refs / files-backend.con commit packed_ref_store: get rid of the `ref_cache` entirely (9dd389f)
   1#include "../cache.h"
   2#include "../config.h"
   3#include "../refs.h"
   4#include "refs-internal.h"
   5#include "ref-cache.h"
   6#include "packed-backend.h"
   7#include "../iterator.h"
   8#include "../dir-iterator.h"
   9#include "../lockfile.h"
  10#include "../object.h"
  11#include "../dir.h"
  12
  13struct ref_lock {
  14        char *ref_name;
  15        struct lock_file *lk;
  16        struct object_id old_oid;
  17};
  18
  19/*
  20 * Future: need to be in "struct repository"
  21 * when doing a full libification.
  22 */
  23struct files_ref_store {
  24        struct ref_store base;
  25        unsigned int store_flags;
  26
  27        char *gitdir;
  28        char *gitcommondir;
  29
  30        struct ref_cache *loose;
  31
  32        struct ref_store *packed_ref_store;
  33};
  34
  35static void clear_loose_ref_cache(struct files_ref_store *refs)
  36{
  37        if (refs->loose) {
  38                free_ref_cache(refs->loose);
  39                refs->loose = NULL;
  40        }
  41}
  42
  43/*
  44 * Create a new submodule ref cache and add it to the internal
  45 * set of caches.
  46 */
  47static struct ref_store *files_ref_store_create(const char *gitdir,
  48                                                unsigned int flags)
  49{
  50        struct files_ref_store *refs = xcalloc(1, sizeof(*refs));
  51        struct ref_store *ref_store = (struct ref_store *)refs;
  52        struct strbuf sb = STRBUF_INIT;
  53
  54        base_ref_store_init(ref_store, &refs_be_files);
  55        refs->store_flags = flags;
  56
  57        refs->gitdir = xstrdup(gitdir);
  58        get_common_dir_noenv(&sb, gitdir);
  59        refs->gitcommondir = strbuf_detach(&sb, NULL);
  60        strbuf_addf(&sb, "%s/packed-refs", refs->gitcommondir);
  61        refs->packed_ref_store = packed_ref_store_create(sb.buf, flags);
  62        strbuf_release(&sb);
  63
  64        return ref_store;
  65}
  66
  67/*
  68 * Die if refs is not the main ref store. caller is used in any
  69 * necessary error messages.
  70 */
  71static void files_assert_main_repository(struct files_ref_store *refs,
  72                                         const char *caller)
  73{
  74        if (refs->store_flags & REF_STORE_MAIN)
  75                return;
  76
  77        die("BUG: operation %s only allowed for main ref store", caller);
  78}
  79
  80/*
  81 * Downcast ref_store to files_ref_store. Die if ref_store is not a
  82 * files_ref_store. required_flags is compared with ref_store's
  83 * store_flags to ensure the ref_store has all required capabilities.
  84 * "caller" is used in any necessary error messages.
  85 */
  86static struct files_ref_store *files_downcast(struct ref_store *ref_store,
  87                                              unsigned int required_flags,
  88                                              const char *caller)
  89{
  90        struct files_ref_store *refs;
  91
  92        if (ref_store->be != &refs_be_files)
  93                die("BUG: ref_store is type \"%s\" not \"files\" in %s",
  94                    ref_store->be->name, caller);
  95
  96        refs = (struct files_ref_store *)ref_store;
  97
  98        if ((refs->store_flags & required_flags) != required_flags)
  99                die("BUG: operation %s requires abilities 0x%x, but only have 0x%x",
 100                    caller, required_flags, refs->store_flags);
 101
 102        return refs;
 103}
 104
 105static void files_reflog_path(struct files_ref_store *refs,
 106                              struct strbuf *sb,
 107                              const char *refname)
 108{
 109        if (!refname) {
 110                /*
 111                 * FIXME: of course this is wrong in multi worktree
 112                 * setting. To be fixed real soon.
 113                 */
 114                strbuf_addf(sb, "%s/logs", refs->gitcommondir);
 115                return;
 116        }
 117
 118        switch (ref_type(refname)) {
 119        case REF_TYPE_PER_WORKTREE:
 120        case REF_TYPE_PSEUDOREF:
 121                strbuf_addf(sb, "%s/logs/%s", refs->gitdir, refname);
 122                break;
 123        case REF_TYPE_NORMAL:
 124                strbuf_addf(sb, "%s/logs/%s", refs->gitcommondir, refname);
 125                break;
 126        default:
 127                die("BUG: unknown ref type %d of ref %s",
 128                    ref_type(refname), refname);
 129        }
 130}
 131
 132static void files_ref_path(struct files_ref_store *refs,
 133                           struct strbuf *sb,
 134                           const char *refname)
 135{
 136        switch (ref_type(refname)) {
 137        case REF_TYPE_PER_WORKTREE:
 138        case REF_TYPE_PSEUDOREF:
 139                strbuf_addf(sb, "%s/%s", refs->gitdir, refname);
 140                break;
 141        case REF_TYPE_NORMAL:
 142                strbuf_addf(sb, "%s/%s", refs->gitcommondir, refname);
 143                break;
 144        default:
 145                die("BUG: unknown ref type %d of ref %s",
 146                    ref_type(refname), refname);
 147        }
 148}
 149
 150/*
 151 * Read the loose references from the namespace dirname into dir
 152 * (without recursing).  dirname must end with '/'.  dir must be the
 153 * directory entry corresponding to dirname.
 154 */
 155static void loose_fill_ref_dir(struct ref_store *ref_store,
 156                               struct ref_dir *dir, const char *dirname)
 157{
 158        struct files_ref_store *refs =
 159                files_downcast(ref_store, REF_STORE_READ, "fill_ref_dir");
 160        DIR *d;
 161        struct dirent *de;
 162        int dirnamelen = strlen(dirname);
 163        struct strbuf refname;
 164        struct strbuf path = STRBUF_INIT;
 165        size_t path_baselen;
 166
 167        files_ref_path(refs, &path, dirname);
 168        path_baselen = path.len;
 169
 170        d = opendir(path.buf);
 171        if (!d) {
 172                strbuf_release(&path);
 173                return;
 174        }
 175
 176        strbuf_init(&refname, dirnamelen + 257);
 177        strbuf_add(&refname, dirname, dirnamelen);
 178
 179        while ((de = readdir(d)) != NULL) {
 180                struct object_id oid;
 181                struct stat st;
 182                int flag;
 183
 184                if (de->d_name[0] == '.')
 185                        continue;
 186                if (ends_with(de->d_name, ".lock"))
 187                        continue;
 188                strbuf_addstr(&refname, de->d_name);
 189                strbuf_addstr(&path, de->d_name);
 190                if (stat(path.buf, &st) < 0) {
 191                        ; /* silently ignore */
 192                } else if (S_ISDIR(st.st_mode)) {
 193                        strbuf_addch(&refname, '/');
 194                        add_entry_to_dir(dir,
 195                                         create_dir_entry(dir->cache, refname.buf,
 196                                                          refname.len, 1));
 197                } else {
 198                        if (!refs_resolve_ref_unsafe(&refs->base,
 199                                                     refname.buf,
 200                                                     RESOLVE_REF_READING,
 201                                                     oid.hash, &flag)) {
 202                                oidclr(&oid);
 203                                flag |= REF_ISBROKEN;
 204                        } else if (is_null_oid(&oid)) {
 205                                /*
 206                                 * It is so astronomically unlikely
 207                                 * that NULL_SHA1 is the SHA-1 of an
 208                                 * actual object that we consider its
 209                                 * appearance in a loose reference
 210                                 * file to be repo corruption
 211                                 * (probably due to a software bug).
 212                                 */
 213                                flag |= REF_ISBROKEN;
 214                        }
 215
 216                        if (check_refname_format(refname.buf,
 217                                                 REFNAME_ALLOW_ONELEVEL)) {
 218                                if (!refname_is_safe(refname.buf))
 219                                        die("loose refname is dangerous: %s", refname.buf);
 220                                oidclr(&oid);
 221                                flag |= REF_BAD_NAME | REF_ISBROKEN;
 222                        }
 223                        add_entry_to_dir(dir,
 224                                         create_ref_entry(refname.buf, &oid, flag));
 225                }
 226                strbuf_setlen(&refname, dirnamelen);
 227                strbuf_setlen(&path, path_baselen);
 228        }
 229        strbuf_release(&refname);
 230        strbuf_release(&path);
 231        closedir(d);
 232
 233        /*
 234         * Manually add refs/bisect, which, being per-worktree, might
 235         * not appear in the directory listing for refs/ in the main
 236         * repo.
 237         */
 238        if (!strcmp(dirname, "refs/")) {
 239                int pos = search_ref_dir(dir, "refs/bisect/", 12);
 240
 241                if (pos < 0) {
 242                        struct ref_entry *child_entry = create_dir_entry(
 243                                        dir->cache, "refs/bisect/", 12, 1);
 244                        add_entry_to_dir(dir, child_entry);
 245                }
 246        }
 247}
 248
 249static struct ref_cache *get_loose_ref_cache(struct files_ref_store *refs)
 250{
 251        if (!refs->loose) {
 252                /*
 253                 * Mark the top-level directory complete because we
 254                 * are about to read the only subdirectory that can
 255                 * hold references:
 256                 */
 257                refs->loose = create_ref_cache(&refs->base, loose_fill_ref_dir);
 258
 259                /* We're going to fill the top level ourselves: */
 260                refs->loose->root->flag &= ~REF_INCOMPLETE;
 261
 262                /*
 263                 * Add an incomplete entry for "refs/" (to be filled
 264                 * lazily):
 265                 */
 266                add_entry_to_dir(get_ref_dir(refs->loose->root),
 267                                 create_dir_entry(refs->loose, "refs/", 5, 1));
 268        }
 269        return refs->loose;
 270}
 271
 272static int files_read_raw_ref(struct ref_store *ref_store,
 273                              const char *refname, unsigned char *sha1,
 274                              struct strbuf *referent, unsigned int *type)
 275{
 276        struct files_ref_store *refs =
 277                files_downcast(ref_store, REF_STORE_READ, "read_raw_ref");
 278        struct strbuf sb_contents = STRBUF_INIT;
 279        struct strbuf sb_path = STRBUF_INIT;
 280        const char *path;
 281        const char *buf;
 282        struct stat st;
 283        int fd;
 284        int ret = -1;
 285        int save_errno;
 286        int remaining_retries = 3;
 287
 288        *type = 0;
 289        strbuf_reset(&sb_path);
 290
 291        files_ref_path(refs, &sb_path, refname);
 292
 293        path = sb_path.buf;
 294
 295stat_ref:
 296        /*
 297         * We might have to loop back here to avoid a race
 298         * condition: first we lstat() the file, then we try
 299         * to read it as a link or as a file.  But if somebody
 300         * changes the type of the file (file <-> directory
 301         * <-> symlink) between the lstat() and reading, then
 302         * we don't want to report that as an error but rather
 303         * try again starting with the lstat().
 304         *
 305         * We'll keep a count of the retries, though, just to avoid
 306         * any confusing situation sending us into an infinite loop.
 307         */
 308
 309        if (remaining_retries-- <= 0)
 310                goto out;
 311
 312        if (lstat(path, &st) < 0) {
 313                if (errno != ENOENT)
 314                        goto out;
 315                if (refs_read_raw_ref(refs->packed_ref_store, refname,
 316                                      sha1, referent, type)) {
 317                        errno = ENOENT;
 318                        goto out;
 319                }
 320                ret = 0;
 321                goto out;
 322        }
 323
 324        /* Follow "normalized" - ie "refs/.." symlinks by hand */
 325        if (S_ISLNK(st.st_mode)) {
 326                strbuf_reset(&sb_contents);
 327                if (strbuf_readlink(&sb_contents, path, 0) < 0) {
 328                        if (errno == ENOENT || errno == EINVAL)
 329                                /* inconsistent with lstat; retry */
 330                                goto stat_ref;
 331                        else
 332                                goto out;
 333                }
 334                if (starts_with(sb_contents.buf, "refs/") &&
 335                    !check_refname_format(sb_contents.buf, 0)) {
 336                        strbuf_swap(&sb_contents, referent);
 337                        *type |= REF_ISSYMREF;
 338                        ret = 0;
 339                        goto out;
 340                }
 341                /*
 342                 * It doesn't look like a refname; fall through to just
 343                 * treating it like a non-symlink, and reading whatever it
 344                 * points to.
 345                 */
 346        }
 347
 348        /* Is it a directory? */
 349        if (S_ISDIR(st.st_mode)) {
 350                /*
 351                 * Even though there is a directory where the loose
 352                 * ref is supposed to be, there could still be a
 353                 * packed ref:
 354                 */
 355                if (refs_read_raw_ref(refs->packed_ref_store, refname,
 356                                      sha1, referent, type)) {
 357                        errno = EISDIR;
 358                        goto out;
 359                }
 360                ret = 0;
 361                goto out;
 362        }
 363
 364        /*
 365         * Anything else, just open it and try to use it as
 366         * a ref
 367         */
 368        fd = open(path, O_RDONLY);
 369        if (fd < 0) {
 370                if (errno == ENOENT && !S_ISLNK(st.st_mode))
 371                        /* inconsistent with lstat; retry */
 372                        goto stat_ref;
 373                else
 374                        goto out;
 375        }
 376        strbuf_reset(&sb_contents);
 377        if (strbuf_read(&sb_contents, fd, 256) < 0) {
 378                int save_errno = errno;
 379                close(fd);
 380                errno = save_errno;
 381                goto out;
 382        }
 383        close(fd);
 384        strbuf_rtrim(&sb_contents);
 385        buf = sb_contents.buf;
 386        if (starts_with(buf, "ref:")) {
 387                buf += 4;
 388                while (isspace(*buf))
 389                        buf++;
 390
 391                strbuf_reset(referent);
 392                strbuf_addstr(referent, buf);
 393                *type |= REF_ISSYMREF;
 394                ret = 0;
 395                goto out;
 396        }
 397
 398        /*
 399         * Please note that FETCH_HEAD has additional
 400         * data after the sha.
