git.oblomov.eu Git - git/blob - refs/files-backend.c

   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
  13 struct 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  */
  23 struct 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
  35 static 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  */
  47 static 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  */
  71 static 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  */
  86 static 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
 105 static void files_reflog_path(struct files_ref_store *refs,
 106                               struct strbuf *sb,
 107                               const char *refname)
 108 {
 109         switch (ref_type(refname)) {
 110         case REF_TYPE_PER_WORKTREE:
 111         case REF_TYPE_PSEUDOREF:
 112                 strbuf_addf(sb, "%s/logs/%s", refs->gitdir, refname);
 113                 break;
 114         case REF_TYPE_NORMAL:
 115                 strbuf_addf(sb, "%s/logs/%s", refs->gitcommondir, refname);
 116                 break;
 117         default:
 118                 die("BUG: unknown ref type %d of ref %s",
 119                     ref_type(refname), refname);
 120         }
 121 }
 122
 123 static void files_ref_path(struct files_ref_store *refs,
 124                            struct strbuf *sb,
 125                            const char *refname)
 126 {
 127         switch (ref_type(refname)) {
 128         case REF_TYPE_PER_WORKTREE:
 129         case REF_TYPE_PSEUDOREF:
 130                 strbuf_addf(sb, "%s/%s", refs->gitdir, refname);
 131                 break;
 132         case REF_TYPE_NORMAL:
 133                 strbuf_addf(sb, "%s/%s", refs->gitcommondir, refname);
 134                 break;
 135         default:
 136                 die("BUG: unknown ref type %d of ref %s",
 137                     ref_type(refname), refname);
 138         }
 139 }
 140
 141 /*
 142  * Read the loose references from the namespace dirname into dir
 143  * (without recursing).  dirname must end with '/'.  dir must be the
 144  * directory entry corresponding to dirname.
 145  */
 146 static void loose_fill_ref_dir(struct ref_store *ref_store,
 147                                struct ref_dir *dir, const char *dirname)
 148 {
 149         struct files_ref_store *refs =
 150                 files_downcast(ref_store, REF_STORE_READ, "fill_ref_dir");
 151         DIR *d;
 152         struct dirent *de;
 153         int dirnamelen = strlen(dirname);
 154         struct strbuf refname;
 155         struct strbuf path = STRBUF_INIT;
 156         size_t path_baselen;
 157
 158         files_ref_path(refs, &path, dirname);
 159         path_baselen = path.len;
 160
 161         d = opendir(path.buf);
 162         if (!d) {
 163                 strbuf_release(&path);
 164                 return;
 165         }
 166
 167         strbuf_init(&refname, dirnamelen + 257);
 168         strbuf_add(&refname, dirname, dirnamelen);
 169
 170         while ((de = readdir(d)) != NULL) {
 171                 struct object_id oid;
 172                 struct stat st;
 173                 int flag;
 174
 175                 if (de->d_name[0] == '.')
 176                         continue;
 177                 if (ends_with(de->d_name, ".lock"))
 178                         continue;
 179                 strbuf_addstr(&refname, de->d_name);
 180                 strbuf_addstr(&path, de->d_name);
 181                 if (stat(path.buf, &st) < 0) {
 182                         ; /* silently ignore */
 183                 } else if (S_ISDIR(st.st_mode)) {
 184                         strbuf_addch(&refname, '/');
 185                         add_entry_to_dir(dir,
 186                                          create_dir_entry(dir->cache, refname.buf,
 187                                                           refname.len, 1));
 188                 } else {
 189                         if (!refs_resolve_ref_unsafe(&refs->base,
 190                                                      refname.buf,
 191                                                      RESOLVE_REF_READING,
 192                                                      oid.hash, &flag)) {
 193                                 oidclr(&oid);
 194                                 flag |= REF_ISBROKEN;
 195                         } else if (is_null_oid(&oid)) {
 196                                 /*
 197                                  * It is so astronomically unlikely
 198                                  * that NULL_SHA1 is the SHA-1 of an
 199                                  * actual object that we consider its
 200                                  * appearance in a loose reference
 201                                  * file to be repo corruption
 202                                  * (probably due to a software bug).
 203                                  */
 204                                 flag |= REF_ISBROKEN;
 205                         }
 206
 207                         if (check_refname_format(refname.buf,
 208                                                  REFNAME_ALLOW_ONELEVEL)) {
 209                                 if (!refname_is_safe(refname.buf))
 210                                         die("loose refname is dangerous: %s", refname.buf);
 211                                 oidclr(&oid);
 212                                 flag |= REF_BAD_NAME | REF_ISBROKEN;
 213                         }
 214                         add_entry_to_dir(dir,
 215                                          create_ref_entry(refname.buf, &oid, flag));
 216                 }
 217                 strbuf_setlen(&refname, dirnamelen);
 218                 strbuf_setlen(&path, path_baselen);
 219         }
 220         strbuf_release(&refname);
 221         strbuf_release(&path);
 222         closedir(d);
 223
 224         /*
 225          * Manually add refs/bisect, which, being per-worktree, might
 226          * not appear in the directory listing for refs/ in the main
 227          * repo.
 228          */
 229         if (!strcmp(dirname, "refs/")) {
 230                 int pos = search_ref_dir(dir, "refs/bisect/", 12);
 231
 232                 if (pos < 0) {
 233                         struct ref_entry *child_entry = create_dir_entry(
 234                                         dir->cache, "refs/bisect/", 12, 1);
 235                         add_entry_to_dir(dir, child_entry);
 236                 }
 237         }
 238 }
 239
 240 static struct ref_cache *get_loose_ref_cache(struct files_ref_store *refs)
 241 {
 242         if (!refs->loose) {
 243                 /*
 244                  * Mark the top-level directory complete because we
 245                  * are about to read the only subdirectory that can
 246                  * hold references:
 247                  */
 248                 refs->loose = create_ref_cache(&refs->base, loose_fill_ref_dir);
 249
 250                 /* We're going to fill the top level ourselves: */
 251                 refs->loose->root->flag &= ~REF_INCOMPLETE;
 252
 253                 /*
 254                  * Add an incomplete entry for "refs/" (to be filled
 255                  * lazily):
 256                  */
 257                 add_entry_to_dir(get_ref_dir(refs->loose->root),
 258                                  create_dir_entry(refs->loose, "refs/", 5, 1));
 259         }
 260         return refs->loose;
 261 }
 262
 263 static int files_read_raw_ref(struct ref_store *ref_store,
 264                               const char *refname, unsigned char *sha1,
 265                               struct strbuf *referent, unsigned int *type)
 266 {
 267         struct files_ref_store *refs =
 268                 files_downcast(ref_store, REF_STORE_READ, "read_raw_ref");
 269         struct strbuf sb_contents = STRBUF_INIT;
 270         struct strbuf sb_path = STRBUF_INIT;
 271         const char *path;
 272         const char *buf;
 273         struct stat st;
 274         int fd;
 275         int ret = -1;
 276         int save_errno;
 277         int remaining_retries = 3;
 278
 279         *type = 0;
 280         strbuf_reset(&sb_path);
 281
 282         files_ref_path(refs, &sb_path, refname);
 283
 284         path = sb_path.buf;
 285
 286 stat_ref:
 287         /*
 288          * We might have to loop back here to avoid a race
 289          * condition: first we lstat() the file, then we try
 290          * to read it as a link or as a file.  But if somebody
 291          * changes the type of the file (file <-> directory
 292          * <-> symlink) between the lstat() and reading, then
 293          * we don't want to report that as an error but rather
 294          * try again starting with the lstat().
 295          *
 296          * We'll keep a count of the retries, though, just to avoid
 297          * any confusing situation sending us into an infinite loop.
 298          */
 299
 300         if (remaining_retries-- <= 0)
 301                 goto out;
 302
 303         if (lstat(path, &st) < 0) {
 304                 if (errno != ENOENT)
 305                         goto out;
 306                 if (refs_read_raw_ref(refs->packed_ref_store, refname,
 307                                       sha1, referent, type)) {
 308                         errno = ENOENT;
 309                         goto out;
 310                 }
 311                 ret = 0;
 312                 goto out;
 313         }
 314
 315         /* Follow "normalized" - ie "refs/.." symlinks by hand */
 316         if (S_ISLNK(st.st_mode)) {
 317                 strbuf_reset(&sb_contents);
 318                 if (strbuf_readlink(&sb_contents, path, 0) < 0) {
 319                         if (errno == ENOENT || errno == EINVAL)
 320                                 /* inconsistent with lstat; retry */
 321                                 goto stat_ref;
 322                         else
 323                                 goto out;
 324                 }
 325                 if (starts_with(sb_contents.buf, "refs/") &&
 326                     !check_refname_format(sb_contents.buf, 0)) {
 327                         strbuf_swap(&sb_contents, referent);
 328                         *type |= REF_ISSYMREF;
 329                         ret = 0;
 330                         goto out;
 331                 }
 332                 /*
 333                  * It doesn't look like a refname; fall through to just
 334                  * treating it like a non-symlink, and reading whatever it
 335                  * points to.
 336                  */
 337         }
 338
 339         /* Is it a directory? */
 340         if (S_ISDIR(st.st_mode)) {
 341                 /*
 342                  * Even though there is a directory where the loose
 343                  * ref is supposed to be, there could still be a
 344                  * packed ref:
 345                  */
 346                 if (refs_read_raw_ref(refs->packed_ref_store, refname,
 347                                       sha1, referent, type)) {
 348                         errno = EISDIR;
 349                         goto out;
 350                 }
 351                 ret = 0;
 352                 goto out;
 353         }
 354
 355         /*
 356          * Anything else, just open it and try to use it as
 357          * a ref
 358          */
 359         fd = open(path, O_RDONLY);
 360         if (fd < 0) {
 361                 if (errno == ENOENT && !S_ISLNK(st.st_mode))
 362                         /* inconsistent with lstat; retry */
 363                         goto stat_ref;
 364                 else
 365                         goto out;
 366         }
 367         strbuf_reset(&sb_contents);
 368         if (strbuf_read(&sb_contents, fd, 256) < 0) {
 369                 int save_errno = errno;
 370                 close(fd);
 371                 errno = save_errno;
 372                 goto out;
 373         }
 374         close(fd);
 375         strbuf_rtrim(&sb_contents);
 376         buf = sb_contents.buf;
 377         if (starts_with(buf, "ref:")) {
 378                 buf += 4;
 379                 while (isspace(*buf))
 380                         buf++;
 381
 382                 strbuf_reset(referent);
 383                 strbuf_addstr(referent, buf);
 384                 *type |= REF_ISSYMREF;
 385                 ret = 0;
 386                 goto out;
 387         }
 388
 389         /*
 390          * Please note that FETCH_HEAD has additional
 391          * data after the sha.
 392          */
 393         if (get_sha1_hex(buf, sha1) ||
 394             (buf[40] != '\0' && !isspace(buf[40]))) {
 395                 *type |= REF_ISBROKEN;
 396                 errno = EINVAL;
 397                 goto out;
 398         }
 399
 400         ret = 0;
 401
 402 out:
 403         save_errno = errno;
 404         strbuf_release(&sb_path);
 405         strbuf_release(&sb_contents);
 406         errno = save_errno;
 407         return ret;
 408 }
 409
 410 static void unlock_ref(struct ref_lock *lock)
 411 {
 412         rollback_lock_file(&lock->lk);
 413         free(lock->ref_name);
 414         free(lock);
 415 }
 416
 417 /*
 418  * Lock refname, without following symrefs, and set *lock_p to point
 419  * at a newly-allocated lock object. Fill in lock->old_oid, referent,
 420  * and type similarly to read_raw_ref().
 421  *
 422  * The caller must verify that refname is a "safe" reference name (in
 423  * the sense of refname_is_safe()) before calling this function.
 424  *
 425  * If the reference doesn't already exist, verify that refname doesn't
 426  * have a D/F conflict with any existing references. extras and skip
 427  * are passed to refs_verify_refname_available() for this check.
 428  *
 429  * If mustexist is not set and the reference is not found or is
 430  * broken, lock the reference anyway but clear sha1.
 431  *
 432  * Return 0 on success. On failure, write an error message to err and
 433  * return TRANSACTION_NAME_CONFLICT or TRANSACTION_GENERIC_ERROR.
 434  *
 435  * Implementation note: This function is basically
 436  *
 437  *     lock reference
 438  *     read_raw_ref()
 439  *
 440  * but it includes a lot more code to
 441  * - Deal with possible races with other processes
 442  * - Avoid calling refs_verify_refname_available() when it can be
 443  *   avoided, namely if we were successfully able to read the ref
 444  * - Generate informative error messages in the case of failure
 445  */
 446 static int lock_raw_ref(struct files_ref_store *refs,
 447                         const char *refname, int mustexist,
 448                         const struct string_list *extras,
 449                         const struct string_list *skip,
 450                         struct ref_lock **lock_p,
 451                         struct strbuf *referent,
 452                         unsigned int *type,
 453                         struct strbuf *err)
 454 {
 455         struct ref_lock *lock;
 456         struct strbuf ref_file = STRBUF_INIT;
 457         int attempts_remaining = 3;
 458         int ret = TRANSACTION_GENERIC_ERROR;
 459
 460         assert(err);
 461         files_assert_main_repository(refs, "lock_raw_ref");
 462
 463         *type = 0;
 464
 465         /* First lock the file so it can't change out from under us. */
 466
 467         *lock_p = lock = xcalloc(1, sizeof(*lock));
 468
 469         lock->ref_name = xstrdup(refname);
 470         files_ref_path(refs, &ref_file, refname);
 471
 472 retry:
 473         switch (safe_create_leading_directories(ref_file.buf)) {
 474         case SCLD_OK:
 475                 break; /* success */
 476         case SCLD_EXISTS:
 477                 /*
 478                  * Suppose refname is "refs/foo/bar". We just failed
 479                  * to create the containing directory, "refs/foo",
 480                  * because there was a non-directory in the way. This
 481                  * indicates a D/F conflict, probably because of
 482                  * another reference such as "refs/foo". There is no
 483                  * reason to expect this error to be transitory.
