of this path. As we introduce the 'symref-verify' command in the upcoming commits, it is important to fix this. So let's export this to a function called `ref_update_expects_existing_old_ref()` and expose it internally via 'refs-internal.h'. Helped-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-06-06refs: implement logic to migrate between ref storage formatsPatrick Steinhardt
With the introduction of the new "reftable" backend, users may want to migrate repositories between the backends without having to recreate the whole repository. Add the logic to do so. The implementation is generic and works with arbitrary ref storage formats so that a backend does not need to implement any migration logic. It does have a few limitations though: - We do not migrate repositories with worktrees, because worktrees have separate ref storages. It makes the overall affair more complex if we have to migrate multiple storages at once. - We do not migrate reflogs, because we have no interfaces to write many reflog entries. - We do not lock the repository for concurrent access, and thus concurrent writes may end up with weird in-between states. There is no way to fully lock the "files" backend for writes due to its format, and thus we punt on this topic altogether and defer to the user to avoid those from happening. In other words, this version is a minimum viable product for migrating a repository's ref storage format. It works alright for bare repos, which often have neither worktrees nor reflogs. But it will not work for many other repositories without some preparations. These limitations are not set into stone though, and ideally we will eventually address them over time. The logic is not yet used by anything, and thus there are no tests for it. Those will be added in the next commit. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-06-06refs: implement removal of ref storagesPatrick Steinhardt
We're about to introduce logic to migrate ref storages. One part of the migration will be to delete the files that are part of the old ref storage format. We don't yet have a way to delete such data generically across ref backends though. Implement a new `delete` callback and expose it via a new `ref_storage_delete()` function. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-06-06refs: allow to skip creation of reflog entriesPatrick Steinhardt
The ref backends do not have any way to disable the creation of reflog entries. This will be required for upcoming ref format migration logic so that we do not create any entries that didn't exist in the original ref database. Provide a new `REF_SKIP_CREATE_REFLOG` flag that allows the caller to disable reflog entry creation. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-06-06refs: pass storage format to `ref_store_init()` explicitlyPatrick Steinhardt
We're about to introduce logic to migrate refs from one storage format to another one. This will require us to initialize a ref store with a different format than the one used by the passed-in repository. Prepare for this by accepting the desired ref storage format as parameter. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-06-06refs: convert ref storage format to an enumPatrick Steinhardt
The ref storage format is tracked as a simple unsigned integer, which makes it harder than necessary to discover what that integer actually is or where its values are defined. Convert the ref storage format to instead be an enum. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-28Merge branch 'ps/pseudo-ref-terminology'Junio C Hamano
Terminology to call various ref-like things are getting straightened out. * ps/pseudo-ref-terminology: refs: refuse to write pseudorefs ref-filter: properly distinuish pseudo and root refs refs: pseudorefs are no refs refs: classify HEAD as a root ref refs: do not check ref existence in `is_root_ref()` refs: rename `is_special_ref()` to `is_pseudo_ref()` refs: rename `is_pseudoref()` to `is_root_ref()` Documentation/glossary: define root refs as refs Documentation/glossary: clarify limitations of pseudorefs Documentation/glossary: redefine pseudorefs as special refs
2024-05-23Merge branch 'ps/pseudo-ref-terminology' into ps/ref-storage-migrationJunio C Hamano
* ps/pseudo-ref-terminology: refs: refuse to write pseudorefs ref-filter: properly distinuish pseudo and root refs refs: pseudorefs are no refs refs: classify HEAD as a root ref refs: do not check ref existence in `is_root_ref()` refs: rename `is_special_ref()` to `is_pseudo_ref()` refs: rename `is_pseudoref()` to `is_root_ref()` Documentation/glossary: define root refs as refs Documentation/glossary: clarify limitations of pseudorefs Documentation/glossary: redefine pseudorefs as special refs
2024-05-23Merge branch 'ps/refs-without-the-repository-updates' into ↵Junio C Hamano
ps/ref-storage-migration * ps/refs-without-the-repository-updates: refs/packed: remove references to `the_hash_algo` refs/files: remove references to `the_hash_algo` refs/files: use correct repository refs: remove `dwim_log()` refs: drop `git_default_branch_name()` refs: pass repo when peeling objects refs: move object peeling into "object.c" refs: pass ref store when detecting dangling symrefs refs: convert iteration over replace refs to accept ref store refs: retrieve worktree ref stores via associated repository refs: refactor `resolve_gitlink_ref()` to accept a repository refs: pass repo when retrieving submodule ref store refs: track ref stores via strmap refs: implement releasing ref storages refs: rename `init_db` callback to avoid confusion refs: adjust names for `init` and `init_db` callbacks