 401         */
 402        if (get_sha1_hex(buf, sha1) ||
 403            (buf[40] != '\0' && !isspace(buf[40]))) {
 404                *type |= REF_ISBROKEN;
 405                errno = EINVAL;
 406                goto out;
 407        }
 408
 409        ret = 0;
 410
 411out:
 412        save_errno = errno;
 413        strbuf_release(&sb_path);
 414        strbuf_release(&sb_contents);
 415        errno = save_errno;
 416        return ret;
 417}
 418
 419static void unlock_ref(struct ref_lock *lock)
 420{
 421        /* Do not free lock->lk -- atexit() still looks at them */
 422        if (lock->lk)
 423                rollback_lock_file(lock->lk);
 424        free(lock->ref_name);
 425        free(lock);
 426}
 427
 428/*
 429 * Lock refname, without following symrefs, and set *lock_p to point
 430 * at a newly-allocated lock object. Fill in lock->old_oid, referent,
 431 * and type similarly to read_raw_ref().
 432 *
 433 * The caller must verify that refname is a "safe" reference name (in
 434 * the sense of refname_is_safe()) before calling this function.
 435 *
 436 * If the reference doesn't already exist, verify that refname doesn't
 437 * have a D/F conflict with any existing references. extras and skip
 438 * are passed to refs_verify_refname_available() for this check.
 439 *
 440 * If mustexist is not set and the reference is not found or is
 441 * broken, lock the reference anyway but clear sha1.
 442 *
 443 * Return 0 on success. On failure, write an error message to err and
 444 * return TRANSACTION_NAME_CONFLICT or TRANSACTION_GENERIC_ERROR.
 445 *
 446 * Implementation note: This function is basically
 447 *
 448 *     lock reference
 449 *     read_raw_ref()
 450 *
 451 * but it includes a lot more code to
 452 * - Deal with possible races with other processes
 453 * - Avoid calling refs_verify_refname_available() when it can be
 454 *   avoided, namely if we were successfully able to read the ref
 455 * - Generate informative error messages in the case of failure
 456 */
 457static int lock_raw_ref(struct files_ref_store *refs,
 458                        const char *refname, int mustexist,
 459                        const struct string_list *extras,
 460                        const struct string_list *skip,
 461                        struct ref_lock **lock_p,
 462                        struct strbuf *referent,
 463                        unsigned int *type,
 464                        struct strbuf *err)
 465{
 466        struct ref_lock *lock;
 467        struct strbuf ref_file = STRBUF_INIT;
 468        int attempts_remaining = 3;
 469        int ret = TRANSACTION_GENERIC_ERROR;
 470
 471        assert(err);
 472        files_assert_main_repository(refs, "lock_raw_ref");
 473
 474        *type = 0;
 475
 476        /* First lock the file so it can't change out from under us. */
 477
 478        *lock_p = lock = xcalloc(1, sizeof(*lock));
 479
 480        lock->ref_name = xstrdup(refname);
 481        files_ref_path(refs, &ref_file, refname);
 482
 483retry:
 484        switch (safe_create_leading_directories(ref_file.buf)) {
 485        case SCLD_OK:
 486                break; /* success */
 487        case SCLD_EXISTS:
 488                /*
 489                 * Suppose refname is "refs/foo/bar". We just failed
 490                 * to create the containing directory, "refs/foo",
 491                 * because there was a non-directory in the way. This
 492                 * indicates a D/F conflict, probably because of
 493                 * another reference such as "refs/foo". There is no
 494                 * reason to expect this error to be transitory.
 495                 */
 496                if (refs_verify_refname_available(&refs->base, refname,
 497                                                  extras, skip, err)) {
 498                        if (mustexist) {
 499                                /*
 500                                 * To the user the relevant error is
 501                                 * that the "mustexist" reference is
 502                                 * missing:
 503                                 */
 504                                strbuf_reset(err);
 505                                strbuf_addf(err, "unable to resolve reference '%s'",
 506                                            refname);
 507                        } else {
 508                                /*
 509                                 * The error message set by
 510                                 * refs_verify_refname_available() is
 511                                 * OK.
 512                                 */
 513                                ret = TRANSACTION_NAME_CONFLICT;
 514                        }
 515                } else {
 516                        /*
 517                         * The file that is in the way isn't a loose
 518                         * reference. Report it as a low-level
 519                         * failure.
 520                         */
 521                        strbuf_addf(err, "unable to create lock file %s.lock; "
 522                                    "non-directory in the way",
 523                                    ref_file.buf);
 524                }
 525                goto error_return;
 526        case SCLD_VANISHED:
 527                /* Maybe another process was tidying up. Try again. */
 528                if (--attempts_remaining > 0)
 529                        goto retry;
 530                /* fall through */
 531        default:
 532                strbuf_addf(err, "unable to create directory for %s",
 533                            ref_file.buf);
 534                goto error_return;
 535        }
 536
 537        if (!lock->lk)
 538                lock->lk = xcalloc(1, sizeof(struct lock_file));
 539
 540        if (hold_lock_file_for_update_timeout(
 541                            lock->lk, ref_file.buf, LOCK_NO_DEREF,
 542                            get_files_ref_lock_timeout_ms()) < 0) {
 543                if (errno == ENOENT && --attempts_remaining > 0) {
 544                        /*
 545                         * Maybe somebody just deleted one of the
 546                         * directories leading to ref_file.  Try
 547                         * again:
 548                         */
 549                        goto retry;
 550                } else {
 551                        unable_to_lock_message(ref_file.buf, errno, err);
 552                        goto error_return;
 553                }
 554        }
 555
 556        /*
 557         * Now we hold the lock and can read the reference without
 558         * fear that its value will change.
 559         */
 560
 561        if (files_read_raw_ref(&refs->base, refname,
 562                               lock->old_oid.hash, referent, type)) {
 563                if (errno == ENOENT) {
 564                        if (mustexist) {
 565                                /* Garden variety missing reference. */
 566                                strbuf_addf(err, "unable to resolve reference '%s'",
 567                                            refname);
 568                                goto error_return;
 569                        } else {
 570                                /*
 571                                 * Reference is missing, but that's OK. We
 572                                 * know that there is not a conflict with
 573                                 * another loose reference because
 574                                 * (supposing that we are trying to lock
 575                                 * reference "refs/foo/bar"):
 576                                 *
 577                                 * - We were successfully able to create
 578                                 *   the lockfile refs/foo/bar.lock, so we
 579                                 *   know there cannot be a loose reference
 580                                 *   named "refs/foo".
 581                                 *
 582                                 * - We got ENOENT and not EISDIR, so we
 583                                 *   know that there cannot be a loose
 584                                 *   reference named "refs/foo/bar/baz".
 585                                 */
 586                        }
 587                } else if (errno == EISDIR) {
 588                        /*
 589                         * There is a directory in the way. It might have
 590                         * contained references that have been deleted. If
 591                         * we don't require that the reference already
 592                         * exists, try to remove the directory so that it
 593                         * doesn't cause trouble when we want to rename the
 594                         * lockfile into place later.
 595                         */
 596                        if (mustexist) {
 597                                /* Garden variety missing reference. */
 598                                strbuf_addf(err, "unable to resolve reference '%s'",
 599                                            refname);
 600                                goto error_return;
 601                        } else if (remove_dir_recursively(&ref_file,
 602                                                          REMOVE_DIR_EMPTY_ONLY)) {
 603                                if (refs_verify_refname_available(
 604                                                    &refs->base, refname,
 605                                                    extras, skip, err)) {
 606                                        /*
 607                                         * The error message set by
 608                                         * verify_refname_available() is OK.
 609                                         */
 610                                        ret = TRANSACTION_NAME_CONFLICT;
 611                                        goto error_return;
 612                                } else {
 613                                        /*
 614                                         * We can't delete the directory,
 615                                         * but we also don't know of any
 616                                         * references that it should
 617                                         * contain.
 618                                         */
 619                                        strbuf_addf(err, "there is a non-empty directory '%s' "
 620                                                    "blocking reference '%s'",
 621                                                    ref_file.buf, refname);
 622                                        goto error_return;
 623                                }
 624                        }
 625                } else if (errno == EINVAL && (*type & REF_ISBROKEN)) {
 626                        strbuf_addf(err, "unable to resolve reference '%s': "
 627                                    "reference broken", refname);
 628                        goto error_return;
 629                } else {
 630                        strbuf_addf(err, "unable to resolve reference '%s': %s",
 631                                    refname, strerror(errno));
 632                        goto error_return;
 633                }
 634
 635                /*
 636                 * If the ref did not exist and we are creating it,
 637                 * make sure there is no existing packed ref that
 638                 * conflicts with refname:
 639                 */
 640                if (refs_verify_refname_available(
 641                                    refs->packed_ref_store, refname,
 642                                    extras, skip, err))
 643                        goto error_return;
 644        }
 645
 646        ret = 0;
 647        goto out;
 648
 649error_return:
 650        unlock_ref(lock);
 651        *lock_p = NULL;
 652
 653out:
 654        strbuf_release(&ref_file);
 655        return ret;
 656}
 657
 658struct files_ref_iterator {
 659        struct ref_iterator base;
 660
 661        struct ref_iterator *iter0;
 662        unsigned int flags;
 663};
 664
 665static int files_ref_iterator_advance(struct ref_iterator *ref_iterator)
 666{
 667        struct files_ref_iterator *iter =
 668                (struct files_ref_iterator *)ref_iterator;
 669        int ok;
 670
 671        while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) {
 672                if (iter->flags & DO_FOR_EACH_PER_WORKTREE_ONLY &&
 673                    ref_type(iter->iter0->refname) != REF_TYPE_PER_WORKTREE)
 674                        continue;
 675
 676                if (!(iter->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
 677                    !ref_resolves_to_object(iter->iter0->refname,
 678                                            iter->iter0->oid,
 679                                            iter->iter0->flags))
 680                        continue;
 681
 682                iter->base.refname = iter->iter0->refname;
 683                iter->base.oid = iter->iter0->oid;
 684                iter->base.flags = iter->iter0->flags;
 685                return ITER_OK;
 686        }
 687
 688        iter->iter0 = NULL;
 689        if (ref_iterator_abort(ref_iterator) != ITER_DONE)
 690                ok = ITER_ERROR;
 691
 692        return ok;
 693}
 694
 695static int files_ref_iterator_peel(struct ref_iterator *ref_iterator,
 696                                   struct object_id *peeled)
 697{
 698        struct files_ref_iterator *iter =
 699                (struct files_ref_iterator *)ref_iterator;
 700
 701        return ref_iterator_peel(iter->iter0, peeled);
 702}
 703
 704static int files_ref_iterator_abort(struct ref_iterator *ref_iterator)
 705{
 706        struct files_ref_iterator *iter =
 707                (struct files_ref_iterator *)ref_iterator;
 708        int ok = ITER_DONE;
 709
 710        if (iter->iter0)
 711                ok = ref_iterator_abort(iter->iter0);
 712
 713        base_ref_iterator_free(ref_iterator);
 714        return ok;
 715}
 716
 717static struct ref_iterator_vtable files_ref_iterator_vtable = {
 718        files_ref_iterator_advance,
 719        files_ref_iterator_peel,
 720        files_ref_iterator_abort
 721};
 722
 723static struct ref_iterator *files_ref_iterator_begin(
 724                struct ref_store *ref_store,
 725                const char *prefix, unsigned int flags)
 726{
 727        struct files_ref_store *refs;
 728        struct ref_iterator *loose_iter, *packed_iter, *overlay_iter;
 729        struct files_ref_iterator *iter;
 730        struct ref_iterator *ref_iterator;
 731        unsigned int required_flags = REF_STORE_READ;
 732
 733        if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN))
 734                required_flags |= REF_STORE_ODB;
 735
 736        refs = files_downcast(ref_store, required_flags, "ref_iterator_begin");
 737
 738        /*
 739         * We must make sure that all loose refs are read before
 740         * accessing the packed-refs file; this avoids a race
 741         * condition if loose refs are migrated to the packed-refs
 742         * file by a simultaneous process, but our in-memory view is
 743         * from before the migration. We ensure this as follows:
 744         * First, we call start the loose refs iteration with its
 745         * `prime_ref` argument set to true. This causes the loose
 746         * references in the subtree to be pre-read into the cache.
 747         * (If they've already been read, that's OK; we only need to
 748         * guarantee that they're read before the packed refs, not
 749         * *how much* before.) After that, we call
 750         * packed_ref_iterator_begin(), which internally checks
 751         * whether the packed-ref cache is up to date with what is on
 752         * disk, and re-reads it if not.
 753         */
 754
 755        loose_iter = cache_ref_iterator_begin(get_loose_ref_cache(refs),
 756                                              prefix, 1);
 757
 758        /*
 759         * The packed-refs file might contain broken references, for
 760         * example an old version of a reference that points at an
 761         * object that has since been garbage-collected. This is OK as
 762         * long as there is a corresponding loose reference that
 763         * overrides it, and we don't want to emit an error message in
 764         * this case. So ask the packed_ref_store for all of its
 765         * references, and (if needed) do our own check for broken
 766         * ones in files_ref_iterator_advance(), after we have merged
 767         * the packed and loose references.
