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#include "cache.h"
#include "refs.h"
#include "iterator.h"
struct ref_transaction;
* Data structures and functions for the internal use of the refs
* module. Code outside of the refs module should use only the public
* functions defined in "refs.h", and should *not* include this file.
* The following flags can appear in `ref_update::flags`. Their
* numerical values must not conflict with those of REF_NO_DEREF and
* REF_FORCE_CREATE_REFLOG, which are also stored in
* `ref_update::flags`.
* The reference should be updated to new_oid.
#define REF_HAVE_NEW (1 << 2)
* The current reference's value should be checked to make sure that
* it agrees with old_oid.
#define REF_HAVE_OLD (1 << 3)
* Used as a flag in ref_update::flags when we want to log a ref
* update but not actually perform it. This is used when a symbolic
* ref update is split up.
#define REF_LOG_ONLY (1 << 7)
* Return the length of time to retry acquiring a loose reference lock
* before giving up, in milliseconds:
long get_files_ref_lock_timeout_ms(void);
* Return true iff refname is minimally safe. "Safe" here means that
* deleting a loose reference by this name will not do any damage, for
* example by causing a file that is not a reference to be deleted.
* This function does not check that the reference name is legal; for
* that, use check_refname_format().
* A refname that starts with "refs/" is considered safe iff it
* doesn't contain any "." or ".." components or consecutive '/'
* characters, end with '/', or (on Windows) contain any '\'
* characters. Names that do not start with "refs/" are considered
* safe iff they consist entirely of upper case characters and '_'
* (like "HEAD" and "MERGE_HEAD" but not "config" or "FOO/BAR").
int refname_is_safe(const char *refname);
* Helper function: return true if refname, which has the specified
* oid and flags, can be resolved to an object in the database. If the
* referred-to object does not exist, emit a warning and return false.
int ref_resolves_to_object(const char *refname,
struct repository *repo,
const struct object_id *oid,
unsigned int flags);
enum peel_status {
/* object was peeled successfully: */
* object cannot be peeled because the named object (or an
* object referred to by a tag in the peel chain), does not
* exist.
/* object cannot be peeled because it is not a tag: */
/* ref_entry contains no peeled value because it is a symref: */
* ref_entry cannot be peeled because it is broken (i.e., the
* symbolic reference cannot even be resolved to an object
* name):
* Peel the named object; i.e., if the object is a tag, resolve the
* tag recursively until a non-tag is found. If successful, store the
* result to oid and return PEEL_PEELED. If the object is not a tag
* or is not valid, return PEEL_NON_TAG or PEEL_INVALID, respectively,
* and leave oid unchanged.
enum peel_status peel_object(const struct object_id *name, struct object_id *oid);
* Information needed for a single ref update. Set new_oid to the new
* value or to null_oid to delete the ref. To check the old value
* while the ref is locked, set (flags & REF_HAVE_OLD) and set old_oid
* to the old value, or to null_oid to ensure the ref does not exist
* before update.
struct ref_update {
* If (flags & REF_HAVE_NEW), set the reference to this value
* (or delete it, if `new_oid` is `null_oid`).
struct object_id new_oid;
* If (flags & REF_HAVE_OLD), check that the reference
* previously had this value (or didn't previously exist, if
* `old_oid` is `null_oid`).
struct object_id old_oid;
* REF_HAVE_NEW, REF_HAVE_OLD, or backend-specific flags.
unsigned int flags;
void *backend_data;
unsigned int type;
char *msg;
* If this ref_update was split off of a symref update via
* split_symref_update(), then this member points at that
* update. This is used for two purposes:
* 1. When reporting errors, we report the refname under which
* the update was originally requested.
* 2. When we read the old value of this reference, we
* propagate it back to its parent update for recording in
* the latter's reflog.
struct ref_update *parent_update;
const char refname[FLEX_ARRAY];
int refs_read_raw_ref(struct ref_store *ref_store, const char *refname,
struct object_id *oid, struct strbuf *referent,
unsigned int *type, int *failure_errno);
* Write an error to `err` and return a nonzero value iff the same
* refname appears multiple times in `refnames`. `refnames` must be
* sorted on entry to this function.
int ref_update_reject_duplicates(struct string_list *refnames,
struct strbuf *err);
* Add a ref_update with the specified properties to transaction, and
* return a pointer to the new object. This function does not verify
* that refname is well-formed. new_oid and old_oid are only
* dereferenced if the REF_HAVE_NEW and REF_HAVE_OLD bits,
* respectively, are set in flags.
struct ref_update *ref_transaction_add_update(
struct ref_transaction *transaction,
const char *refname, unsigned int flags,
const struct object_id *new_oid,
const struct object_id *old_oid,
const char *msg);
* Transaction states.