2024-05-20Merge branch 'kn/ref-transaction-symref'Junio C Hamano
Updates to symbolic refs can now be made as a part of ref transaction. * kn/ref-transaction-symref: refs: remove `create_symref` and associated dead code refs: rename `refs_create_symref()` to `refs_update_symref()` refs: use transaction in `refs_create_symref()` refs: add support for transactional symref updates refs: move `original_update_refname` to 'refs.c' refs: support symrefs in 'reference-transaction' hook files-backend: extract out `create_symref_lock()` refs: accept symref values in `ref_transaction_update()`
2024-05-17refs: remove `dwim_log()`Patrick Steinhardt
Remove `dwim_log()` in favor of `repo_dwim_log()` so that we can get rid of one more dependency on `the_repository`. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-17refs: drop `git_default_branch_name()`Patrick Steinhardt
The `git_default_branch_name()` function is a thin wrapper around `repo_default_branch_name()` with two differences: - We implicitly rely on `the_repository`. - We cache the default branch name. None of the callsites of `git_default_branch_name()` are hot code paths though, so the caching of the branch name is not really required. Refactor the callsites to use `repo_default_branch_name()` instead and drop `git_default_branch_name()`, thus getting rid of one more case where we rely on `the_repository`. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-17refs: pass repo when peeling objectsPatrick Steinhardt
Both `peel_object()` and `peel_iterated_oid()` implicitly rely on `the_repository` to look up objects. Despite the fact that we want to get rid of `the_repository`, it also leads to some restrictions in our ref iterators when trying to retrieve the peeled value for a repository other than `the_repository`. Refactor these functions such that both take a repository as argument and remove the now-unnecessary restrictions. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-17refs: move object peeling into "object.c"Patrick Steinhardt
Peeling an object has nothing to do with refs, but we still have the code in "refs.c". Move it over into "object.c", which is a more natural place to put it. Ideally, we'd also move `peel_iterated_oid()` over into "object.c". But this function is tied to the refs interfaces because it uses a global ref iterator variable to optimize peeling when the iterator already has the peeled object ID readily available. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-17refs: pass ref store when detecting dangling symrefsPatrick Steinhardt
Both `warn_dangling_symref()` and `warn_dangling_symrefs()` derive the ref store via `the_repository`. Adapt them to instead take in the ref store as a parameter. While at it, rename the functions to have a `ref_` prefix to align them with other functions that take a ref store. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-17refs: convert iteration over replace refs to accept ref storePatrick Steinhardt
The function `for_each_replace_ref()` is a bit of an oddball across the refs interfaces as it accepts a pointer to the repository instead of a pointer to the ref store. The only reason for us to accept a repository is so that we can eventually pass it back to the callback function that the caller has provided. This is somewhat arbitrary though, as callers that need the repository can instead make it accessible via the callback payload. Refactor the function to instead accept the ref store and adjust callers accordingly. This allows us to get rid of some of the boilerplate that we had to carry to pass along the repository and brings us in line with the other functions that iterate through refs. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-17refs: retrieve worktree ref stores via associated repositoryPatrick Steinhardt
Similar as with the preceding commit, the worktree ref stores are always looked up via `the_repository`. Also, again, those ref stores are stored in a global map. Refactor the code so that worktrees have a pointer to their repository. Like this, we can move the global map into `struct repository` and stop using `the_repository`. With this change, we can now in theory look up worktree ref stores for repositories other than `the_repository`. In practice, the worktree code will need further changes to look up arbitrary worktrees. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-17refs: refactor `resolve_gitlink_ref()` to accept a repositoryPatrick Steinhardt
In `resolve_gitlink_ref()` we implicitly rely on `the_repository` to look up the submodule ref store. Now that we can look up submodule ref stores for arbitrary repositories we can improve this function to instead accept a repository as parameter for which we want to resolve the gitlink. Do so and adjust callers accordingly. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-17refs: pass repo when retrieving submodule ref storePatrick Steinhardt
