refs / refs-internal.hon commit files-backend: cheapen refname_available check when locking refs (8ec617c)
   1#ifndef REFS_REFS_INTERNAL_H
   2#define REFS_REFS_INTERNAL_H
   3
   4/*
   5 * Data structures and functions for the internal use of the refs
   6 * module. Code outside of the refs module should use only the public
   7 * functions defined in "refs.h", and should *not* include this file.
   8 */
   9
  10/*
  11 * Flag passed to lock_ref_sha1_basic() telling it to tolerate broken
  12 * refs (i.e., because the reference is about to be deleted anyway).
  13 */
  14#define REF_DELETING    0x02
  15
  16/*
  17 * Used as a flag in ref_update::flags when a loose ref is being
  18 * pruned. This flag must only be used when REF_NODEREF is set.
  19 */
  20#define REF_ISPRUNING   0x04
  21
  22/*
  23 * Used as a flag in ref_update::flags when the reference should be
  24 * updated to new_sha1.
  25 */
  26#define REF_HAVE_NEW    0x08
  27
  28/*
  29 * Used as a flag in ref_update::flags when old_sha1 should be
  30 * checked.
  31 */
  32#define REF_HAVE_OLD    0x10
  33
  34/*
  35 * Used as a flag in ref_update::flags when the lockfile needs to be
  36 * committed.
  37 */
  38#define REF_NEEDS_COMMIT 0x20
  39
  40/*
  41 * 0x40 is REF_FORCE_CREATE_REFLOG, so skip it if you're adding a
  42 * value to ref_update::flags
  43 */
  44
  45/*
  46 * Used as a flag in ref_update::flags when we want to log a ref
  47 * update but not actually perform it.  This is used when a symbolic
  48 * ref update is split up.
  49 */
  50#define REF_LOG_ONLY 0x80
  51
  52/*
  53 * Internal flag, meaning that the containing ref_update was via an
  54 * update to HEAD.
  55 */
  56#define REF_UPDATE_VIA_HEAD 0x100
  57
  58/*
  59 * Used as a flag in ref_update::flags when the loose reference has
  60 * been deleted.
  61 */
  62#define REF_DELETED_LOOSE 0x200
  63
  64/*
  65 * Return true iff refname is minimally safe. "Safe" here means that
  66 * deleting a loose reference by this name will not do any damage, for
  67 * example by causing a file that is not a reference to be deleted.
  68 * This function does not check that the reference name is legal; for
  69 * that, use check_refname_format().
  70 *
  71 * A refname that starts with "refs/" is considered safe iff it
  72 * doesn't contain any "." or ".." components or consecutive '/'
  73 * characters, end with '/', or (on Windows) contain any '\'
  74 * characters. Names that do not start with "refs/" are considered
  75 * safe iff they consist entirely of upper case characters and '_'
  76 * (like "HEAD" and "MERGE_HEAD" but not "config" or "FOO/BAR").
  77 */
  78int refname_is_safe(const char *refname);
  79
  80/*
  81 * Helper function: return true if refname, which has the specified
  82 * oid and flags, can be resolved to an object in the database. If the
  83 * referred-to object does not exist, emit a warning and return false.
  84 */
  85int ref_resolves_to_object(const char *refname,
  86                           const struct object_id *oid,
  87                           unsigned int flags);
  88
  89enum peel_status {
  90        /* object was peeled successfully: */
  91        PEEL_PEELED = 0,
  92
  93        /*
  94         * object cannot be peeled because the named object (or an
  95         * object referred to by a tag in the peel chain), does not
  96         * exist.
  97         */
  98        PEEL_INVALID = -1,
  99
 100        /* object cannot be peeled because it is not a tag: */
 101        PEEL_NON_TAG = -2,
 102
 103        /* ref_entry contains no peeled value because it is a symref: */
 104        PEEL_IS_SYMREF = -3,
 105
 106        /*
 107         * ref_entry cannot be peeled because it is broken (i.e., the
 108         * symbolic reference cannot even be resolved to an object
 109         * name):
 110         */
 111        PEEL_BROKEN = -4
 112};
 113
 114/*
 115 * Peel the named object; i.e., if the object is a tag, resolve the
 116 * tag recursively until a non-tag is found.  If successful, store the
 117 * result to sha1 and return PEEL_PEELED.  If the object is not a tag
 118 * or is not valid, return PEEL_NON_TAG or PEEL_INVALID, respectively,
 119 * and leave sha1 unchanged.