* OPEN: The transaction is initialized and new updates can still be
* added to it. An OPEN transaction can be prepared,
* committed, freed, or aborted (freeing and aborting an open
* transaction are equivalent).
* PREPARED: ref_transaction_prepare(), which locks all of the
* references involved in the update and checks that the
* update has no errors, has been called successfully for the
* transaction. A PREPARED transaction can be committed or
* aborted.
* CLOSED: The transaction is no longer active. A transaction becomes
* CLOSED if there is a failure while building the transaction
* or if a transaction is committed or aborted. A CLOSED
* transaction can only be freed.
enum ref_transaction_state {
* Data structure for holding a reference transaction, which can
* consist of checks and updates to multiple references, carried out
* as atomically as possible. This structure is opaque to callers.
struct ref_transaction {
struct ref_store *ref_store;
struct ref_update **updates;
size_t alloc;
size_t nr;
enum ref_transaction_state state;
void *backend_data;
* Check for entries in extras that are within the specified
* directory, where dirname is a reference directory name including
* the trailing slash (e.g., "refs/heads/foo/"). Ignore any
* conflicting references that are found in skip. If there is a
* conflicting reference, return its name.
* extras and skip must be sorted lists of reference names. Either one
* can be NULL, signifying the empty list.
const char *find_descendant_ref(const char *dirname,
const struct string_list *extras,
const struct string_list *skip);
/* We allow "recursive" symbolic refs. Only within reason, though */
* These flags are passed to refs_ref_iterator_begin() (and do_for_each_ref(),
* which feeds it).
enum do_for_each_ref_flags {
* Include broken references in a do_for_each_ref*() iteration, which
* would normally be omitted. This includes both refs that point to
* missing objects (a true repository corruption), ones with illegal
* names (which we prefer not to expose to callers), as well as
* dangling symbolic refs (i.e., those that point to a non-existent
* ref; this is not a corruption, but as they have no valid oid, we
* omit them from normal iteration results).
* Only include per-worktree refs in a do_for_each_ref*() iteration.
* Normally this will be used with a files ref_store, since that's
* where all reference backends will presumably store their
* per-worktree refs.
* Omit dangling symrefs from output; this only has an effect with
* INCLUDE_BROKEN, since they are otherwise not included at all.
* Reference iterators
* A reference iterator encapsulates the state of an in-progress
* iteration over references. Create an instance of `struct
* ref_iterator` via one of the functions in this module.
* A freshly-created ref_iterator doesn't yet point at a reference. To
* advance the iterator, call ref_iterator_advance(). If successful,
* this sets the iterator's refname, oid, and flags fields to describe
* the next reference and returns ITER_OK. The data pointed at by
* refname and oid belong to the iterator; if you want to retain them
* after calling ref_iterator_advance() again or calling
* ref_iterator_abort(), you must make a copy. When the iteration has
* been exhausted, ref_iterator_advance() releases any resources
* associated with the iteration, frees the ref_iterator object, and
* returns ITER_DONE. If you want to abort the iteration early, call
* ref_iterator_abort(), which also frees the ref_iterator object and
* any associated resources. If there was an internal error advancing
* to the next entry, ref_iterator_advance() aborts the iteration,
* frees the ref_iterator, and returns ITER_ERROR.
* The reference currently being looked at can be peeled by calling
* ref_iterator_peel(). This function is often faster than peel_ref(),
* so it should be preferred when iterating over references.
* Putting it all together, a typical iteration looks like this:
* int ok;
* struct ref_iterator *iter = ...;
* while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
* if (want_to_stop_iteration()) {
* ok = ref_iterator_abort(iter);
* break;
* }
* // Access information about the current reference:
* if (!(iter->flags & REF_ISSYMREF))
* printf("%s is %s\n", iter->refname, oid_to_hex(iter->oid));
* // If you need to peel the reference:
* ref_iterator_peel(iter, &oid);
* }
* if (ok != ITER_DONE)
* handle_error();
struct ref_iterator {
struct ref_iterator_vtable *vtable;
* Does this `ref_iterator` iterate over references in order
* by refname?
unsigned int ordered : 1;
const char *refname;
const struct object_id *oid;
unsigned int flags;
* Advance the iterator to the first or next item and return ITER_OK.