Looking up submodule ref stores has two deficiencies: - The initialized subrepo will be attributed to `the_repository`. - The submodule ref store will be tracked in a global map. This makes it impossible to have submodule ref stores for a repository other than `the_repository`. Modify the function to accept the parent repository as parameter and move the global map into `struct repository`. Like this it becomes possible to look up submodule ref stores for arbitrary repositories. Note that this also adds a new reference to `the_repository` in `resolve_gitlink_ref()`, which is part of the refs interfaces. This will get adjusted in the next patch. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-17refs: track ref stores via strmapPatrick Steinhardt
The refs code has two global maps that track the submodule and worktree ref stores. Even though both of these maps track values by strings, we still use a `struct hashmap` instead of a `struct strmap`. This has the benefit of saving us an allocation because we can combine key and value in a single struct. But it does introduce significant complexity that is completely unneeded. Refactor the code to use `struct strmap`s instead to reduce complexity. It's unlikely that this will have any real-world impact on performance given that most repositories likely won't have all that many ref stores. Furthermore, this refactoring allows us to de-globalize those maps and move them into `struct repository` in a subsequent commit more easily. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-17refs: implement releasing ref storagesPatrick Steinhardt
Ref storages are typically only initialized once for `the_repository` and then never released. Until now we got away with that without causing memory leaks because `the_repository` stays reachable, and because the ref backend is reachable via `the_repository` its memory basically never leaks. This is about to change though because of the upcoming migration logic, which will create a secondary ref storage. In that case, we will either have to release the old or new ref storage to avoid leaks. Implement a new `release` callback and expose it via a new `ref_storage_release()` function. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-17refs: rename `init_db` callback to avoid confusionPatrick Steinhardt
Reference backends have two callbacks `init` and `init_db`. The similarity of these two callbacks has repeatedly confused me whenever I was looking at them, where I always had to look up which of them does what. Rename the `init_db` callback to `create_on_disk`, which should hopefully be clearer. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-15refs: refuse to write pseudorefsPatrick Steinhardt
Pseudorefs are not stored in the ref database as by definition, they carry additional metadata that essentially makes them not a ref. As such, writing pseudorefs via the ref backend does not make any sense whatsoever as the ref backend wouldn't know how exactly to store the data. Restrict writing pseudorefs via the ref backend. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-15ref-filter: properly distinuish pseudo and root refsPatrick Steinhardt
The ref-filter interfaces currently define root refs as either a detached HEAD or a pseudo ref. Pseudo refs aren't root refs though, so let's properly distinguish those ref types. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-15refs: pseudorefs are no refsPatrick Steinhardt
The `is_root_ref()` function will happily clarify a pseudoref as a root ref, even though pseudorefs are no refs. Next to being wrong, it also leads to inconsistent behaviour across ref backends: while the "files" backend accidentally knows to parse those pseudorefs and thus yields them to the caller, the "reftable" backend won't ever see the pseudoref at all because they are never stored in the "reftable" backend. Fix this issue by filtering out pseudorefs in `is_root_ref()`. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-15refs: classify HEAD as a root refPatrick Steinhardt
Root refs are those refs that live in the root of the ref hierarchy. Our old and venerable "HEAD" reference falls into this category, but we don't yet classify it as such in `is_root_ref()`. Adapt the function to also treat "HEAD" as a root ref. This change is safe to do for all current callers: - `ref_kind_from_refname()` already handles "HEAD" explicitly before calling `is_root_ref()`. - The "files" and "reftable" backends explicitly call both `is_root_ref()` and `is_headref()` together. This also aligns behaviour or `is_root_ref()` and `is_headref()` such that we stop checking for ref existence. This changes semantics for our backends: - In the reftable backend we already know that the ref must exist because `is_headref()` is called as part of the ref iterator. The existence check is thus redundant, and the change is safe to do. - In the files backend we use it when populating root refs, where we would skip adding the "HEAD" file if it was not possible to resolve it. The new behaviour is to instead mark "HEAD" as broken, which will cause us to emit warnings in various places. As there are no callers of `is_headref()` left afer the refactoring, we can absorb it completely into `is_root_ref()`. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-15refs: do not check ref existence in `is_root_ref()`Patrick Steinhardt