 120 */
 121enum peel_status peel_object(const unsigned char *name, unsigned char *sha1);
 122
 123/*
 124 * Copy the reflog message msg to buf, which has been allocated sufficiently
 125 * large, while cleaning up the whitespaces.  Especially, convert LF to space,
 126 * because reflog file is one line per entry.
 127 */
 128int copy_reflog_msg(char *buf, const char *msg);
 129
 130/**
 131 * Information needed for a single ref update. Set new_sha1 to the new
 132 * value or to null_sha1 to delete the ref. To check the old value
 133 * while the ref is locked, set (flags & REF_HAVE_OLD) and set
 134 * old_sha1 to the old value, or to null_sha1 to ensure the ref does
 135 * not exist before update.
 136 */
 137struct ref_update {
 138
 139        /*
 140         * If (flags & REF_HAVE_NEW), set the reference to this value:
 141         */
 142        struct object_id new_oid;
 143
 144        /*
 145         * If (flags & REF_HAVE_OLD), check that the reference
 146         * previously had this value:
 147         */
 148        struct object_id old_oid;
 149
 150        /*
 151         * One or more of REF_HAVE_NEW, REF_HAVE_OLD, REF_NODEREF,
 152         * REF_DELETING, REF_ISPRUNING, REF_LOG_ONLY,
 153         * REF_UPDATE_VIA_HEAD, REF_NEEDS_COMMIT, and
 154         * REF_DELETED_LOOSE:
 155         */
 156        unsigned int flags;
 157
 158        void *backend_data;
 159        unsigned int type;
 160        char *msg;
 161
 162        /*
 163         * If this ref_update was split off of a symref update via
 164         * split_symref_update(), then this member points at that
 165         * update. This is used for two purposes:
 166         * 1. When reporting errors, we report the refname under which
 167         *    the update was originally requested.
 168         * 2. When we read the old value of this reference, we
 169         *    propagate it back to its parent update for recording in
 170         *    the latter's reflog.
 171         */
 172        struct ref_update *parent_update;
 173
 174        const char refname[FLEX_ARRAY];
 175};
 176
 177int refs_read_raw_ref(struct ref_store *ref_store,
 178                      const char *refname, unsigned char *sha1,
 179                      struct strbuf *referent, unsigned int *type);
 180
 181/*
 182 * Write an error to `err` and return a nonzero value iff the same
 183 * refname appears multiple times in `refnames`. `refnames` must be
 184 * sorted on entry to this function.
 185 */
 186int ref_update_reject_duplicates(struct string_list *refnames,
 187                                 struct strbuf *err);
 188
 189/*
 190 * Add a ref_update with the specified properties to transaction, and
 191 * return a pointer to the new object. This function does not verify
 192 * that refname is well-formed. new_sha1 and old_sha1 are only
 193 * dereferenced if the REF_HAVE_NEW and REF_HAVE_OLD bits,
 194 * respectively, are set in flags.
 195 */
 196struct ref_update *ref_transaction_add_update(
 197                struct ref_transaction *transaction,
 198                const char *refname, unsigned int flags,
 199                const unsigned char *new_sha1,
 200                const unsigned char *old_sha1,
 201                const char *msg);
 202
 203/*
 204 * Transaction states.
 205 *
 206 * OPEN:   The transaction is initialized and new updates can still be
 207 *         added to it. An OPEN transaction can be prepared,
 208 *         committed, freed, or aborted (freeing and aborting an open
 209 *         transaction are equivalent).
 210 *
 211 * PREPARED: ref_transaction_prepare(), which locks all of the
 212 *         references involved in the update and checks that the
 213 *         update has no errors, has been called successfully for the
 214 *         transaction. A PREPARED transaction can be committed or
 215 *         aborted.
