builtin/fsck.c

   1 #include "builtin.h"
   2 #include "cache.h"
   3 #include "commit.h"
   4 #include "tree.h"
   5 #include "blob.h"
   6 #include "tag.h"
   7 #include "refs.h"
   8 #include "pack.h"
   9 #include "cache-tree.h"
  10 #include "tree-walk.h"
  11 #include "fsck.h"
  12 #include "parse-options.h"
  13 #include "dir.h"
  14 #include "progress.h"
  15 #include "streaming.h"
  16 #include "decorate.h"
  17
  18 #define REACHABLE 0x0001
  19 #define SEEN      0x0002
  20 #define HAS_OBJ   0x0004
  21
  22 static int show_root;
  23 static int show_tags;
  24 static int show_unreachable;
  25 static int include_reflogs = 1;
  26 static int check_full = 1;
  27 static int connectivity_only;
  28 static int check_strict;
  29 static int keep_cache_objects;
  30 static struct fsck_options fsck_walk_options = FSCK_OPTIONS_DEFAULT;
  31 static struct fsck_options fsck_obj_options = FSCK_OPTIONS_DEFAULT;
  32 static struct object_id head_oid;
  33 static const char *head_points_at;
  34 static int errors_found;
  35 static int write_lost_and_found;
  36 static int verbose;
  37 static int show_progress = -1;
  38 static int show_dangling = 1;
  39 static int name_objects;
  40 #define ERROR_OBJECT 01
  41 #define ERROR_REACHABLE 02
  42 #define ERROR_PACK 04
  43 #define ERROR_REFS 010
  44
  45 static const char *describe_object(struct object *obj)
  46 {
  47         static struct strbuf buf = STRBUF_INIT;
  48         char *name = name_objects ?
  49                 lookup_decoration(fsck_walk_options.object_names, obj) : NULL;
  50
  51         strbuf_reset(&buf);
  52         strbuf_addstr(&buf, oid_to_hex(&obj->oid));
  53         if (name)
  54                 strbuf_addf(&buf, " (%s)", name);
  55
  56         return buf.buf;
  57 }
  58
  59 static int fsck_config(const char *var, const char *value, void *cb)
  60 {
  61         if (strcmp(var, "fsck.skiplist") == 0) {
  62                 const char *path;
  63                 struct strbuf sb = STRBUF_INIT;
  64
  65                 if (git_config_pathname(&path, var, value))
  66                         return 1;
  67                 strbuf_addf(&sb, "skiplist=%s", path);
  68                 free((char *)path);
  69                 fsck_set_msg_types(&fsck_obj_options, sb.buf);
  70                 strbuf_release(&sb);
  71                 return 0;
  72         }
  73
  74         if (skip_prefix(var, "fsck.", &var)) {
  75                 fsck_set_msg_type(&fsck_obj_options, var, value);
  76                 return 0;
  77         }
  78
  79         return git_default_config(var, value, cb);
  80 }
  81
  82 static void objreport(struct object *obj, const char *msg_type,
  83                         const char *err)
  84 {
  85         fprintf(stderr, "%s in %s %s: %s\n",
  86                 msg_type, typename(obj->type), describe_object(obj), err);
  87 }
  88
  89 static int objerror(struct object *obj, const char *err)
  90 {
  91         errors_found |= ERROR_OBJECT;
  92         objreport(obj, "error", err);
  93         return -1;
  94 }
  95
  96 static int fsck_error_func(struct fsck_options *o,
  97         struct object *obj, int type, const char *message)
  98 {
  99         objreport(obj, (type == FSCK_WARN) ? "warning" : "error", message);
 100         return (type == FSCK_WARN) ? 0 : 1;
 101 }
 102
 103 static struct object_array pending;
 104
 105 static int mark_object(struct object *obj, int type, void *data, struct fsck_options *options)
 106 {
 107         struct object *parent = data;
 108
 109         /*
 110          * The only case data is NULL or type is OBJ_ANY is when
 111          * mark_object_reachable() calls us.  All the callers of
 112          * that function has non-NULL obj hence ...