 484                  */
 485                 if (refs_verify_refname_available(&refs->base, refname,
 486                                                   extras, skip, err)) {
 487                         if (mustexist) {
 488                                 /*
 489                                  * To the user the relevant error is
 490                                  * that the "mustexist" reference is
 491                                  * missing:
 492                                  */
 493                                 strbuf_reset(err);
 494                                 strbuf_addf(err, "unable to resolve reference '%s'",
 495                                             refname);
 496                         } else {
 497                                 /*
 498                                  * The error message set by
 499                                  * refs_verify_refname_available() is
 500                                  * OK.
 501                                  */
 502                                 ret = TRANSACTION_NAME_CONFLICT;
 503                         }
 504                 } else {
 505                         /*
 506                          * The file that is in the way isn't a loose
 507                          * reference. Report it as a low-level
 508                          * failure.
 509                          */
 510                         strbuf_addf(err, "unable to create lock file %s.lock; "
 511                                     "non-directory in the way",
 512                                     ref_file.buf);
 513                 }
 514                 goto error_return;
 515         case SCLD_VANISHED:
 516                 /* Maybe another process was tidying up. Try again. */
 517                 if (--attempts_remaining > 0)
 518                         goto retry;
 519                 /* fall through */
 520         default:
 521                 strbuf_addf(err, "unable to create directory for %s",
 522                             ref_file.buf);
 523                 goto error_return;
 524         }
 525
 526         if (hold_lock_file_for_update_timeout(
 527                             &lock->lk, ref_file.buf, LOCK_NO_DEREF,
 528                             get_files_ref_lock_timeout_ms()) < 0) {
 529                 if (errno == ENOENT && --attempts_remaining > 0) {
 530                         /*
 531                          * Maybe somebody just deleted one of the
 532                          * directories leading to ref_file.  Try
 533                          * again:
 534                          */
 535                         goto retry;
 536                 } else {
 537                         unable_to_lock_message(ref_file.buf, errno, err);
 538                         goto error_return;
 539                 }
 540         }
 541
 542         /*
 543          * Now we hold the lock and can read the reference without
 544          * fear that its value will change.
 545          */
 546
 547         if (files_read_raw_ref(&refs->base, refname,
 548                                lock->old_oid.hash, referent, type)) {
 549                 if (errno == ENOENT) {
 550                         if (mustexist) {
 551                                 /* Garden variety missing reference. */
 552                                 strbuf_addf(err, "unable to resolve reference '%s'",
 553                                             refname);
 554                                 goto error_return;
 555                         } else {
 556                                 /*
 557                                  * Reference is missing, but that's OK. We
 558                                  * know that there is not a conflict with
 559                                  * another loose reference because
 560                                  * (supposing that we are trying to lock
 561                                  * reference "refs/foo/bar"):
 562                                  *
 563                                  * - We were successfully able to create
 564                                  *   the lockfile refs/foo/bar.lock, so we
 565                                  *   know there cannot be a loose reference
 566                                  *   named "refs/foo".
 567                                  *
 568                                  * - We got ENOENT and not EISDIR, so we
 569                                  *   know that there cannot be a loose
 570                                  *   reference named "refs/foo/bar/baz".
 571                                  */
 572                         }
 573                 } else if (errno == EISDIR) {
 574                         /*
 575                          * There is a directory in the way. It might have
 576                          * contained references that have been deleted. If
 577                          * we don't require that the reference already
 578                          * exists, try to remove the directory so that it
 579                          * doesn't cause trouble when we want to rename the
 580                          * lockfile into place later.
 581                          */
 582                         if (mustexist) {
 583                                 /* Garden variety missing reference. */
 584                                 strbuf_addf(err, "unable to resolve reference '%s'",
 585                                             refname);
 586                                 goto error_return;
 587                         } else if (remove_dir_recursively(&ref_file,
 588                                                           REMOVE_DIR_EMPTY_ONLY)) {
 589                                 if (refs_verify_refname_available(
 590                                                     &refs->base, refname,
 591                                                     extras, skip, err)) {
 592                                         /*
 593                                          * The error message set by
 594                                          * verify_refname_available() is OK.
 595                                          */
 596                                         ret = TRANSACTION_NAME_CONFLICT;
 597                                         goto error_return;
 598                                 } else {
 599                                         /*
 600                                          * We can't delete the directory,
 601                                          * but we also don't know of any
 602                                          * references that it should
 603                                          * contain.
 604                                          */
 605                                         strbuf_addf(err, "there is a non-empty directory '%s' "
 606                                                     "blocking reference '%s'",
 607                                                     ref_file.buf, refname);
 608                                         goto error_return;
 609                                 }
 610                         }
 611                 } else if (errno == EINVAL && (*type & REF_ISBROKEN)) {
 612                         strbuf_addf(err, "unable to resolve reference '%s': "
 613                                     "reference broken", refname);
 614                         goto error_return;
 615                 } else {
 616                         strbuf_addf(err, "unable to resolve reference '%s': %s",
 617                                     refname, strerror(errno));
 618                         goto error_return;
 619                 }
 620
 621                 /*
 622                  * If the ref did not exist and we are creating it,
 623                  * make sure there is no existing packed ref that
 624                  * conflicts with refname:
 625                  */
 626                 if (refs_verify_refname_available(
 627                                     refs->packed_ref_store, refname,
 628                                     extras, skip, err))
 629                         goto error_return;
 630         }
 631
 632         ret = 0;
 633         goto out;
 634
 635 error_return:
 636         unlock_ref(lock);
 637         *lock_p = NULL;
 638
 639 out:
 640         strbuf_release(&ref_file);
 641         return ret;
 642 }
 643
 644 static int files_peel_ref(struct ref_store *ref_store,
 645                           const char *refname, unsigned char *sha1)
 646 {
 647         struct files_ref_store *refs =
 648                 files_downcast(ref_store, REF_STORE_READ | REF_STORE_ODB,
 649                                "peel_ref");
 650         int flag;
 651         unsigned char base[20];
 652
 653         if (current_ref_iter && current_ref_iter->refname == refname) {
 654                 struct object_id peeled;
 655
 656                 if (ref_iterator_peel(current_ref_iter, &peeled))
 657                         return -1;
 658                 hashcpy(sha1, peeled.hash);
 659                 return 0;
 660         }
 661
 662         if (refs_read_ref_full(ref_store, refname,
 663                                RESOLVE_REF_READING, base, &flag))
 664                 return -1;
 665
 666         /*
 667          * If the reference is packed, read its ref_entry from the
 668          * cache in the hope that we already know its peeled value.
 669          * We only try this optimization on packed references because
 670          * (a) forcing the filling of the loose reference cache could
 671          * be expensive and (b) loose references anyway usually do not
 672          * have REF_KNOWS_PEELED.
 673          */
 674         if (flag & REF_ISPACKED &&
 675             !refs_peel_ref(refs->packed_ref_store, refname, sha1))
 676                 return 0;
 677
 678         return peel_object(base, sha1);
 679 }
 680
 681 struct files_ref_iterator {
 682         struct ref_iterator base;
 683
 684         struct ref_iterator *iter0;
 685         unsigned int flags;
 686 };
 687
 688 static int files_ref_iterator_advance(struct ref_iterator *ref_iterator)
 689 {
 690         struct files_ref_iterator *iter =
 691                 (struct files_ref_iterator *)ref_iterator;
 692         int ok;
 693
 694         while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) {
 695                 if (iter->flags & DO_FOR_EACH_PER_WORKTREE_ONLY &&
 696                     ref_type(iter->iter0->refname) != REF_TYPE_PER_WORKTREE)
 697                         continue;
 698
 699                 if (!(iter->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
 700                     !ref_resolves_to_object(iter->iter0->refname,
 701                                             iter->iter0->oid,
 702                                             iter->iter0->flags))
 703                         continue;
 704
 705                 iter->base.refname = iter->iter0->refname;
 706                 iter->base.oid = iter->iter0->oid;
 707                 iter->base.flags = iter->iter0->flags;
 708                 return ITER_OK;
 709         }
 710
 711         iter->iter0 = NULL;
 712         if (ref_iterator_abort(ref_iterator) != ITER_DONE)
 713                 ok = ITER_ERROR;
 714
 715         return ok;
 716 }
 717
 718 static int files_ref_iterator_peel(struct ref_iterator *ref_iterator,
 719                                    struct object_id *peeled)
 720 {
 721         struct files_ref_iterator *iter =
 722                 (struct files_ref_iterator *)ref_iterator;
 723
 724         return ref_iterator_peel(iter->iter0, peeled);
 725 }
 726
 727 static int files_ref_iterator_abort(struct ref_iterator *ref_iterator)
 728 {
 729         struct files_ref_iterator *iter =
 730                 (struct files_ref_iterator *)ref_iterator;
 731         int ok = ITER_DONE;
 732
 733         if (iter->iter0)
 734                 ok = ref_iterator_abort(iter->iter0);
 735
 736         base_ref_iterator_free(ref_iterator);
 737         return ok;
 738 }
 739
 740 static struct ref_iterator_vtable files_ref_iterator_vtable = {
 741         files_ref_iterator_advance,
 742         files_ref_iterator_peel,
 743         files_ref_iterator_abort
 744 };
 745
 746 static struct ref_iterator *files_ref_iterator_begin(
 747                 struct ref_store *ref_store,
 748                 const char *prefix, unsigned int flags)
 749 {
 750         struct files_ref_store *refs;
 751         struct ref_iterator *loose_iter, *packed_iter;
 752         struct files_ref_iterator *iter;
 753         struct ref_iterator *ref_iterator;
 754         unsigned int required_flags = REF_STORE_READ;
 755
 756         if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN))
 757                 required_flags |= REF_STORE_ODB;
 758
 759         refs = files_downcast(ref_store, required_flags, "ref_iterator_begin");
 760
 761         iter = xcalloc(1, sizeof(*iter));
 762         ref_iterator = &iter->base;
 763         base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable);
 764
 765         /*
 766          * We must make sure that all loose refs are read before
 767          * accessing the packed-refs file; this avoids a race
 768          * condition if loose refs are migrated to the packed-refs
 769          * file by a simultaneous process, but our in-memory view is
 770          * from before the migration. We ensure this as follows:
 771          * First, we call start the loose refs iteration with its
 772          * `prime_ref` argument set to true. This causes the loose
 773          * references in the subtree to be pre-read into the cache.
 774          * (If they've already been read, that's OK; we only need to
 775          * guarantee that they're read before the packed refs, not
 776          * *how much* before.) After that, we call
 777          * packed_ref_iterator_begin(), which internally checks
 778          * whether the packed-ref cache is up to date with what is on
 779          * disk, and re-reads it if not.
 780          */
 781
 782         loose_iter = cache_ref_iterator_begin(get_loose_ref_cache(refs),
 783                                               prefix, 1);
 784
 785         /*
 786          * The packed-refs file might contain broken references, for
 787          * example an old version of a reference that points at an
 788          * object that has since been garbage-collected. This is OK as
 789          * long as there is a corresponding loose reference that
 790          * overrides it, and we don't want to emit an error message in
 791          * this case. So ask the packed_ref_store for all of its
 792          * references, and (if needed) do our own check for broken
 793          * ones in files_ref_iterator_advance(), after we have merged
 794          * the packed and loose references.
 795          */
 796         packed_iter = refs_ref_iterator_begin(
 797                         refs->packed_ref_store, prefix, 0,
 798                         DO_FOR_EACH_INCLUDE_BROKEN);
 799
 800         iter->iter0 = overlay_ref_iterator_begin(loose_iter, packed_iter);
 801         iter->flags = flags;
 802
 803         return ref_iterator;
 804 }
 805
 806 /*
 807  * Verify that the reference locked by lock has the value old_sha1.
 808  * Fail if the reference doesn't exist and mustexist is set. Return 0
 809  * on success. On error, write an error message to err, set errno, and
 810  * return a negative value.
 811  */
 812 static int verify_lock(struct ref_store *ref_store, struct ref_lock *lock,
 813                        const unsigned char *old_sha1, int mustexist,
 814                        struct strbuf *err)
 815 {
 816         assert(err);
 817
 818         if (refs_read_ref_full(ref_store, lock->ref_name,
 819                                mustexist ? RESOLVE_REF_READING : 0,
 820                                lock->old_oid.hash, NULL)) {
 821                 if (old_sha1) {
 822                         int save_errno = errno;
 823                         strbuf_addf(err, "can't verify ref '%s'", lock->ref_name);
 824                         errno = save_errno;
 825                         return -1;
 826                 } else {
 827                         oidclr(&lock->old_oid);
 828                         return 0;
 829                 }
 830         }
 831         if (old_sha1 && hashcmp(lock->old_oid.hash, old_sha1)) {
 832                 strbuf_addf(err, "ref '%s' is at %s but expected %s",
 833                             lock->ref_name,
 834                             oid_to_hex(&lock->old_oid),
 835                             sha1_to_hex(old_sha1));
 836                 errno = EBUSY;
 837                 return -1;
 838         }
 839         return 0;
 840 }
 841
 842 static int remove_empty_directories(struct strbuf *path)
 843 {
 844         /*
 845          * we want to create a file but there is a directory there;
 846          * if that is an empty directory (or a directory that contains
 847          * only empty directories), remove them.
 848          */
 849         return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY);
 850 }
 851
 852 static int create_reflock(const char *path, void *cb)
 853 {
 854         struct lock_file *lk = cb;
 855
 856         return hold_lock_file_for_update_timeout(
 857                         lk, path, LOCK_NO_DEREF,
 858                         get_files_ref_lock_timeout_ms()) < 0 ? -1 : 0;
 859 }
 860
 861 /*
 862  * Locks a ref returning the lock on success and NULL on failure.