 768         */
 769        packed_iter = refs_ref_iterator_begin(
 770                        refs->packed_ref_store, prefix, 0,
 771                        DO_FOR_EACH_INCLUDE_BROKEN);
 772
 773        overlay_iter = overlay_ref_iterator_begin(loose_iter, packed_iter);
 774
 775        iter = xcalloc(1, sizeof(*iter));
 776        ref_iterator = &iter->base;
 777        base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable,
 778                               overlay_iter->ordered);
 779        iter->iter0 = overlay_iter;
 780        iter->flags = flags;
 781
 782        return ref_iterator;
 783}
 784
 785/*
 786 * Verify that the reference locked by lock has the value old_sha1.
 787 * Fail if the reference doesn't exist and mustexist is set. Return 0
 788 * on success. On error, write an error message to err, set errno, and
 789 * return a negative value.
 790 */
 791static int verify_lock(struct ref_store *ref_store, struct ref_lock *lock,
 792                       const unsigned char *old_sha1, int mustexist,
 793                       struct strbuf *err)
 794{
 795        assert(err);
 796
 797        if (refs_read_ref_full(ref_store, lock->ref_name,
 798                               mustexist ? RESOLVE_REF_READING : 0,
 799                               lock->old_oid.hash, NULL)) {
 800                if (old_sha1) {
 801                        int save_errno = errno;
 802                        strbuf_addf(err, "can't verify ref '%s'", lock->ref_name);
 803                        errno = save_errno;
 804                        return -1;
 805                } else {
 806                        oidclr(&lock->old_oid);
 807                        return 0;
 808                }
 809        }
 810        if (old_sha1 && hashcmp(lock->old_oid.hash, old_sha1)) {
 811                strbuf_addf(err, "ref '%s' is at %s but expected %s",
 812                            lock->ref_name,
 813                            oid_to_hex(&lock->old_oid),
 814                            sha1_to_hex(old_sha1));
 815                errno = EBUSY;
 816                return -1;
 817        }
 818        return 0;
 819}
 820
 821static int remove_empty_directories(struct strbuf *path)
 822{
 823        /*
 824         * we want to create a file but there is a directory there;
 825         * if that is an empty directory (or a directory that contains
 826         * only empty directories), remove them.
 827         */
 828        return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY);
 829}
 830
 831static int create_reflock(const char *path, void *cb)
 832{
 833        struct lock_file *lk = cb;
 834
 835        return hold_lock_file_for_update_timeout(
 836                        lk, path, LOCK_NO_DEREF,
 837                        get_files_ref_lock_timeout_ms()) < 0 ? -1 : 0;
 838}
 839
 840/*
 841 * Locks a ref returning the lock on success and NULL on failure.
 842 * On failure errno is set to something meaningful.
 843 */
 844static struct ref_lock *lock_ref_sha1_basic(struct files_ref_store *refs,
 845                                            const char *refname,
 846                                            const unsigned char *old_sha1,
 847                                            const struct string_list *extras,
 848                                            const struct string_list *skip,
 849                                            unsigned int flags, int *type,
 850                                            struct strbuf *err)
 851{
 852        struct strbuf ref_file = STRBUF_INIT;
 853        struct ref_lock *lock;
 854        int last_errno = 0;
 855        int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
 856        int resolve_flags = RESOLVE_REF_NO_RECURSE;
 857        int resolved;
 858
 859        files_assert_main_repository(refs, "lock_ref_sha1_basic");
 860        assert(err);
 861
 862        lock = xcalloc(1, sizeof(struct ref_lock));
 863
 864        if (mustexist)
 865                resolve_flags |= RESOLVE_REF_READING;
 866        if (flags & REF_DELETING)
 867                resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME;
 868
 869        files_ref_path(refs, &ref_file, refname);
 870        resolved = !!refs_resolve_ref_unsafe(&refs->base,
 871                                             refname, resolve_flags,
 872                                             lock->old_oid.hash, type);
 873        if (!resolved && errno == EISDIR) {
 874                /*
 875                 * we are trying to lock foo but we used to
 876                 * have foo/bar which now does not exist;
 877                 * it is normal for the empty directory 'foo'
 878                 * to remain.
 879                 */
 880                if (remove_empty_directories(&ref_file)) {
 881                        last_errno = errno;
 882                        if (!refs_verify_refname_available(
 883                                            &refs->base,
 884                                            refname, extras, skip, err))
 885                                strbuf_addf(err, "there are still refs under '%s'",
 886                                            refname);
 887                        goto error_return;
 888                }
 889                resolved = !!refs_resolve_ref_unsafe(&refs->base,
 890                                                     refname, resolve_flags,
 891                                                     lock->old_oid.hash, type);
 892        }
 893        if (!resolved) {
 894                last_errno = errno;
 895                if (last_errno != ENOTDIR ||
 896                    !refs_verify_refname_available(&refs->base, refname,
 897                                                   extras, skip, err))
 898                        strbuf_addf(err, "unable to resolve reference '%s': %s",
 899                                    refname, strerror(last_errno));
 900
 901                goto error_return;
 902        }
 903
 904        /*
 905         * If the ref did not exist and we are creating it, make sure
 906         * there is no existing packed ref whose name begins with our
 907         * refname, nor a packed ref whose name is a proper prefix of
 908         * our refname.
 909         */
 910        if (is_null_oid(&lock->old_oid) &&
 911            refs_verify_refname_available(refs->packed_ref_store, refname,
 912                                          extras, skip, err)) {
 913                last_errno = ENOTDIR;
 914                goto error_return;
 915        }
 916
 917        lock->lk = xcalloc(1, sizeof(struct lock_file));
 918
 919        lock->ref_name = xstrdup(refname);
 920
 921        if (raceproof_create_file(ref_file.buf, create_reflock, lock->lk)) {
 922                last_errno = errno;
 923                unable_to_lock_message(ref_file.buf, errno, err);
 924                goto error_return;
 925        }
 926
 927        if (verify_lock(&refs->base, lock, old_sha1, mustexist, err)) {
 928                last_errno = errno;
 929                goto error_return;
 930        }
 931        goto out;
 932
 933 error_return:
 934        unlock_ref(lock);
 935        lock = NULL;
 936
 937 out:
 938        strbuf_release(&ref_file);
 939        errno = last_errno;
 940        return lock;
 941}
 942
 943struct ref_to_prune {
 944        struct ref_to_prune *next;
 945        unsigned char sha1[20];
 946        char name[FLEX_ARRAY];
 947};
 948
 949enum {
 950        REMOVE_EMPTY_PARENTS_REF = 0x01,
 951        REMOVE_EMPTY_PARENTS_REFLOG = 0x02
 952};
 953
 954/*
 955 * Remove empty parent directories associated with the specified
 956 * reference and/or its reflog, but spare [logs/]refs/ and immediate
 957 * subdirs. flags is a combination of REMOVE_EMPTY_PARENTS_REF and/or
 958 * REMOVE_EMPTY_PARENTS_REFLOG.
 959 */
 960static void try_remove_empty_parents(struct files_ref_store *refs,
 961                                     const char *refname,
 962                                     unsigned int flags)
 963{
 964        struct strbuf buf = STRBUF_INIT;
 965        struct strbuf sb = STRBUF_INIT;
 966        char *p, *q;
 967        int i;
 968
 969        strbuf_addstr(&buf, refname);
 970        p = buf.buf;
 971        for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
 972                while (*p && *p != '/')
 973                        p++;
 974                /* tolerate duplicate slashes; see check_refname_format() */
 975                while (*p == '/')
 976                        p++;
 977        }
 978        q = buf.buf + buf.len;
 979        while (flags & (REMOVE_EMPTY_PARENTS_REF | REMOVE_EMPTY_PARENTS_REFLOG)) {
 980                while (q > p && *q != '/')
 981                        q--;
 982                while (q > p && *(q-1) == '/')
 983                        q--;
 984                if (q == p)
 985                        break;
 986                strbuf_setlen(&buf, q - buf.buf);
 987
 988                strbuf_reset(&sb);
 989                files_ref_path(refs, &sb, buf.buf);
 990                if ((flags & REMOVE_EMPTY_PARENTS_REF) && rmdir(sb.buf))
 991                        flags &= ~REMOVE_EMPTY_PARENTS_REF;
 992
 993                strbuf_reset(&sb);
 994                files_reflog_path(refs, &sb, buf.buf);
 995                if ((flags & REMOVE_EMPTY_PARENTS_REFLOG) && rmdir(sb.buf))
 996                        flags &= ~REMOVE_EMPTY_PARENTS_REFLOG;
 997        }
 998        strbuf_release(&buf);
 999        strbuf_release(&sb);
1000}
1001
1002/* make sure nobody touched the ref, and unlink */
1003static void prune_ref(struct files_ref_store *refs, struct ref_to_prune *r)
1004{
1005        struct ref_transaction *transaction;
1006        struct strbuf err = STRBUF_INIT;
1007
1008        if (check_refname_format(r->name, 0))
1009                return;
1010
1011        transaction = ref_store_transaction_begin(&refs->base, &err);
1012        if (!transaction ||
1013            ref_transaction_delete(transaction, r->name, r->sha1,
1014                                   REF_ISPRUNING | REF_NODEREF, NULL, &err) ||
1015            ref_transaction_commit(transaction, &err)) {
1016                ref_transaction_free(transaction);
1017                error("%s", err.buf);
1018                strbuf_release(&err);
1019                return;
1020        }
1021        ref_transaction_free(transaction);
1022        strbuf_release(&err);
1023}
1024
1025/*
1026 * Prune the loose versions of the references in the linked list
1027 * `*refs_to_prune`, freeing the entries in the list as we go.
1028 */
1029static void prune_refs(struct files_ref_store *refs, struct ref_to_prune **refs_to_prune)
1030{
1031        while (*refs_to_prune) {
1032                struct ref_to_prune *r = *refs_to_prune;
1033                *refs_to_prune = r->next;
1034                prune_ref(refs, r);
1035                free(r);
1036        }
1037}
1038
1039/*
1040 * Return true if the specified reference should be packed.
1041 */
1042static int should_pack_ref(const char *refname,
1043                           const struct object_id *oid, unsigned int ref_flags,
1044                           unsigned int pack_flags)
1045{
1046        /* Do not pack per-worktree refs: */
1047        if (ref_type(refname) != REF_TYPE_NORMAL)
1048                return 0;
1049
1050        /* Do not pack non-tags unless PACK_REFS_ALL is set: */
1051        if (!(pack_flags & PACK_REFS_ALL) && !starts_with(refname, "refs/tags/"))
1052                return 0;
1053
1054        /* Do not pack symbolic refs: */
1055        if (ref_flags & REF_ISSYMREF)
1056                return 0;
1057
1058        /* Do not pack broken refs: */
1059        if (!ref_resolves_to_object(refname, oid, ref_flags))
1060                return 0;
1061
1062        return 1;
1063}
1064
1065static int files_pack_refs(struct ref_store *ref_store, unsigned int flags)
1066{
1067        struct files_ref_store *refs =
1068                files_downcast(ref_store, REF_STORE_WRITE | REF_STORE_ODB,
1069                               "pack_refs");
1070        struct ref_iterator *iter;
1071        int ok;
1072        struct ref_to_prune *refs_to_prune = NULL;
1073        struct strbuf err = STRBUF_INIT;
1074        struct ref_transaction *transaction;
1075
1076        transaction = ref_store_transaction_begin(refs->packed_ref_store, &err);
1077        if (!transaction)
1078                return -1;
1079
1080        packed_refs_lock(refs->packed_ref_store, LOCK_DIE_ON_ERROR, &err);
1081
1082        iter = cache_ref_iterator_begin(get_loose_ref_cache(refs), NULL, 0);
1083        while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
1084                /*
1085                 * If the loose reference can be packed, add an entry
1086                 * in the packed ref cache. If the reference should be
1087                 * pruned, also add it to refs_to_prune.
1088                 */
1089                if (!should_pack_ref(iter->refname, iter->oid, iter->flags,
1090                                     flags))
1091                        continue;
1092
1093                /*
1094                 * Add a reference creation for this reference to the
1095                 * packed-refs transaction:
1096                 */
1097                if (ref_transaction_update(transaction, iter->refname,
1098                                           iter->oid->hash, NULL,
1099                                           REF_NODEREF, NULL, &err))
1100                        die("failure preparing to create packed reference %s: %s",
1101                            iter->refname, err.buf);
1102
1103                /* Schedule the loose reference for pruning if requested. */
1104                if ((flags & PACK_REFS_PRUNE)) {
1105                        struct ref_to_prune *n;
1106                        FLEX_ALLOC_STR(n, name, iter->refname);
1107                        hashcpy(n->sha1, iter->oid->hash);
1108                        n->next = refs_to_prune;
1109                        refs_to_prune = n;
1110                }
1111        }
1112        if (ok != ITER_DONE)
1113                die("error while iterating over references");
1114
1115        if (ref_transaction_commit(transaction, &err))
1116                die("unable to write new packed-refs: %s", err.buf);
1117
1118        ref_transaction_free(transaction);
1119
1120        packed_refs_unlock(refs->packed_ref_store);
1121
1122        prune_refs(refs, &refs_to_prune);
1123        strbuf_release(&err);
1124        return 0;
1125}
1126
1127static int files_delete_refs(struct ref_store *ref_store, const char *msg,
1128                             struct string_list *refnames, unsigned int flags)
1129{
1130        struct files_ref_store *refs =
1131                files_downcast(ref_store, REF_STORE_WRITE, "delete_refs");
1132        struct strbuf err = STRBUF_INIT;
1133        int i, result = 0;
1134
1135        if (!refnames->nr)
1136                return 0;
1137
1138        if (packed_refs_lock(refs->packed_ref_store, 0, &err))
1139                goto error;
1140
1141        if (refs_delete_refs(refs->packed_ref_store, msg, refnames, flags)) {
1142                packed_refs_unlock(refs->packed_ref_store);
1143                goto error;
1144        }
1145
1146        packed_refs_unlock(refs->packed_ref_store);
1147
1148        for (i = 0; i < refnames->nr; i++) {
1149                const char *refname = refnames->items[i].string;
1150
1151                if (refs_delete_ref(&refs->base, msg, refname, NULL, flags))
1152                        result |= error(_("could not remove reference %s"), refname);
1153        }
1154
1155        strbuf_release(&err);
1156        return result;
1157
1158error:
1159        /*
1160         * If we failed to rewrite the packed-refs file, then it is
1161         * unsafe to try to remove loose refs, because doing so might
1162         * expose an obsolete packed value for a reference that might
1163         * even point at an object that has been garbage collected.