Before this patch series, root refs except for "HEAD" and our special refs were classified as pseudorefs. Furthermore, our terminology clarified that pseudorefs must not be symbolic refs. This restriction is enforced in `is_root_ref()`, which explicitly checks that a supposed root ref resolves to an object ID without recursing. This has been extremely confusing right from the start because (in old terminology) a ref name may sometimes be a pseudoref and sometimes not depending on whether it is a symbolic or regular ref. This behaviour does not seem reasonable at all and I very much doubt that it results in anything sane. Last but not least, the current behaviour can actually lead to a segfault when calling `is_root_ref()` with a reference that either does not exist or that is a symbolic ref because we never initialized `oid`, but then read it via `is_null_oid()`. We have now changed terminology to clarify that pseudorefs are really only "MERGE_HEAD" and "FETCH_HEAD", whereas all the other refs that live in the root of the ref hierarchy are just plain refs. Thus, we do not need to check whether the ref is symbolic or not. In fact, we can now avoid looking up the ref completely as the name is sufficient for us to figure out whether something would be a root ref or not. This change of course changes semantics for our callers. As there are only three of them we can assess each of them individually: - "ref-filter.c:ref_kind_from_refname()" uses it to classify refs. It's clear that the intent is to classify based on the ref name, only. - "refs/reftable_backend.c:reftable_ref_iterator_advance()" uses it to filter root refs. Again, using existence checks is pointless here as the iterator has just surfaced the ref, so we know it does exist. - "refs/files_backend.c:add_pseudoref_and_head_entries()" uses it to determine whether it should add a ref to the root directory of its iterator. This had the effect that we skipped over any files that are either a symbolic ref, or which are not a ref at all. The new behaviour is to include symbolic refs know, which aligns us with the adapted terminology. Furthermore, files which look like root refs but aren't are now mark those as "broken". As broken refs are not surfaced by our tooling, this should not lead to a change in user-visible behaviour, but may cause us to emit warnings. This feels like the right thing to do as we would otherwise just silently ignore corrupted root refs completely. So in all cases the existence check was either superfluous, not in line with the adapted terminology or masked potential issues. This commit thus changes the behaviour as proposed and drops the existence check altogether. Add a test that verifies that this does not change user-visible behaviour. Namely, we still don't want to show broken refs to the user by default in git-for-each-ref(1). What this does allow though is for internal callers to surface dangling root refs when they pass in the `DO_FOR_EACH_INCLUDE_BROKEN` flag. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-15refs: rename `is_special_ref()` to `is_pseudo_ref()`Patrick Steinhardt
Rename `is_special_ref()` to `is_pseudo_ref()` to adapt to the newly defined terminology in our gitglossary(7). Note that in the preceding commit we have just renamed `is_pseudoref()` to `is_root_ref()`, where there may be confusion for in-flight patch series that add new calls to `is_pseudoref()`. In order to intentionally break such patch series we have thus picked `is_pseudo_ref()` instead of `is_pseudoref()` as the new name. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-15refs: rename `is_pseudoref()` to `is_root_ref()`Patrick Steinhardt
Rename `is_pseudoref()` to `is_root_ref()` to adapt to the newly defined terminology in our gitglossary(7). Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-07refs: remove functions without ref storePatrick Steinhardt
The preceding commit has rewritten all callers of ref-related functions to use the equivalents that accept a `struct ref_store`. Consequently, the respective variants without the ref store are now unused. Remove them. There are likely patch series in-flight that use the now-removed functions. To help the authors, the old implementations have been added to "refs.c" in an ifdef'd section as a reference for how to migrate each of the respective callers. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-07cocci: apply rules to rewrite callers of "refs" interfacesPatrick Steinhardt
Apply the rules that rewrite callers of "refs" interfaces to explicitly pass `struct ref_store`. The resulting patch has been applied with the `--whitespace=fix` option. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-07refs: add `exclude_patterns` parameter to `for_each_fullref_in()`Patrick Steinhardt