 863  * On failure errno is set to something meaningful.
 864  */
 865 static struct ref_lock *lock_ref_sha1_basic(struct files_ref_store *refs,
 866                                             const char *refname,
 867                                             const unsigned char *old_sha1,
 868                                             const struct string_list *extras,
 869                                             const struct string_list *skip,
 870                                             unsigned int flags, int *type,
 871                                             struct strbuf *err)
 872 {
 873         struct strbuf ref_file = STRBUF_INIT;
 874         struct ref_lock *lock;
 875         int last_errno = 0;
 876         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
 877         int resolve_flags = RESOLVE_REF_NO_RECURSE;
 878         int resolved;
 879
 880         files_assert_main_repository(refs, "lock_ref_sha1_basic");
 881         assert(err);
 882
 883         lock = xcalloc(1, sizeof(struct ref_lock));
 884
 885         if (mustexist)
 886                 resolve_flags |= RESOLVE_REF_READING;
 887         if (flags & REF_DELETING)
 888                 resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME;
 889
 890         files_ref_path(refs, &ref_file, refname);
 891         resolved = !!refs_resolve_ref_unsafe(&refs->base,
 892                                              refname, resolve_flags,
 893                                              lock->old_oid.hash, type);
 894         if (!resolved && errno == EISDIR) {
 895                 /*
 896                  * we are trying to lock foo but we used to
 897                  * have foo/bar which now does not exist;
 898                  * it is normal for the empty directory 'foo'
 899                  * to remain.
 900                  */
 901                 if (remove_empty_directories(&ref_file)) {
 902                         last_errno = errno;
 903                         if (!refs_verify_refname_available(
 904                                             &refs->base,
 905                                             refname, extras, skip, err))
 906                                 strbuf_addf(err, "there are still refs under '%s'",
 907                                             refname);
 908                         goto error_return;
 909                 }
 910                 resolved = !!refs_resolve_ref_unsafe(&refs->base,
 911                                                      refname, resolve_flags,
 912                                                      lock->old_oid.hash, type);
 913         }
 914         if (!resolved) {
 915                 last_errno = errno;
 916                 if (last_errno != ENOTDIR ||
 917                     !refs_verify_refname_available(&refs->base, refname,
 918                                                    extras, skip, err))
 919                         strbuf_addf(err, "unable to resolve reference '%s': %s",
 920                                     refname, strerror(last_errno));
 921
 922                 goto error_return;
 923         }
 924
 925         /*
 926          * If the ref did not exist and we are creating it, make sure
 927          * there is no existing packed ref whose name begins with our
 928          * refname, nor a packed ref whose name is a proper prefix of
 929          * our refname.
 930          */
 931         if (is_null_oid(&lock->old_oid) &&
 932             refs_verify_refname_available(refs->packed_ref_store, refname,
 933                                           extras, skip, err)) {
 934                 last_errno = ENOTDIR;
 935                 goto error_return;
 936         }
 937
 938         lock->ref_name = xstrdup(refname);
 939
 940         if (raceproof_create_file(ref_file.buf, create_reflock, &lock->lk)) {
 941                 last_errno = errno;
 942                 unable_to_lock_message(ref_file.buf, errno, err);
 943                 goto error_return;
 944         }
 945
 946         if (verify_lock(&refs->base, lock, old_sha1, mustexist, err)) {
 947                 last_errno = errno;
 948                 goto error_return;
 949         }
 950         goto out;
 951
 952  error_return:
 953         unlock_ref(lock);
 954         lock = NULL;
 955
 956  out:
 957         strbuf_release(&ref_file);
 958         errno = last_errno;
 959         return lock;
 960 }
 961
 962 struct ref_to_prune {
 963         struct ref_to_prune *next;
 964         unsigned char sha1[20];
 965         char name[FLEX_ARRAY];
 966 };
 967
 968 enum {
 969         REMOVE_EMPTY_PARENTS_REF = 0x01,
 970         REMOVE_EMPTY_PARENTS_REFLOG = 0x02
 971 };
 972
 973 /*
 974  * Remove empty parent directories associated with the specified
 975  * reference and/or its reflog, but spare [logs/]refs/ and immediate
 976  * subdirs. flags is a combination of REMOVE_EMPTY_PARENTS_REF and/or
 977  * REMOVE_EMPTY_PARENTS_REFLOG.
 978  */
 979 static void try_remove_empty_parents(struct files_ref_store *refs,
 980                                      const char *refname,
 981                                      unsigned int flags)
 982 {
 983         struct strbuf buf = STRBUF_INIT;
 984         struct strbuf sb = STRBUF_INIT;
 985         char *p, *q;
 986         int i;
 987
 988         strbuf_addstr(&buf, refname);
 989         p = buf.buf;
 990         for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
 991                 while (*p && *p != '/')
 992                         p++;
 993                 /* tolerate duplicate slashes; see check_refname_format() */
 994                 while (*p == '/')
 995                         p++;
 996         }
 997         q = buf.buf + buf.len;
 998         while (flags & (REMOVE_EMPTY_PARENTS_REF | REMOVE_EMPTY_PARENTS_REFLOG)) {
 999                 while (q > p && *q != '/')
1000                         q--;
1001                 while (q > p && *(q-1) == '/')
1002                         q--;
1003                 if (q == p)
1004                         break;
1005                 strbuf_setlen(&buf, q - buf.buf);
1006
1007                 strbuf_reset(&sb);
1008                 files_ref_path(refs, &sb, buf.buf);
1009                 if ((flags & REMOVE_EMPTY_PARENTS_REF) && rmdir(sb.buf))
1010                         flags &= ~REMOVE_EMPTY_PARENTS_REF;
1011
1012                 strbuf_reset(&sb);
1013                 files_reflog_path(refs, &sb, buf.buf);
1014                 if ((flags & REMOVE_EMPTY_PARENTS_REFLOG) && rmdir(sb.buf))
1015                         flags &= ~REMOVE_EMPTY_PARENTS_REFLOG;
1016         }
1017         strbuf_release(&buf);
1018         strbuf_release(&sb);
1019 }
1020
1021 /* make sure nobody touched the ref, and unlink */
1022 static void prune_ref(struct files_ref_store *refs, struct ref_to_prune *r)
1023 {
1024         struct ref_transaction *transaction;
1025         struct strbuf err = STRBUF_INIT;
1026
1027         if (check_refname_format(r->name, 0))
1028                 return;
1029
1030         transaction = ref_store_transaction_begin(&refs->base, &err);
1031         if (!transaction ||
1032             ref_transaction_delete(transaction, r->name, r->sha1,
1033                                    REF_ISPRUNING | REF_NODEREF, NULL, &err) ||
1034             ref_transaction_commit(transaction, &err)) {
1035                 ref_transaction_free(transaction);
1036                 error("%s", err.buf);
1037                 strbuf_release(&err);
1038                 return;
1039         }
1040         ref_transaction_free(transaction);
1041         strbuf_release(&err);
1042 }
1043
1044 /*
1045  * Prune the loose versions of the references in the linked list
1046  * `*refs_to_prune`, freeing the entries in the list as we go.
1047  */
1048 static void prune_refs(struct files_ref_store *refs, struct ref_to_prune **refs_to_prune)
1049 {
1050         while (*refs_to_prune) {
1051                 struct ref_to_prune *r = *refs_to_prune;
1052                 *refs_to_prune = r->next;
1053                 prune_ref(refs, r);
1054                 free(r);
1055         }
1056 }
1057
1058 /*
1059  * Return true if the specified reference should be packed.
1060  */
1061 static int should_pack_ref(const char *refname,
1062                            const struct object_id *oid, unsigned int ref_flags,
1063                            unsigned int pack_flags)
1064 {
1065         /* Do not pack per-worktree refs: */
1066         if (ref_type(refname) != REF_TYPE_NORMAL)
1067                 return 0;
1068
1069         /* Do not pack non-tags unless PACK_REFS_ALL is set: */
1070         if (!(pack_flags & PACK_REFS_ALL) && !starts_with(refname, "refs/tags/"))
1071                 return 0;
1072
1073         /* Do not pack symbolic refs: */
1074         if (ref_flags & REF_ISSYMREF)
1075                 return 0;
1076
1077         /* Do not pack broken refs: */
1078         if (!ref_resolves_to_object(refname, oid, ref_flags))
1079                 return 0;
1080
1081         return 1;
1082 }
1083
1084 static int files_pack_refs(struct ref_store *ref_store, unsigned int flags)
1085 {
1086         struct files_ref_store *refs =
1087                 files_downcast(ref_store, REF_STORE_WRITE | REF_STORE_ODB,
1088                                "pack_refs");
1089         struct ref_iterator *iter;
1090         int ok;
1091         struct ref_to_prune *refs_to_prune = NULL;
1092         struct strbuf err = STRBUF_INIT;
1093         struct ref_transaction *transaction;
1094
1095         transaction = ref_store_transaction_begin(refs->packed_ref_store, &err);
1096         if (!transaction)
1097                 return -1;
1098
1099         packed_refs_lock(refs->packed_ref_store, LOCK_DIE_ON_ERROR, &err);
1100
1101         iter = cache_ref_iterator_begin(get_loose_ref_cache(refs), NULL, 0);
1102         while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
1103                 /*
1104                  * If the loose reference can be packed, add an entry
1105                  * in the packed ref cache. If the reference should be
1106                  * pruned, also add it to refs_to_prune.
1107                  */
1108                 if (!should_pack_ref(iter->refname, iter->oid, iter->flags,
1109                                      flags))
1110                         continue;
1111
1112                 /*
1113                  * Add a reference creation for this reference to the
1114                  * packed-refs transaction:
1115                  */
1116                 if (ref_transaction_update(transaction, iter->refname,
1117                                            iter->oid->hash, NULL,
1118                                            REF_NODEREF, NULL, &err))
1119                         die("failure preparing to create packed reference %s: %s",
1120                             iter->refname, err.buf);
1121
1122                 /* Schedule the loose reference for pruning if requested. */
1123                 if ((flags & PACK_REFS_PRUNE)) {
1124                         struct ref_to_prune *n;
1125                         FLEX_ALLOC_STR(n, name, iter->refname);
1126                         hashcpy(n->sha1, iter->oid->hash);
1127                         n->next = refs_to_prune;
1128                         refs_to_prune = n;
1129                 }
1130         }
1131         if (ok != ITER_DONE)
1132                 die("error while iterating over references");
1133
1134         if (ref_transaction_commit(transaction, &err))
1135                 die("unable to write new packed-refs: %s", err.buf);
1136
1137         ref_transaction_free(transaction);
1138
1139         packed_refs_unlock(refs->packed_ref_store);
1140
1141         prune_refs(refs, &refs_to_prune);
1142         strbuf_release(&err);
1143         return 0;
1144 }
1145
1146 static int files_delete_refs(struct ref_store *ref_store, const char *msg,
1147                              struct string_list *refnames, unsigned int flags)
1148 {
1149         struct files_ref_store *refs =
1150                 files_downcast(ref_store, REF_STORE_WRITE, "delete_refs");
1151         struct strbuf err = STRBUF_INIT;
1152         int i, result = 0;
1153
1154         if (!refnames->nr)
1155                 return 0;
1156
1157         if (packed_refs_lock(refs->packed_ref_store, 0, &err))
1158                 goto error;
1159
1160         if (refs_delete_refs(refs->packed_ref_store, msg, refnames, flags)) {
1161                 packed_refs_unlock(refs->packed_ref_store);
1162                 goto error;
1163         }
1164
1165         packed_refs_unlock(refs->packed_ref_store);
1166
1167         for (i = 0; i < refnames->nr; i++) {
1168                 const char *refname = refnames->items[i].string;
1169
1170                 if (refs_delete_ref(&refs->base, msg, refname, NULL, flags))
1171                         result |= error(_("could not remove reference %s"), refname);
1172         }
1173
1174         strbuf_release(&err);
1175         return result;
1176
1177 error:
1178         /*
1179          * If we failed to rewrite the packed-refs file, then it is
1180          * unsafe to try to remove loose refs, because doing so might
1181          * expose an obsolete packed value for a reference that might
1182          * even point at an object that has been garbage collected.
1183          */
1184         if (refnames->nr == 1)
1185                 error(_("could not delete reference %s: %s"),
1186                       refnames->items[0].string, err.buf);
1187         else
1188                 error(_("could not delete references: %s"), err.buf);
1189
1190         strbuf_release(&err);
1191         return -1;
1192 }
1193
1194 /*
1195  * People using contrib's git-new-workdir have .git/logs/refs ->
1196  * /some/other/path/.git/logs/refs, and that may live on another device.
1197  *
1198  * IOW, to avoid cross device rename errors, the temporary renamed log must
1199  * live into logs/refs.
1200  */
1201 #define TMP_RENAMED_LOG  "refs/.tmp-renamed-log"
1202
1203 struct rename_cb {
1204         const char *tmp_renamed_log;
1205         int true_errno;
1206 };
1207
1208 static int rename_tmp_log_callback(const char *path, void *cb_data)
1209 {
1210         struct rename_cb *cb = cb_data;
1211
1212         if (rename(cb->tmp_renamed_log, path)) {
1213                 /*
1214                  * rename(a, b) when b is an existing directory ought
1215                  * to result in ISDIR, but Solaris 5.8 gives ENOTDIR.
1216                  * Sheesh. Record the true errno for error reporting,
1217                  * but report EISDIR to raceproof_create_file() so
1218                  * that it knows to retry.