 216 *
 217 * CLOSED: The transaction is no longer active. A transaction becomes
 218 *         CLOSED if there is a failure while building the transaction
 219 *         or if a transaction is committed or aborted. A CLOSED
 220 *         transaction can only be freed.
 221 */
 222enum ref_transaction_state {
 223        REF_TRANSACTION_OPEN     = 0,
 224        REF_TRANSACTION_PREPARED = 1,
 225        REF_TRANSACTION_CLOSED   = 2
 226};
 227
 228/*
 229 * Data structure for holding a reference transaction, which can
 230 * consist of checks and updates to multiple references, carried out
 231 * as atomically as possible.  This structure is opaque to callers.
 232 */
 233struct ref_transaction {
 234        struct ref_store *ref_store;
 235        struct ref_update **updates;
 236        size_t alloc;
 237        size_t nr;
 238        enum ref_transaction_state state;
 239};
 240
 241/*
 242 * Check for entries in extras that are within the specified
 243 * directory, where dirname is a reference directory name including
 244 * the trailing slash (e.g., "refs/heads/foo/"). Ignore any
 245 * conflicting references that are found in skip. If there is a
 246 * conflicting reference, return its name.
 247 *
 248 * extras and skip must be sorted lists of reference names. Either one
 249 * can be NULL, signifying the empty list.
 250 */
 251const char *find_descendant_ref(const char *dirname,
 252                                const struct string_list *extras,
 253                                const struct string_list *skip);
 254
 255/*
 256 * Check whether an attempt to rename old_refname to new_refname would
 257 * cause a D/F conflict with any existing reference (other than
 258 * possibly old_refname). If there would be a conflict, emit an error
 259 * message and return false; otherwise, return true.
 260 *
 261 * Note that this function is not safe against all races with other
 262 * processes (though rename_ref() catches some races that might get by
 263 * this check).
 264 */
 265int refs_rename_ref_available(struct ref_store *refs,
 266                              const char *old_refname,
 267                              const char *new_refname);
 268
 269/* We allow "recursive" symbolic refs. Only within reason, though */
 270#define SYMREF_MAXDEPTH 5
 271
 272/* Include broken references in a do_for_each_ref*() iteration: */
 273#define DO_FOR_EACH_INCLUDE_BROKEN 0x01
 274
 275/*
 276 * Reference iterators
 277 *
 278 * A reference iterator encapsulates the state of an in-progress
 279 * iteration over references. Create an instance of `struct
 280 * ref_iterator` via one of the functions in this module.
 281 *
 282 * A freshly-created ref_iterator doesn't yet point at a reference. To
 283 * advance the iterator, call ref_iterator_advance(). If successful,
 284 * this sets the iterator's refname, oid, and flags fields to describe
 285 * the next reference and returns ITER_OK. The data pointed at by
 286 * refname and oid belong to the iterator; if you want to retain them
 287 * after calling ref_iterator_advance() again or calling
 288 * ref_iterator_abort(), you must make a copy. When the iteration has
 289 * been exhausted, ref_iterator_advance() releases any resources
 290 * assocated with the iteration, frees the ref_iterator object, and
 291 * returns ITER_DONE. If you want to abort the iteration early, call
 292 * ref_iterator_abort(), which also frees the ref_iterator object and
 293 * any associated resources. If there was an internal error advancing
 294 * to the next entry, ref_iterator_advance() aborts the iteration,
 295 * frees the ref_iterator, and returns ITER_ERROR.
 296 *
 297 * The reference currently being looked at can be peeled by calling
 298 * ref_iterator_peel(). This function is often faster than peel_ref(),
 299 * so it should be preferred when iterating over references.