1164         */
1165        if (refnames->nr == 1)
1166                error(_("could not delete reference %s: %s"),
1167                      refnames->items[0].string, err.buf);
1168        else
1169                error(_("could not delete references: %s"), err.buf);
1170
1171        strbuf_release(&err);
1172        return -1;
1173}
1174
1175/*
1176 * People using contrib's git-new-workdir have .git/logs/refs ->
1177 * /some/other/path/.git/logs/refs, and that may live on another device.
1178 *
1179 * IOW, to avoid cross device rename errors, the temporary renamed log must
1180 * live into logs/refs.
1181 */
1182#define TMP_RENAMED_LOG  "refs/.tmp-renamed-log"
1183
1184struct rename_cb {
1185        const char *tmp_renamed_log;
1186        int true_errno;
1187};
1188
1189static int rename_tmp_log_callback(const char *path, void *cb_data)
1190{
1191        struct rename_cb *cb = cb_data;
1192
1193        if (rename(cb->tmp_renamed_log, path)) {
1194                /*
1195                 * rename(a, b) when b is an existing directory ought
1196                 * to result in ISDIR, but Solaris 5.8 gives ENOTDIR.
1197                 * Sheesh. Record the true errno for error reporting,
1198                 * but report EISDIR to raceproof_create_file() so
1199                 * that it knows to retry.
1200                 */
1201                cb->true_errno = errno;
1202                if (errno == ENOTDIR)
1203                        errno = EISDIR;
1204                return -1;
1205        } else {
1206                return 0;
1207        }
1208}
1209
1210static int rename_tmp_log(struct files_ref_store *refs, const char *newrefname)
1211{
1212        struct strbuf path = STRBUF_INIT;
1213        struct strbuf tmp = STRBUF_INIT;
1214        struct rename_cb cb;
1215        int ret;
1216
1217        files_reflog_path(refs, &path, newrefname);
1218        files_reflog_path(refs, &tmp, TMP_RENAMED_LOG);
1219        cb.tmp_renamed_log = tmp.buf;
1220        ret = raceproof_create_file(path.buf, rename_tmp_log_callback, &cb);
1221        if (ret) {
1222                if (errno == EISDIR)
1223                        error("directory not empty: %s", path.buf);
1224                else
1225                        error("unable to move logfile %s to %s: %s",
1226                              tmp.buf, path.buf,
1227                              strerror(cb.true_errno));
1228        }
1229
1230        strbuf_release(&path);
1231        strbuf_release(&tmp);
1232        return ret;
1233}
1234
1235static int write_ref_to_lockfile(struct ref_lock *lock,
1236                                 const struct object_id *oid, struct strbuf *err);
1237static int commit_ref_update(struct files_ref_store *refs,
1238                             struct ref_lock *lock,
1239                             const struct object_id *oid, const char *logmsg,
1240                             struct strbuf *err);
1241
1242static int files_rename_ref(struct ref_store *ref_store,
1243                            const char *oldrefname, const char *newrefname,
1244                            const char *logmsg)
1245{
1246        struct files_ref_store *refs =
1247                files_downcast(ref_store, REF_STORE_WRITE, "rename_ref");
1248        struct object_id oid, orig_oid;
1249        int flag = 0, logmoved = 0;
1250        struct ref_lock *lock;
1251        struct stat loginfo;
1252        struct strbuf sb_oldref = STRBUF_INIT;
1253        struct strbuf sb_newref = STRBUF_INIT;
1254        struct strbuf tmp_renamed_log = STRBUF_INIT;
1255        int log, ret;
1256        struct strbuf err = STRBUF_INIT;
1257
1258        files_reflog_path(refs, &sb_oldref, oldrefname);
1259        files_reflog_path(refs, &sb_newref, newrefname);
1260        files_reflog_path(refs, &tmp_renamed_log, TMP_RENAMED_LOG);
1261
1262        log = !lstat(sb_oldref.buf, &loginfo);
1263        if (log && S_ISLNK(loginfo.st_mode)) {
1264                ret = error("reflog for %s is a symlink", oldrefname);
1265                goto out;
1266        }
1267
1268        if (!refs_resolve_ref_unsafe(&refs->base, oldrefname,
1269                                     RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
1270                                orig_oid.hash, &flag)) {
1271                ret = error("refname %s not found", oldrefname);
1272                goto out;
1273        }
1274
1275        if (flag & REF_ISSYMREF) {
1276                ret = error("refname %s is a symbolic ref, renaming it is not supported",
1277                            oldrefname);
1278                goto out;
1279        }
1280        if (!refs_rename_ref_available(&refs->base, oldrefname, newrefname)) {
1281                ret = 1;
1282                goto out;
1283        }
1284
1285        if (log && rename(sb_oldref.buf, tmp_renamed_log.buf)) {
1286                ret = error("unable to move logfile logs/%s to logs/"TMP_RENAMED_LOG": %s",
1287                            oldrefname, strerror(errno));
1288                goto out;
1289        }
1290
1291        if (refs_delete_ref(&refs->base, logmsg, oldrefname,
1292                            orig_oid.hash, REF_NODEREF)) {
1293                error("unable to delete old %s", oldrefname);
1294                goto rollback;
1295        }
1296
1297        /*
1298         * Since we are doing a shallow lookup, oid is not the
1299         * correct value to pass to delete_ref as old_oid. But that
1300         * doesn't matter, because an old_oid check wouldn't add to
1301         * the safety anyway; we want to delete the reference whatever
1302         * its current value.
1303         */
1304        if (!refs_read_ref_full(&refs->base, newrefname,
1305                                RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
1306                                oid.hash, NULL) &&
1307            refs_delete_ref(&refs->base, NULL, newrefname,
1308                            NULL, REF_NODEREF)) {
1309                if (errno == EISDIR) {
1310                        struct strbuf path = STRBUF_INIT;
1311                        int result;
1312
1313                        files_ref_path(refs, &path, newrefname);
1314                        result = remove_empty_directories(&path);
1315                        strbuf_release(&path);
1316
1317                        if (result) {
1318                                error("Directory not empty: %s", newrefname);
1319                                goto rollback;
1320                        }
1321                } else {
1322                        error("unable to delete existing %s", newrefname);
1323                        goto rollback;
1324                }
1325        }
1326
1327        if (log && rename_tmp_log(refs, newrefname))
1328                goto rollback;
1329
1330        logmoved = log;
1331
1332        lock = lock_ref_sha1_basic(refs, newrefname, NULL, NULL, NULL,
1333                                   REF_NODEREF, NULL, &err);
1334        if (!lock) {
1335                error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
1336                strbuf_release(&err);
1337                goto rollback;
1338        }
1339        oidcpy(&lock->old_oid, &orig_oid);
1340
1341        if (write_ref_to_lockfile(lock, &orig_oid, &err) ||
1342            commit_ref_update(refs, lock, &orig_oid, logmsg, &err)) {
1343                error("unable to write current sha1 into %s: %s", newrefname, err.buf);
1344                strbuf_release(&err);
1345                goto rollback;
1346        }
1347
1348        ret = 0;
1349        goto out;
1350
1351 rollback:
1352        lock = lock_ref_sha1_basic(refs, oldrefname, NULL, NULL, NULL,
1353                                   REF_NODEREF, NULL, &err);
1354        if (!lock) {
1355                error("unable to lock %s for rollback: %s", oldrefname, err.buf);
1356                strbuf_release(&err);
1357                goto rollbacklog;
1358        }
1359
1360        flag = log_all_ref_updates;
1361        log_all_ref_updates = LOG_REFS_NONE;
1362        if (write_ref_to_lockfile(lock, &orig_oid, &err) ||
1363            commit_ref_update(refs, lock, &orig_oid, NULL, &err)) {
1364                error("unable to write current sha1 into %s: %s", oldrefname, err.buf);
1365                strbuf_release(&err);
1366        }
1367        log_all_ref_updates = flag;
1368
1369 rollbacklog:
1370        if (logmoved && rename(sb_newref.buf, sb_oldref.buf))
1371                error("unable to restore logfile %s from %s: %s",
1372                        oldrefname, newrefname, strerror(errno));
1373        if (!logmoved && log &&
1374            rename(tmp_renamed_log.buf, sb_oldref.buf))
1375                error("unable to restore logfile %s from logs/"TMP_RENAMED_LOG": %s",
1376                        oldrefname, strerror(errno));
1377        ret = 1;
1378 out:
1379        strbuf_release(&sb_newref);
1380        strbuf_release(&sb_oldref);
1381        strbuf_release(&tmp_renamed_log);
1382
1383        return ret;
1384}
1385
1386static int close_ref(struct ref_lock *lock)
1387{
1388        if (close_lock_file(lock->lk))
1389                return -1;
1390        return 0;
1391}
1392
1393static int commit_ref(struct ref_lock *lock)
1394{
1395        char *path = get_locked_file_path(lock->lk);
1396        struct stat st;
1397
1398        if (!lstat(path, &st) && S_ISDIR(st.st_mode)) {
1399                /*
1400                 * There is a directory at the path we want to rename
1401                 * the lockfile to. Hopefully it is empty; try to
1402                 * delete it.
1403                 */
1404                size_t len = strlen(path);
1405                struct strbuf sb_path = STRBUF_INIT;
1406
1407                strbuf_attach(&sb_path, path, len, len);
1408
1409                /*
1410                 * If this fails, commit_lock_file() will also fail
1411                 * and will report the problem.
1412                 */
1413                remove_empty_directories(&sb_path);
1414                strbuf_release(&sb_path);
1415        } else {
1416                free(path);
1417        }
1418
1419        if (commit_lock_file(lock->lk))
1420                return -1;
1421        return 0;
1422}
1423
1424static int open_or_create_logfile(const char *path, void *cb)
1425{
1426        int *fd = cb;
1427
1428        *fd = open(path, O_APPEND | O_WRONLY | O_CREAT, 0666);
1429        return (*fd < 0) ? -1 : 0;
1430}
1431
1432/*
1433 * Create a reflog for a ref. If force_create = 0, only create the
1434 * reflog for certain refs (those for which should_autocreate_reflog
1435 * returns non-zero). Otherwise, create it regardless of the reference
1436 * name. If the logfile already existed or was created, return 0 and
1437 * set *logfd to the file descriptor opened for appending to the file.
1438 * If no logfile exists and we decided not to create one, return 0 and
1439 * set *logfd to -1. On failure, fill in *err, set *logfd to -1, and
1440 * return -1.
1441 */
1442static int log_ref_setup(struct files_ref_store *refs,
1443                         const char *refname, int force_create,
1444                         int *logfd, struct strbuf *err)
1445{
1446        struct strbuf logfile_sb = STRBUF_INIT;
1447        char *logfile;
1448
1449        files_reflog_path(refs, &logfile_sb, refname);
1450        logfile = strbuf_detach(&logfile_sb, NULL);
1451
1452        if (force_create || should_autocreate_reflog(refname)) {
1453                if (raceproof_create_file(logfile, open_or_create_logfile, logfd)) {
1454                        if (errno == ENOENT)
1455                                strbuf_addf(err, "unable to create directory for '%s': "
1456                                            "%s", logfile, strerror(errno));
1457                        else if (errno == EISDIR)
1458                                strbuf_addf(err, "there are still logs under '%s'",
1459                                            logfile);
1460                        else
1461                                strbuf_addf(err, "unable to append to '%s': %s",
1462                                            logfile, strerror(errno));
1463
1464                        goto error;
1465                }
1466        } else {
1467                *logfd = open(logfile, O_APPEND | O_WRONLY, 0666);
1468                if (*logfd < 0) {
1469                        if (errno == ENOENT || errno == EISDIR) {
1470                                /*
1471                                 * The logfile doesn't already exist,
1472                                 * but that is not an error; it only
1473                                 * means that we won't write log
1474                                 * entries to it.
