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Diffstat (limited to 'refs/refs-internal.h')
| -rw-r--r-- | refs/refs-internal.h | 692 |
1 files changed, 692 insertions, 0 deletions
diff --git a/refs/refs-internal.h b/refs/refs-internal.h new file mode 100644 index 0000000000..708b26082a --- /dev/null +++ b/refs/refs-internal.h @@ -0,0 +1,692 @@ +#ifndef REFS_REFS_INTERNAL_H +#define REFS_REFS_INTERNAL_H + +/* + * 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. + */ + +/* + * Flag passed to lock_ref_sha1_basic() telling it to tolerate broken + * refs (i.e., because the reference is about to be deleted anyway). + */ +#define REF_DELETING 0x02 + +/* + * Used as a flag in ref_update::flags when a loose ref is being + * pruned. This flag must only be used when REF_NODEREF is set. + */ +#define REF_ISPRUNING 0x04 + +/* + * Used as a flag in ref_update::flags when the reference should be + * updated to new_sha1. + */ +#define REF_HAVE_NEW 0x08 + +/* + * Used as a flag in ref_update::flags when old_sha1 should be + * checked. + */ +#define REF_HAVE_OLD 0x10 + +/* + * Used as a flag in ref_update::flags when the lockfile needs to be + * committed. + */ +#define REF_NEEDS_COMMIT 0x20 + +/* + * 0x40 is REF_FORCE_CREATE_REFLOG, so skip it if you're adding a + * value to ref_update::flags + */ + +/* + * 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 0x80 + +/* + * Internal flag, meaning that the containing ref_update was via an + * update to HEAD. + */ +#define REF_UPDATE_VIA_HEAD 0x100 + +/* + * 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(). + * + * We consider a refname that starts with "refs/" to be safe as long + * as any ".." components that it might contain do not escape "refs/". + * 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); + +enum peel_status { + /* object was peeled successfully: */ + PEEL_PEELED = 0, + + /* + * object cannot be peeled because the named object (or an + * object referred to by a tag in the peel chain), does not + * exist. + */ + PEEL_INVALID = -1, + + /* object cannot be peeled because it is not a tag: */ + PEEL_NON_TAG = -2, + + /* ref_entry contains no peeled value because it is a symref: */ + PEEL_IS_SYMREF = -3, + + /* + * ref_entry cannot be peeled because it is broken (i.e., the + * symbolic reference cannot even be resolved to an object + * name): + */ + PEEL_BROKEN = -4 +}; + +/* + * 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 sha1 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 sha1 unchanged. + */ +enum peel_status peel_object(const unsigned char *name, unsigned char *sha1); + +/* + * 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 verify_refname_available(const char *newname, + const struct string_list *extras, + const struct string_list *skip, + struct strbuf *err); + +/* + * Copy the reflog message msg to buf, which has been allocated sufficiently + * large, while cleaning up the whitespaces. Especially, convert LF to space, + * because reflog file is one line per entry. + */ +int copy_reflog_msg(char *buf, const char *msg); + +int should_autocreate_reflog(const char *refname); + +/** + * Information needed for a single ref update. Set new_sha1 to the new + * value or to null_sha1 to delete the ref. To check the old value + * while the ref is locked, set (flags & REF_HAVE_OLD) and set + * old_sha1 to the old value, or to null_sha1 to ensure the ref does + * not exist before update. + */ +struct ref_update { + + /* + * If (flags & REF_HAVE_NEW), set the reference to this value: + */ + unsigned char new_sha1[20]; + + /* + * If (flags & REF_HAVE_OLD), check that the reference + * previously had this value: + */ + unsigned char old_sha1[20]; + + /* + * One or more of REF_HAVE_NEW, REF_HAVE_OLD, REF_NODEREF, + * REF_DELETING, REF_ISPRUNING, REF_LOG_ONLY, and + * REF_UPDATE_VIA_HEAD: + */ + 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]; +}; + +/* + * 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_sha1 and old_sha1 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 unsigned char *new_sha1, + const unsigned char *old_sha1, + const char *msg); + +/* + * Transaction states. + * OPEN: The transaction is in a valid state and can accept new updates. + * An OPEN transaction can be committed. + * CLOSED: A closed transaction is no longer active and no other operations + * than free can be used on it in this state. + * A transaction can either become closed by successfully committing + * an active transaction or if there is a failure while building + * the transaction thus rendering it failed/inactive. + */ +enum ref_transaction_state { + REF_TRANSACTION_OPEN = 0, + REF_TRANSACTION_CLOSED = 1 +}; + +/* + * 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_update **updates; + size_t alloc; + size_t nr; + enum ref_transaction_state state; +}; + +int files_log_ref_write(const char *refname, const unsigned char *old_sha1, + const unsigned char *new_sha1, const char *msg, + int flags, struct strbuf *err); + +/* + * 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); + +/* + * Check whether an attempt to rename old_refname to new_refname would + * cause a D/F conflict with any existing reference (other than + * possibly old_refname). If there would be a conflict, emit an error + * message and return false; otherwise, return true. + * + * Note that this function is not safe against all races with other + * processes (though rename_ref() catches some races that might get by + * this check). + */ +int rename_ref_available(const char *old_refname, const char *new_refname); + +/* We allow "recursive" symbolic refs. Only