 113          */
 114         if (!obj) {
 115                 /* ... these references to parent->fld are safe here */
 116                 printf("broken link from %7s %s\n",
 117                            typename(parent->type), describe_object(parent));
 118                 printf("broken link from %7s %s\n",
 119                            (type == OBJ_ANY ? "unknown" : typename(type)), "unknown");
 120                 errors_found |= ERROR_REACHABLE;
 121                 return 1;
 122         }
 123
 124         if (type != OBJ_ANY && obj->type != type)
 125                 /* ... and the reference to parent is safe here */
 126                 objerror(parent, "wrong object type in link");
 127
 128         if (obj->flags & REACHABLE)
 129                 return 0;
 130         obj->flags |= REACHABLE;
 131         if (!(obj->flags & HAS_OBJ)) {
 132                 if (parent && !has_object_file(&obj->oid)) {
 133                         printf("broken link from %7s %s\n",
 134                                  typename(parent->type), describe_object(parent));
 135                         printf("              to %7s %s\n",
 136                                  typename(obj->type), describe_object(obj));
 137                         errors_found |= ERROR_REACHABLE;
 138                 }
 139                 return 1;
 140         }
 141
 142         add_object_array(obj, NULL, &pending);
 143         return 0;
 144 }
 145
 146 static void mark_object_reachable(struct object *obj)
 147 {
 148         mark_object(obj, OBJ_ANY, NULL, NULL);
 149 }
 150
 151 static int traverse_one_object(struct object *obj)
 152 {
 153         int result;
 154         struct tree *tree = NULL;
 155
 156         if (obj->type == OBJ_TREE) {
 157                 tree = (struct tree *)obj;
 158                 if (parse_tree(tree) < 0)
 159                         return 1; /* error already displayed */
 160         }
 161         result = fsck_walk(obj, obj, &fsck_walk_options);
 162         if (tree)
 163                 free_tree_buffer(tree);
 164         return result;
 165 }
 166
 167 static int traverse_reachable(void)
 168 {
 169         struct progress *progress = NULL;
 170         unsigned int nr = 0;
 171         int result = 0;
 172         if (show_progress)
 173                 progress = start_progress_delay(_("Checking connectivity"), 0, 0, 2);
 174         while (pending.nr) {
 175                 struct object_array_entry *entry;
 176                 struct object *obj;
 177
 178                 entry = pending.objects + --pending.nr;
 179                 obj = entry->item;
 180                 result |= traverse_one_object(obj);
 181                 display_progress(progress, ++nr);
 182         }
 183         stop_progress(&progress);
 184         return !!result;
 185 }
 186
 187 static int mark_used(struct object *obj, int type, void *data, struct fsck_options *options)
 188 {
 189         if (!obj)
 190                 return 1;
 191         obj->used = 1;
 192         return 0;
 193 }
 194
 195 /*
 196  * Check a single reachable object
 197  */
 198 static void check_reachable_object(struct object *obj)
 199 {
 200         /*
 201          * We obviously want the object to be parsed,
 202          * except if it was in a pack-file and we didn't
 203          * do a full fsck
 204          */
 205         if (!(obj->flags & HAS_OBJ)) {
 206                 if (has_sha1_pack(obj->oid.hash))
 207                         return; /* it is in pack - forget about it */
 208                 if (connectivity_only && has_object_file(&obj->oid))
 209                         return;
 210                 printf("missing %s %s\n", typename(obj->type),
 211                         describe_object(obj));
 212                 errors_found |= ERROR_REACHABLE;
 213                 return;
 214         }
 215 }
 216
 217 /*
 218  * Check a single unreachable object
 219  */
 220 static void check_unreachable_object(struct object *obj)
 221 {
 222         /*
 223          * Missing unreachable object? Ignore it. It's not like
 224          * we miss it (since it can't be reached), nor do we want
 225          * to complain about it being unreachable (since it does
 226          * not exist).
 227          */
 228         if (!obj->parsed)
 229                 return;
 230
 231         /*
 232          * Unreachable object that exists? Show it if asked to,
 233          * since this is something that is prunable.
 234          */
 235         if (show_unreachable) {
 236                 printf("unreachable %s %s\n", typename(obj->type),
 237                         describe_object(obj));
 238                 return;
 239         }
 240
 241         /*
 242          * "!used" means that nothing at all points to it, including
 243          * other unreachable objects. In other words, it's the "tip"
 244          * of some set of unreachable objects, usually a commit that
 245          * got dropped.
 246          *
 247          * Such starting points are more interesting than some random
 248          * set of unreachable objects, so we show them even if the user
 249          * hasn't asked for _all_ unreachable objects. If you have
 250          * deleted a branch by mistake, this is a prime candidate to
 251          * start looking at, for example.