1475                                 */
1476                                ;
1477                        } else {
1478                                strbuf_addf(err, "unable to append to '%s': %s",
1479                                            logfile, strerror(errno));
1480                                goto error;
1481                        }
1482                }
1483        }
1484
1485        if (*logfd >= 0)
1486                adjust_shared_perm(logfile);
1487
1488        free(logfile);
1489        return 0;
1490
1491error:
1492        free(logfile);
1493        return -1;
1494}
1495
1496static int files_create_reflog(struct ref_store *ref_store,
1497                               const char *refname, int force_create,
1498                               struct strbuf *err)
1499{
1500        struct files_ref_store *refs =
1501                files_downcast(ref_store, REF_STORE_WRITE, "create_reflog");
1502        int fd;
1503
1504        if (log_ref_setup(refs, refname, force_create, &fd, err))
1505                return -1;
1506
1507        if (fd >= 0)
1508                close(fd);
1509
1510        return 0;
1511}
1512
1513static int log_ref_write_fd(int fd, const struct object_id *old_oid,
1514                            const struct object_id *new_oid,
1515                            const char *committer, const char *msg)
1516{
1517        int msglen, written;
1518        unsigned maxlen, len;
1519        char *logrec;
1520
1521        msglen = msg ? strlen(msg) : 0;
1522        maxlen = strlen(committer) + msglen + 100;
1523        logrec = xmalloc(maxlen);
1524        len = xsnprintf(logrec, maxlen, "%s %s %s\n",
1525                        oid_to_hex(old_oid),
1526                        oid_to_hex(new_oid),
1527                        committer);
1528        if (msglen)
1529                len += copy_reflog_msg(logrec + len - 1, msg) - 1;
1530
1531        written = len <= maxlen ? write_in_full(fd, logrec, len) : -1;
1532        free(logrec);
1533        if (written != len)
1534                return -1;
1535
1536        return 0;
1537}
1538
1539static int files_log_ref_write(struct files_ref_store *refs,
1540                               const char *refname, const struct object_id *old_oid,
1541                               const struct object_id *new_oid, const char *msg,
1542                               int flags, struct strbuf *err)
1543{
1544        int logfd, result;
1545
1546        if (log_all_ref_updates == LOG_REFS_UNSET)
1547                log_all_ref_updates = is_bare_repository() ? LOG_REFS_NONE : LOG_REFS_NORMAL;
1548
1549        result = log_ref_setup(refs, refname,
1550                               flags & REF_FORCE_CREATE_REFLOG,
1551                               &logfd, err);
1552
1553        if (result)
1554                return result;
1555
1556        if (logfd < 0)
1557                return 0;
1558        result = log_ref_write_fd(logfd, old_oid, new_oid,
1559                                  git_committer_info(0), msg);
1560        if (result) {
1561                struct strbuf sb = STRBUF_INIT;
1562                int save_errno = errno;
1563
1564                files_reflog_path(refs, &sb, refname);
1565                strbuf_addf(err, "unable to append to '%s': %s",
1566                            sb.buf, strerror(save_errno));
1567                strbuf_release(&sb);
1568                close(logfd);
1569                return -1;
1570        }
1571        if (close(logfd)) {
1572                struct strbuf sb = STRBUF_INIT;
1573                int save_errno = errno;
1574
1575                files_reflog_path(refs, &sb, refname);
1576                strbuf_addf(err, "unable to append to '%s': %s",
1577                            sb.buf, strerror(save_errno));
1578                strbuf_release(&sb);
1579                return -1;
1580        }
1581        return 0;
1582}
1583
1584/*
1585 * Write sha1 into the open lockfile, then close the lockfile. On
1586 * errors, rollback the lockfile, fill in *err and
1587 * return -1.
1588 */
1589static int write_ref_to_lockfile(struct ref_lock *lock,
1590                                 const struct object_id *oid, struct strbuf *err)
1591{
1592        static char term = '\n';
1593        struct object *o;
1594        int fd;
1595
1596        o = parse_object(oid);
1597        if (!o) {
1598                strbuf_addf(err,
1599                            "trying to write ref '%s' with nonexistent object %s",
1600                            lock->ref_name, oid_to_hex(oid));
1601                unlock_ref(lock);
1602                return -1;
1603        }
1604        if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1605                strbuf_addf(err,
1606                            "trying to write non-commit object %s to branch '%s'",
1607                            oid_to_hex(oid), lock->ref_name);
1608                unlock_ref(lock);
1609                return -1;
1610        }
1611        fd = get_lock_file_fd(lock->lk);
1612        if (write_in_full(fd, oid_to_hex(oid), GIT_SHA1_HEXSZ) != GIT_SHA1_HEXSZ ||
1613            write_in_full(fd, &term, 1) != 1 ||
1614            close_ref(lock) < 0) {
1615                strbuf_addf(err,
1616                            "couldn't write '%s'", get_lock_file_path(lock->lk));
1617                unlock_ref(lock);
1618                return -1;
1619        }
1620        return 0;
1621}
1622
1623/*
1624 * Commit a change to a loose reference that has already been written
1625 * to the loose reference lockfile. Also update the reflogs if
1626 * necessary, using the specified lockmsg (which can be NULL).
1627 */
1628static int commit_ref_update(struct files_ref_store *refs,
1629                             struct ref_lock *lock,
1630                             const struct object_id *oid, const char *logmsg,
1631                             struct strbuf *err)
1632{
1633        files_assert_main_repository(refs, "commit_ref_update");
1634
1635        clear_loose_ref_cache(refs);
1636        if (files_log_ref_write(refs, lock->ref_name,
1637                                &lock->old_oid, oid,
1638                                logmsg, 0, err)) {
1639                char *old_msg = strbuf_detach(err, NULL);
1640                strbuf_addf(err, "cannot update the ref '%s': %s",
1641                            lock->ref_name, old_msg);
1642                free(old_msg);
1643                unlock_ref(lock);
1644                return -1;
1645        }
1646
1647        if (strcmp(lock->ref_name, "HEAD") != 0) {
1648                /*
1649                 * Special hack: If a branch is updated directly and HEAD
1650                 * points to it (may happen on the remote side of a push
1651                 * for example) then logically the HEAD reflog should be
1652                 * updated too.
1653                 * A generic solution implies reverse symref information,
1654                 * but finding all symrefs pointing to the given branch
1655                 * would be rather costly for this rare event (the direct
1656                 * update of a branch) to be worth it.  So let's cheat and
1657                 * check with HEAD only which should cover 99% of all usage
1658                 * scenarios (even 100% of the default ones).
1659                 */
1660                struct object_id head_oid;
1661                int head_flag;
1662                const char *head_ref;
1663
1664                head_ref = refs_resolve_ref_unsafe(&refs->base, "HEAD",
1665                                                   RESOLVE_REF_READING,
1666                                                   head_oid.hash, &head_flag);
1667                if (head_ref && (head_flag & REF_ISSYMREF) &&
1668                    !strcmp(head_ref, lock->ref_name)) {
1669                        struct strbuf log_err = STRBUF_INIT;
1670                        if (files_log_ref_write(refs, "HEAD",
1671                                                &lock->old_oid, oid,
1672                                                logmsg, 0, &log_err)) {
1673                                error("%s", log_err.buf);
1674                                strbuf_release(&log_err);
1675                        }
1676                }
1677        }
1678
1679        if (commit_ref(lock)) {
1680                strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
1681                unlock_ref(lock);
1682                return -1;
1683        }
1684
1685        unlock_ref(lock);
1686        return 0;
1687}
1688
1689static int create_ref_symlink(struct ref_lock *lock, const char *target)
1690{
1691        int ret = -1;
1692#ifndef NO_SYMLINK_HEAD
1693        char *ref_path = get_locked_file_path(lock->lk);
1694        unlink(ref_path);
1695        ret = symlink(target, ref_path);
1696        free(ref_path);
1697
1698        if (ret)
1699                fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1700#endif
1701        return ret;
1702}
1703
1704static void update_symref_reflog(struct files_ref_store *refs,
1705                                 struct ref_lock *lock, const char *refname,
1706                                 const char *target, const char *logmsg)
1707{
1708        struct strbuf err = STRBUF_INIT;
1709        struct object_id new_oid;
1710        if (logmsg &&
1711            !refs_read_ref_full(&refs->base, target,
1712                                RESOLVE_REF_READING, new_oid.hash, NULL) &&
1713            files_log_ref_write(refs, refname, &lock->old_oid,
1714                                &new_oid, logmsg, 0, &err)) {
1715                error("%s", err.buf);
1716                strbuf_release(&err);
1717        }
1718}
1719
1720static int create_symref_locked(struct files_ref_store *refs,
1721                                struct ref_lock *lock, const char *refname,
1722                                const char *target, const char *logmsg)
1723{
1724        if (prefer_symlink_refs && !create_ref_symlink(lock, target)) {
1725                update_symref_reflog(refs, lock, refname, target, logmsg);
1726                return 0;
1727        }
1728
1729        if (!fdopen_lock_file(lock->lk, "w"))
1730                return error("unable to fdopen %s: %s",
1731                             lock->lk->tempfile.filename.buf, strerror(errno));
1732
1733        update_symref_reflog(refs, lock, refname, target, logmsg);
1734
1735        /* no error check; commit_ref will check ferror */
1736        fprintf(lock->lk->tempfile.fp, "ref: %s\n", target);
1737        if (commit_ref(lock) < 0)
1738                return error("unable to write symref for %s: %s", refname,
1739                             strerror(errno));
1740        return 0;
1741}
1742
1743static int files_create_symref(struct ref_store *ref_store,
1744                               const char *refname, const char *target,
1745                               const char *logmsg)
1746{
1747        struct files_ref_store *refs =
1748                files_downcast(ref_store, REF_STORE_WRITE, "create_symref");
1749        struct strbuf err = STRBUF_INIT;
1750        struct ref_lock *lock;
1751        int ret;
1752
1753        lock = lock_ref_sha1_basic(refs, refname, NULL,
1754                                   NULL, NULL, REF_NODEREF, NULL,
1755                                   &err);
1756        if (!lock) {
1757                error("%s", err.buf);
1758                strbuf_release(&err);
1759                return -1;
1760        }
1761
1762        ret = create_symref_locked(refs, lock, refname, target, logmsg);
1763        unlock_ref(lock);
1764        return ret;
1765}
1766
1767static int files_reflog_exists(struct ref_store *ref_store,
1768                               const char *refname)
1769{
1770        struct files_ref_store *refs =
1771                files_downcast(ref_store, REF_STORE_READ, "reflog_exists");
1772        struct strbuf sb = STRBUF_INIT;
1773        struct stat st;
1774        int ret;
1775
1776        files_reflog_path(refs, &sb, refname);
1777        ret = !lstat(sb.buf, &st) && S_ISREG(st.st_mode);
1778        strbuf_release(&sb);
1779        return ret;
1780}
1781
1782static int files_delete_reflog(struct ref_store *ref_store,
1783                               const char *refname)
1784{
1785        struct files_ref_store *refs =
1786                files_downcast(ref_store, REF_STORE_WRITE, "delete_reflog");
1787        struct strbuf sb = STRBUF_INIT;
1788        int ret;
1789
1790        files_reflog_path(refs, &sb, refname);
1791        ret = remove_path(sb.buf);
1792        strbuf_release(&sb);
1793        return ret;
1794}
1795
1796static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
1797{
1798        struct object_id ooid, noid;
1799        char *email_end, *message;
1800        timestamp_t timestamp;
1801        int tz;
1802        const char *p = sb->buf;
1803
1804        /* old SP new SP name <email> SP time TAB msg LF */
1805        if (!sb->len || sb->buf[sb->len - 1] != '\n' ||
1806            parse_oid_hex(p, &ooid, &p) || *p++ != ' ' ||
1807            parse_oid_hex(p, &noid, &p) || *p++ != ' ' ||
1808            !(email_end = strchr(p, '>')) ||
1809            email_end[1] != ' ' ||
1810            !(timestamp = parse_timestamp(email_end + 2, &message, 10)) ||
1811            !message || message[0] != ' ' ||
1812            (message[1] != '+' && message[1] != '-') ||
1813            !isdigit(message[2]) || !isdigit(message[3]) ||
1814            !isdigit(message[4]) || !isdigit(message[5]))
1815                return 0; /* corrupt? */
1816        email_end[1] = '\0';
1817        tz = strtol(message + 1, NULL, 10);
1818        if (message[6] != '\t')
1819                message += 6;
1820        else
1821                message += 7;
1822        return fn(&ooid, &noid, p, timestamp, tz, message, cb_data);
1823}
1824
1825static char *find_beginning_of_line(char *bob, char *scan)
1826{
1827        while (bob < scan && *(--scan) != '\n')
1828                ; /* keep scanning backwards */
1829        /*
1830         * Return either beginning of the buffer, or LF at the end of
1831         * the previous line.
1832         */
1833        return scan;
1834}
1835
1836static int files_for_each_reflog_ent_reverse(struct ref_store *ref_store,
1837                                             const char *refname,
1838                                             each_reflog_ent_fn fn,
1839                                             void *cb_data)
1840{
1841        struct files_ref_store *refs =
1842                files_downcast(ref_store, REF_STORE_READ,
1843                               "for_each_reflog_ent_reverse");
1844        struct strbuf sb = STRBUF_INIT;
1845        FILE *logfp;
1846        long pos;
1847        int ret = 0, at_tail = 1;
1848
1849        files_reflog_path(refs, &sb, refname);
1850        logfp = fopen(sb.buf, "r");
1851        strbuf_release(&sb);
1852        if (!logfp)
1853                return -1;
1854
1855        /* Jump to the end */
1856        if (fseek(logfp, 0, SEEK_END) < 0)
1857                ret = error("cannot seek back reflog for %s: %s",
1858                            refname, strerror(errno));
1859        pos = ftell(logfp);
1860        while (!ret && 0 < pos) {
1861                int cnt;
1862                size_t nread;
1863                char buf[BUFSIZ];
1864                char *endp, *scanp;
1865
1866                /* Fill next block from the end */
1867                cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
1868                if (fseek(logfp, pos - cnt, SEEK_SET)) {
1869                        ret = error("cannot seek back reflog for %s: %s",
1870                                    refname, strerror(errno));
1871                        break;
1872                }
1873                nread = fread(buf, cnt, 1, logfp);
1874                if (nread != 1) {
1875                        ret = error("cannot read %d bytes from reflog for %s: %s",
1876                                    cnt, refname, strerror(errno));
1877                        break;
1878                }
1879                pos -= cnt;
1880
1881                scanp = endp = buf + cnt;
1882                if (at_tail && scanp[-1] == '\n')
1883                        /* Looking at the final LF at the end of the file */
1884                        scanp--;
1885                at_tail = 0;
1886
1887                while (buf < scanp) {
1888                        /*
1889                         * terminating LF of the previous line, or the beginning
1890                         * of the buffer.