1219                  */
1220                 cb->true_errno = errno;
1221                 if (errno == ENOTDIR)
1222                         errno = EISDIR;
1223                 return -1;
1224         } else {
1225                 return 0;
1226         }
1227 }
1228
1229 static int rename_tmp_log(struct files_ref_store *refs, const char *newrefname)
1230 {
1231         struct strbuf path = STRBUF_INIT;
1232         struct strbuf tmp = STRBUF_INIT;
1233         struct rename_cb cb;
1234         int ret;
1235
1236         files_reflog_path(refs, &path, newrefname);
1237         files_reflog_path(refs, &tmp, TMP_RENAMED_LOG);
1238         cb.tmp_renamed_log = tmp.buf;
1239         ret = raceproof_create_file(path.buf, rename_tmp_log_callback, &cb);
1240         if (ret) {
1241                 if (errno == EISDIR)
1242                         error("directory not empty: %s", path.buf);
1243                 else
1244                         error("unable to move logfile %s to %s: %s",
1245                               tmp.buf, path.buf,
1246                               strerror(cb.true_errno));
1247         }
1248
1249         strbuf_release(&path);
1250         strbuf_release(&tmp);
1251         return ret;
1252 }
1253
1254 static int write_ref_to_lockfile(struct ref_lock *lock,
1255                                  const struct object_id *oid, struct strbuf *err);
1256 static int commit_ref_update(struct files_ref_store *refs,
1257                              struct ref_lock *lock,
1258                              const struct object_id *oid, const char *logmsg,
1259                              struct strbuf *err);
1260
1261 static int files_rename_ref(struct ref_store *ref_store,
1262                             const char *oldrefname, const char *newrefname,
1263                             const char *logmsg)
1264 {
1265         struct files_ref_store *refs =
1266                 files_downcast(ref_store, REF_STORE_WRITE, "rename_ref");
1267         struct object_id oid, orig_oid;
1268         int flag = 0, logmoved = 0;
1269         struct ref_lock *lock;
1270         struct stat loginfo;
1271         struct strbuf sb_oldref = STRBUF_INIT;
1272         struct strbuf sb_newref = STRBUF_INIT;
1273         struct strbuf tmp_renamed_log = STRBUF_INIT;
1274         int log, ret;
1275         struct strbuf err = STRBUF_INIT;
1276
1277         files_reflog_path(refs, &sb_oldref, oldrefname);
1278         files_reflog_path(refs, &sb_newref, newrefname);
1279         files_reflog_path(refs, &tmp_renamed_log, TMP_RENAMED_LOG);
1280
1281         log = !lstat(sb_oldref.buf, &loginfo);
1282         if (log && S_ISLNK(loginfo.st_mode)) {
1283                 ret = error("reflog for %s is a symlink", oldrefname);
1284                 goto out;
1285         }
1286
1287         if (!refs_resolve_ref_unsafe(&refs->base, oldrefname,
1288                                      RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
1289                                 orig_oid.hash, &flag)) {
1290                 ret = error("refname %s not found", oldrefname);
1291                 goto out;
1292         }
1293
1294         if (flag & REF_ISSYMREF) {
1295                 ret = error("refname %s is a symbolic ref, renaming it is not supported",
1296                             oldrefname);
1297                 goto out;
1298         }
1299         if (!refs_rename_ref_available(&refs->base, oldrefname, newrefname)) {
1300                 ret = 1;
1301                 goto out;
1302         }
1303
1304         if (log && rename(sb_oldref.buf, tmp_renamed_log.buf)) {
1305                 ret = error("unable to move logfile logs/%s to logs/"TMP_RENAMED_LOG": %s",
1306                             oldrefname, strerror(errno));
1307                 goto out;
1308         }
1309
1310         if (refs_delete_ref(&refs->base, logmsg, oldrefname,
1311                             orig_oid.hash, REF_NODEREF)) {
1312                 error("unable to delete old %s", oldrefname);
1313                 goto rollback;
1314         }
1315
1316         /*
1317          * Since we are doing a shallow lookup, oid is not the
1318          * correct value to pass to delete_ref as old_oid. But that
1319          * doesn't matter, because an old_oid check wouldn't add to
1320          * the safety anyway; we want to delete the reference whatever
1321          * its current value.
1322          */
1323         if (!refs_read_ref_full(&refs->base, newrefname,
1324                                 RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
1325                                 oid.hash, NULL) &&
1326             refs_delete_ref(&refs->base, NULL, newrefname,
1327                             NULL, REF_NODEREF)) {
1328                 if (errno == EISDIR) {
1329                         struct strbuf path = STRBUF_INIT;
1330                         int result;
1331
1332                         files_ref_path(refs, &path, newrefname);
1333                         result = remove_empty_directories(&path);
1334                         strbuf_release(&path);
1335
1336                         if (result) {
1337                                 error("Directory not empty: %s", newrefname);
1338                                 goto rollback;
1339                         }
1340                 } else {
1341                         error("unable to delete existing %s", newrefname);
1342                         goto rollback;
1343                 }
1344         }
1345
1346         if (log && rename_tmp_log(refs, newrefname))
1347                 goto rollback;
1348
1349         logmoved = log;
1350
1351         lock = lock_ref_sha1_basic(refs, newrefname, NULL, NULL, NULL,
1352                                    REF_NODEREF, NULL, &err);
1353         if (!lock) {
1354                 error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
1355                 strbuf_release(&err);
1356                 goto rollback;
1357         }
1358         oidcpy(&lock->old_oid, &orig_oid);
1359
1360         if (write_ref_to_lockfile(lock, &orig_oid, &err) ||
1361             commit_ref_update(refs, lock, &orig_oid, logmsg, &err)) {
1362                 error("unable to write current sha1 into %s: %s", newrefname, err.buf);
1363                 strbuf_release(&err);
1364                 goto rollback;
1365         }
1366
1367         ret = 0;
1368         goto out;
1369
1370  rollback:
1371         lock = lock_ref_sha1_basic(refs, oldrefname, NULL, NULL, NULL,
1372                                    REF_NODEREF, NULL, &err);
1373         if (!lock) {
1374                 error("unable to lock %s for rollback: %s", oldrefname, err.buf);
1375                 strbuf_release(&err);
1376                 goto rollbacklog;
1377         }
1378
1379         flag = log_all_ref_updates;
1380         log_all_ref_updates = LOG_REFS_NONE;
1381         if (write_ref_to_lockfile(lock, &orig_oid, &err) ||
1382             commit_ref_update(refs, lock, &orig_oid, NULL, &err)) {
1383                 error("unable to write current sha1 into %s: %s", oldrefname, err.buf);
1384                 strbuf_release(&err);
1385         }
1386         log_all_ref_updates = flag;
1387
1388  rollbacklog:
1389         if (logmoved && rename(sb_newref.buf, sb_oldref.buf))
1390                 error("unable to restore logfile %s from %s: %s",
1391                         oldrefname, newrefname, strerror(errno));
1392         if (!logmoved && log &&
1393             rename(tmp_renamed_log.buf, sb_oldref.buf))
1394                 error("unable to restore logfile %s from logs/"TMP_RENAMED_LOG": %s",
1395                         oldrefname, strerror(errno));
1396         ret = 1;
1397  out:
1398         strbuf_release(&sb_newref);
1399         strbuf_release(&sb_oldref);
1400         strbuf_release(&tmp_renamed_log);
1401
1402         return ret;
1403 }
1404
1405 static int close_ref_gently(struct ref_lock *lock)
1406 {
1407         if (close_lock_file_gently(&lock->lk))
1408                 return -1;
1409         return 0;
1410 }
1411
1412 static int commit_ref(struct ref_lock *lock)
1413 {
1414         char *path = get_locked_file_path(&lock->lk);
1415         struct stat st;
1416
1417         if (!lstat(path, &st) && S_ISDIR(st.st_mode)) {
1418                 /*
1419                  * There is a directory at the path we want to rename
1420                  * the lockfile to. Hopefully it is empty; try to
1421                  * delete it.
1422                  */
1423                 size_t len = strlen(path);
1424                 struct strbuf sb_path = STRBUF_INIT;
1425
1426                 strbuf_attach(&sb_path, path, len, len);
1427
1428                 /*
1429                  * If this fails, commit_lock_file() will also fail
1430                  * and will report the problem.
1431                  */
1432                 remove_empty_directories(&sb_path);
1433                 strbuf_release(&sb_path);
1434         } else {
1435                 free(path);
1436         }
1437
1438         if (commit_lock_file(&lock->lk))
1439                 return -1;
1440         return 0;
1441 }
1442
1443 static int open_or_create_logfile(const char *path, void *cb)
1444 {
1445         int *fd = cb;
1446
1447         *fd = open(path, O_APPEND | O_WRONLY | O_CREAT, 0666);
1448         return (*fd < 0) ? -1 : 0;
1449 }
1450
1451 /*
1452  * Create a reflog for a ref. If force_create = 0, only create the
1453  * reflog for certain refs (those for which should_autocreate_reflog
1454  * returns non-zero). Otherwise, create it regardless of the reference
1455  * name. If the logfile already existed or was created, return 0 and
1456  * set *logfd to the file descriptor opened for appending to the file.
1457  * If no logfile exists and we decided not to create one, return 0 and
1458  * set *logfd to -1. On failure, fill in *err, set *logfd to -1, and
1459  * return -1.
1460  */
1461 static int log_ref_setup(struct files_ref_store *refs,
1462                          const char *refname, int force_create,
1463                          int *logfd, struct strbuf *err)
1464 {
1465         struct strbuf logfile_sb = STRBUF_INIT;
1466         char *logfile;
1467
1468         files_reflog_path(refs, &logfile_sb, refname);
1469         logfile = strbuf_detach(&logfile_sb, NULL);
1470
1471         if (force_create || should_autocreate_reflog(refname)) {
1472                 if (raceproof_create_file(logfile, open_or_create_logfile, logfd)) {
1473                         if (errno == ENOENT)
1474                                 strbuf_addf(err, "unable to create directory for '%s': "
1475                                             "%s", logfile, strerror(errno));
1476                         else if (errno == EISDIR)
1477                                 strbuf_addf(err, "there are still logs under '%s'",
1478                                             logfile);
1479                         else
1480                                 strbuf_addf(err, "unable to append to '%s': %s",
1481                                             logfile, strerror(errno));
1482
1483                         goto error;
1484                 }
1485         } else {
1486                 *logfd = open(logfile, O_APPEND | O_WRONLY, 0666);
1487                 if (*logfd < 0) {
1488                         if (errno == ENOENT || errno == EISDIR) {
1489                                 /*
1490                                  * The logfile doesn't already exist,
1491                                  * but that is not an error; it only
1492                                  * means that we won't write log
1493                                  * entries to it.
1494                                  */
1495                                 ;
1496                         } else {
1497                                 strbuf_addf(err, "unable to append to '%s': %s",
1498                                             logfile, strerror(errno));
1499                                 goto error;
1500                         }
1501                 }
1502         }
1503
1504         if (*logfd >= 0)
1505                 adjust_shared_perm(logfile);
1506
1507         free(logfile);
1508         return 0;
1509
1510 error:
1511         free(logfile);
1512         return -1;
1513 }
1514
1515 static int files_create_reflog(struct ref_store *ref_store,
1516                                const char *refname, int force_create,
1517                                struct strbuf *err)
1518 {
1519         struct files_ref_store *refs =
1520                 files_downcast(ref_store, REF_STORE_WRITE, "create_reflog");
1521         int fd;
1522
1523         if (log_ref_setup(refs, refname, force_create, &fd, err))
1524                 return -1;
1525
1526         if (fd >= 0)
1527                 close(fd);
1528
1529         return 0;
1530 }
1531
1532 static int log_ref_write_fd(int fd, const struct object_id *old_oid,
1533                             const struct object_id *new_oid,
1534                             const char *committer, const char *msg)
1535 {
1536         int msglen, written;
1537         unsigned maxlen, len;
1538         char *logrec;
1539
1540         msglen = msg ? strlen(msg) : 0;
1541         maxlen = strlen(committer) + msglen + 100;
1542         logrec = xmalloc(maxlen);
1543         len = xsnprintf(logrec, maxlen, "%s %s %s\n",
1544                         oid_to_hex(old_oid),
1545                         oid_to_hex(new_oid),
1546                         committer);
1547         if (msglen)
1548                 len += copy_reflog_msg(logrec + len - 1, msg) - 1;
1549
1550         written = len <= maxlen ? write_in_full(fd, logrec, len) : -1;
1551         free(logrec);
1552         if (written < 0)
1553                 return -1;
1554
1555         return 0;
1556 }
1557
1558 static int files_log_ref_write(struct files_ref_store *refs,
1559                                const char *refname, const struct object_id *old_oid,
1560                                const struct object_id *new_oid, const char *msg,
1561                                int flags, struct strbuf *err)
1562 {
1563         int logfd, result;
1564
1565         if (log_all_ref_updates == LOG_REFS_UNSET)
1566                 log_all_ref_updates = is_bare_repository() ? LOG_REFS_NONE : LOG_REFS_NORMAL;
1567
1568         result = log_ref_setup(refs, refname,
1569                                flags & REF_FORCE_CREATE_REFLOG,
1570                                &logfd, err);
1571
1572         if (result)
1573                 return result;
1574
1575         if (logfd < 0)
1576                 return 0;
1577         result = log_ref_write_fd(logfd, old_oid, new_oid,
1578                                   git_committer_info(0), msg);
1579         if (result) {
1580                 struct strbuf sb = STRBUF_INIT;
1581                 int save_errno = errno;
1582
1583                 files_reflog_path(refs, &sb, refname);
1584                 strbuf_addf(err, "unable to append to '%s': %s",
1585                             sb.buf, strerror(save_errno));
1586                 strbuf_release(&sb);
1587                 close(logfd);
1588                 return -1;
1589         }
1590         if (close(logfd)) {
1591                 struct strbuf sb = STRBUF_INIT;
1592                 int save_errno = errno;
1593
1594                 files_reflog_path(refs, &sb, refname);
1595                 strbuf_addf(err, "unable to append to '%s': %s",
1596                             sb.buf, strerror(save_errno));
1597                 strbuf_release(&sb);
1598                 return -1;
1599         }
1600         return 0;
1601 }
1602
1603 /*
1604  * Write sha1 into the open lockfile, then close the lockfile. On
1605  * errors, rollback the lockfile, fill in *err and
1606  * return -1.