within reason, though */ +#define SYMREF_MAXDEPTH 5 + +/* Include broken references in a do_for_each_ref*() iteration: */ +#define DO_FOR_EACH_INCLUDE_BROKEN 0x01 + +/* + * 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 + * assocated 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; + 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 + * ITER_ERROR. + */ +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); + +/* + * 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. + */ +struct ref_iterator *merge_ref_iterator_begin( + 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. + */ +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. + * 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); + +/* + * 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: */ + +typedef int ref_iterator_advance_fn(struct ref_iterator *ref_iterator); + +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_ref_iterator(struct ref_iterator *iter, + each_ref_fn fn, void *cb_data); + +/* + * 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. + */ +#define DO_FOR_EACH_PER_WORKTREE_ONLY 0x02 + +struct ref_store; + +/* refs backends */ + +/* + * Initialize the ref_store for the specified submodule, or for the + * main repository if submodule == NULL. 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(const char *submodule); + +typedef int ref_init_db_fn(struct ref_store *refs, 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 peel_ref_fn(struct ref_store *ref_store, + const char *refname, unsigned char *sha1); +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, + 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); + +/* + * Iterate over the references in the specified ref_store that are + * within find_containing_dir(prefix). If prefix is NULL or the empty + * string, iterate over all references in the submodule. + */ +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, + int force_create, 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, const unsigned char *sha1, + 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 sha1 + * (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 sha1 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 + * OUTPUT REFERENCE NAMES ARE VALIDATED WITHIN THIS FUNCTION. + * + * Return 0 on success. If the ref doesn't exist, set errno to ENOENT + * and return -1. If the ref exists but is neither a symbolic ref nor + * a sha1, it is broken; set REF_ISBROKEN in type, set errno to + * EINVAL, and return -1. If there is another error reading the ref, + * set errno appropriately and return -1. + * + * 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, unsigned char *sha1, + struct strbuf *referent, unsigned int *type); + +typedef int verify_refname_available_fn(struct ref_store *ref_store, + const char *newname, + const struct string_list *extras, + const struct string_list *skip, + struct strbuf *err); + +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_commit_fn *transaction_commit; + ref_transaction_commit_fn *initial_transaction_commit; + + pack_refs_fn *pack_refs; + peel_ref_fn *peel_ref; + create_symref_fn *create_symref; + delete_refs_fn *delete_refs; + rename_ref_fn *rename_ref; + + ref_iterator_begin_fn *iterator_begin; + read_raw_ref_fn *read_raw_ref; + verify_refname_available_fn *verify_refname_available; + + 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; + +/* + * A representation of the reference store for the main repository or + * a submodule. The ref_store instances for submodules are kept in a + * linked list. + */ +struct ref_store { + /* The backend describing this ref_store's storage scheme: */ + const struct ref_storage_be *be; + + /* + * The name of the submodule represented by this object, or + * the empty string if it represents the main repository's + * reference store: + */ + const char *submodule; + + /* + * Submodule reference store instances are stored in a linked + * list using this pointer. + */ + struct ref_store *next; +}; + +/* + * Fill in the generic part of refs for the specified submodule and + * add it to our collection of reference stores. + */ +void base_ref_store_init(struct ref_store *refs, + const struct ref_storage_be *be, + const char *submodule); + +/* + * Create, record, and return a ref_store instance for the specified + * submodule (or the main repository if submodule is NULL). + * + * For backwards compatibility, submodule=="" is treated the same as + * submodule==NULL. + */ +struct ref_store *ref_store_init(const char *submodule); + +/* + * Return the ref_store instance for the specified submodule (or the + * main repository if submodule is NULL). If that ref_store hasn't + * been initialized yet, return NULL. + * + * For backwards compatibility, submodule=="" is treated the same as + * submodule==NULL. + */ +struct ref_store *lookup_ref_store(const char *submodule); + +/* + * Return the ref_store instance for the specified submodule. For the + * main repository, use submodule==NULL; such a call cannot fail. For + * a submodule, the submodule must exist and be a nonbare repository, + * otherwise return NULL. If the requested reference store has not yet + * been initialized, initialize it first. + * + * For backwards compatibility, submodule=="" is treated the same as + * submodule==NULL. + */ +struct ref_store *get_ref_store(const char *submodule); + +/* + * Die if refs is for a submodule (i.e., not for the main repository). + * caller is used in any necessary error messages. + */ +void assert_main_repository(struct ref_store *refs, const char *caller); + +#endif /* REFS_REFS_INTERNAL_H */ |