1891                         */
1892                        char *bp;
1893
1894                        bp = find_beginning_of_line(buf, scanp);
1895
1896                        if (*bp == '\n') {
1897                                /*
1898                                 * The newline is the end of the previous line,
1899                                 * so we know we have complete line starting
1900                                 * at (bp + 1). Prefix it onto any prior data
1901                                 * we collected for the line and process it.
1902                                 */
1903                                strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
1904                                scanp = bp;
1905                                endp = bp + 1;
1906                                ret = show_one_reflog_ent(&sb, fn, cb_data);
1907                                strbuf_reset(&sb);
1908                                if (ret)
1909                                        break;
1910                        } else if (!pos) {
1911                                /*
1912                                 * We are at the start of the buffer, and the
1913                                 * start of the file; there is no previous
1914                                 * line, and we have everything for this one.
1915                                 * Process it, and we can end the loop.
1916                                 */
1917                                strbuf_splice(&sb, 0, 0, buf, endp - buf);
1918                                ret = show_one_reflog_ent(&sb, fn, cb_data);
1919                                strbuf_reset(&sb);
1920                                break;
1921                        }
1922
1923                        if (bp == buf) {
1924                                /*
1925                                 * We are at the start of the buffer, and there
1926                                 * is more file to read backwards. Which means
1927                                 * we are in the middle of a line. Note that we
1928                                 * may get here even if *bp was a newline; that
1929                                 * just means we are at the exact end of the
1930                                 * previous line, rather than some spot in the
1931                                 * middle.
1932                                 *
1933                                 * Save away what we have to be combined with
1934                                 * the data from the next read.
1935                                 */
1936                                strbuf_splice(&sb, 0, 0, buf, endp - buf);
1937                                break;
1938                        }
1939                }
1940
1941        }
1942        if (!ret && sb.len)
1943                die("BUG: reverse reflog parser had leftover data");
1944
1945        fclose(logfp);
1946        strbuf_release(&sb);
1947        return ret;
1948}
1949
1950static int files_for_each_reflog_ent(struct ref_store *ref_store,
1951                                     const char *refname,
1952                                     each_reflog_ent_fn fn, void *cb_data)
1953{
1954        struct files_ref_store *refs =
1955                files_downcast(ref_store, REF_STORE_READ,
1956                               "for_each_reflog_ent");
1957        FILE *logfp;
1958        struct strbuf sb = STRBUF_INIT;
1959        int ret = 0;
1960
1961        files_reflog_path(refs, &sb, refname);
1962        logfp = fopen(sb.buf, "r");
1963        strbuf_release(&sb);
1964        if (!logfp)
1965                return -1;
1966
1967        while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
1968                ret = show_one_reflog_ent(&sb, fn, cb_data);
1969        fclose(logfp);
1970        strbuf_release(&sb);
1971        return ret;
1972}
1973
1974struct files_reflog_iterator {
1975        struct ref_iterator base;
1976
1977        struct ref_store *ref_store;
1978        struct dir_iterator *dir_iterator;
1979        struct object_id oid;
1980};
1981
1982static int files_reflog_iterator_advance(struct ref_iterator *ref_iterator)
1983{
1984        struct files_reflog_iterator *iter =
1985                (struct files_reflog_iterator *)ref_iterator;
1986        struct dir_iterator *diter = iter->dir_iterator;
1987        int ok;
1988
1989        while ((ok = dir_iterator_advance(diter)) == ITER_OK) {
1990                int flags;
1991
1992                if (!S_ISREG(diter->st.st_mode))
1993                        continue;
1994                if (diter->basename[0] == '.')
1995                        continue;
1996                if (ends_with(diter->basename, ".lock"))
1997                        continue;
1998
1999                if (refs_read_ref_full(iter->ref_store,
2000                                       diter->relative_path, 0,
2001                                       iter->oid.hash, &flags)) {
2002                        error("bad ref for %s", diter->path.buf);
2003                        continue;
2004                }
2005
2006                iter->base.refname = diter->relative_path;
2007                iter->base.oid = &iter->oid;
2008                iter->base.flags = flags;
2009                return ITER_OK;
2010        }
2011
2012        iter->dir_iterator = NULL;
2013        if (ref_iterator_abort(ref_iterator) == ITER_ERROR)
2014                ok = ITER_ERROR;
2015        return ok;
2016}
2017
2018static int files_reflog_iterator_peel(struct ref_iterator *ref_iterator,
2019                                   struct object_id *peeled)
2020{
2021        die("BUG: ref_iterator_peel() called for reflog_iterator");
2022}
2023
2024static int files_reflog_iterator_abort(struct ref_iterator *ref_iterator)
2025{
2026        struct files_reflog_iterator *iter =
2027                (struct files_reflog_iterator *)ref_iterator;
2028        int ok = ITER_DONE;
2029
2030        if (iter->dir_iterator)
2031                ok = dir_iterator_abort(iter->dir_iterator);
2032
2033        base_ref_iterator_free(ref_iterator);
2034        return ok;
2035}
2036
2037static struct ref_iterator_vtable files_reflog_iterator_vtable = {
2038        files_reflog_iterator_advance,
2039        files_reflog_iterator_peel,
2040        files_reflog_iterator_abort
2041};
2042
2043static struct ref_iterator *files_reflog_iterator_begin(struct ref_store *ref_store)
2044{
2045        struct files_ref_store *refs =
2046                files_downcast(ref_store, REF_STORE_READ,
2047                               "reflog_iterator_begin");
2048        struct files_reflog_iterator *iter = xcalloc(1, sizeof(*iter));
2049        struct ref_iterator *ref_iterator = &iter->base;
2050        struct strbuf sb = STRBUF_INIT;
2051
2052        base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable, 0);
2053        files_reflog_path(refs, &sb, NULL);
2054        iter->dir_iterator = dir_iterator_begin(sb.buf);
2055        iter->ref_store = ref_store;
2056        strbuf_release(&sb);
2057        return ref_iterator;
2058}
2059
2060/*
2061 * If update is a direct update of head_ref (the reference pointed to
2062 * by HEAD), then add an extra REF_LOG_ONLY update for HEAD.
2063 */
2064static int split_head_update(struct ref_update *update,
2065                             struct ref_transaction *transaction,
2066                             const char *head_ref,
2067                             struct string_list *affected_refnames,
2068                             struct strbuf *err)
2069{
2070        struct string_list_item *item;
2071        struct ref_update *new_update;
2072
2073        if ((update->flags & REF_LOG_ONLY) ||
2074            (update->flags & REF_ISPRUNING) ||
2075            (update->flags & REF_UPDATE_VIA_HEAD))
2076                return 0;
2077
2078        if (strcmp(update->refname, head_ref))
2079                return 0;
2080
2081        /*
2082         * First make sure that HEAD is not already in the
2083         * transaction. This insertion is O(N) in the transaction
2084         * size, but it happens at most once per transaction.
2085         */
2086        item = string_list_insert(affected_refnames, "HEAD");
2087        if (item->util) {
2088                /* An entry already existed */
2089                strbuf_addf(err,
2090                            "multiple updates for 'HEAD' (including one "
2091                            "via its referent '%s') are not allowed",
2092                            update->refname);
2093                return TRANSACTION_NAME_CONFLICT;
2094        }
2095
2096        new_update = ref_transaction_add_update(
2097                        transaction, "HEAD",
2098                        update->flags | REF_LOG_ONLY | REF_NODEREF,
2099                        update->new_oid.hash, update->old_oid.hash,
2100                        update->msg);
2101
2102        item->util = new_update;
2103
2104        return 0;
2105}
2106
2107/*
2108 * update is for a symref that points at referent and doesn't have
2109 * REF_NODEREF set. Split it into two updates:
2110 * - The original update, but with REF_LOG_ONLY and REF_NODEREF set
2111 * - A new, separate update for the referent reference
2112 * Note that the new update will itself be subject to splitting when
2113 * the iteration gets to it.
2114 */
2115static int split_symref_update(struct files_ref_store *refs,
2116                               struct ref_update *update,
2117                               const char *referent,
2118                               struct ref_transaction *transaction,
2119                               struct string_list *affected_refnames,
2120                               struct strbuf *err)
2121{
2122        struct string_list_item *item;
2123        struct ref_update *new_update;
2124        unsigned int new_flags;
2125
2126        /*
2127         * First make sure that referent is not already in the
2128         * transaction. This insertion is O(N) in the transaction
2129         * size, but it happens at most once per symref in a
2130         * transaction.
2131         */
2132        item = string_list_insert(affected_refnames, referent);
2133        if (item->util) {
2134                /* An entry already existed */
2135                strbuf_addf(err,
2136                            "multiple updates for '%s' (including one "
2137                            "via symref '%s') are not allowed",
2138                            referent, update->refname);
2139                return TRANSACTION_NAME_CONFLICT;
2140        }
2141
2142        new_flags = update->flags;
2143        if (!strcmp(update->refname, "HEAD")) {
2144                /*
2145                 * Record that the new update came via HEAD, so that
2146                 * when we process it, split_head_update() doesn't try
2147                 * to add another reflog update for HEAD. Note that
2148                 * this bit will be propagated if the new_update
2149                 * itself needs to be split.
2150                 */
2151                new_flags |= REF_UPDATE_VIA_HEAD;
2152        }
2153
2154        new_update = ref_transaction_add_update(
2155                        transaction, referent, new_flags,
2156                        update->new_oid.hash, update->old_oid.hash,
2157                        update->msg);
2158
2159        new_update->parent_update = update;
2160
2161        /*
2162         * Change the symbolic ref update to log only. Also, it
2163         * doesn't need to check its old SHA-1 value, as that will be
2164         * done when new_update is processed.
2165         */
2166        update->flags |= REF_LOG_ONLY | REF_NODEREF;
2167        update->flags &= ~REF_HAVE_OLD;
2168
2169        item->util = new_update;
2170
2171        return 0;
2172}
2173
2174/*
2175 * Return the refname under which update was originally requested.
2176 */
2177static const char *original_update_refname(struct ref_update *update)
2178{
2179        while (update->parent_update)
2180                update = update->parent_update;
2181
2182        return update->refname;
2183}
2184
2185/*
2186 * Check whether the REF_HAVE_OLD and old_oid values stored in update
2187 * are consistent with oid, which is the reference's current value. If
2188 * everything is OK, return 0; otherwise, write an error message to
2189 * err and return -1.
2190 */
2191static int check_old_oid(struct ref_update *update, struct object_id *oid,
2192                         struct strbuf *err)
2193{
2194        if (!(update->flags & REF_HAVE_OLD) ||
2195                   !oidcmp(oid, &update->old_oid))
2196                return 0;
2197
2198        if (is_null_oid(&update->old_oid))
2199                strbuf_addf(err, "cannot lock ref '%s': "
2200                            "reference already exists",
2201                            original_update_refname(update));
2202        else if (is_null_oid(oid))
2203                strbuf_addf(err, "cannot lock ref '%s': "
2204                            "reference is missing but expected %s",
2205                            original_update_refname(update),
2206                            oid_to_hex(&update->old_oid));
2207        else
2208                strbuf_addf(err, "cannot lock ref '%s': "
2209                            "is at %s but expected %s",
2210                            original_update_refname(update),
2211                            oid_to_hex(oid),
2212                            oid_to_hex(&update->old_oid));
2213
2214        return -1;
2215}
2216
2217/*
2218 * Prepare for carrying out update:
2219 * - Lock the reference referred to by update.
2220 * - Read the reference under lock.
2221 * - Check that its old SHA-1 value (if specified) is correct, and in
2222 *   any case record it in update->lock->old_oid for later use when
2223 *   writing the reflog.
2224 * - If it is a symref update without REF_NODEREF, split it up into a
2225 *   REF_LOG_ONLY update of the symref and add a separate update for
2226 *   the referent to transaction.
2227 * - If it is an update of head_ref, add a corresponding REF_LOG_ONLY
2228 *   update of HEAD.
