path: root/refs.h

#ifndef REFS_H
#define REFS_H

struct object_id;
struct ref_store;
struct repository;
struct strbuf;
struct string_list;
struct string_list_item;
struct worktree;

/*
 * Resolve a reference, recursively following symbolic refererences.
 *
 * Return the name of the non-symbolic reference that ultimately pointed
 * at the resolved object name.  The return value, if not NULL, is a
 * pointer into either a static buffer or the input ref.
 *
 * If oid is non-NULL, store the referred-to object's name in it.
 *
 * If the reference cannot be resolved to an object, the behavior
 * depends on the RESOLVE_REF_READING flag:
 *
 * - If RESOLVE_REF_READING is set, return NULL.
 *
 * - If RESOLVE_REF_READING is not set, clear oid and return the name of
 *   the last reference name in the chain, which will either be a non-symbolic
 *   reference or an undefined reference.  If this is a prelude to
 *   "writing" to the ref, the return value is the name of the ref
 *   that will actually be created or changed.
 *
 * If the RESOLVE_REF_NO_RECURSE flag is passed, only resolves one
 * level of symbolic reference.  The value stored in oid for a symbolic
 * reference will always be null_oid in this case, and the return
 * value is the reference that the symref refers to directly.
 *
 * If flags is non-NULL, set the value that it points to the
 * combination of REF_ISPACKED (if the reference was found among the
 * packed references), REF_ISSYMREF (if the initial reference was a
 * symbolic reference), REF_BAD_NAME (if the reference name is ill
 * formed --- see RESOLVE_REF_ALLOW_BAD_NAME below), and REF_ISBROKEN
 * (if the ref is malformed or has a bad name). See refs.h for more detail
 * on each flag.
 *
 * If ref is not a properly-formatted, normalized reference, return
 * NULL.  If more than MAXDEPTH recursive symbolic lookups are needed,
 * give up and return NULL.
 *
 * RESOLVE_REF_ALLOW_BAD_NAME allows resolving refs even when their
 * name is invalid according to git-check-ref-format(1).  If the name
 * is bad then the value stored in oid will be null_oid and the two
 * flags REF_ISBROKEN and REF_BAD_NAME will be set.
 *
 * Even with RESOLVE_REF_ALLOW_BAD_NAME, names that escape the refs/
 * directory and do not consist of all caps and underscores cannot be
 * resolved. The function returns NULL for such ref names.
 * Caps and underscores refers to the special refs, such as HEAD,
 * FETCH_HEAD and friends, that all live outside of the refs/ directory.
 */
#define RESOLVE_REF_READING 0x01
#define RESOLVE_REF_NO_RECURSE 0x02
#define RESOLVE_REF_ALLOW_BAD_NAME 0x04

const char *refs_resolve_ref_unsafe(struct ref_store *refs,
				    const char *refname,
				    int resolve_flags,
				    struct object_id *oid,
				    int *flags);
const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
			       struct object_id *oid, int *flags);

char *refs_resolve_refdup(struct ref_store *refs,
			  const char *refname, int resolve_flags,
			  struct object_id *oid, int *flags);
char *resolve_refdup(const char *refname, int resolve_flags,
		     struct object_id *oid, int *flags);

int refs_read_ref_full(struct ref_store *refs, const char *refname,
		       int resolve_flags, struct object_id *oid, int *flags);
int read_ref_full(const char *refname, int resolve_flags,
		  struct object_id *oid, int *flags);
int read_ref(const char *refname, struct object_id *oid);

/*
 * Return 0 if a reference named refname could be created without
 * conflicting with the name of an existing reference. Otherwise,
 * return a negative value and write an explanation to err. If extras
 * is non-NULL, it is a list of additional refnames with which refname
 * is not allowed to conflict. If skip is non-NULL, ignore potential
 * conflicts with refs in skip (e.g., because they are scheduled for
 * deletion in the same operation). Behavior is undefined if the same
 * name is listed in both extras and skip.
 *
 * Two reference names conflict if one of them exactly matches the
 * leading components of the other; e.g., "foo/bar" conflicts with
 * both "foo" and with "foo/bar/baz" but not with "foo/bar" or
 * "foo/barbados".
 *
 * extras and skip must be sorted.
 */

int refs_verify_refname_available(struct ref_store *refs,
				  const char *refname,
				  const struct string_list *extras,
				  const struct string_list *skip,
				  struct strbuf *err);

int ref_exists(const char *refname);

int should_autocreate_reflog(const char *refname);

int is_branch(const char *refname);

int refs_init_db(struct strbuf *err);