 252          */
 253         if (!obj->used) {
 254                 if (show_dangling)
 255                         printf("dangling %s %s\n", typename(obj->type),
 256                                describe_object(obj));
 257                 if (write_lost_and_found) {
 258                         char *filename = git_pathdup("lost-found/%s/%s",
 259                                 obj->type == OBJ_COMMIT ? "commit" : "other",
 260                                 describe_object(obj));
 261                         FILE *f;
 262
 263                         if (safe_create_leading_directories_const(filename)) {
 264                                 error("Could not create lost-found");
 265                                 free(filename);
 266                                 return;
 267                         }
 268                         if (!(f = fopen(filename, "w")))
 269                                 die_errno("Could not open '%s'", filename);
 270                         if (obj->type == OBJ_BLOB) {
 271                                 if (stream_blob_to_fd(fileno(f), obj->oid.hash, NULL, 1))
 272                                         die_errno("Could not write '%s'", filename);
 273                         } else
 274                                 fprintf(f, "%s\n", describe_object(obj));
 275                         if (fclose(f))
 276                                 die_errno("Could not finish '%s'",
 277                                           filename);
 278                         free(filename);
 279                 }
 280                 return;
 281         }
 282
 283         /*
 284          * Otherwise? It's there, it's unreachable, and some other unreachable
 285          * object points to it. Ignore it - it's not interesting, and we showed
 286          * all the interesting cases above.
 287          */
 288 }
 289
 290 static void check_object(struct object *obj)
 291 {
 292         if (verbose)
 293                 fprintf(stderr, "Checking %s\n", describe_object(obj));
 294
 295         if (obj->flags & REACHABLE)
 296                 check_reachable_object(obj);
 297         else
 298                 check_unreachable_object(obj);
 299 }
 300
 301 static void check_connectivity(void)
 302 {
 303         int i, max;
 304
 305         /* Traverse the pending reachable objects */
 306         traverse_reachable();
 307
 308         /* Look up all the requirements, warn about missing objects.. */
 309         max = get_max_object_index();
 310         if (verbose)
 311                 fprintf(stderr, "Checking connectivity (%d objects)\n", max);
 312
 313         for (i = 0; i < max; i++) {
 314                 struct object *obj = get_indexed_object(i);
 315
 316                 if (obj)
 317                         check_object(obj);
 318         }
 319 }
 320
 321 static int fsck_obj(struct object *obj)
 322 {
 323         if (obj->flags & SEEN)
 324                 return 0;
 325         obj->flags |= SEEN;
 326
 327         if (verbose)
 328                 fprintf(stderr, "Checking %s %s\n",
 329                         typename(obj->type), describe_object(obj));
 330
 331         if (fsck_walk(obj, NULL, &fsck_obj_options))
 332                 objerror(obj, "broken links");
 333         if (fsck_object(obj, NULL, 0, &fsck_obj_options))
 334                 return -1;
 335
 336         if (obj->type == OBJ_TREE) {
 337                 struct tree *item = (struct tree *) obj;
 338
 339                 free_tree_buffer(item);
 340         }
 341
 342         if (obj->type == OBJ_COMMIT) {
 343                 struct commit *commit = (struct commit *) obj;
 344
 345                 free_commit_buffer(commit);
 346
 347                 if (!commit->parents && show_root)
 348                         printf("root %s\n", describe_object(&commit->object));
 349         }
 350
 351         if (obj->type == OBJ_TAG) {
 352                 struct tag *tag = (struct tag *) obj;
 353
 354                 if (show_tags && tag->tagged) {
 355                         printf("tagged %s %s", typename(tag->tagged->type),
 356                                 describe_object(tag->tagged));
 357                         printf(" (%s) in %s\n", tag->tag,
 358                                 describe_object(&tag->object));
 359                 }
 360         }
 361
 362         return 0;
 363 }
 364
 365 static int fsck_sha1(const unsigned char *sha1)
 366 {
 367         struct object *obj = parse_object(sha1);
 368         if (!obj) {
 369                 errors_found |= ERROR_OBJECT;
 370                 return error("%s: object corrupt or missing",
 371                              sha1_to_hex(sha1));
 372         }
 373         obj->flags |= HAS_OBJ;
 374         return fsck_obj(obj);
 375 }
 376
 377 static int fsck_obj_buffer(const unsigned char *sha1, enum object_type type,
 378                            unsigned long size, void *buffer, int *eaten)
 379 {
 380         /*
 381          * Note, buffer may be NULL if type is OBJ_BLOB. See
 382          * verify_packfile(), data_valid variable for details.