1607  */
1608 static int write_ref_to_lockfile(struct ref_lock *lock,
1609                                  const struct object_id *oid, struct strbuf *err)
1610 {
1611         static char term = '\n';
1612         struct object *o;
1613         int fd;
1614
1615         o = parse_object(oid);
1616         if (!o) {
1617                 strbuf_addf(err,
1618                             "trying to write ref '%s' with nonexistent object %s",
1619                             lock->ref_name, oid_to_hex(oid));
1620                 unlock_ref(lock);
1621                 return -1;
1622         }
1623         if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1624                 strbuf_addf(err,
1625                             "trying to write non-commit object %s to branch '%s'",
1626                             oid_to_hex(oid), lock->ref_name);
1627                 unlock_ref(lock);
1628                 return -1;
1629         }
1630         fd = get_lock_file_fd(&lock->lk);
1631         if (write_in_full(fd, oid_to_hex(oid), GIT_SHA1_HEXSZ) < 0 ||
1632             write_in_full(fd, &term, 1) < 0 ||
1633             close_ref_gently(lock) < 0) {
1634                 strbuf_addf(err,
1635                             "couldn't write '%s'", get_lock_file_path(&lock->lk));
1636                 unlock_ref(lock);
1637                 return -1;
1638         }
1639         return 0;
1640 }
1641
1642 /*
1643  * Commit a change to a loose reference that has already been written
1644  * to the loose reference lockfile. Also update the reflogs if
1645  * necessary, using the specified lockmsg (which can be NULL).
1646  */
1647 static int commit_ref_update(struct files_ref_store *refs,
1648                              struct ref_lock *lock,
1649                              const struct object_id *oid, const char *logmsg,
1650                              struct strbuf *err)
1651 {
1652         files_assert_main_repository(refs, "commit_ref_update");
1653
1654         clear_loose_ref_cache(refs);
1655         if (files_log_ref_write(refs, lock->ref_name,
1656                                 &lock->old_oid, oid,
1657                                 logmsg, 0, err)) {
1658                 char *old_msg = strbuf_detach(err, NULL);
1659                 strbuf_addf(err, "cannot update the ref '%s': %s",
1660                             lock->ref_name, old_msg);
1661                 free(old_msg);
1662                 unlock_ref(lock);
1663                 return -1;
1664         }
1665
1666         if (strcmp(lock->ref_name, "HEAD") != 0) {
1667                 /*
1668                  * Special hack: If a branch is updated directly and HEAD
1669                  * points to it (may happen on the remote side of a push
1670                  * for example) then logically the HEAD reflog should be
1671                  * updated too.
1672                  * A generic solution implies reverse symref information,
1673                  * but finding all symrefs pointing to the given branch
1674                  * would be rather costly for this rare event (the direct
1675                  * update of a branch) to be worth it.  So let's cheat and
1676                  * check with HEAD only which should cover 99% of all usage
1677                  * scenarios (even 100% of the default ones).
1678                  */
1679                 struct object_id head_oid;
1680                 int head_flag;
1681                 const char *head_ref;
1682
1683                 head_ref = refs_resolve_ref_unsafe(&refs->base, "HEAD",
1684                                                    RESOLVE_REF_READING,
1685                                                    head_oid.hash, &head_flag);
1686                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1687                     !strcmp(head_ref, lock->ref_name)) {
1688                         struct strbuf log_err = STRBUF_INIT;
1689                         if (files_log_ref_write(refs, "HEAD",
1690                                                 &lock->old_oid, oid,
1691                                                 logmsg, 0, &log_err)) {
1692                                 error("%s", log_err.buf);
1693                                 strbuf_release(&log_err);
1694                         }
1695                 }
1696         }
1697
1698         if (commit_ref(lock)) {
1699                 strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
1700                 unlock_ref(lock);
1701                 return -1;
1702         }
1703
1704         unlock_ref(lock);
1705         return 0;
1706 }
1707
1708 static int create_ref_symlink(struct ref_lock *lock, const char *target)
1709 {
1710         int ret = -1;
1711 #ifndef NO_SYMLINK_HEAD
1712         char *ref_path = get_locked_file_path(&lock->lk);
1713         unlink(ref_path);
1714         ret = symlink(target, ref_path);
1715         free(ref_path);
1716
1717         if (ret)
1718                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1719 #endif
1720         return ret;
1721 }
1722
1723 static void update_symref_reflog(struct files_ref_store *refs,
1724                                  struct ref_lock *lock, const char *refname,
1725                                  const char *target, const char *logmsg)
1726 {
1727         struct strbuf err = STRBUF_INIT;
1728         struct object_id new_oid;
1729         if (logmsg &&
1730             !refs_read_ref_full(&refs->base, target,
1731                                 RESOLVE_REF_READING, new_oid.hash, NULL) &&
1732             files_log_ref_write(refs, refname, &lock->old_oid,
1733                                 &new_oid, logmsg, 0, &err)) {
1734                 error("%s", err.buf);
1735                 strbuf_release(&err);
1736         }
1737 }
1738
1739 static int create_symref_locked(struct files_ref_store *refs,
1740                                 struct ref_lock *lock, const char *refname,
1741                                 const char *target, const char *logmsg)
1742 {
1743         if (prefer_symlink_refs && !create_ref_symlink(lock, target)) {
1744                 update_symref_reflog(refs, lock, refname, target, logmsg);
1745                 return 0;
1746         }
1747
1748         if (!fdopen_lock_file(&lock->lk, "w"))
1749                 return error("unable to fdopen %s: %s",
1750                              lock->lk.tempfile->filename.buf, strerror(errno));
1751
1752         update_symref_reflog(refs, lock, refname, target, logmsg);
1753
1754         /* no error check; commit_ref will check ferror */
1755         fprintf(lock->lk.tempfile->fp, "ref: %s\n", target);
1756         if (commit_ref(lock) < 0)
1757                 return error("unable to write symref for %s: %s", refname,
1758                              strerror(errno));
1759         return 0;
1760 }
1761
1762 static int files_create_symref(struct ref_store *ref_store,
1763                                const char *refname, const char *target,
1764                                const char *logmsg)
1765 {
1766         struct files_ref_store *refs =
1767                 files_downcast(ref_store, REF_STORE_WRITE, "create_symref");
1768         struct strbuf err = STRBUF_INIT;
1769         struct ref_lock *lock;
1770         int ret;
1771
1772         lock = lock_ref_sha1_basic(refs, refname, NULL,
1773                                    NULL, NULL, REF_NODEREF, NULL,
1774                                    &err);
1775         if (!lock) {
1776                 error("%s", err.buf);
1777                 strbuf_release(&err);
1778                 return -1;
1779         }
1780
1781         ret = create_symref_locked(refs, lock, refname, target, logmsg);
1782         unlock_ref(lock);
1783         return ret;
1784 }
1785
1786 static int files_reflog_exists(struct ref_store *ref_store,
1787                                const char *refname)
1788 {
1789         struct files_ref_store *refs =
1790                 files_downcast(ref_store, REF_STORE_READ, "reflog_exists");
1791         struct strbuf sb = STRBUF_INIT;
1792         struct stat st;
1793         int ret;
1794
1795         files_reflog_path(refs, &sb, refname);
1796         ret = !lstat(sb.buf, &st) && S_ISREG(st.st_mode);
1797         strbuf_release(&sb);
1798         return ret;
1799 }
1800
1801 static int files_delete_reflog(struct ref_store *ref_store,
1802                                const char *refname)
1803 {
1804         struct files_ref_store *refs =
1805                 files_downcast(ref_store, REF_STORE_WRITE, "delete_reflog");
1806         struct strbuf sb = STRBUF_INIT;
1807         int ret;
1808
1809         files_reflog_path(refs, &sb, refname);
1810         ret = remove_path(sb.buf);
1811         strbuf_release(&sb);
1812         return ret;
1813 }
1814
1815 static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
1816 {
1817         struct object_id ooid, noid;
1818         char *email_end, *message;
1819         timestamp_t timestamp;
1820         int tz;
1821         const char *p = sb->buf;
1822
1823         /* old SP new SP name <email> SP time TAB msg LF */
1824         if (!sb->len || sb->buf[sb->len - 1] != '\n' ||
1825             parse_oid_hex(p, &ooid, &p) || *p++ != ' ' ||
1826             parse_oid_hex(p, &noid, &p) || *p++ != ' ' ||
1827             !(email_end = strchr(p, '>')) ||
1828             email_end[1] != ' ' ||
1829             !(timestamp = parse_timestamp(email_end + 2, &message, 10)) ||
1830             !message || message[0] != ' ' ||
1831             (message[1] != '+' && message[1] != '-') ||
1832             !isdigit(message[2]) || !isdigit(message[3]) ||
1833             !isdigit(message[4]) || !isdigit(message[5]))
1834                 return 0; /* corrupt? */
1835         email_end[1] = '\0';
1836         tz = strtol(message + 1, NULL, 10);
1837         if (message[6] != '\t')
1838                 message += 6;
1839         else
1840                 message += 7;
1841         return fn(&ooid, &noid, p, timestamp, tz, message, cb_data);
1842 }
1843
1844 static char *find_beginning_of_line(char *bob, char *scan)
1845 {
1846         while (bob < scan && *(--scan) != '\n')
1847                 ; /* keep scanning backwards */
1848         /*
1849          * Return either beginning of the buffer, or LF at the end of
1850          * the previous line.
1851          */
1852         return scan;
1853 }
1854
1855 static int files_for_each_reflog_ent_reverse(struct ref_store *ref_store,
1856                                              const char *refname,
1857                                              each_reflog_ent_fn fn,
1858                                              void *cb_data)
1859 {
1860         struct files_ref_store *refs =
1861                 files_downcast(ref_store, REF_STORE_READ,
1862                                "for_each_reflog_ent_reverse");
1863         struct strbuf sb = STRBUF_INIT;
1864         FILE *logfp;
1865         long pos;
1866         int ret = 0, at_tail = 1;
1867
1868         files_reflog_path(refs, &sb, refname);
1869         logfp = fopen(sb.buf, "r");
1870         strbuf_release(&sb);
1871         if (!logfp)
1872                 return -1;
1873
1874         /* Jump to the end */
1875         if (fseek(logfp, 0, SEEK_END) < 0)
1876                 ret = error("cannot seek back reflog for %s: %s",
1877                             refname, strerror(errno));
1878         pos = ftell(logfp);
1879         while (!ret && 0 < pos) {
1880                 int cnt;
1881                 size_t nread;
1882                 char buf[BUFSIZ];
1883                 char *endp, *scanp;
1884
1885                 /* Fill next block from the end */
1886                 cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
1887                 if (fseek(logfp, pos - cnt, SEEK_SET)) {
1888                         ret = error("cannot seek back reflog for %s: %s",
1889                                     refname, strerror(errno));
1890                         break;
1891                 }
1892                 nread = fread(buf, cnt, 1, logfp);
1893                 if (nread != 1) {
1894                         ret = error("cannot read %d bytes from reflog for %s: %s",
1895                                     cnt, refname, strerror(errno));
1896                         break;
1897                 }
1898                 pos -= cnt;
1899
1900                 scanp = endp = buf + cnt;
1901                 if (at_tail && scanp[-1] == '\n')
1902                         /* Looking at the final LF at the end of the file */
1903                         scanp--;
1904                 at_tail = 0;
1905
1906                 while (buf < scanp) {
1907                         /*
1908                          * terminating LF of the previous line, or the beginning
1909                          * of the buffer.
1910                          */
1911                         char *bp;
1912
1913                         bp = find_beginning_of_line(buf, scanp);
1914
1915                         if (*bp == '\n') {
1916                                 /*
1917                                  * The newline is the end of the previous line,
1918                                  * so we know we have complete line starting
1919                                  * at (bp + 1). Prefix it onto any prior data
1920                                  * we collected for the line and process it.
1921                                  */
1922                                 strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
1923                                 scanp = bp;
1924                                 endp = bp + 1;
1925                                 ret = show_one_reflog_ent(&sb, fn, cb_data);
1926                                 strbuf_reset(&sb);
1927                                 if (ret)
1928                                         break;
1929                         } else if (!pos) {
1930                                 /*
1931                                  * We are at the start of the buffer, and the
1932                                  * start of the file; there is no previous
1933                                  * line, and we have everything for this one.
1934                                  * Process it, and we can end the loop.
1935                                  */
1936                                 strbuf_splice(&sb, 0, 0, buf, endp - buf);
1937                                 ret = show_one_reflog_ent(&sb, fn, cb_data);
1938                                 strbuf_reset(&sb);
1939                                 break;
1940                         }
1941
1942                         if (bp == buf) {
1943                                 /*
1944                                  * We are at the start of the buffer, and there
1945                                  * is more file to read backwards. Which means
1946                                  * we are in the middle of a line. Note that we
1947                                  * may get here even if *bp was a newline; that
1948                                  * just means we are at the exact end of the
1949                                  * previous line, rather than some spot in the
1950                                  * middle.
1951                                  *
1952                                  * Save away what we have to be combined with
1953                                  * the data from the next read.