2229 */
2230static int lock_ref_for_update(struct files_ref_store *refs,
2231                               struct ref_update *update,
2232                               struct ref_transaction *transaction,
2233                               const char *head_ref,
2234                               struct string_list *affected_refnames,
2235                               struct strbuf *err)
2236{
2237        struct strbuf referent = STRBUF_INIT;
2238        int mustexist = (update->flags & REF_HAVE_OLD) &&
2239                !is_null_oid(&update->old_oid);
2240        int ret;
2241        struct ref_lock *lock;
2242
2243        files_assert_main_repository(refs, "lock_ref_for_update");
2244
2245        if ((update->flags & REF_HAVE_NEW) && is_null_oid(&update->new_oid))
2246                update->flags |= REF_DELETING;
2247
2248        if (head_ref) {
2249                ret = split_head_update(update, transaction, head_ref,
2250                                        affected_refnames, err);
2251                if (ret)
2252                        return ret;
2253        }
2254
2255        ret = lock_raw_ref(refs, update->refname, mustexist,
2256                           affected_refnames, NULL,
2257                           &lock, &referent,
2258                           &update->type, err);
2259        if (ret) {
2260                char *reason;
2261
2262                reason = strbuf_detach(err, NULL);
2263                strbuf_addf(err, "cannot lock ref '%s': %s",
2264                            original_update_refname(update), reason);
2265                free(reason);
2266                return ret;
2267        }
2268
2269        update->backend_data = lock;
2270
2271        if (update->type & REF_ISSYMREF) {
2272                if (update->flags & REF_NODEREF) {
2273                        /*
2274                         * We won't be reading the referent as part of
2275                         * the transaction, so we have to read it here
2276                         * to record and possibly check old_sha1:
2277                         */
2278                        if (refs_read_ref_full(&refs->base,
2279                                               referent.buf, 0,
2280                                               lock->old_oid.hash, NULL)) {
2281                                if (update->flags & REF_HAVE_OLD) {
2282                                        strbuf_addf(err, "cannot lock ref '%s': "
2283                                                    "error reading reference",
2284                                                    original_update_refname(update));
2285                                        return -1;
2286                                }
2287                        } else if (check_old_oid(update, &lock->old_oid, err)) {
2288                                return TRANSACTION_GENERIC_ERROR;
2289                        }
2290                } else {
2291                        /*
2292                         * Create a new update for the reference this
2293                         * symref is pointing at. Also, we will record
2294                         * and verify old_sha1 for this update as part
2295                         * of processing the split-off update, so we
2296                         * don't have to do it here.
2297                         */
2298                        ret = split_symref_update(refs, update,
2299                                                  referent.buf, transaction,
2300                                                  affected_refnames, err);
2301                        if (ret)
2302                                return ret;
2303                }
2304        } else {
2305                struct ref_update *parent_update;
2306
2307                if (check_old_oid(update, &lock->old_oid, err))
2308                        return TRANSACTION_GENERIC_ERROR;
2309
2310                /*
2311                 * If this update is happening indirectly because of a
2312                 * symref update, record the old SHA-1 in the parent
2313                 * update:
2314                 */
2315                for (parent_update = update->parent_update;
2316                     parent_update;
2317                     parent_update = parent_update->parent_update) {
2318                        struct ref_lock *parent_lock = parent_update->backend_data;
2319                        oidcpy(&parent_lock->old_oid, &lock->old_oid);
2320                }
2321        }
2322
2323        if ((update->flags & REF_HAVE_NEW) &&
2324            !(update->flags & REF_DELETING) &&
2325            !(update->flags & REF_LOG_ONLY)) {
2326                if (!(update->type & REF_ISSYMREF) &&
2327                    !oidcmp(&lock->old_oid, &update->new_oid)) {
2328                        /*
2329                         * The reference already has the desired
2330                         * value, so we don't need to write it.
2331                         */
2332                } else if (write_ref_to_lockfile(lock, &update->new_oid,
2333                                                 err)) {
2334                        char *write_err = strbuf_detach(err, NULL);
2335
2336                        /*
2337                         * The lock was freed upon failure of
2338                         * write_ref_to_lockfile():
2339                         */
2340                        update->backend_data = NULL;
2341                        strbuf_addf(err,
2342                                    "cannot update ref '%s': %s",
2343                                    update->refname, write_err);
2344                        free(write_err);
2345                        return TRANSACTION_GENERIC_ERROR;
2346                } else {
2347                        update->flags |= REF_NEEDS_COMMIT;
2348                }
2349        }
2350        if (!(update->flags & REF_NEEDS_COMMIT)) {
2351                /*
2352                 * We didn't call write_ref_to_lockfile(), so
2353                 * the lockfile is still open. Close it to
2354                 * free up the file descriptor:
2355                 */
2356                if (close_ref(lock)) {
2357                        strbuf_addf(err, "couldn't close '%s.lock'",
2358                                    update->refname);
2359                        return TRANSACTION_GENERIC_ERROR;
2360                }
2361        }
2362        return 0;
2363}
2364
2365struct files_transaction_backend_data {
2366        struct ref_transaction *packed_transaction;
2367        int packed_refs_locked;
2368};
2369
2370/*
2371 * Unlock any references in `transaction` that are still locked, and
2372 * mark the transaction closed.
2373 */
2374static void files_transaction_cleanup(struct files_ref_store *refs,
2375                                      struct ref_transaction *transaction)
2376{
2377        size_t i;
2378        struct files_transaction_backend_data *backend_data =
2379                transaction->backend_data;
2380        struct strbuf err = STRBUF_INIT;
2381
2382        for (i = 0; i < transaction->nr; i++) {
2383                struct ref_update *update = transaction->updates[i];
2384                struct ref_lock *lock = update->backend_data;
2385
2386                if (lock) {
2387                        unlock_ref(lock);
2388                        update->backend_data = NULL;
2389                }
2390        }
2391
2392        if (backend_data->packed_transaction &&
2393            ref_transaction_abort(backend_data->packed_transaction, &err)) {
2394                error("error aborting transaction: %s", err.buf);
2395                strbuf_release(&err);
2396        }
2397
2398        if (backend_data->packed_refs_locked)
2399                packed_refs_unlock(refs->packed_ref_store);
2400
2401        free(backend_data);
2402
2403        transaction->state = REF_TRANSACTION_CLOSED;
2404}
2405
2406static int files_transaction_prepare(struct ref_store *ref_store,
2407                                     struct ref_transaction *transaction,
2408                                     struct strbuf *err)
2409{
2410        struct files_ref_store *refs =
2411                files_downcast(ref_store, REF_STORE_WRITE,
2412                               "ref_transaction_prepare");
2413        size_t i;
2414        int ret = 0;
2415        struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
2416        char *head_ref = NULL;
2417        int head_type;
2418        struct object_id head_oid;
2419        struct files_transaction_backend_data *backend_data;
2420        struct ref_transaction *packed_transaction = NULL;
2421
2422        assert(err);
2423
2424        if (!transaction->nr)
2425                goto cleanup;
2426
2427        backend_data = xcalloc(1, sizeof(*backend_data));
2428        transaction->backend_data = backend_data;
2429
2430        /*
2431         * Fail if a refname appears more than once in the
2432         * transaction. (If we end up splitting up any updates using
2433         * split_symref_update() or split_head_update(), those
2434         * functions will check that the new updates don't have the
2435         * same refname as any existing ones.)
2436         */
2437        for (i = 0; i < transaction->nr; i++) {
2438                struct ref_update *update = transaction->updates[i];
2439                struct string_list_item *item =
2440                        string_list_append(&affected_refnames, update->refname);
2441
2442                /*
2443                 * We store a pointer to update in item->util, but at
2444                 * the moment we never use the value of this field
2445                 * except to check whether it is non-NULL.
2446                 */
2447                item->util = update;
2448        }
2449        string_list_sort(&affected_refnames);
2450        if (ref_update_reject_duplicates(&affected_refnames, err)) {
2451                ret = TRANSACTION_GENERIC_ERROR;
2452                goto cleanup;
2453        }
2454
2455        /*
2456         * Special hack: If a branch is updated directly and HEAD
2457         * points to it (may happen on the remote side of a push
2458         * for example) then logically the HEAD reflog should be
2459         * updated too.
2460         *
2461         * A generic solution would require reverse symref lookups,
2462         * but finding all symrefs pointing to a given branch would be
2463         * rather costly for this rare event (the direct update of a
2464         * branch) to be worth it. So let's cheat and check with HEAD
2465         * only, which should cover 99% of all usage scenarios (even
2466         * 100% of the default ones).
2467         *
2468         * So if HEAD is a symbolic reference, then record the name of
2469         * the reference that it points to. If we see an update of
2470         * head_ref within the transaction, then split_head_update()
2471         * arranges for the reflog of HEAD to be updated, too.
2472         */
2473        head_ref = refs_resolve_refdup(ref_store, "HEAD",
2474                                       RESOLVE_REF_NO_RECURSE,
2475                                       head_oid.hash, &head_type);
2476
2477        if (head_ref && !(head_type & REF_ISSYMREF)) {
2478                FREE_AND_NULL(head_ref);
2479        }
2480
2481        /*
2482         * Acquire all locks, verify old values if provided, check
2483         * that new values are valid, and write new values to the
2484         * lockfiles, ready to be activated. Only keep one lockfile
2485         * open at a time to avoid running out of file descriptors.
2486         * Note that lock_ref_for_update() might append more updates
2487         * to the transaction.
2488         */
2489        for (i = 0; i < transaction->nr; i++) {
2490                struct ref_update *update = transaction->updates[i];
2491
2492                ret = lock_ref_for_update(refs, update, transaction,
2493                                          head_ref, &affected_refnames, err);
2494                if (ret)
2495                        break;
2496
2497                if (update->flags & REF_DELETING &&
2498                    !(update->flags & REF_LOG_ONLY) &&
2499                    !(update->flags & REF_ISPRUNING)) {
2500                        /*
2501                         * This reference has to be deleted from
2502                         * packed-refs if it exists there.
2503                         */
2504                        if (!packed_transaction) {
2505                                packed_transaction = ref_store_transaction_begin(
2506                                                refs->packed_ref_store, err);
2507                                if (!packed_transaction) {
2508                                        ret = TRANSACTION_GENERIC_ERROR;
2509                                        goto cleanup;
2510                                }
2511
2512                                backend_data->packed_transaction =
2513                                        packed_transaction;
2514                        }
2515
2516                        ref_transaction_add_update(
2517                                        packed_transaction, update->refname,
2518                                        update->flags & ~REF_HAVE_OLD,
2519                                        update->new_oid.hash, update->old_oid.hash,
2520                                        NULL);
2521                }
2522        }
2523
2524        if (packed_transaction) {
2525                if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
2526                        ret = TRANSACTION_GENERIC_ERROR;
2527                        goto cleanup;
2528                }
2529                backend_data->packed_refs_locked = 1;
2530                ret = ref_transaction_prepare(packed_transaction, err);
2531        }
2532
2533cleanup:
2534        free(head_ref);
2535        string_list_clear(&affected_refnames, 0);
2536
2537        if (ret)
2538                files_transaction_cleanup(refs, transaction);
2539        else
2540                transaction->state = REF_TRANSACTION_PREPARED;
2541
2542        return ret;
2543}
2544
2545static int files_transaction_finish(struct ref_store *ref_store,
2546                                    struct ref_transaction *transaction,
2547                                    struct strbuf *err)
2548{
2549        struct files_ref_store *refs =
2550                files_downcast(ref_store, 0, "ref_transaction_finish");
2551        size_t i;
2552        int ret = 0;
2553        struct strbuf sb = STRBUF_INIT;
2554        struct files_transaction_backend_data *backend_data;
2555        struct ref_transaction *packed_transaction;
2556
2557
2558        assert(err);
2559
2560        if (!transaction->nr) {
2561                transaction->state = REF_TRANSACTION_CLOSED;
2562                return 0;
2563        }
2564
2565        backend_data = transaction->backend_data;
2566        packed_transaction = backend_data->packed_transaction;
2567
2568        /* Perform updates first so live commits remain referenced */
2569        for (i = 0; i < transaction->nr; i++) {
2570                struct ref_update *update = transaction->updates[i];
2571                struct ref_lock *lock = update->backend_data;
2572
2573                if (update->flags & REF_NEEDS_COMMIT ||
2574                    update->flags & REF_LOG_ONLY) {
2575                        if (files_log_ref_write(refs,
2576                                                lock->ref_name,
2577                                                &lock->old_oid,
2578                                                &update->new_oid,
2579                                                update->msg, update->flags,
2580                                                err)) {
2581                                char *old_msg = strbuf_detach(err, NULL);
2582
2583                                strbuf_addf(err, "cannot update the ref '%s': %s",
2584                                            lock->ref_name, old_msg);
2585                                free(old_msg);
2586                                unlock_ref(lock);
2587                                update->backend_data = NULL;
2588                                ret = TRANSACTION_GENERIC_ERROR;
2589                                goto cleanup;
2590                        }
2591                }
2592                if (update->flags & REF_NEEDS_COMMIT) {
2593                        clear_loose_ref_cache(refs);
2594                        if (commit_ref(lock)) {
2595                                strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
2596                                unlock_ref(lock);
2597                                update->backend_data = NULL;
2598                                ret = TRANSACTION_GENERIC_ERROR;
2599                                goto cleanup;
2600                        }
2601                }
2602        }
2603
2604        /*
2605         * Now that updates are safely completed, we can perform
2606         * deletes. First delete the reflogs of any references that
2607         * will be deleted, since (in the unexpected event of an
2608         * error) leaving a reference without a reflog is less bad
2609         * than leaving a reflog without a reference (the latter is a
2610         * mildly invalid repository state):
2611         */
2612        for (i = 0; i < transaction->nr; i++) {
2613                struct ref_update *update = transaction->updates[i];
2614                if (update->flags & REF_DELETING &&
2615                    !(update->flags & REF_LOG_ONLY) &&
2616                    !(update->flags & REF_ISPRUNING)) {
2617                        strbuf_reset(&sb);
2618                        files_reflog_path(refs, &sb, update->refname);
2619                        if (!unlink_or_warn(sb.buf))
2620                                try_remove_empty_parents(refs, update->refname,
2621                                                         REMOVE_EMPTY_PARENTS_REFLOG);
2622                }
2623        }
2624
2625        /*
2626         * Perform deletes now that updates are safely completed.
