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