* If the iteration is exhausted, free the resources associated with
* the ref_iterator and return ITER_DONE. On errors, free the iterator
* resources and return ITER_ERROR. It is a bug to use ref_iterator or
* call this function again after it has returned ITER_DONE or
int ref_iterator_advance(struct ref_iterator *ref_iterator);
* If possible, peel the reference currently being viewed by the
* iterator. Return 0 on success.
int ref_iterator_peel(struct ref_iterator *ref_iterator,
struct object_id *peeled);
* End the iteration before it has been exhausted, freeing the
* reference iterator and any associated resources and returning
* ITER_DONE. If the abort itself failed, return ITER_ERROR.
int ref_iterator_abort(struct ref_iterator *ref_iterator);
* An iterator over nothing (its first ref_iterator_advance() call
* returns ITER_DONE).
struct ref_iterator *empty_ref_iterator_begin(void);
* Return true iff ref_iterator is an empty_ref_iterator.
int is_empty_ref_iterator(struct ref_iterator *ref_iterator);
* Return an iterator that goes over each reference in `refs` for
* which the refname begins with prefix. If trim is non-zero, then
* trim that many characters off the beginning of each refname.
* The output is ordered by refname.
struct ref_iterator *refs_ref_iterator_begin(
struct ref_store *refs,
const char *prefix, int trim,
enum do_for_each_ref_flags flags);
* A callback function used to instruct merge_ref_iterator how to
* interleave the entries from iter0 and iter1. The function should
* return one of the constants defined in enum iterator_selection. It
* must not advance either of the iterators itself.
* The function must be prepared to handle the case that iter0 and/or
* iter1 is NULL, which indicates that the corresponding sub-iterator
* has been exhausted. Its return value must be consistent with the
* current states of the iterators; e.g., it must not return
* ITER_SKIP_1 if iter1 has already been exhausted.
typedef enum iterator_selection ref_iterator_select_fn(
struct ref_iterator *iter0, struct ref_iterator *iter1,
void *cb_data);
* Iterate over the entries from iter0 and iter1, with the values
* interleaved as directed by the select function. The iterator takes
* ownership of iter0 and iter1 and frees them when the iteration is
* over. A derived class should set `ordered` to 1 or 0 based on
* whether it generates its output in order by reference name.
struct ref_iterator *merge_ref_iterator_begin(
int ordered,
struct ref_iterator *iter0, struct ref_iterator *iter1,
ref_iterator_select_fn *select, void *cb_data);
* An iterator consisting of the union of the entries from front and
* back. If there are entries common to the two sub-iterators, use the
* one from front. Each iterator must iterate over its entries in
* strcmp() order by refname for this to work.
* The new iterator takes ownership of its arguments and frees them
* when the iteration is over. As a convenience to callers, if front
* or back is an empty_ref_iterator, then abort that one immediately
* and return the other iterator directly, without wrapping it.
struct ref_iterator *overlay_ref_iterator_begin(
struct ref_iterator *front, struct ref_iterator *back);
* Wrap iter0, only letting through the references whose names start
* with prefix. If trim is set, set iter->refname to the name of the
* reference with that many characters trimmed off the front;
* otherwise set it to the full refname. The new iterator takes over
* ownership of iter0 and frees it when iteration is over. It makes
* its own copy of prefix.
* As an convenience to callers, if prefix is the empty string and
* trim is zero, this function returns iter0 directly, without
* wrapping it.
* The resulting ref_iterator is ordered if iter0 is.
struct ref_iterator *prefix_ref_iterator_begin(struct ref_iterator *iter0,
const char *prefix,
int trim);
/* Internal implementation of reference iteration: */
* Base class constructor for ref_iterators. Initialize the
* ref_iterator part of iter, setting its vtable pointer as specified.
* `ordered` should be set to 1 if the iterator will iterate over
* references in order by refname; otherwise it should be set to 0.
* This is meant to be called only by the initializers of derived
* classes.
void base_ref_iterator_init(struct ref_iterator *iter,
struct ref_iterator_vtable *vtable,
int ordered);
* Base class destructor for ref_iterators. Destroy the ref_iterator
* part of iter and shallow-free the object. This is meant to be
* called only by the destructors of derived classes.
void base_ref_iterator_free(struct ref_iterator *iter);
/* Virtual function declarations for ref_iterators: */
* backend-specific implementation of ref_iterator_advance. For symrefs, the
* function should set REF_ISSYMREF, and it should also dereference the symref
* to provide the OID referent. It should respect do_for_each_ref_flags
* that were passed to refs_ref_iterator_begin().
typedef int ref_iterator_advance_fn(struct ref_iterator *ref_iterator);
* Peels the current ref, returning 0 for success or -1 for failure.
typedef int ref_iterator_peel_fn(struct ref_iterator *ref_iterator,
struct object_id *peeled);
* Implementations of this function should free any resources specific
* to the derived class, then call base_ref_iterator_free() to clean
* up and free the ref_iterator object.
typedef int ref_iterator_abort_fn(struct ref_iterator *ref_iterator);
struct ref_iterator_vtable {
ref_iterator_advance_fn *advance;
ref_iterator_peel_fn *peel;
ref_iterator_abort_fn *abort;
* current_ref_iter is a performance hack: when iterating over
* references using the for_each_ref*() functions, current_ref_iter is
* set to the reference iterator before calling the callback function.