 383          */
 384         struct object *obj;
 385         obj = parse_object_buffer(sha1, type, size, buffer, eaten);
 386         if (!obj) {
 387                 errors_found |= ERROR_OBJECT;
 388                 return error("%s: object corrupt or missing", sha1_to_hex(sha1));
 389         }
 390         obj->flags = HAS_OBJ;
 391         return fsck_obj(obj);
 392 }
 393
 394 static int default_refs;
 395
 396 static void fsck_handle_reflog_sha1(const char *refname, unsigned char *sha1,
 397         unsigned long timestamp)
 398 {
 399         struct object *obj;
 400
 401         if (!is_null_sha1(sha1)) {
 402                 obj = lookup_object(sha1);
 403                 if (obj) {
 404                         if (timestamp && name_objects)
 405                                 add_decoration(fsck_walk_options.object_names,
 406                                         obj,
 407                                         xstrfmt("%s@{%ld}", refname, timestamp));
 408                         obj->used = 1;
 409                         mark_object_reachable(obj);
 410                 } else {
 411                         error("%s: invalid reflog entry %s", refname, sha1_to_hex(sha1));
 412                         errors_found |= ERROR_REACHABLE;
 413                 }
 414         }
 415 }
 416
 417 static int fsck_handle_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
 418                 const char *email, unsigned long timestamp, int tz,
 419                 const char *message, void *cb_data)
 420 {
 421         const char *refname = cb_data;
 422
 423         if (verbose)
 424                 fprintf(stderr, "Checking reflog %s->%s\n",
 425                         sha1_to_hex(osha1), sha1_to_hex(nsha1));
 426
 427         fsck_handle_reflog_sha1(refname, osha1, 0);
 428         fsck_handle_reflog_sha1(refname, nsha1, timestamp);
 429         return 0;
 430 }
 431
 432 static int fsck_handle_reflog(const char *logname, const struct object_id *oid,
 433                               int flag, void *cb_data)
 434 {
 435         for_each_reflog_ent(logname, fsck_handle_reflog_ent, (void *)logname);
 436         return 0;
 437 }
 438
 439 static int fsck_handle_ref(const char *refname, const struct object_id *oid,
 440                            int flag, void *cb_data)
 441 {
 442         struct object *obj;
 443
 444         obj = parse_object(oid->hash);
 445         if (!obj) {
 446                 error("%s: invalid sha1 pointer %s", refname, oid_to_hex(oid));
 447                 errors_found |= ERROR_REACHABLE;
 448                 /* We'll continue with the rest despite the error.. */
 449                 return 0;
 450         }
 451         if (obj->type != OBJ_COMMIT && is_branch(refname)) {
 452                 error("%s: not a commit", refname);
 453                 errors_found |= ERROR_REFS;
 454         }
 455         default_refs++;
 456         obj->used = 1;
 457         if (name_objects)
 458                 add_decoration(fsck_walk_options.object_names,
 459                         obj, xstrdup(refname));
 460         mark_object_reachable(obj);
 461
 462         return 0;
 463 }
 464
 465 static void get_default_heads(void)
 466 {
 467         if (head_points_at && !is_null_oid(&head_oid))
 468                 fsck_handle_ref("HEAD", &head_oid, 0, NULL);
 469         for_each_rawref(fsck_handle_ref, NULL);
 470         if (include_reflogs)
 471                 for_each_reflog(fsck_handle_reflog, NULL);
 472
 473         /*
 474          * Not having any default heads isn't really fatal, but
 475          * it does mean that "--unreachable" no longer makes any
 476          * sense (since in this case everything will obviously
 477          * be unreachable by definition.
 478          *
 479          * Showing dangling objects is valid, though (as those
 480          * dangling objects are likely lost heads).
 481          *
 482          * So we just print a warning about it, and clear the
 483          * "show_unreachable" flag.