The `for_each_fullref_in()` function is supposedly the ref-store-less equivalent of `refs_for_each_fullref_in()`, but the latter has gained a new parameter `exclude_patterns` over time. Bring these two functions back in sync again by adding the parameter to the former function, as well. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-07refs: introduce missing functions that accept a `struct ref_store`Patrick Steinhardt
While most of the functions in "refs.h" have a variant that accepts a `struct ref_store`, some don't. Callers of these functions are thus forced to implicitly rely on `the_repository` to figure out the ref store that is to be used. Introduce those missing functions to address this shortcoming. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-07refs: rename `refs_create_symref()` to `refs_update_symref()`Karthik Nayak
The `refs_create_symref()` function is used to update/create a symref. But it doesn't check the old target of the symref, if existing. It force updates the symref. In this regard, the name `refs_create_symref()` is a bit misleading. So let's rename it to `refs_update_symref()`. This is akin to how 'git-update-ref(1)' also allows us to create apart from update. While we're here, rename the arguments in the function to clarify what they actually signify and reduce confusion. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-07refs: use transaction in `refs_create_symref()`Karthik Nayak
The `refs_create_symref()` function updates a symref to a given new target. To do this, it uses a ref-backend specific function `create_symref()`. In the previous commits, we introduced symref support in transactions. This means we can now use transactions to perform symref updates and don't have to resort to `create_symref()`. Doing this allows us to remove and cleanup `create_symref()`, which we will do in the following commit. Modify the expected error message for a test in 't/t0610-reftable-basics.sh', since the error is now thrown from 'refs.c'. This is because in transactional updates, F/D conflicts are caught before we're in the reference backend. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-07refs: add support for transactional symref updatesKarthik Nayak
The reference backends currently support transactional reference updates. While this is exposed to users via 'git-update-ref' and its '--stdin' mode, it is also used internally within various commands. However, we do not support transactional updates of symrefs. This commit adds support for symrefs in both the 'files' and the 'reftable' backend. Here, we add and use `ref_update_has_null_new_value()`, a helper function which is used to check if there is a new_value in a reference update. The new value could either be a symref target `new_target` or a OID `new_oid`. We also add another common function `ref_update_check_old_target` which will be used to check if the update's old_target corresponds to a reference's current target. Now transactional updates (verify, create, delete, update) can be used for: - regular refs - symbolic refs - conversion of regular to symbolic refs and vice versa This also allows us to expose this to users via new commands in 'git-update-ref' in the future. Note that a dangling symref update does not record a new reflog entry, which is unchanged before and after this commit. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-07refs: move `original_update_refname` to 'refs.c'Karthik Nayak
The files backend and the reftable backend implement `original_update_refname` to obtain the original refname of the update. Move it out to 'refs.c' and only expose it internally to the refs library. This will be used in an upcoming commit to also introduce another common functionality for the two backends. We also rename the function to `ref_update_original_update_refname` to keep it consistent with the upcoming other 'ref_update_*' functions that'll be introduced. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-07refs: support symrefs in 'reference-transaction' hookKarthik Nayak
The 'reference-transaction' hook runs whenever a reference update is made to the system. In a previous commit, we added the `old_target` and `new_target` fields to the `reference_transaction_update()`. In following commits we'll also add the code to handle symref's in the reference backends. Support symrefs also in the 'reference-transaction' hook, by modifying the current format: <old-oid> SP <new-oid> SP <ref-name> LF to be be: <old-value> SP <new-value> SP <ref-name> LF where for regular refs the output would not change and remain the same. But when either 'old-value' or 'new-value' is a symref, we print the ref as 'ref:<ref-target>'. This does break backward compatibility, but the 'reference-transaction' hook's documentation always stated that support for symbolic references may be added in the future. We do not add any tests in this commit since there is no git command which activates this flow, in an upcoming commit, we'll start using transaction based symref updates as the default, we'll add tests there for the hook too. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-07refs: accept symref values in `ref_transaction_update()`Karthik Nayak