/*
 * If refname is a non-symbolic reference that refers to a tag object,
 * and the tag can be (recursively) dereferenced to a non-tag object,
 * store the object ID of the referred-to object to oid and return 0.
 * If any of these conditions are not met, return a non-zero value.
 * Symbolic references are considered unpeelable, even if they
 * ultimately resolve to a peelable tag.
 */
int refs_peel_ref(struct ref_store *refs, const char *refname,
		  struct object_id *oid);
int peel_ref(const char *refname, struct object_id *oid);

/**
 * Resolve refname in the nested "gitlink" repository in the specified
 * submodule (which must be non-NULL). If the resolution is
 * successful, return 0 and set oid to the name of the object;
 * otherwise, return a non-zero value.
 */
int resolve_gitlink_ref(const char *submodule, const char *refname,
			struct object_id *oid);

/*
 * Return true iff abbrev_name is a possible abbreviation for
 * full_name according to the rules defined by ref_rev_parse_rules in
 * refs.c.
 */
int refname_match(const char *abbrev_name, const char *full_name);

/*
 * Given a 'prefix' expand it by the rules in 'ref_rev_parse_rules' and add
 * the results to 'prefixes'
 */
struct argv_array;
void expand_ref_prefix(struct argv_array *prefixes, const char *prefix);

int expand_ref(struct repository *r, const char *str, int len, struct object_id *oid, char **ref);
int repo_dwim_ref(struct repository *r, const char *str, int len, struct object_id *oid, char **ref);
int repo_dwim_log(struct repository *r, const char *str, int len, struct object_id *oid, char **ref);
int dwim_ref(const char *str, int len, struct object_id *oid, char **ref);
int dwim_log(const char *str, int len, struct object_id *oid, char **ref);

/*
 * A ref_transaction represents a collection of reference updates that
 * should succeed or fail together.
 *
 * Calling sequence
 * ----------------
 *
 * - Allocate and initialize a `struct ref_transaction` by calling
 *   `ref_transaction_begin()`.
 *
 * - Specify the intended ref updates by calling one or more of the
 *   following functions:
 *   - `ref_transaction_update()`
 *   - `ref_transaction_create()`
 *   - `ref_transaction_delete()`
 *   - `ref_transaction_verify()`
 *
 * - Then either:
 *
 *   - Optionally call `ref_transaction_prepare()` to prepare the
 *     transaction. This locks all references, checks preconditions,
 *     etc. but doesn't finalize anything. If this step fails, the
 *     transaction has been closed and can only be freed. If this step
 *     succeeds, then `ref_transaction_commit()` is almost certain to
 *     succeed. However, you can still call `ref_transaction_abort()`
 *     if you decide not to commit the transaction after all.
 *
 *   - Call `ref_transaction_commit()` to execute the transaction,
 *     make the changes permanent, and release all locks. If you
 *     haven't already called `ref_transaction_prepare()`, then
 *     `ref_transaction_commit()` calls it for you.
 *
 *   Or
 *
 *   - Call `initial_ref_transaction_commit()` if the ref database is
 *     known to be empty and have no other writers (e.g. during
 *     clone). This is likely to be much faster than
 *     `ref_transaction_commit()`. `ref_transaction_prepare()` should
 *     *not* be called before `initial_ref_transaction_commit()`.
 *
 * - Then finally, call `ref_transaction_free()` to free the
 *   `ref_transaction` data structure.
 *
 * At any time before calling `ref_transaction_commit()`, you can call
 * `ref_transaction_abort()` to abort the transaction, rollback any
 * locks, and free any associated resources (including the
 * `ref_transaction` data structure).
 *
 * Putting it all together, a complete reference update looks like
 *
 *         struct ref_transaction *transaction;
 *         struct strbuf err = STRBUF_INIT;
 *         int ret = 0;
 *
 *         transaction = ref_store_transaction_begin(refs, &err);
 *         if (!transaction ||
 *             ref_transaction_update(...) ||
 *             ref_transaction_create(...) ||
 *             ...etc... ||
 *             ref_transaction_commit(transaction, &err)) {
 *                 error("%s", err.buf);
 *                 ret = -1;
 *         }
 *         ref_transaction_free(transaction);
 *         strbuf_release(&err);
 *         return ret;
 *
 * Error handling
 * --------------
 *
 * On error, transaction functions append a message about what
 * went wrong to the 'err' argument.  The message mentions what
 * ref was being updated (if any) when the error occurred so it
 * can be passed to 'die' or 'error' as-is.
 *
 * The message is appended to err without first clearing err.