* If the callback function calls peel_ref(), then peel_ref() first
* checks whether the reference to be peeled is the one referred to by
* the iterator (it usually is) and if so, asks the iterator for the
* peeled version of the reference if it is available. This avoids a
* refname lookup in a common case. current_ref_iter is set to NULL
* when the iteration is over.
extern struct ref_iterator *current_ref_iter;
* The common backend for the for_each_*ref* functions. Call fn for
* each reference in iter. If the iterator itself ever returns
* ITER_ERROR, return -1. If fn ever returns a non-zero value, stop
* the iteration and return that value. Otherwise, return 0. In any
* case, free the iterator when done. This function is basically an
* adapter between the callback style of reference iteration and the
* iterator style.
int do_for_each_repo_ref_iterator(struct repository *r,
struct ref_iterator *iter,
each_repo_ref_fn fn, void *cb_data);
struct ref_store;
/* refs backends */
/* ref_store_init flags */
#define REF_STORE_READ (1 << 0)
#define REF_STORE_WRITE (1 << 1) /* can perform update operations */
#define REF_STORE_ODB (1 << 2) /* has access to object database */
#define REF_STORE_MAIN (1 << 3)
* Initialize the ref_store for the specified gitdir. These functions
* should call base_ref_store_init() to initialize the shared part of
* the ref_store and to record the ref_store for later lookup.
typedef struct ref_store *ref_store_init_fn(struct repository *repo,
const char *gitdir,
unsigned int flags);
typedef int ref_init_db_fn(struct ref_store *refs, struct strbuf *err);
typedef int ref_transaction_prepare_fn(struct ref_store *refs,
struct ref_transaction *transaction,
struct strbuf *err);
typedef int ref_transaction_finish_fn(struct ref_store *refs,
struct ref_transaction *transaction,
struct strbuf *err);
typedef int ref_transaction_abort_fn(struct ref_store *refs,
struct ref_transaction *transaction,
struct strbuf *err);
typedef int ref_transaction_commit_fn(struct ref_store *refs,
struct ref_transaction *transaction,
struct strbuf *err);
typedef int pack_refs_fn(struct ref_store *ref_store, unsigned int flags);
typedef int create_symref_fn(struct ref_store *ref_store,
const char *ref_target,
const char *refs_heads_master,
const char *logmsg);
typedef int delete_refs_fn(struct ref_store *ref_store, const char *msg,
struct string_list *refnames, unsigned int flags);
typedef int rename_ref_fn(struct ref_store *ref_store,
const char *oldref, const char *newref,
const char *logmsg);
typedef int copy_ref_fn(struct ref_store *ref_store,
const char *oldref, const char *newref,
const char *logmsg);
* Iterate over the references in `ref_store` whose names start with
* `prefix`. `prefix` is matched as a literal string, without regard
* for path separators. If prefix is NULL or the empty string, iterate
* over all references in `ref_store`. The output is ordered by
* refname.
typedef struct ref_iterator *ref_iterator_begin_fn(
struct ref_store *ref_store,
const char *prefix, unsigned int flags);
/* reflog functions */
* Iterate over the references in the specified ref_store that have a
* reflog. The refs are iterated over in arbitrary order.
typedef struct ref_iterator *reflog_iterator_begin_fn(
struct ref_store *ref_store);
typedef int for_each_reflog_ent_fn(struct ref_store *ref_store,
const char *refname,
each_reflog_ent_fn fn,
void *cb_data);
typedef int for_each_reflog_ent_reverse_fn(struct ref_store *ref_store,
const char *refname,
each_reflog_ent_fn fn,
void *cb_data);
typedef int reflog_exists_fn(struct ref_store *ref_store, const char *refname);
typedef int create_reflog_fn(struct ref_store *ref_store, const char *refname,
struct strbuf *err);
typedef int delete_reflog_fn(struct ref_store *ref_store, const char *refname);
typedef int reflog_expire_fn(struct ref_store *ref_store,
const char *refname,
unsigned int flags,
reflog_expiry_prepare_fn prepare_fn,
reflog_expiry_should_prune_fn should_prune_fn,
reflog_expiry_cleanup_fn cleanup_fn,
void *policy_cb_data);
* Read a reference from the specified reference store, non-recursively.