1954                                  */
1955                                 strbuf_splice(&sb, 0, 0, buf, endp - buf);
1956                                 break;
1957                         }
1958                 }
1959
1960         }
1961         if (!ret && sb.len)
1962                 die("BUG: reverse reflog parser had leftover data");
1963
1964         fclose(logfp);
1965         strbuf_release(&sb);
1966         return ret;
1967 }
1968
1969 static int files_for_each_reflog_ent(struct ref_store *ref_store,
1970                                      const char *refname,
1971                                      each_reflog_ent_fn fn, void *cb_data)
1972 {
1973         struct files_ref_store *refs =
1974                 files_downcast(ref_store, REF_STORE_READ,
1975                                "for_each_reflog_ent");
1976         FILE *logfp;
1977         struct strbuf sb = STRBUF_INIT;
1978         int ret = 0;
1979
1980         files_reflog_path(refs, &sb, refname);
1981         logfp = fopen(sb.buf, "r");
1982         strbuf_release(&sb);
1983         if (!logfp)
1984                 return -1;
1985
1986         while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
1987                 ret = show_one_reflog_ent(&sb, fn, cb_data);
1988         fclose(logfp);
1989         strbuf_release(&sb);
1990         return ret;
1991 }
1992
1993 struct files_reflog_iterator {
1994         struct ref_iterator base;
1995
1996         struct ref_store *ref_store;
1997         struct dir_iterator *dir_iterator;
1998         struct object_id oid;
1999 };
2000
2001 static int files_reflog_iterator_advance(struct ref_iterator *ref_iterator)
2002 {
2003         struct files_reflog_iterator *iter =
2004                 (struct files_reflog_iterator *)ref_iterator;
2005         struct dir_iterator *diter = iter->dir_iterator;
2006         int ok;
2007
2008         while ((ok = dir_iterator_advance(diter)) == ITER_OK) {
2009                 int flags;
2010
2011                 if (!S_ISREG(diter->st.st_mode))
2012                         continue;
2013                 if (diter->basename[0] == '.')
2014                         continue;
2015                 if (ends_with(diter->basename, ".lock"))
2016                         continue;
2017
2018                 if (refs_read_ref_full(iter->ref_store,
2019                                        diter->relative_path, 0,
2020                                        iter->oid.hash, &flags)) {
2021                         error("bad ref for %s", diter->path.buf);
2022                         continue;
2023                 }
2024
2025                 iter->base.refname = diter->relative_path;
2026                 iter->base.oid = &iter->oid;
2027                 iter->base.flags = flags;
2028                 return ITER_OK;
2029         }
2030
2031         iter->dir_iterator = NULL;
2032         if (ref_iterator_abort(ref_iterator) == ITER_ERROR)
2033                 ok = ITER_ERROR;
2034         return ok;
2035 }
2036
2037 static int files_reflog_iterator_peel(struct ref_iterator *ref_iterator,
2038                                    struct object_id *peeled)
2039 {
2040         die("BUG: ref_iterator_peel() called for reflog_iterator");
2041 }
2042
2043 static int files_reflog_iterator_abort(struct ref_iterator *ref_iterator)
2044 {
2045         struct files_reflog_iterator *iter =
2046                 (struct files_reflog_iterator *)ref_iterator;
2047         int ok = ITER_DONE;
2048
2049         if (iter->dir_iterator)
2050                 ok = dir_iterator_abort(iter->dir_iterator);
2051
2052         base_ref_iterator_free(ref_iterator);
2053         return ok;
2054 }
2055
2056 static struct ref_iterator_vtable files_reflog_iterator_vtable = {
2057         files_reflog_iterator_advance,
2058         files_reflog_iterator_peel,
2059         files_reflog_iterator_abort
2060 };
2061
2062 static struct ref_iterator *reflog_iterator_begin(struct ref_store *ref_store,
2063                                                   const char *gitdir)
2064 {
2065         struct files_reflog_iterator *iter = xcalloc(1, sizeof(*iter));
2066         struct ref_iterator *ref_iterator = &iter->base;
2067         struct strbuf sb = STRBUF_INIT;
2068
2069         base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable);
2070         strbuf_addf(&sb, "%s/logs", gitdir);
2071         iter->dir_iterator = dir_iterator_begin(sb.buf);
2072         iter->ref_store = ref_store;
2073         strbuf_release(&sb);
2074
2075         return ref_iterator;
2076 }
2077
2078 static enum iterator_selection reflog_iterator_select(
2079         struct ref_iterator *iter_worktree,
2080         struct ref_iterator *iter_common,
2081         void *cb_data)
2082 {
2083         if (iter_worktree) {
2084                 /*
2085                  * We're a bit loose here. We probably should ignore
2086                  * common refs if they are accidentally added as
2087                  * per-worktree refs.
2088                  */
2089                 return ITER_SELECT_0;
2090         } else if (iter_common) {
2091                 if (ref_type(iter_common->refname) == REF_TYPE_NORMAL)
2092                         return ITER_SELECT_1;
2093
2094                 /*
2095                  * The main ref store may contain main worktree's
2096                  * per-worktree refs, which should be ignored
2097                  */
2098                 return ITER_SKIP_1;
2099         } else
2100                 return ITER_DONE;
2101 }
2102
2103 static struct ref_iterator *files_reflog_iterator_begin(struct ref_store *ref_store)
2104 {
2105         struct files_ref_store *refs =
2106                 files_downcast(ref_store, REF_STORE_READ,
2107                                "reflog_iterator_begin");
2108
2109         if (!strcmp(refs->gitdir, refs->gitcommondir)) {
2110                 return reflog_iterator_begin(ref_store, refs->gitcommondir);
2111         } else {
2112                 return merge_ref_iterator_begin(
2113                         reflog_iterator_begin(ref_store, refs->gitdir),
2114                         reflog_iterator_begin(ref_store, refs->gitcommondir),
2115                         reflog_iterator_select, refs);
2116         }
2117 }
2118
2119 /*
2120  * If update is a direct update of head_ref (the reference pointed to
2121  * by HEAD), then add an extra REF_LOG_ONLY update for HEAD.
2122  */
2123 static int split_head_update(struct ref_update *update,
2124                              struct ref_transaction *transaction,
2125                              const char *head_ref,
2126                              struct string_list *affected_refnames,
2127                              struct strbuf *err)
2128 {
2129         struct string_list_item *item;
2130         struct ref_update *new_update;
2131
2132         if ((update->flags & REF_LOG_ONLY) ||
2133             (update->flags & REF_ISPRUNING) ||
2134             (update->flags & REF_UPDATE_VIA_HEAD))
2135                 return 0;
2136
2137         if (strcmp(update->refname, head_ref))
2138                 return 0;
2139
2140         /*
2141          * First make sure that HEAD is not already in the
2142          * transaction. This check is O(lg N) in the transaction
2143          * size, but it happens at most once per transaction.
2144          */
2145         if (string_list_has_string(affected_refnames, "HEAD")) {
2146                 /* An entry already existed */
2147                 strbuf_addf(err,
2148                             "multiple updates for 'HEAD' (including one "
2149                             "via its referent '%s') are not allowed",
2150                             update->refname);
2151                 return TRANSACTION_NAME_CONFLICT;
2152         }
2153
2154         new_update = ref_transaction_add_update(
2155                         transaction, "HEAD",
2156                         update->flags | REF_LOG_ONLY | REF_NODEREF,
2157                         update->new_oid.hash, update->old_oid.hash,
2158                         update->msg);
2159
2160         /*
2161          * Add "HEAD". This insertion is O(N) in the transaction
2162          * size, but it happens at most once per transaction.
2163          * Add new_update->refname instead of a literal "HEAD".
2164          */
2165         if (strcmp(new_update->refname, "HEAD"))
2166                 BUG("%s unexpectedly not 'HEAD'", new_update->refname);
2167         item = string_list_insert(affected_refnames, new_update->refname);
2168         item->util = new_update;
2169
2170         return 0;
2171 }
2172
2173 /*
2174  * update is for a symref that points at referent and doesn't have
2175  * REF_NODEREF set. Split it into two updates:
2176  * - The original update, but with REF_LOG_ONLY and REF_NODEREF set
2177  * - A new, separate update for the referent reference
2178  * Note that the new update will itself be subject to splitting when
2179  * the iteration gets to it.
2180  */
2181 static int split_symref_update(struct files_ref_store *refs,
2182                                struct ref_update *update,
2183                                const char *referent,
2184                                struct ref_transaction *transaction,
2185                                struct string_list *affected_refnames,
2186                                struct strbuf *err)
2187 {
2188         struct string_list_item *item;
2189         struct ref_update *new_update;
2190         unsigned int new_flags;
2191
2192         /*
2193          * First make sure that referent is not already in the
2194          * transaction. This check is O(lg N) in the transaction
2195          * size, but it happens at most once per symref in a
2196          * transaction.
2197          */
2198         if (string_list_has_string(affected_refnames, referent)) {
2199                 /* An entry already exists */
2200                 strbuf_addf(err,
2201                             "multiple updates for '%s' (including one "
2202                             "via symref '%s') are not allowed",
2203                             referent, update->refname);
2204                 return TRANSACTION_NAME_CONFLICT;
2205         }
2206
2207         new_flags = update->flags;
2208         if (!strcmp(update->refname, "HEAD")) {
2209                 /*
2210                  * Record that the new update came via HEAD, so that
2211                  * when we process it, split_head_update() doesn't try
2212                  * to add another reflog update for HEAD. Note that
2213                  * this bit will be propagated if the new_update
2214                  * itself needs to be split.
2215                  */
2216                 new_flags |= REF_UPDATE_VIA_HEAD;
2217         }
2218
2219         new_update = ref_transaction_add_update(
2220                         transaction, referent, new_flags,
2221                         update->new_oid.hash, update->old_oid.hash,
2222                         update->msg);
2223
2224         new_update->parent_update = update;
2225
2226         /*
2227          * Change the symbolic ref update to log only. Also, it
2228          * doesn't need to check its old SHA-1 value, as that will be
2229          * done when new_update is processed.
2230          */
2231         update->flags |= REF_LOG_ONLY | REF_NODEREF;
2232         update->flags &= ~REF_HAVE_OLD;
2233
2234         /*
2235          * Add the referent. This insertion is O(N) in the transaction
2236          * size, but it happens at most once per symref in a
2237          * transaction. Make sure to add new_update->refname, which will
2238          * be valid as long as affected_refnames is in use, and NOT
2239          * referent, which might soon be freed by our caller.
2240          */
2241         item = string_list_insert(affected_refnames, new_update->refname);
2242         if (item->util)
2243                 BUG("%s unexpectedly found in affected_refnames",
2244                     new_update->refname);
2245         item->util = new_update;
2246
2247         return 0;
2248 }
2249
2250 /*
2251  * Return the refname under which update was originally requested.
2252  */
2253 static const char *original_update_refname(struct ref_update *update)
2254 {
2255         while (update->parent_update)
2256                 update = update->parent_update;
2257
2258         return update->refname;
2259 }
2260
2261 /*
2262  * Check whether the REF_HAVE_OLD and old_oid values stored in update
2263  * are consistent with oid, which is the reference's current value. If
2264  * everything is OK, return 0; otherwise, write an error message to
2265  * err and return -1.
2266  */
2267 static int check_old_oid(struct ref_update *update, struct object_id *oid,
2268                          struct strbuf *err)
2269 {
2270         if (!(update->flags & REF_HAVE_OLD) ||
2271                    !oidcmp(oid, &update->old_oid))
2272                 return 0;
2273
2274         if (is_null_oid(&update->old_oid))
2275                 strbuf_addf(err, "cannot lock ref '%s': "
2276                             "reference already exists",
2277                             original_update_refname(update));
2278         else if (is_null_oid(oid))
2279                 strbuf_addf(err, "cannot lock ref '%s': "
2280                             "reference is missing but expected %s",
2281                             original_update_refname(update),
2282                             oid_to_hex(&update->old_oid));
2283         else
2284                 strbuf_addf(err, "cannot lock ref '%s': "
2285                             "is at %s but expected %s",
2286                             original_update_refname(update),
2287                             oid_to_hex(oid),
2288                             oid_to_hex(&update->old_oid));
2289
2290         return -1;
2291 }
2292
2293 /*
2294  * Prepare for carrying out update:
2295  * - Lock the reference referred to by update.
2296  * - Read the reference under lock.
2297  * - Check that its old SHA-1 value (if specified) is correct, and in
2298  *   any case record it in update->lock->old_oid for later use when
2299  *   writing the reflog.
2300  * - If it is a symref update without REF_NODEREF, split it up into a
2301  *   REF_LOG_ONLY update of the symref and add a separate update for
2302  *   the referent to transaction.
2303  * - If it is an update of head_ref, add a corresponding REF_LOG_ONLY
2304  *   update of HEAD.
2305  */
2306 static int lock_ref_for_update(struct files_ref_store *refs,
2307                                struct ref_update *update,
2308                                struct ref_transaction *transaction,
2309                                const char *head_ref,
2310                                struct string_list *affected_refnames,
2311                                struct strbuf *err)
2312 {
2313         struct strbuf referent = STRBUF_INIT;
2314         int mustexist = (update->flags & REF_HAVE_OLD) &&
2315                 !is_null_oid(&update->old_oid);
2316         int ret = 0;
2317         struct ref_lock *lock;
2318
2319         files_assert_main_repository(refs, "lock_ref_for_update");
2320
2321         if ((update->flags & REF_HAVE_NEW) && is_null_oid(&update->new_oid))
2322                 update->flags |= REF_DELETING;
2323
2324         if (head_ref) {
2325                 ret = split_head_update(update, transaction, head_ref,
2326                                         affected_refnames, err);
2327                 if (ret)
2328                         goto out;
2329         }
2330
2331         ret = lock_raw_ref(refs, update->refname, mustexist,
2332                            affected_refnames, NULL,
2333                            &lock, &referent,
2334                            &update->type, err);
2335         if (ret) {
2336                 char *reason;
2337
2338                 reason = strbuf_detach(err, NULL);
2339                 strbuf_addf(err, "cannot lock ref '%s': %s",
2340                             original_update_refname(update), reason);
2341                 free(reason);
2342                 goto out;
2343         }
2344
2345         update->backend_data = lock;
2346
2347         if (update->type & REF_ISSYMREF) {
2348                 if (update->flags & REF_NODEREF) {
2349                         /*
2350                          * We won't be reading the referent as part of
2351                          * the transaction, so we have to read it here
2352                          * to record and possibly check old_sha1:
2353                          */
2354                         if (refs_read_ref_full(&refs->base,
2355                                                referent.buf, 0,
2356                                                lock->old_oid.hash, NULL)) {
2357                                 if (update->flags & REF_HAVE_OLD) {
2358                                         strbuf_addf(err, "cannot lock ref '%s': "
2359                                                     "error reading reference",
2360                                                     original_update_refname(update));
2361                                         ret = TRANSACTION_GENERIC_ERROR;
2362                                         goto out;
2363                                 }
2364                         } else if (check_old_oid(update, &lock->old_oid, err)) {
2365                                 ret = TRANSACTION_GENERIC_ERROR;
2366                                 goto out;
2367                         }
2368                 } else {
2369                         /*
2370                          * Create a new update for the reference this
2371                          * symref is pointing at. Also, we will record
2372                          * and verify old_sha1 for this update as part
2373                          * of processing the split-off update, so we
2374                          * don't have to do it here.