 300 *
 301 * Putting it all together, a typical iteration looks like this:
 302 *
 303 *     int ok;
 304 *     struct ref_iterator *iter = ...;
 305 *
 306 *     while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
 307 *             if (want_to_stop_iteration()) {
 308 *                     ok = ref_iterator_abort(iter);
 309 *                     break;
 310 *             }
 311 *
 312 *             // Access information about the current reference:
 313 *             if (!(iter->flags & REF_ISSYMREF))
 314 *                     printf("%s is %s\n", iter->refname, oid_to_hex(&iter->oid));
 315 *
 316 *             // If you need to peel the reference:
 317 *             ref_iterator_peel(iter, &oid);
 318 *     }
 319 *
 320 *     if (ok != ITER_DONE)
 321 *             handle_error();
 322 */
 323struct ref_iterator {
 324        struct ref_iterator_vtable *vtable;
 325        const char *refname;
 326        const struct object_id *oid;
 327        unsigned int flags;
 328};
 329
 330/*
 331 * Advance the iterator to the first or next item and return ITER_OK.
 332 * If the iteration is exhausted, free the resources associated with
 333 * the ref_iterator and return ITER_DONE. On errors, free the iterator
 334 * resources and return ITER_ERROR. It is a bug to use ref_iterator or
 335 * call this function again after it has returned ITER_DONE or
 336 * ITER_ERROR.
 337 */
 338int ref_iterator_advance(struct ref_iterator *ref_iterator);
 339
 340/*
 341 * If possible, peel the reference currently being viewed by the
 342 * iterator. Return 0 on success.
 343 */
 344int ref_iterator_peel(struct ref_iterator *ref_iterator,
 345                      struct object_id *peeled);
 346
 347/*
 348 * End the iteration before it has been exhausted, freeing the
 349 * reference iterator and any associated resources and returning
 350 * ITER_DONE. If the abort itself failed, return ITER_ERROR.
 351 */
 352int ref_iterator_abort(struct ref_iterator *ref_iterator);
 353
 354/*
 355 * An iterator over nothing (its first ref_iterator_advance() call
 356 * returns ITER_DONE).
 357 */
 358struct ref_iterator *empty_ref_iterator_begin(void);
 359
 360/*
 361 * Return true iff ref_iterator is an empty_ref_iterator.
 362 */
 363int is_empty_ref_iterator(struct ref_iterator *ref_iterator);
 364
 365/*
 366 * Return an iterator that goes over each reference in `refs` for
 367 * which the refname begins with prefix. If trim is non-zero, then
 368 * trim that many characters off the beginning of each refname. flags
 369 * can be DO_FOR_EACH_INCLUDE_BROKEN to include broken references in
 370 * the iteration.
 371 */
 372struct ref_iterator *refs_ref_iterator_begin(
 373                struct ref_store *refs,
 374                const char *prefix, int trim, int flags);
 375
 376/*
 377 * A callback function used to instruct merge_ref_iterator how to
 378 * interleave the entries from iter0 and iter1. The function should
 379 * return one of the constants defined in enum iterator_selection. It
 380 * must not advance either of the iterators itself.
 381 *
 382 * The function must be prepared to handle the case that iter0 and/or
 383 * iter1 is NULL, which indicates that the corresponding sub-iterator
 384 * has been exhausted. Its return value must be consistent with the
 385 * current states of the iterators; e.g., it must not return
 386 * ITER_SKIP_1 if iter1 has already been exhausted.
 387 */
 388typedef enum iterator_selection ref_iterator_select_fn(
 389                struct ref_iterator *iter0, struct ref_iterator *iter1,
 390                void *cb_data);
 391
 392/*
 393 * Iterate over the entries from iter0 and iter1, with the values
 394 * interleaved as directed by the select function. The iterator takes
 395 * ownership of iter0 and iter1 and frees them when the iteration is
 396 * over.
 397 */
 398struct ref_iterator *merge_ref_iterator_begin(
 399                struct ref_iterator *iter0, struct ref_iterator *iter1,
 400                ref_iterator_select_fn *select, void *cb_data);
 401
 402/*
 403 * An iterator consisting of the union of the entries from front and
 404 * back. If there are entries common to the two sub-iterators, use the
 405 * one from front. Each iterator must iterate over its entries in
 406 * strcmp() order by refname for this to work.
 407 *
 408 * The new iterator takes ownership of its arguments and frees them
 409 * when the iteration is over. As a convenience to callers, if front
 410 * or back is an empty_ref_iterator, then abort that one immediately
 411 * and return the other iterator directly, without wrapping it.