2627         *
2628         * First delete any packed versions of the references, while
2629         * retaining the packed-refs lock:
2630         */
2631        if (packed_transaction) {
2632                ret = ref_transaction_commit(packed_transaction, err);
2633                ref_transaction_free(packed_transaction);
2634                packed_transaction = NULL;
2635                backend_data->packed_transaction = NULL;
2636                if (ret)
2637                        goto cleanup;
2638        }
2639
2640        /* Now delete the loose versions of the references: */
2641        for (i = 0; i < transaction->nr; i++) {
2642                struct ref_update *update = transaction->updates[i];
2643                struct ref_lock *lock = update->backend_data;
2644
2645                if (update->flags & REF_DELETING &&
2646                    !(update->flags & REF_LOG_ONLY)) {
2647                        if (!(update->type & REF_ISPACKED) ||
2648                            update->type & REF_ISSYMREF) {
2649                                /* It is a loose reference. */
2650                                strbuf_reset(&sb);
2651                                files_ref_path(refs, &sb, lock->ref_name);
2652                                if (unlink_or_msg(sb.buf, err)) {
2653                                        ret = TRANSACTION_GENERIC_ERROR;
2654                                        goto cleanup;
2655                                }
2656                                update->flags |= REF_DELETED_LOOSE;
2657                        }
2658                }
2659        }
2660
2661        clear_loose_ref_cache(refs);
2662
2663cleanup:
2664        files_transaction_cleanup(refs, transaction);
2665
2666        for (i = 0; i < transaction->nr; i++) {
2667                struct ref_update *update = transaction->updates[i];
2668
2669                if (update->flags & REF_DELETED_LOOSE) {
2670                        /*
2671                         * The loose reference was deleted. Delete any
2672                         * empty parent directories. (Note that this
2673                         * can only work because we have already
2674                         * removed the lockfile.)
2675                         */
2676                        try_remove_empty_parents(refs, update->refname,
2677                                                 REMOVE_EMPTY_PARENTS_REF);
2678                }
2679        }
2680
2681        strbuf_release(&sb);
2682        return ret;
2683}
2684
2685static int files_transaction_abort(struct ref_store *ref_store,
2686                                   struct ref_transaction *transaction,
2687                                   struct strbuf *err)
2688{
2689        struct files_ref_store *refs =
2690                files_downcast(ref_store, 0, "ref_transaction_abort");
2691
2692        files_transaction_cleanup(refs, transaction);
2693        return 0;
2694}
2695
2696static int ref_present(const char *refname,
2697                       const struct object_id *oid, int flags, void *cb_data)
2698{
2699        struct string_list *affected_refnames = cb_data;
2700
2701        return string_list_has_string(affected_refnames, refname);
2702}
2703
2704static int files_initial_transaction_commit(struct ref_store *ref_store,
2705                                            struct ref_transaction *transaction,
2706                                            struct strbuf *err)
2707{
2708        struct files_ref_store *refs =
2709                files_downcast(ref_store, REF_STORE_WRITE,
2710                               "initial_ref_transaction_commit");
2711        size_t i;
2712        int ret = 0;
2713        struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
2714        struct ref_transaction *packed_transaction = NULL;
2715
2716        assert(err);
2717
2718        if (transaction->state != REF_TRANSACTION_OPEN)
2719                die("BUG: commit called for transaction that is not open");
2720
2721        /* Fail if a refname appears more than once in the transaction: */
2722        for (i = 0; i < transaction->nr; i++)
2723                string_list_append(&affected_refnames,
2724                                   transaction->updates[i]->refname);
2725        string_list_sort(&affected_refnames);
2726        if (ref_update_reject_duplicates(&affected_refnames, err)) {
2727                ret = TRANSACTION_GENERIC_ERROR;
2728                goto cleanup;
2729        }
2730
2731        /*
2732         * It's really undefined to call this function in an active
2733         * repository or when there are existing references: we are
2734         * only locking and changing packed-refs, so (1) any
2735         * simultaneous processes might try to change a reference at
2736         * the same time we do, and (2) any existing loose versions of
2737         * the references that we are setting would have precedence
2738         * over our values. But some remote helpers create the remote
2739         * "HEAD" and "master" branches before calling this function,
2740         * so here we really only check that none of the references
2741         * that we are creating already exists.
2742         */
2743        if (refs_for_each_rawref(&refs->base, ref_present,
2744                                 &affected_refnames))
2745                die("BUG: initial ref transaction called with existing refs");
2746
2747        packed_transaction = ref_store_transaction_begin(refs->packed_ref_store, err);
2748        if (!packed_transaction) {
2749                ret = TRANSACTION_GENERIC_ERROR;
2750                goto cleanup;
2751        }
2752
2753        for (i = 0; i < transaction->nr; i++) {
2754                struct ref_update *update = transaction->updates[i];
2755
2756                if ((update->flags & REF_HAVE_OLD) &&
2757                    !is_null_oid(&update->old_oid))
2758                        die("BUG: initial ref transaction with old_sha1 set");
2759                if (refs_verify_refname_available(&refs->base, update->refname,
2760                                                  &affected_refnames, NULL,
2761                                                  err)) {
2762                        ret = TRANSACTION_NAME_CONFLICT;
2763                        goto cleanup;
2764                }
2765
2766                /*
2767                 * Add a reference creation for this reference to the
2768                 * packed-refs transaction:
2769                 */
2770                ref_transaction_add_update(packed_transaction, update->refname,
2771                                           update->flags & ~REF_HAVE_OLD,
2772                                           update->new_oid.hash, update->old_oid.hash,
2773                                           NULL);
2774        }
2775
2776        if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
2777                ret = TRANSACTION_GENERIC_ERROR;
2778                goto cleanup;
2779        }
2780
2781        if (initial_ref_transaction_commit(packed_transaction, err)) {
2782                ret = TRANSACTION_GENERIC_ERROR;
2783                goto cleanup;
2784        }
2785
2786cleanup:
2787        if (packed_transaction)
2788                ref_transaction_free(packed_transaction);
2789        packed_refs_unlock(refs->packed_ref_store);
2790        transaction->state = REF_TRANSACTION_CLOSED;
2791        string_list_clear(&affected_refnames, 0);
2792        return ret;
2793}
2794
2795struct expire_reflog_cb {
2796        unsigned int flags;
2797        reflog_expiry_should_prune_fn *should_prune_fn;
2798        void *policy_cb;
2799        FILE *newlog;
2800        struct object_id last_kept_oid;
2801};
2802
2803static int expire_reflog_ent(struct object_id *ooid, struct object_id *noid,
2804                             const char *email, timestamp_t timestamp, int tz,
2805                             const char *message, void *cb_data)
2806{
2807        struct expire_reflog_cb *cb = cb_data;
2808        struct expire_reflog_policy_cb *policy_cb = cb->policy_cb;
2809
2810        if (cb->flags & EXPIRE_REFLOGS_REWRITE)
2811                ooid = &cb->last_kept_oid;
2812
2813        if ((*cb->should_prune_fn)(ooid, noid, email, timestamp, tz,
2814                                   message, policy_cb)) {
2815                if (!cb->newlog)
2816                        printf("would prune %s", message);
2817                else if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
2818                        printf("prune %s", message);
2819        } else {
2820                if (cb->newlog) {
2821                        fprintf(cb->newlog, "%s %s %s %"PRItime" %+05d\t%s",
2822                                oid_to_hex(ooid), oid_to_hex(noid),
2823                                email, timestamp, tz, message);
2824                        oidcpy(&cb->last_kept_oid, noid);
2825                }
2826                if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
2827                        printf("keep %s", message);
2828        }
2829        return 0;
2830}
2831
2832static int files_reflog_expire(struct ref_store *ref_store,
2833                               const char *refname, const unsigned char *sha1,
2834                               unsigned int flags,
2835                               reflog_expiry_prepare_fn prepare_fn,
2836                               reflog_expiry_should_prune_fn should_prune_fn,
2837                               reflog_expiry_cleanup_fn cleanup_fn,
2838                               void *policy_cb_data)
2839{
2840        struct files_ref_store *refs =
2841                files_downcast(ref_store, REF_STORE_WRITE, "reflog_expire");
2842        static struct lock_file reflog_lock;
2843        struct expire_reflog_cb cb;
2844        struct ref_lock *lock;
2845        struct strbuf log_file_sb = STRBUF_INIT;
2846        char *log_file;
2847        int status = 0;
2848        int type;
2849        struct strbuf err = STRBUF_INIT;
2850        struct object_id oid;
2851
2852        memset(&cb, 0, sizeof(cb));
2853        cb.flags = flags;
2854        cb.policy_cb = policy_cb_data;
2855        cb.should_prune_fn = should_prune_fn;
2856
2857        /*
2858         * The reflog file is locked by holding the lock on the
2859         * reference itself, plus we might need to update the
2860         * reference if --updateref was specified:
2861         */
2862        lock = lock_ref_sha1_basic(refs, refname, sha1,
2863                                   NULL, NULL, REF_NODEREF,
2864                                   &type, &err);
2865        if (!lock) {
2866                error("cannot lock ref '%s': %s", refname, err.buf);
2867                strbuf_release(&err);
2868                return -1;
2869        }
2870        if (!refs_reflog_exists(ref_store, refname)) {
2871                unlock_ref(lock);
2872                return 0;
2873        }
2874
2875        files_reflog_path(refs, &log_file_sb, refname);
2876        log_file = strbuf_detach(&log_file_sb, NULL);
2877        if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
2878                /*
2879                 * Even though holding $GIT_DIR/logs/$reflog.lock has
2880                 * no locking implications, we use the lock_file
2881                 * machinery here anyway because it does a lot of the
2882                 * work we need, including cleaning up if the program
2883                 * exits unexpectedly.
2884                 */
2885                if (hold_lock_file_for_update(&reflog_lock, log_file, 0) < 0) {
2886                        struct strbuf err = STRBUF_INIT;
2887                        unable_to_lock_message(log_file, errno, &err);
2888                        error("%s", err.buf);
2889                        strbuf_release(&err);
2890                        goto failure;
2891                }
2892                cb.newlog = fdopen_lock_file(&reflog_lock, "w");
2893                if (!cb.newlog) {
2894                        error("cannot fdopen %s (%s)",
2895                              get_lock_file_path(&reflog_lock), strerror(errno));
2896                        goto failure;
2897                }
2898        }
2899
2900        hashcpy(oid.hash, sha1);
2901
2902        (*prepare_fn)(refname, &oid, cb.policy_cb);
2903        refs_for_each_reflog_ent(ref_store, refname, expire_reflog_ent, &cb);
2904        (*cleanup_fn)(cb.policy_cb);
2905
2906        if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
2907                /*
2908                 * It doesn't make sense to adjust a reference pointed
2909                 * to by a symbolic ref based on expiring entries in
2910                 * the symbolic reference's reflog. Nor can we update
2911                 * a reference if there are no remaining reflog
2912                 * entries.
2913                 */
2914                int update = (flags & EXPIRE_REFLOGS_UPDATE_REF) &&
2915                        !(type & REF_ISSYMREF) &&
2916                        !is_null_oid(&cb.last_kept_oid);
2917
2918                if (close_lock_file(&reflog_lock)) {
2919                        status |= error("couldn't write %s: %s", log_file,
2920                                        strerror(errno));
2921                } else if (update &&
2922                           (write_in_full(get_lock_file_fd(lock->lk),
2923                                oid_to_hex(&cb.last_kept_oid), GIT_SHA1_HEXSZ) != GIT_SHA1_HEXSZ ||
2924                            write_str_in_full(get_lock_file_fd(lock->lk), "\n") != 1 ||
2925                            close_ref(lock) < 0)) {
2926                        status |= error("couldn't write %s",
2927                                        get_lock_file_path(lock->lk));
2928                        rollback_lock_file(&reflog_lock);
2929                } else if (commit_lock_file(&reflog_lock)) {
2930                        status |= error("unable to write reflog '%s' (%s)",
2931                                        log_file, strerror(errno));
2932                } else if (update && commit_ref(lock)) {
2933                        status |= error("couldn't set %s", lock->ref_name);
2934                }
2935        }
2936        free(log_file);
2937        unlock_ref(lock);
2938        return status;
2939
2940 failure:
2941        rollback_lock_file(&reflog_lock);
2942        free(log_file);
2943        unlock_ref(lock);
2944        return -1;
2945}
2946
2947static int files_init_db(struct ref_store *ref_store, struct strbuf *err)
2948{
2949        struct files_ref_store *refs =
2950                files_downcast(ref_store, REF_STORE_WRITE, "init_db");
2951        struct strbuf sb = STRBUF_INIT;
2952
2953        /*
2954         * Create .git/refs/{heads,tags}
2955         */
2956        files_ref_path(refs, &sb, "refs/heads");
2957        safe_create_dir(sb.buf, 1);
2958
2959        strbuf_reset(&sb);
2960        files_ref_path(refs, &sb, "refs/tags");
2961        safe_create_dir(sb.buf, 1);
2962
2963        strbuf_release(&sb);
2964        return 0;
2965}
2966
2967struct ref_storage_be refs_be_files = {
2968        NULL,
2969        "files",
2970        files_ref_store_create,
2971        files_init_db,
2972        files_transaction_prepare,
2973        files_transaction_finish,
2974        files_transaction_abort,
2975        files_initial_transaction_commit,
2976
2977        files_pack_refs,
2978        files_create_symref,
2979        files_delete_refs,
2980        files_rename_ref,
2981
2982        files_ref_iterator_begin,
2983        files_read_raw_ref,
2984
2985        files_reflog_iterator_begin,
2986        files_for_each_reflog_ent,
2987        files_for_each_reflog_ent_reverse,
2988        files_reflog_exists,
2989        files_create_reflog,
2990        files_delete_reflog,
2991        files_reflog_expire
2992};