2375                          */
2376                         ret = split_symref_update(refs, update,
2377                                                   referent.buf, transaction,
2378                                                   affected_refnames, err);
2379                         if (ret)
2380                                 goto out;
2381                 }
2382         } else {
2383                 struct ref_update *parent_update;
2384
2385                 if (check_old_oid(update, &lock->old_oid, err)) {
2386                         ret = TRANSACTION_GENERIC_ERROR;
2387                         goto out;
2388                 }
2389
2390                 /*
2391                  * If this update is happening indirectly because of a
2392                  * symref update, record the old SHA-1 in the parent
2393                  * update:
2394                  */
2395                 for (parent_update = update->parent_update;
2396                      parent_update;
2397                      parent_update = parent_update->parent_update) {
2398                         struct ref_lock *parent_lock = parent_update->backend_data;
2399                         oidcpy(&parent_lock->old_oid, &lock->old_oid);
2400                 }
2401         }
2402
2403         if ((update->flags & REF_HAVE_NEW) &&
2404             !(update->flags & REF_DELETING) &&
2405             !(update->flags & REF_LOG_ONLY)) {
2406                 if (!(update->type & REF_ISSYMREF) &&
2407                     !oidcmp(&lock->old_oid, &update->new_oid)) {
2408                         /*
2409                          * The reference already has the desired
2410                          * value, so we don't need to write it.
2411                          */
2412                 } else if (write_ref_to_lockfile(lock, &update->new_oid,
2413                                                  err)) {
2414                         char *write_err = strbuf_detach(err, NULL);
2415
2416                         /*
2417                          * The lock was freed upon failure of
2418                          * write_ref_to_lockfile():
2419                          */
2420                         update->backend_data = NULL;
2421                         strbuf_addf(err,
2422                                     "cannot update ref '%s': %s",
2423                                     update->refname, write_err);
2424                         free(write_err);
2425                         ret = TRANSACTION_GENERIC_ERROR;
2426                         goto out;
2427                 } else {
2428                         update->flags |= REF_NEEDS_COMMIT;
2429                 }
2430         }
2431         if (!(update->flags & REF_NEEDS_COMMIT)) {
2432                 /*
2433                  * We didn't call write_ref_to_lockfile(), so
2434                  * the lockfile is still open. Close it to
2435                  * free up the file descriptor:
2436                  */
2437                 if (close_ref_gently(lock)) {
2438                         strbuf_addf(err, "couldn't close '%s.lock'",
2439                                     update->refname);
2440                         ret = TRANSACTION_GENERIC_ERROR;
2441                         goto out;
2442                 }
2443         }
2444
2445 out:
2446         strbuf_release(&referent);
2447         return ret;
2448 }
2449
2450 struct files_transaction_backend_data {
2451         struct ref_transaction *packed_transaction;
2452         int packed_refs_locked;
2453 };
2454
2455 /*
2456  * Unlock any references in `transaction` that are still locked, and
2457  * mark the transaction closed.
2458  */
2459 static void files_transaction_cleanup(struct files_ref_store *refs,
2460                                       struct ref_transaction *transaction)
2461 {
2462         size_t i;
2463         struct files_transaction_backend_data *backend_data =
2464                 transaction->backend_data;
2465         struct strbuf err = STRBUF_INIT;
2466
2467         for (i = 0; i < transaction->nr; i++) {
2468                 struct ref_update *update = transaction->updates[i];
2469                 struct ref_lock *lock = update->backend_data;
2470
2471                 if (lock) {
2472                         unlock_ref(lock);
2473                         update->backend_data = NULL;
2474                 }
2475         }
2476
2477         if (backend_data->packed_transaction &&
2478             ref_transaction_abort(backend_data->packed_transaction, &err)) {
2479                 error("error aborting transaction: %s", err.buf);
2480                 strbuf_release(&err);
2481         }
2482
2483         if (backend_data->packed_refs_locked)
2484                 packed_refs_unlock(refs->packed_ref_store);
2485
2486         free(backend_data);
2487
2488         transaction->state = REF_TRANSACTION_CLOSED;
2489 }
2490
2491 static int files_transaction_prepare(struct ref_store *ref_store,
2492                                      struct ref_transaction *transaction,
2493                                      struct strbuf *err)
2494 {
2495         struct files_ref_store *refs =
2496                 files_downcast(ref_store, REF_STORE_WRITE,
2497                                "ref_transaction_prepare");
2498         size_t i;
2499         int ret = 0;
2500         struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
2501         char *head_ref = NULL;
2502         int head_type;
2503         struct object_id head_oid;
2504         struct files_transaction_backend_data *backend_data;
2505         struct ref_transaction *packed_transaction = NULL;
2506
2507         assert(err);
2508
2509         if (!transaction->nr)
2510                 goto cleanup;
2511
2512         backend_data = xcalloc(1, sizeof(*backend_data));
2513         transaction->backend_data = backend_data;
2514
2515         /*
2516          * Fail if a refname appears more than once in the
2517          * transaction. (If we end up splitting up any updates using
2518          * split_symref_update() or split_head_update(), those
2519          * functions will check that the new updates don't have the
2520          * same refname as any existing ones.)
2521          */
2522         for (i = 0; i < transaction->nr; i++) {
2523                 struct ref_update *update = transaction->updates[i];
2524                 struct string_list_item *item =
2525                         string_list_append(&affected_refnames, update->refname);
2526
2527                 /*
2528                  * We store a pointer to update in item->util, but at
2529                  * the moment we never use the value of this field
2530                  * except to check whether it is non-NULL.
2531                  */
2532                 item->util = update;
2533         }
2534         string_list_sort(&affected_refnames);
2535         if (ref_update_reject_duplicates(&affected_refnames, err)) {
2536                 ret = TRANSACTION_GENERIC_ERROR;
2537                 goto cleanup;
2538         }
2539
2540         /*
2541          * Special hack: If a branch is updated directly and HEAD
2542          * points to it (may happen on the remote side of a push
2543          * for example) then logically the HEAD reflog should be
2544          * updated too.
2545          *
2546          * A generic solution would require reverse symref lookups,
2547          * but finding all symrefs pointing to a given branch would be
2548          * rather costly for this rare event (the direct update of a
2549          * branch) to be worth it. So let's cheat and check with HEAD
2550          * only, which should cover 99% of all usage scenarios (even
2551          * 100% of the default ones).
2552          *
2553          * So if HEAD is a symbolic reference, then record the name of
2554          * the reference that it points to. If we see an update of
2555          * head_ref within the transaction, then split_head_update()
2556          * arranges for the reflog of HEAD to be updated, too.
2557          */
2558         head_ref = refs_resolve_refdup(ref_store, "HEAD",
2559                                        RESOLVE_REF_NO_RECURSE,
2560                                        head_oid.hash, &head_type);
2561
2562         if (head_ref && !(head_type & REF_ISSYMREF)) {
2563                 FREE_AND_NULL(head_ref);
2564         }
2565
2566         /*
2567          * Acquire all locks, verify old values if provided, check
2568          * that new values are valid, and write new values to the
2569          * lockfiles, ready to be activated. Only keep one lockfile
2570          * open at a time to avoid running out of file descriptors.
2571          * Note that lock_ref_for_update() might append more updates
2572          * to the transaction.
2573          */
2574         for (i = 0; i < transaction->nr; i++) {
2575                 struct ref_update *update = transaction->updates[i];
2576
2577                 ret = lock_ref_for_update(refs, update, transaction,
2578                                           head_ref, &affected_refnames, err);
2579                 if (ret)
2580                         break;
2581
2582                 if (update->flags & REF_DELETING &&
2583                     !(update->flags & REF_LOG_ONLY) &&
2584                     !(update->flags & REF_ISPRUNING)) {
2585                         /*
2586                          * This reference has to be deleted from
2587                          * packed-refs if it exists there.
2588                          */
2589                         if (!packed_transaction) {
2590                                 packed_transaction = ref_store_transaction_begin(
2591                                                 refs->packed_ref_store, err);
2592                                 if (!packed_transaction) {
2593                                         ret = TRANSACTION_GENERIC_ERROR;
2594                                         goto cleanup;
2595                                 }
2596
2597                                 backend_data->packed_transaction =
2598                                         packed_transaction;
2599                         }
2600
2601                         ref_transaction_add_update(
2602                                         packed_transaction, update->refname,
2603                                         update->flags & ~REF_HAVE_OLD,
2604                                         update->new_oid.hash, update->old_oid.hash,
2605                                         NULL);
2606                 }
2607         }
2608
2609         if (packed_transaction) {
2610                 if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
2611                         ret = TRANSACTION_GENERIC_ERROR;
2612                         goto cleanup;
2613                 }
2614                 backend_data->packed_refs_locked = 1;
2615                 ret = ref_transaction_prepare(packed_transaction, err);
2616         }
2617
2618 cleanup:
2619         free(head_ref);
2620         string_list_clear(&affected_refnames, 0);
2621
2622         if (ret)
2623                 files_transaction_cleanup(refs, transaction);
2624         else
2625                 transaction->state = REF_TRANSACTION_PREPARED;
2626
2627         return ret;
2628 }
2629
2630 static int files_transaction_finish(struct ref_store *ref_store,
2631                                     struct ref_transaction *transaction,
2632                                     struct strbuf *err)
2633 {
2634         struct files_ref_store *refs =
2635                 files_downcast(ref_store, 0, "ref_transaction_finish");
2636         size_t i;
2637         int ret = 0;
2638         struct strbuf sb = STRBUF_INIT;
2639         struct files_transaction_backend_data *backend_data;
2640         struct ref_transaction *packed_transaction;
2641
2642
2643         assert(err);
2644
2645         if (!transaction->nr) {
2646                 transaction->state = REF_TRANSACTION_CLOSED;
2647                 return 0;
2648         }
2649
2650         backend_data = transaction->backend_data;
2651         packed_transaction = backend_data->packed_transaction;
2652
2653         /* Perform updates first so live commits remain referenced */
2654         for (i = 0; i < transaction->nr; i++) {
2655                 struct ref_update *update = transaction->updates[i];
2656                 struct ref_lock *lock = update->backend_data;
2657
2658                 if (update->flags & REF_NEEDS_COMMIT ||
2659                     update->flags & REF_LOG_ONLY) {
2660                         if (files_log_ref_write(refs,
2661                                                 lock->ref_name,
2662                                                 &lock->old_oid,
2663                                                 &update->new_oid,
2664                                                 update->msg, update->flags,
2665                                                 err)) {
2666                                 char *old_msg = strbuf_detach(err, NULL);
2667
2668                                 strbuf_addf(err, "cannot update the ref '%s': %s",
2669                                             lock->ref_name, old_msg);
2670                                 free(old_msg);
2671                                 unlock_ref(lock);
2672                                 update->backend_data = NULL;
2673                                 ret = TRANSACTION_GENERIC_ERROR;
2674                                 goto cleanup;
2675                         }
2676                 }
2677                 if (update->flags & REF_NEEDS_COMMIT) {
2678                         clear_loose_ref_cache(refs);
2679                         if (commit_ref(lock)) {
2680                                 strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
2681                                 unlock_ref(lock);
2682                                 update->backend_data = NULL;
2683                                 ret = TRANSACTION_GENERIC_ERROR;
2684                                 goto cleanup;
2685                         }
2686                 }
2687         }
2688
2689         /*
2690          * Now that updates are safely completed, we can perform
2691          * deletes. First delete the reflogs of any references that
2692          * will be deleted, since (in the unexpected event of an
2693          * error) leaving a reference without a reflog is less bad
2694          * than leaving a reflog without a reference (the latter is a
2695          * mildly invalid repository state):
2696          */
2697         for (i = 0; i < transaction->nr; i++) {
2698                 struct ref_update *update = transaction->updates[i];
2699                 if (update->flags & REF_DELETING &&
2700                     !(update->flags & REF_LOG_ONLY) &&
2701                     !(update->flags & REF_ISPRUNING)) {
2702                         strbuf_reset(&sb);
2703                         files_reflog_path(refs, &sb, update->refname);
2704                         if (!unlink_or_warn(sb.buf))
2705                                 try_remove_empty_parents(refs, update->refname,
2706                                                          REMOVE_EMPTY_PARENTS_REFLOG);
2707                 }
2708         }
2709
2710         /*
2711          * Perform deletes now that updates are safely completed.