 412 */
 413struct ref_iterator *overlay_ref_iterator_begin(
 414                struct ref_iterator *front, struct ref_iterator *back);
 415
 416/*
 417 * Wrap iter0, only letting through the references whose names start
 418 * with prefix. If trim is set, set iter->refname to the name of the
 419 * reference with that many characters trimmed off the front;
 420 * otherwise set it to the full refname. The new iterator takes over
 421 * ownership of iter0 and frees it when iteration is over. It makes
 422 * its own copy of prefix.
 423 *
 424 * As an convenience to callers, if prefix is the empty string and
 425 * trim is zero, this function returns iter0 directly, without
 426 * wrapping it.
 427 */
 428struct ref_iterator *prefix_ref_iterator_begin(struct ref_iterator *iter0,
 429                                               const char *prefix,
 430                                               int trim);
 431
 432/* Internal implementation of reference iteration: */
 433
 434/*
 435 * Base class constructor for ref_iterators. Initialize the
 436 * ref_iterator part of iter, setting its vtable pointer as specified.
 437 * This is meant to be called only by the initializers of derived
 438 * classes.
 439 */
 440void base_ref_iterator_init(struct ref_iterator *iter,
 441                            struct ref_iterator_vtable *vtable);
 442
 443/*
 444 * Base class destructor for ref_iterators. Destroy the ref_iterator
 445 * part of iter and shallow-free the object. This is meant to be
 446 * called only by the destructors of derived classes.
 447 */
 448void base_ref_iterator_free(struct ref_iterator *iter);
 449
 450/* Virtual function declarations for ref_iterators: */
 451
 452typedef int ref_iterator_advance_fn(struct ref_iterator *ref_iterator);
 453
 454typedef int ref_iterator_peel_fn(struct ref_iterator *ref_iterator,
 455                                 struct object_id *peeled);
 456
 457/*
 458 * Implementations of this function should free any resources specific
 459 * to the derived class, then call base_ref_iterator_free() to clean
 460 * up and free the ref_iterator object.
 461 */
 462typedef int ref_iterator_abort_fn(struct ref_iterator *ref_iterator);
 463
 464struct ref_iterator_vtable {
 465        ref_iterator_advance_fn *advance;
 466        ref_iterator_peel_fn *peel;
 467        ref_iterator_abort_fn *abort;
 468};
 469
 470/*
 471 * current_ref_iter is a performance hack: when iterating over
 472 * references using the for_each_ref*() functions, current_ref_iter is
 473 * set to the reference iterator before calling the callback function.
 474 * If the callback function calls peel_ref(), then peel_ref() first
 475 * checks whether the reference to be peeled is the one referred to by
 476 * the iterator (it usually is) and if so, asks the iterator for the
 477 * peeled version of the reference if it is available. This avoids a
 478 * refname lookup in a common case. current_ref_iter is set to NULL
 479 * when the iteration is over.
 480 */
 481extern struct ref_iterator *current_ref_iter;
 482
 483/*
 484 * The common backend for the for_each_*ref* functions. Call fn for
 485 * each reference in iter. If the iterator itself ever returns
 486 * ITER_ERROR, return -1. If fn ever returns a non-zero value, stop
 487 * the iteration and return that value. Otherwise, return 0. In any
 488 * case, free the iterator when done. This function is basically an
 489 * adapter between the callback style of reference iteration and the
 490 * iterator style.
 491 */
 492int do_for_each_ref_iterator(struct ref_iterator *iter,
 493                             each_ref_fn fn, void *cb_data);
 494
 495/*
 496 * Only include per-worktree refs in a do_for_each_ref*() iteration.
 497 * Normally this will be used with a files ref_store, since that's
 498 * where all reference backends will presumably store their
 499 * per-worktree refs.