The function `ref_transaction_update()` obtains ref information and flags to create a `ref_update` and add them to the transaction at hand. To extend symref support in transactions, we need to also accept the old and new ref targets and process it. This commit adds the required parameters to the function and modifies all call sites. The two parameters added are `new_target` and `old_target`. The `new_target` is used to denote what the reference should point to when the transaction is applied. Some functions allow this parameter to be NULL, meaning that the reference is not changed. The `old_target` denotes the value the reference must have before the update. Some functions allow this parameter to be NULL, meaning that the old value of the reference is not checked. We also update the internal function `ref_transaction_add_update()` similarly to take the two new parameters. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-03-05Merge branch 'kn/for-all-refs'Junio C Hamano
"git for-each-ref" learned "--include-root-refs" option to show even the stuff outside the 'refs/' hierarchy. * kn/for-all-refs: for-each-ref: add new option to include root refs ref-filter: rename 'FILTER_REFS_ALL' to 'FILTER_REFS_REGULAR' refs: introduce `refs_for_each_include_root_refs()` refs: extract out `loose_fill_ref_dir_regular_file()` refs: introduce `is_pseudoref()` and `is_headref()`
2024-03-05Merge branch 'jk/reflog-special-cases-fix'Junio C Hamano
The logic to access reflog entries by date and number had ugly corner cases at the boundaries, which have been cleaned up. * jk/reflog-special-cases-fix: read_ref_at(): special-case ref@{0} for an empty reflog get_oid_basic(): special-case ref@{n} for oldest reflog entry Revert "refs: allow @{n} to work with n-sized reflog"
2024-02-26read_ref_at(): special-case ref@{0} for an empty reflogJeff King
The previous commit special-cased get_oid_basic()'s handling of ref@{n} for a reflog with n entries. But its special case doesn't work for ref@{0} in an empty reflog, because read_ref_at() dies when it notices the empty reflog! We can make this work by special-casing this in read_ref_at(). It's somewhat gross, for two reasons: 1. We have no reflog entry to describe in the "msg" out-parameter. So we have to leave it uninitialized or make something up. 2. Likewise, we have no oid to put in the "oid" out-parameter. Leaving it untouched is actually the best thing here, as all of the callers will have initialized it with the current ref value via repo_dwim_log(). This is rather subtle, but it is how things worked in 6436a20284 (refs: allow @{n} to work with n-sized reflog, 2021-01-07) before we reverted it. The key difference from 6436a20284 here is that we'll return "1" to indicate that we _didn't_ find the requested reflog entry. Coupled with the special-casing in get_oid_basic() in the previous commit, that's enough to make looking up ref@{0} work, and we can flip 6436a20284's test back to expect_success. It also means that the call in show-branch which segfaulted with 6436a20284 (and which is now tested in t3202) remains OK. The caller notices that we could not find any reflog entry, and so it breaks out of its loop, showing nothing. This is different from the current behavior of producing an error, but it's just as reasonable (and is exactly what we'd do if you asked it to walk starting at ref@{1} but there was only 1 entry). Thus nobody should actually look at the reflog entry info we return. But we'll still put in some fake values just to be on the safe side, since this is such a subtle and confusing interface. Likewise, we'll document what's going on in a comment above the function declaration. If this were a function with a lot of callers, the footgun would probably not be worth it. But it has only ever had two callers in its 18-year existence, and it seems unlikely to grow more. So let's hold our noses and let users enjoy the convenience of a simulated ref@{0}. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-02-26get_oid_basic(): special-case ref@{n} for oldest reflog entryJeff King
The goal of 6436a20284 (refs: allow @{n} to work with n-sized reflog, 2021-01-07) was that if we have "n" entries in a reflog, we should still be able to resolve ref@{n} by looking at the "old" value of the oldest entry. Commit 6436a20284 tried to put the logic into read_ref_at() by shifting its idea of "n" by one. But we reverted that in the previous commit, since it led to bugs in other callers which cared about the details of the reflog entry we found. Instead, let's put the special case into the caller that resolves @{n}, as it cares only about the oid. read_ref_at() is even kind enough to return the "old" value from the final reflog; it just returns "1" to signal to us that we ran off the end of the reflog. But we can notice in the caller that we read just enough records for that "old" value to be the one we're looking for, and use it. Note that read_ref_at() could notice this case, too, and just return 0. But we don't want to do that, because the caller must be made aware that we only found the oid, not an actual reflog entry (and the call sites in show-branch do care about this). There is one complication, though. When read_ref_at() hits a truncated reflog, it will return the "old" value of the oldest entry only if it is not the null oid. Otherwise, it actually returns the "new" value from that entry! This bit of fudging is due to d1a4489a56 (avoid null SHA1 in oldest reflog, 2008-07-08), where asking for "ref@{20.years.ago}" for a ref created recently will produce the initial value as a convenience (even though technically it did not exist 20 years ago). But this convenience is only useful for time-based cutoffs. For count-based cutoffs, get_oid_basic() has always simply complained about going too far back: $ git rev-parse HEAD@{20} fatal: log for 'HEAD' only has 16 entries and we should continue to do so, rather than returning a nonsense value (there's even a test in t1508 already which covers this). So let's have the d1a4489a56 code kick in only when doing timestamp-based cutoffs. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-02-26Revert "refs: allow @{n} to work with n-sized reflog"Jeff King
This reverts commit 6436a20284f33d42103cac93bd82e65bebb31526. The idea of that commit is that if read_ref_at() is counting back to the Nth reflog but the reflog is short by one entry (e.g., because it was pruned), we can find the oid of the missing entry by looking at the "before" oid value of the entry that comes after it (whereas before, we looked at the "after" value of each entry and complained that we couldn't find the one from before the truncation). This works fine for resolving the oid of ref@{n}, as it is used by get_oid_basic(), which does not look at any other aspect of the reflog we found (e.g., its timestamp or message). But there's another caller of read_ref_at(): in show-branch we use it to walk over the reflog, and we do care about the reflog entry. And so that commit broke "show-branch --reflog"; it shows the reflog message for ref@{0} as ref@{1}, ref@{1} as ref@{2}, and so on. For example, in the new test in t3202 we produce: ! [branch@{0}] (0 seconds ago) commit: three ! [branch@{1}] (0 seconds ago) commit: three ! [branch@{2}] (60 seconds ago) commit: two ! [branch@{3}] (2 minutes ago) reset: moving to HEAD^ instead of the correct: ! [branch@{0}] (0 seconds ago) commit: three ! [branch@{1}] (60 seconds ago) commit: two ! [branch@{2}] (2 minutes ago) reset: moving to HEAD^ ! [branch@{3}] (2 minutes ago) commit: one But there's another bug, too: because it is looking at the "old" value of the reflog after the one we're interested in, it has to special-case ref@{0} (since there isn't anything after it). That's why it doesn't show the offset bug in the output above. But this special-case code fails to handle the situation where the reflog is empty or missing; it returns success even though the reflog message out-parameter has been left uninitialized. You can't trigger this through get_oid_basic(), but "show-branch --reflog" will pretty reliably segfault as it tries to access the garbage pointer. Fixing the segfault would be pretty easy. But the off-by-one problem is inherent in this approach. So let's start by reverting the commit to give us a clean slate to work with. This isn't a pure revert; all of the code changes are reverted, but for the tests: 1. We'll flip the cases in t1508 to expect_failure; making these work was the goal of 6436a2028, and we'll want to use them for our replacement approach. 2. There's a test in t3202 for "show-branch --reflog", but it expects the broken output! It was added by f2463490c4 (show-branch: show reflog message, 2021-12-02) which was fixing another bug, and I think the author simply didn't notice that the second line showed the wrong reflog. Rather than fixing that test, let's replace it with one that is more thorough (while still covering the reflog message fix from that commit). We'll use a longer reflog, which lets us see more entries (thus making the "off by one" pattern much more clear). And we'll use a more recent timestamp for "now" so that our relative dates have more resolution. That lets us see that the reflog dates are correct (whereas when you are 4 years away, two entries that are 60 seconds apart will have the same "4 years ago" relative date). Because we're adjusting the repository state, I've moved this new test to the end of the script, leaving the other tests undisturbed. We'll also add a new test which covers the missing reflog case; previously it segfaulted, but now it reports the empty reflog). Reported-by: Yasushi SHOJI <yasushi.shoji@gmail.com> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-02-23refs: introduce `refs_for_each_include_root_refs()`Karthik Nayak
Introduce a new ref iteration flag `DO_FOR_EACH_INCLUDE_ROOT_REFS`, which will be used to iterate over regular refs plus pseudorefs and HEAD. Refs which fall outside the `refs/` and aren't either pseudorefs or HEAD are more of a grey area. This is because we don't block the users from creating such refs but they are not officially supported. Introduce `refs_for_each_include_root_refs()` which calls `do_for_each_ref()` with this newly introduced flag. In `refs/files-backend.c`, introduce a new function `add_pseudoref_and_head_entries()` to add pseudorefs and HEAD to the `ref_dir`. We then finally call `add_pseudoref_and_head_entries()` whenever the `DO_FOR_EACH_INCLUDE_ROOT_REFS` flag is set. Any new ref backend will also have to implement similar changes on its end. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>