2712          *
2713          * First delete any packed versions of the references, while
2714          * retaining the packed-refs lock:
2715          */
2716         if (packed_transaction) {
2717                 ret = ref_transaction_commit(packed_transaction, err);
2718                 ref_transaction_free(packed_transaction);
2719                 packed_transaction = NULL;
2720                 backend_data->packed_transaction = NULL;
2721                 if (ret)
2722                         goto cleanup;
2723         }
2724
2725         /* Now delete the loose versions of the references: */
2726         for (i = 0; i < transaction->nr; i++) {
2727                 struct ref_update *update = transaction->updates[i];
2728                 struct ref_lock *lock = update->backend_data;
2729
2730                 if (update->flags & REF_DELETING &&
2731                     !(update->flags & REF_LOG_ONLY)) {
2732                         if (!(update->type & REF_ISPACKED) ||
2733                             update->type & REF_ISSYMREF) {
2734                                 /* It is a loose reference. */
2735                                 strbuf_reset(&sb);
2736                                 files_ref_path(refs, &sb, lock->ref_name);
2737                                 if (unlink_or_msg(sb.buf, err)) {
2738                                         ret = TRANSACTION_GENERIC_ERROR;
2739                                         goto cleanup;
2740                                 }
2741                                 update->flags |= REF_DELETED_LOOSE;
2742                         }
2743                 }
2744         }
2745
2746         clear_loose_ref_cache(refs);
2747
2748 cleanup:
2749         files_transaction_cleanup(refs, transaction);
2750
2751         for (i = 0; i < transaction->nr; i++) {
2752                 struct ref_update *update = transaction->updates[i];
2753
2754                 if (update->flags & REF_DELETED_LOOSE) {
2755                         /*
2756                          * The loose reference was deleted. Delete any
2757                          * empty parent directories. (Note that this
2758                          * can only work because we have already
2759                          * removed the lockfile.)
2760                          */
2761                         try_remove_empty_parents(refs, update->refname,
2762                                                  REMOVE_EMPTY_PARENTS_REF);
2763                 }
2764         }
2765
2766         strbuf_release(&sb);
2767         return ret;
2768 }
2769
2770 static int files_transaction_abort(struct ref_store *ref_store,
2771                                    struct ref_transaction *transaction,
2772                                    struct strbuf *err)
2773 {
2774         struct files_ref_store *refs =
2775                 files_downcast(ref_store, 0, "ref_transaction_abort");
2776
2777         files_transaction_cleanup(refs, transaction);
2778         return 0;
2779 }
2780
2781 static int ref_present(const char *refname,
2782                        const struct object_id *oid, int flags, void *cb_data)
2783 {
2784         struct string_list *affected_refnames = cb_data;
2785
2786         return string_list_has_string(affected_refnames, refname);
2787 }
2788
2789 static int files_initial_transaction_commit(struct ref_store *ref_store,
2790                                             struct ref_transaction *transaction,
2791                                             struct strbuf *err)
2792 {
2793         struct files_ref_store *refs =
2794                 files_downcast(ref_store, REF_STORE_WRITE,
2795                                "initial_ref_transaction_commit");
2796         size_t i;
2797         int ret = 0;
2798         struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
2799         struct ref_transaction *packed_transaction = NULL;
2800
2801         assert(err);
2802
2803         if (transaction->state != REF_TRANSACTION_OPEN)
2804                 die("BUG: commit called for transaction that is not open");
2805
2806         /* Fail if a refname appears more than once in the transaction: */
2807         for (i = 0; i < transaction->nr; i++)
2808                 string_list_append(&affected_refnames,
2809                                    transaction->updates[i]->refname);
2810         string_list_sort(&affected_refnames);
2811         if (ref_update_reject_duplicates(&affected_refnames, err)) {
2812                 ret = TRANSACTION_GENERIC_ERROR;
2813                 goto cleanup;
2814         }
2815
2816         /*
2817          * It's really undefined to call this function in an active
2818          * repository or when there are existing references: we are
2819          * only locking and changing packed-refs, so (1) any
2820          * simultaneous processes might try to change a reference at
2821          * the same time we do, and (2) any existing loose versions of
2822          * the references that we are setting would have precedence
2823          * over our values. But some remote helpers create the remote
2824          * "HEAD" and "master" branches before calling this function,
2825          * so here we really only check that none of the references
2826          * that we are creating already exists.
2827          */
2828         if (refs_for_each_rawref(&refs->base, ref_present,
2829                                  &affected_refnames))
2830                 die("BUG: initial ref transaction called with existing refs");
2831
2832         packed_transaction = ref_store_transaction_begin(refs->packed_ref_store, err);
2833         if (!packed_transaction) {
2834                 ret = TRANSACTION_GENERIC_ERROR;
2835                 goto cleanup;
2836         }
2837
2838         for (i = 0; i < transaction->nr; i++) {
2839                 struct ref_update *update = transaction->updates[i];
2840
2841                 if ((update->flags & REF_HAVE_OLD) &&
2842                     !is_null_oid(&update->old_oid))
2843                         die("BUG: initial ref transaction with old_sha1 set");
2844                 if (refs_verify_refname_available(&refs->base, update->refname,
2845                                                   &affected_refnames, NULL,
2846                                                   err)) {
2847                         ret = TRANSACTION_NAME_CONFLICT;
2848                         goto cleanup;
2849                 }
2850
2851                 /*
2852                  * Add a reference creation for this reference to the
2853                  * packed-refs transaction:
2854                  */
2855                 ref_transaction_add_update(packed_transaction, update->refname,
2856                                            update->flags & ~REF_HAVE_OLD,
2857                                            update->new_oid.hash, update->old_oid.hash,
2858                                            NULL);
2859         }
2860
2861         if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
2862                 ret = TRANSACTION_GENERIC_ERROR;
2863                 goto cleanup;
2864         }
2865
2866         if (initial_ref_transaction_commit(packed_transaction, err)) {
2867                 ret = TRANSACTION_GENERIC_ERROR;
2868                 goto cleanup;
2869         }
2870
2871 cleanup:
2872         if (packed_transaction)
2873                 ref_transaction_free(packed_transaction);
2874         packed_refs_unlock(refs->packed_ref_store);
2875         transaction->state = REF_TRANSACTION_CLOSED;
2876         string_list_clear(&affected_refnames, 0);
2877         return ret;
2878 }
2879
2880 struct expire_reflog_cb {
2881         unsigned int flags;
2882         reflog_expiry_should_prune_fn *should_prune_fn;
2883         void *policy_cb;
2884         FILE *newlog;
2885         struct object_id last_kept_oid;
2886 };
2887
2888 static int expire_reflog_ent(struct object_id *ooid, struct object_id *noid,
2889                              const char *email, timestamp_t timestamp, int tz,
2890                              const char *message, void *cb_data)
2891 {
2892         struct expire_reflog_cb *cb = cb_data;
2893         struct expire_reflog_policy_cb *policy_cb = cb->policy_cb;
2894
2895         if (cb->flags & EXPIRE_REFLOGS_REWRITE)
2896                 ooid = &cb->last_kept_oid;
2897
2898         if ((*cb->should_prune_fn)(ooid, noid, email, timestamp, tz,
2899                                    message, policy_cb)) {
2900                 if (!cb->newlog)
2901                         printf("would prune %s", message);
2902                 else if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
2903                         printf("prune %s", message);
2904         } else {
2905                 if (cb->newlog) {
2906                         fprintf(cb->newlog, "%s %s %s %"PRItime" %+05d\t%s",
2907                                 oid_to_hex(ooid), oid_to_hex(noid),
2908                                 email, timestamp, tz, message);
2909                         oidcpy(&cb->last_kept_oid, noid);
2910                 }
2911                 if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
2912                         printf("keep %s", message);
2913         }
2914         return 0;
2915 }
2916
2917 static int files_reflog_expire(struct ref_store *ref_store,
2918                                const char *refname, const unsigned char *sha1,
2919                                unsigned int flags,
2920                                reflog_expiry_prepare_fn prepare_fn,
2921                                reflog_expiry_should_prune_fn should_prune_fn,
2922                                reflog_expiry_cleanup_fn cleanup_fn,
2923                                void *policy_cb_data)
2924 {
2925         struct files_ref_store *refs =
2926                 files_downcast(ref_store, REF_STORE_WRITE, "reflog_expire");
2927         static struct lock_file reflog_lock;
2928         struct expire_reflog_cb cb;
2929         struct ref_lock *lock;
2930         struct strbuf log_file_sb = STRBUF_INIT;
2931         char *log_file;
2932         int status = 0;
2933         int type;
2934         struct strbuf err = STRBUF_INIT;
2935         struct object_id oid;
2936
2937         memset(&cb, 0, sizeof(cb));
2938         cb.flags = flags;
2939         cb.policy_cb = policy_cb_data;
2940         cb.should_prune_fn = should_prune_fn;
2941
2942         /*
2943          * The reflog file is locked by holding the lock on the
2944          * reference itself, plus we might need to update the
2945          * reference if --updateref was specified:
2946          */
2947         lock = lock_ref_sha1_basic(refs, refname, sha1,
2948                                    NULL, NULL, REF_NODEREF,
2949                                    &type, &err);
2950         if (!lock) {
2951                 error("cannot lock ref '%s': %s", refname, err.buf);
2952                 strbuf_release(&err);
2953                 return -1;
2954         }
2955         if (!refs_reflog_exists(ref_store, refname)) {
2956                 unlock_ref(lock);
2957                 return 0;
2958         }
2959
2960         files_reflog_path(refs, &log_file_sb, refname);
2961         log_file = strbuf_detach(&log_file_sb, NULL);
2962         if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
2963                 /*
2964                  * Even though holding $GIT_DIR/logs/$reflog.lock has
2965                  * no locking implications, we use the lock_file
2966                  * machinery here anyway because it does a lot of the
2967                  * work we need, including cleaning up if the program
2968                  * exits unexpectedly.
2969                  */
2970                 if (hold_lock_file_for_update(&reflog_lock, log_file, 0) < 0) {
2971                         struct strbuf err = STRBUF_INIT;
2972                         unable_to_lock_message(log_file, errno, &err);
2973                         error("%s", err.buf);
2974                         strbuf_release(&err);
2975                         goto failure;
2976                 }
2977                 cb.newlog = fdopen_lock_file(&reflog_lock, "w");
2978                 if (!cb.newlog) {
2979                         error("cannot fdopen %s (%s)",
2980                               get_lock_file_path(&reflog_lock), strerror(errno));
2981                         goto failure;
2982                 }
2983         }
2984
2985         hashcpy(oid.hash, sha1);
2986
2987         (*prepare_fn)(refname, &oid, cb.policy_cb);
2988         refs_for_each_reflog_ent(ref_store, refname, expire_reflog_ent, &cb);
2989         (*cleanup_fn)(cb.policy_cb);
2990
2991         if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
2992                 /*
2993                  * It doesn't make sense to adjust a reference pointed
2994                  * to by a symbolic ref based on expiring entries in
2995                  * the symbolic reference's reflog. Nor can we update
2996                  * a reference if there are no remaining reflog
2997                  * entries.
2998                  */
2999                 int update = (flags & EXPIRE_REFLOGS_UPDATE_REF) &&
3000                         !(type & REF_ISSYMREF) &&
3001                         !is_null_oid(&cb.last_kept_oid);
3002
3003                 if (close_lock_file_gently(&reflog_lock)) {
3004                         status |= error("couldn't write %s: %s", log_file,
3005                                         strerror(errno));
3006                         rollback_lock_file(&reflog_lock);
3007                 } else if (update &&
3008                            (write_in_full(get_lock_file_fd(&lock->lk),
3009                                 oid_to_hex(&cb.last_kept_oid), GIT_SHA1_HEXSZ) < 0 ||
3010                             write_str_in_full(get_lock_file_fd(&lock->lk), "\n") < 1 ||
3011                             close_ref_gently(lock) < 0)) {
3012                         status |= error("couldn't write %s",
3013                                         get_lock_file_path(&lock->lk));
3014                         rollback_lock_file(&reflog_lock);
3015                 } else if (commit_lock_file(&reflog_lock)) {
3016                         status |= error("unable to write reflog '%s' (%s)",
3017                                         log_file, strerror(errno));
3018                 } else if (update && commit_ref(lock)) {
3019                         status |= error("couldn't set %s", lock->ref_name);
3020                 }
3021         }
3022         free(log_file);
3023         unlock_ref(lock);
3024         return status;
3025
3026  failure:
3027         rollback_lock_file(&reflog_lock);
3028         free(log_file);
3029         unlock_ref(lock);
3030         return -1;
3031 }
3032
3033 static int files_init_db(struct ref_store *ref_store, struct strbuf *err)
3034 {
3035         struct files_ref_store *refs =
3036                 files_downcast(ref_store, REF_STORE_WRITE, "init_db");
3037         struct strbuf sb = STRBUF_INIT;
3038
3039         /*
3040          * Create .git/refs/{heads,tags}
3041          */
3042         files_ref_path(refs, &sb, "refs/heads");
3043         safe_create_dir(sb.buf, 1);
3044
3045         strbuf_reset(&sb);
3046         files_ref_path(refs, &sb, "refs/tags");
3047         safe_create_dir(sb.buf, 1);
3048
3049         strbuf_release(&sb);
3050         return 0;
3051 }
3052
3053 struct ref_storage_be refs_be_files = {
3054         NULL,
3055         "files",
3056         files_ref_store_create,
3057         files_init_db,
3058         files_transaction_prepare,
3059         files_transaction_finish,
3060         files_transaction_abort,
3061         files_initial_transaction_commit,
3062
3063         files_pack_refs,
3064         files_peel_ref,
3065         files_create_symref,
3066         files_delete_refs,
3067         files_rename_ref,
3068
3069         files_ref_iterator_begin,
3070         files_read_raw_ref,
3071
3072         files_reflog_iterator_begin,
3073         files_for_each_reflog_ent,
3074         files_for_each_reflog_ent_reverse,
3075         files_reflog_exists,
3076         files_create_reflog,
3077         files_delete_reflog,
3078         files_reflog_expire
3079 };