 500 */
 501#define DO_FOR_EACH_PER_WORKTREE_ONLY 0x02
 502
 503struct ref_store;
 504
 505/* refs backends */
 506
 507/* ref_store_init flags */
 508#define REF_STORE_READ          (1 << 0)
 509#define REF_STORE_WRITE         (1 << 1) /* can perform update operations */
 510#define REF_STORE_ODB           (1 << 2) /* has access to object database */
 511#define REF_STORE_MAIN          (1 << 3)
 512#define REF_STORE_ALL_CAPS      (REF_STORE_READ | \
 513                                 REF_STORE_WRITE | \
 514                                 REF_STORE_ODB | \
 515                                 REF_STORE_MAIN)
 516
 517/*
 518 * Initialize the ref_store for the specified gitdir. These functions
 519 * should call base_ref_store_init() to initialize the shared part of
 520 * the ref_store and to record the ref_store for later lookup.
 521 */
 522typedef struct ref_store *ref_store_init_fn(const char *gitdir,
 523                                            unsigned int flags);
 524
 525typedef int ref_init_db_fn(struct ref_store *refs, struct strbuf *err);
 526
 527typedef int ref_transaction_prepare_fn(struct ref_store *refs,
 528                                       struct ref_transaction *transaction,
 529                                       struct strbuf *err);
 530
 531typedef int ref_transaction_finish_fn(struct ref_store *refs,
 532                                      struct ref_transaction *transaction,
 533                                      struct strbuf *err);
 534
 535typedef int ref_transaction_abort_fn(struct ref_store *refs,
 536                                     struct ref_transaction *transaction,
 537                                     struct strbuf *err);
 538
 539typedef int ref_transaction_commit_fn(struct ref_store *refs,
 540                                      struct ref_transaction *transaction,
 541                                      struct strbuf *err);
 542
 543typedef int pack_refs_fn(struct ref_store *ref_store, unsigned int flags);
 544typedef int peel_ref_fn(struct ref_store *ref_store,
 545                        const char *refname, unsigned char *sha1);
 546typedef int create_symref_fn(struct ref_store *ref_store,
 547                             const char *ref_target,
 548                             const char *refs_heads_master,
 549                             const char *logmsg);
 550typedef int delete_refs_fn(struct ref_store *ref_store, const char *msg,
 551                           struct string_list *refnames, unsigned int flags);
 552typedef int rename_ref_fn(struct ref_store *ref_store,
 553                          const char *oldref, const char *newref,
 554                          const char *logmsg);
 555
 556/*
 557 * Iterate over the references in `ref_store` whose names start with
 558 * `prefix`. `prefix` is matched as a literal string, without regard
 559 * for path separators. If prefix is NULL or the empty string, iterate
 560 * over all references in `ref_store`.
 561 */
 562typedef struct ref_iterator *ref_iterator_begin_fn(
 563                struct ref_store *ref_store,
 564                const char *prefix, unsigned int flags);
 565
 566/* reflog functions */
 567
 568/*
 569 * Iterate over the references in the specified ref_store that have a
 570 * reflog. The refs are iterated over in arbitrary order.
 571 */
 572typedef struct ref_iterator *reflog_iterator_begin_fn(
 573                struct ref_store *ref_store);
 574
 575typedef int for_each_reflog_ent_fn(struct ref_store *ref_store,
 576                                   const char *refname,
 577                                   each_reflog_ent_fn fn,
 578                                   void *cb_data);
 579typedef int for_each_reflog_ent_reverse_fn(struct ref_store *ref_store,
 580                                           const char *refname,
 581                                           each_reflog_ent_fn fn,
 582                                           void *cb_data);
 583typedef int reflog_exists_fn(struct ref_store *ref_store, const char *refname);
 584typedef int create_reflog_fn(struct ref_store *ref_store, const char *refname,
 585                             int force_create, struct strbuf *err);
 586typedef int delete_reflog_fn(struct ref_store *ref_store, const char *refname);
 587typedef int reflog_expire_fn(struct ref_store *ref_store,
 588                             const char *refname, const unsigned char *sha1,
 589                             unsigned int flags,
 590                             reflog_expiry_prepare_fn prepare_fn,
 591                             reflog_expiry_should_prune_fn should_prune_fn,
 592                             reflog_expiry_cleanup_fn cleanup_fn,
 593                             void *policy_cb_data);
 594
 595/*
 596 * Read a reference from the specified reference store, non-recursively.