 484          */
 485         if (!default_refs) {
 486                 fprintf(stderr, "notice: No default references\n");
 487                 show_unreachable = 0;
 488         }
 489 }
 490
 491 static int fsck_loose(const unsigned char *sha1, const char *path, void *data)
 492 {
 493         if (fsck_sha1(sha1))
 494                 errors_found |= ERROR_OBJECT;
 495         return 0;
 496 }
 497
 498 static int fsck_cruft(const char *basename, const char *path, void *data)
 499 {
 500         if (!starts_with(basename, "tmp_obj_"))
 501                 fprintf(stderr, "bad sha1 file: %s\n", path);
 502         return 0;
 503 }
 504
 505 static int fsck_subdir(int nr, const char *path, void *progress)
 506 {
 507         display_progress(progress, nr + 1);
 508         return 0;
 509 }
 510
 511 static void fsck_object_dir(const char *path)
 512 {
 513         struct progress *progress = NULL;
 514
 515         if (verbose)
 516                 fprintf(stderr, "Checking object directory\n");
 517
 518         if (show_progress)
 519                 progress = start_progress(_("Checking object directories"), 256);
 520
 521         for_each_loose_file_in_objdir(path, fsck_loose, fsck_cruft, fsck_subdir,
 522                                       progress);
 523         display_progress(progress, 256);
 524         stop_progress(&progress);
 525 }
 526
 527 static int fsck_head_link(void)
 528 {
 529         int null_is_error = 0;
 530
 531         if (verbose)
 532                 fprintf(stderr, "Checking HEAD link\n");
 533
 534         head_points_at = resolve_ref_unsafe("HEAD", 0, head_oid.hash, NULL);
 535         if (!head_points_at) {
 536                 errors_found |= ERROR_REFS;
 537                 return error("Invalid HEAD");
 538         }
 539         if (!strcmp(head_points_at, "HEAD"))
 540                 /* detached HEAD */
 541                 null_is_error = 1;
 542         else if (!starts_with(head_points_at, "refs/heads/")) {
 543                 errors_found |= ERROR_REFS;
 544                 return error("HEAD points to something strange (%s)",
 545                              head_points_at);
 546         }
 547         if (is_null_oid(&head_oid)) {
 548                 if (null_is_error) {
 549                         errors_found |= ERROR_REFS;
 550                         return error("HEAD: detached HEAD points at nothing");
 551                 }
 552                 fprintf(stderr, "notice: HEAD points to an unborn branch (%s)\n",
 553                         head_points_at + 11);
 554         }
 555         return 0;
 556 }
 557
 558 static int fsck_cache_tree(struct cache_tree *it)
 559 {
 560         int i;
 561         int err = 0;
 562
 563         if (verbose)
 564                 fprintf(stderr, "Checking cache tree\n");
 565
 566         if (0 <= it->entry_count) {
 567                 struct object *obj = parse_object(it->sha1);
 568                 if (!obj) {
 569                         error("%s: invalid sha1 pointer in cache-tree",
 570                               sha1_to_hex(it->sha1));
 571                         errors_found |= ERROR_REFS;
 572                         return 1;
 573                 }
 574                 obj->used = 1;
 575                 if (name_objects)
 576                         add_decoration(fsck_walk_options.object_names,
 577                                 obj, xstrdup(":"));
 578                 mark_object_reachable(obj);
 579                 if (obj->type != OBJ_TREE)
 580                         err |= objerror(obj, "non-tree in cache-tree");
 581         }
 582         for (i = 0; i < it->subtree_nr; i++)
 583                 err |= fsck_cache_tree(it->down[i]->cache_tree);
 584         return err;
 585 }
 586
 587 static char const * const fsck_usage[] = {
 588         N_("git fsck [<options>] [<object>...]"),
 589         NULL
 590 };
 591
 592 static struct option fsck_opts[] = {
 593         OPT__VERBOSE(&verbose, N_("be verbose")),
 594         OPT_BOOL(0, "unreachable", &show_unreachable, N_("show unreachable objects")),
 595         OPT_BOOL(0, "dangling", &show_dangling, N_("show dangling objects")),
 596         OPT_BOOL(0, "tags", &show_tags, N_("report tags")),
 597         OPT_BOOL(0, "root", &show_root, N_("report root nodes")),
 598         OPT_BOOL(0, "cache", &keep_cache_objects, N_("make index objects head nodes")),
 599         OPT_BOOL(0, "reflogs", &include_reflogs, N_("make reflogs head nodes (default)")),
 600         OPT_BOOL(0, "full", &check_full, N_("also consider packs and alternate objects")),
 601         OPT_BOOL(0, "connectivity-only", &connectivity_only, N_("check only connectivity")),
 602         OPT_BOOL(0, "strict", &check_strict, N_("enable more strict checking")),
 603         OPT_BOOL(0, "lost-found", &write_lost_and_found,
 604                                 N_("write dangling objects in .git/lost-found")),
 605         OPT_BOOL(0, "progress", &show_progress, N_("show progress")),
 606         OPT_BOOL(0, "name-objects", &name_objects, N_("show verbose names for reachable objects")),
 607         OPT_END(),
 608 };
 609
 610 int cmd_fsck(int argc, const char **argv, const char *prefix)
 611 {
 612         int i, heads;
 613         struct alternate_object_database *alt;