* Set type to describe the reference, and:
* - If refname is the name of a normal reference, fill in oid
* (leaving referent unchanged).
* - If refname is the name of a symbolic reference, write the full
* name of the reference to which it refers (e.g.
* "refs/heads/master") to referent and set the REF_ISSYMREF bit in
* type (leaving oid unchanged). The caller is responsible for
* validating that referent is a valid reference name.
* WARNING: refname might be used as part of a filename, so it is
* important from a security standpoint that it be safe in the sense
* of refname_is_safe(). Moreover, for symrefs this function sets
* referent to whatever the repository says, which might not be a
* properly-formatted or even safe reference name. NEITHER INPUT NOR
* Return 0 on success, or -1 on failure. If the ref exists but is neither a
* symbolic ref nor an object ID, it is broken. In this case set REF_ISBROKEN in
* type, and return -1 (failure_errno should not be ENOENT)
* failure_errno provides errno codes that are interpreted beyond error
* reporting. The following error codes have special meaning:
* * ENOENT: the ref doesn't exist
* * EISDIR: ref name is a directory
* * ENOTDIR: ref prefix is not a directory
* Backend-specific flags might be set in type as well, regardless of
* outcome.
* It is OK for refname to point into referent. If so:
* - if the function succeeds with REF_ISSYMREF, referent will be
* overwritten and the memory formerly pointed to by it might be
* changed or even freed.
* - in all other cases, referent will be untouched, and therefore
* refname will still be valid and unchanged.
typedef int read_raw_ref_fn(struct ref_store *ref_store, const char *refname,
struct object_id *oid, struct strbuf *referent,
unsigned int *type, int *failure_errno);
* Read a symbolic reference from the specified reference store. This function
* is optional: if not implemented by a backend, then `read_raw_ref_fn` is used
* to read the symbolcic reference instead. It is intended to be implemented
* only in case the backend can optimize the reading of symbolic references.
* Return 0 on success, or -1 on failure. `referent` will be set to the target
* of the symbolic reference on success. This function explicitly does not
* distinguish between error cases and the reference not being a symbolic
* reference to allow backends to optimize this operation in case symbolic and
* non-symbolic references are treated differently.
typedef int read_symbolic_ref_fn(struct ref_store *ref_store, const char *refname,
struct strbuf *referent);
struct ref_storage_be {
struct ref_storage_be *next;
const char *name;
ref_store_init_fn *init;
ref_init_db_fn *init_db;
ref_transaction_prepare_fn *transaction_prepare;
ref_transaction_finish_fn *transaction_finish;
ref_transaction_abort_fn *transaction_abort;
ref_transaction_commit_fn *initial_transaction_commit;
pack_refs_fn *pack_refs;
create_symref_fn *create_symref;
delete_refs_fn *delete_refs;
rename_ref_fn *rename_ref;
copy_ref_fn *copy_ref;
ref_iterator_begin_fn *iterator_begin;
read_raw_ref_fn *read_raw_ref;
read_symbolic_ref_fn *read_symbolic_ref;
reflog_iterator_begin_fn *reflog_iterator_begin;
for_each_reflog_ent_fn *for_each_reflog_ent;
for_each_reflog_ent_reverse_fn *for_each_reflog_ent_reverse;
reflog_exists_fn *reflog_exists;
create_reflog_fn *create_reflog;
delete_reflog_fn *delete_reflog;
reflog_expire_fn *reflog_expire;
extern struct ref_storage_be refs_be_files;
extern struct ref_storage_be refs_be_packed;
* A representation of the reference store for the main repository or
* a submodule. The ref_store instances for submodules are kept in a
* hash map; see get_submodule_ref_store() for more info.
struct ref_store {
/* The backend describing this ref_store's storage scheme: */
const struct ref_storage_be *be;
struct repository *repo;
* The gitdir that this ref_store applies to. Note that this is not
* necessarily repo->gitdir if the repo has multiple worktrees.
char *gitdir;
* Parse contents of a loose ref file. *failure_errno maybe be set to EINVAL for
* invalid contents.
int parse_loose_ref_contents(const char *buf, struct object_id *oid,
struct strbuf *referent, unsigned int *type,
int *failure_errno);
* Fill in the generic part of refs and add it to our collection of
* reference stores.
void base_ref_store_init(struct ref_store *refs, struct repository *repo,
const char *path, const struct ref_storage_be *be);
* Support GIT_TRACE_REFS by optionally wrapping the given ref_store instance.
struct ref_store *maybe_debug_wrap_ref_store(const char *gitdir, struct ref_store *store);