 597 * Set type to describe the reference, and:
 598 *
 599 * - If refname is the name of a normal reference, fill in sha1
 600 *   (leaving referent unchanged).
 601 *
 602 * - If refname is the name of a symbolic reference, write the full
 603 *   name of the reference to which it refers (e.g.
 604 *   "refs/heads/master") to referent and set the REF_ISSYMREF bit in
 605 *   type (leaving sha1 unchanged). The caller is responsible for
 606 *   validating that referent is a valid reference name.
 607 *
 608 * WARNING: refname might be used as part of a filename, so it is
 609 * important from a security standpoint that it be safe in the sense
 610 * of refname_is_safe(). Moreover, for symrefs this function sets
 611 * referent to whatever the repository says, which might not be a
 612 * properly-formatted or even safe reference name. NEITHER INPUT NOR
 613 * OUTPUT REFERENCE NAMES ARE VALIDATED WITHIN THIS FUNCTION.
 614 *
 615 * Return 0 on success. If the ref doesn't exist, set errno to ENOENT
 616 * and return -1. If the ref exists but is neither a symbolic ref nor
 617 * a sha1, it is broken; set REF_ISBROKEN in type, set errno to
 618 * EINVAL, and return -1. If there is another error reading the ref,
 619 * set errno appropriately and return -1.
 620 *
 621 * Backend-specific flags might be set in type as well, regardless of
 622 * outcome.
 623 *
 624 * It is OK for refname to point into referent. If so:
 625 *
 626 * - if the function succeeds with REF_ISSYMREF, referent will be
 627 *   overwritten and the memory formerly pointed to by it might be
 628 *   changed or even freed.
 629 *
 630 * - in all other cases, referent will be untouched, and therefore
 631 *   refname will still be valid and unchanged.
 632 */
 633typedef int read_raw_ref_fn(struct ref_store *ref_store,
 634                            const char *refname, unsigned char *sha1,
 635                            struct strbuf *referent, unsigned int *type);
 636
 637struct ref_storage_be {
 638        struct ref_storage_be *next;
 639        const char *name;
 640        ref_store_init_fn *init;
 641        ref_init_db_fn *init_db;
 642
 643        ref_transaction_prepare_fn *transaction_prepare;
 644        ref_transaction_finish_fn *transaction_finish;
 645        ref_transaction_abort_fn *transaction_abort;
 646        ref_transaction_commit_fn *initial_transaction_commit;
 647
 648        pack_refs_fn *pack_refs;
 649        peel_ref_fn *peel_ref;
 650        create_symref_fn *create_symref;
 651        delete_refs_fn *delete_refs;
 652        rename_ref_fn *rename_ref;
 653
 654        ref_iterator_begin_fn *iterator_begin;
 655        read_raw_ref_fn *read_raw_ref;
 656
 657        reflog_iterator_begin_fn *reflog_iterator_begin;
 658        for_each_reflog_ent_fn *for_each_reflog_ent;
 659        for_each_reflog_ent_reverse_fn *for_each_reflog_ent_reverse;
 660        reflog_exists_fn *reflog_exists;
 661        create_reflog_fn *create_reflog;
 662        delete_reflog_fn *delete_reflog;
 663        reflog_expire_fn *reflog_expire;
 664};
 665
 666extern struct ref_storage_be refs_be_files;
 667extern struct ref_storage_be refs_be_packed;
 668
 669/*
 670 * A representation of the reference store for the main repository or
 671 * a submodule. The ref_store instances for submodules are kept in a
 672 * linked list.
 673 */
 674struct ref_store {
 675        /* The backend describing this ref_store's storage scheme: */
 676        const struct ref_storage_be *be;
 677};
 678
 679/*
 680 * Fill in the generic part of refs and add it to our collection of
 681 * reference stores.
 682 */
 683void base_ref_store_init(struct ref_store *refs,
 684                         const struct ref_storage_be *be);
 685
 686#endif /* REFS_REFS_INTERNAL_H */