 614
 615         errors_found = 0;
 616         check_replace_refs = 0;
 617
 618         argc = parse_options(argc, argv, prefix, fsck_opts, fsck_usage, 0);
 619
 620         fsck_walk_options.walk = mark_object;
 621         fsck_obj_options.walk = mark_used;
 622         fsck_obj_options.error_func = fsck_error_func;
 623         if (check_strict)
 624                 fsck_obj_options.strict = 1;
 625
 626         if (show_progress == -1)
 627                 show_progress = isatty(2);
 628         if (verbose)
 629                 show_progress = 0;
 630
 631         if (write_lost_and_found) {
 632                 check_full = 1;
 633                 include_reflogs = 0;
 634         }
 635
 636         if (name_objects)
 637                 fsck_walk_options.object_names =
 638                         xcalloc(1, sizeof(struct decoration));
 639
 640         git_config(fsck_config, NULL);
 641
 642         fsck_head_link();
 643         if (!connectivity_only) {
 644                 fsck_object_dir(get_object_directory());
 645
 646                 prepare_alt_odb();
 647                 for (alt = alt_odb_list; alt; alt = alt->next) {
 648                         /* directory name, minus trailing slash */
 649                         size_t namelen = alt->name - alt->base - 1;
 650                         struct strbuf name = STRBUF_INIT;
 651                         strbuf_add(&name, alt->base, namelen);
 652                         fsck_object_dir(name.buf);
 653                         strbuf_release(&name);
 654                 }
 655         }
 656
 657         if (check_full) {
 658                 struct packed_git *p;
 659                 uint32_t total = 0, count = 0;
 660                 struct progress *progress = NULL;
 661
 662                 prepare_packed_git();
 663
 664                 if (show_progress) {
 665                         for (p = packed_git; p; p = p->next) {
 666                                 if (open_pack_index(p))
 667                                         continue;
 668                                 total += p->num_objects;
 669                         }
 670
 671                         progress = start_progress(_("Checking objects"), total);
 672                 }
 673                 for (p = packed_git; p; p = p->next) {
 674                         /* verify gives error messages itself */
 675                         if (verify_pack(p, fsck_obj_buffer,
 676                                         progress, count))
 677                                 errors_found |= ERROR_PACK;
 678                         count += p->num_objects;
 679                 }
 680                 stop_progress(&progress);
 681         }
 682
 683         heads = 0;
 684         for (i = 0; i < argc; i++) {
 685                 const char *arg = argv[i];
 686                 unsigned char sha1[20];
 687                 if (!get_sha1(arg, sha1)) {
 688                         struct object *obj = lookup_object(sha1);
 689
 690                         /* Error is printed by lookup_object(). */
 691                         if (!obj)
 692                                 continue;
 693
 694                         obj->used = 1;
 695                         if (name_objects)
 696                                 add_decoration(fsck_walk_options.object_names,
 697                                         obj, xstrdup(arg));
 698                         mark_object_reachable(obj);
 699                         heads++;
 700                         continue;
 701                 }
 702                 error("invalid parameter: expected sha1, got '%s'", arg);
 703         }
 704
 705         /*
 706          * If we've not been given any explicit head information, do the
 707          * default ones from .git/refs. We also consider the index file
 708          * in this case (ie this implies --cache).
 709          */
 710         if (!heads) {
 711                 get_default_heads();
 712                 keep_cache_objects = 1;
 713         }
 714
 715         if (keep_cache_objects) {
 716                 read_cache();
 717                 for (i = 0; i < active_nr; i++) {
 718                         unsigned int mode;
 719                         struct blob *blob;
 720                         struct object *obj;
 721
 722                         mode = active_cache[i]->ce_mode;
 723                         if (S_ISGITLINK(mode))
 724                                 continue;
 725                         blob = lookup_blob(active_cache[i]->sha1);
 726                         if (!blob)
 727                                 continue;
 728                         obj = &blob->object;
 729                         obj->used = 1;
 730                         if (name_objects)
 731                                 add_decoration(fsck_walk_options.object_names,
 732                                         obj,
 733                                         xstrfmt(":%s", active_cache[i]->name));
 734                         mark_object_reachable(obj);
 735                 }
 736                 if (active_cache_tree)
 737                         fsck_cache_tree(active_cache_tree);
 738         }
 739
 740         check_connectivity();
 741         return errors_found;
 742 }